English Special Topic
________________________________________________ Matura 30.09.2000,
8C
Time
Marcus Meisel
Marcus.Meisel@blackbox.at
__________________________________________
, 30.09.2000
page 1
Time
Ausarbeitung zum Englisch Spezialgebiet by Marcus Meisel, 8C
Betreuerin: Mag. Rauchenwald
English Special Topic
________________________________________________ Matura 30.09.2000,
8C
Time
Marcus Meisel
Marcus.Meisel@blackbox.at
__________________________________________
, 30.09.2000
page 2
B) CONTENTS
A) Title Page
page 1
B) Contents
page 2
C) Introduction
page 4
1) Time is an Arrow
page 5
Seeing Things Different
•
The Last Century
page 5
•
The Beginning of Time
page 5
•
Sensing Time
page 5
•
The Arrows of Time
page 5
•
Which Direction?
page 6
•
Intelligent Life
page 6
•
A fourth Arrow?
page 7
Summary
page 7
2) Relativity of Time
page 8
The Beginning
page 8
•
Einstein's Start
page 8
•
The Twin Paradoxon
page 8
It's all Relative
page 9
•
Einstein
page 9
•
Day-to-Day Experiences
page 10
•
A Clue
page 10
•
The Solution
page 11
•
Light
page 11
Einstein's Dreams
page 11
•
Plot
page 11
•
Results
page 12
New Findings
page 12
•
Consequences
page 12
•
Faster than Light
page 12
General Relativity
page 13
•
A Solution
page 13
•
The Trojan Horse
page 13
English Special Topic
________________________________________________ Matura 30.09.2000,
8C
Time
Marcus Meisel
Marcus.Meisel@blackbox.at
__________________________________________
, 30.09.2000
page 3
•
Questions
page 13
3) Space and Time
page 14
A Brief History of Time
page 14
Sinking into Space-Time
page 14
•
Einstein
page 14
•
The Universe as a Sheet
page 15
•
Einstein as Idol
page 15
•
Dynamic Space and Time
page 15
•
Gravitational Effects
page 16
•
Solutions?
page 16
•
A Unifying Theory
page 16
•
Dreams
page 17
•
The Physics of Star Trek
page 17
4) To Build a Time Machine
page 19
The First Thoughts
•
Change Time
page 19
•
The Time Machine
page 19
•
Time Travel
page 20
•
Introducing a New Theory
page 21
Problem: Time Travel
page 21
•
Logical Paradoxon
page 21
•
The Risks of Time Travel
page 21
•
Time Paradoxes
page 22
•
My Favourite
page 23
Creating the Impossible?
page 23
•
Theoretical Basis
page 23
•
Multiply Connected Universes
page 24
•
Time Travel and Baby Universes
page 24
•
Evading the Light Barrier
page 25
•
Inside Out
page 25
I) Conclusion
page 27
II) Glossary
page 28
III)
Bibliography
page 29
IV) Cover sheet
page 30
V) Bookreports
page 31
i)
Einstein's
Dreams
page 32
ii) The Time Machine
page 39
iii) A Brief History of Time
page 45
English Special Topic
________________________________________________ Matura 30.09.2000,
8C
Time
Marcus Meisel
Marcus.Meisel@blackbox.at
__________________________________________
, 30.09.2000
page 4
iiii) The Physics of Star Trek
page 61
VI) Cover sheet
page 65
English Special Topic
________________________________________________ Matura 30.09.2000,
8C
Time
Marcus Meisel
Marcus.Meisel@blackbox.at
__________________________________________
, 30.09.2000
page 5
C) Introduction
S
cientific revolutions, almost by definition, defy common sense.
If all our common-sense notions about the universe were correct, the science would have solved the
secrets of the universe thousands of years ago. The purpose of science is to peal back the layer of the
appearance of objets to reveal their underlying nature. In fact, if appearance and essence were the
same thing, there would be no need for science.
Perhaps the most deeply entrenched common-sense notion about our world is that it is three
dimensional. It goes without saying that length, width, and breadth suffice to describe all objects in our
visible universe. Experiments with babies and animals have shown that we are born with an innate
sense that our world is three dimensional. But to record all events in the universe, we need another
dimension. If we include time as another dimension, then four dimensions are sufficient. No matter
where our instruments have probed, from deep within the atom to the farthest reaches of the galactic
cluster, we have only found evidence for these four dimensions.
T
ime is a very complex dimension. So not only in science, thus also in common usage, time is hard to
understand. There are so many possible meanings implied.
If you just say the word time when you enter different situations, it depends on which room you have
entered. When you enter a restaurant, you will receive the time of the time zone you are right now,
which is the usual answer. But there are many different answers possible. Like if you enter a soccer
stadion. Everybody will yell at you the score, how much time there is left, and to shut up. If you sit in a
plane, and you ask the captain will tell you several times you haven't even thought of: The time of your
arrival and departure in the time zone you left and will arrive, how long your flight was since now and
how long it will take in miles per hour or km per second. Which speed the plain in that moment has,
and which average speed it needs for take off or landing. If you enter a fast-food restaurant and you
just ask "time?", you will hear how long it takes to finish the fries or the burger. If you are in a university
and you ask for "time?", the answer depends again in what room you are. In the dorms you will get a
tired "too late" or a curse like "damn it! I'm late." as answer. On the foodcourt a hectically "just five
more minutes" is the usual answer. And during a physics class, the answer is a long precise definition
of time.
W
hat time really is, nobody truly can tell, but scientists try their hardest to find answers to their
unanswered questions. In this Special Topic "Time" I would like to give an idea of the momentary
situation science is now, and show some possible answers from some of the brightest minds of
mankind.
But also scientists do not agree in every respect. They try to fit all their observations in formulas they
again try to combine all to get a unifying theory about the smallest and the largest things in our universe
we live in.
The aim of science is to penetrate into smaller and bigger dimensions and not to stop until
humankind has a complete theory of all forces and particles that appear in nature.
Like Thomas H. Huxley once said,
The known is finite, the unknown infinite; intellectually we
stand on an islet in the midst of an illimitable ocean of inexpl-
icability. Our business in every generation is to reclaim a little
more land.
On the next pages I would like to give an easy understandable, brief description of what time
is considered to be and want to try to uncover some secrets of Time
English Special Topic
________________________________________________ Matura 30.09.2000,
8C
Time
Marcus Meisel
Marcus.Meisel@blackbox.at
__________________________________________
, 30.09.2000
page 6
1) Time is an Arrow
Seeing Things Different
•
The Last Century
Before the 20
th
century, Newton's laws belonged to the basis of physics. But at the
end of the 19
th
century there were discovered two conflicts, with thermodynamics and
electro-magnetism, that ultimately led to the formulation of first the theory of relativity
and then the quantum theory. Einstein told us that space and time were part of a four-
dimensional space-time and both relative. He was the first to count these to physics
instead of accepting it as simply “existing”. When it was later discovered that the
universe is expanding, scientists quickly realised that everything had to start existing
at a certain point in the past, known as the “Big Bang”.
•
The Beginning of Time
At the Big Bang the universe's density was infinite. Under such conditions all
the laws of science, and therefor all ability to predict the future, would break down. If
there were events earlier than this time, then they could not affect what happens at
the present time. Their existence can be ignored because it would have no
observational consequences. One may say that time had a beginning at the big bang,
in the sense that earlier times simply would not be defined.
•
Sensing Time
We are creatures in time and this has a very great effect on how we think about time
and the temporal aspect of what is real.
The psychological time is very much different from the physical one. It seems that we
are not able to perceive too short events, and that our brain manipulates our
perceptions before they become conscious. Based on experiments, psychologists
therefore suggest that our consciousness is a whole bunch of parallel processes.
People seem to sense time in a very subjective way, a fact that is in conflict with an
universal time. In other cultures, like the Aborigines, there is not even a clear
distinction between past, present and future. But the latter vanished in physics too,
with the invention of relativity.
Many religions and philosophers believe in a cyclic time, and they are consistent with
some scientific theories. Laplace first realised that when everything is predictable,
knowledge of the moment is enough to know the situation in every moment, also in
the future, thus making time obsolete.
•
The Arrows of Time
With the laws of thermodynamics physicists then realised that the universe is
developing towards maximal entropy, or chaos. This made the perpetuum mobile
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8C
Time
Marcus Meisel
Marcus.Meisel@blackbox.at
__________________________________________
, 30.09.2000
page 7
impossible and put an end to Newton's linear time. It also brought an arrow of time
into physics. Based on Boltzmann´s work Poincaré then proved the possibility of a
cyclic universe, but with cycles being incredibly long.
Religions like to believe in creation, which cannot be proven to be wrong. The P'an Ku
myth of China's third century describes the time before creation like that:
In the beginning, was the great cosmic egg. Inside the egg was
chaos , and floating in chaos was P ' an Ku, the divine Embryo.
In India's ninth century, the Mahapurana, one of the most important books was
written. In this book, the beginning of time is described as follows:
If God created the world, where was He before Creation?...
Know that the world is uncreated, as time itself is, without
beginning and end.
It is not entirely impossible that we all live only since some minutes ago, created with
memories of past times. Seen out of this respect, the flow of time can never be
proven, and time itself may as well be an illusion.
•
Which Direction?
The increase of disorder or entropy with time is one example of what is called
an arrow of time, something that distinguishes the past from the future, giving a
direction to time. There are at least three different arrows of time.
First, there is the thermodynamic arrow of time, the direction of time in which disorder
or entropy increases. Then, there is the psychological arrow of time. This is the
direction in which we feel time passes, the direction in which we remember the past
but not the future. Finally, there is the cosmological arrow of time. This is the direction
of time in which the universe is expanding rather than contracting.
The psychological arrow is essentially the same as the thermodynamic arrow, so that
the two would always point in the same direction.
•
Intelligent Life
The no boundary proposal for the universe predicts the existence of a well
defined thermodynamic arrow of time because the universe must start off in a smooth
and ordered state. And the reason why we observe this thermodynamic arrow to
agree with the cosmological arrow is that intelligent beings can exist only in the
expanding phase of our universe.
However, a strong thermodynamic arrow is necessary for intelligent life to operate. In
order to survive, human beings have to consume food, which is an ordered form of
energy, and convert it to heat which is a disordered form of energy. Thus intelligent
life could not exist in a contracting phase of the universe. This is the explanation of
why we observe that the thermodynamic and cosmological arrows of time point in the
same direction.
The contracting phase will be unuitable because it has no strong thermodynamic
arrow of time.
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________________________________________________ Matura 30.09.2000,
8C
Time
Marcus Meisel
Marcus.Meisel@blackbox.at
__________________________________________
, 30.09.2000
page 8
•
A fourth Arrow?
Some scientists interpose a fourth arrow, an arrow that helps to explain the causal
asymmetry. We use "cause" to mark the earlier and "effect" to mark the later of a pair
of events which are related this way. Cause-effect relation is itself asymmetric - that
is, that causes and effects can be distinguished in some way.
Scientists are everything else but the same opinion in which direction they themselves
should research to find answers to the questions the arrows and the asymmetry of
time pose to us. In the respect of the increasing disorder in the course of time, James
Thurber was right as he said:
"It is better to know some of the questions than all of the answers."
Because the more answers we find the more questions arise.
Summary
Up to the beginning of our century people believed in an absolute time.
Newton considered time to be moving like a straight arrow, which unerringly flies
forward toward its target. Nothing could deflect or change the course of this arrow
once it was shot. Einstein, however, abandoned the idea of an absolute time and
showed that time was more like a mighty river, moving forward but often meandering
through twisting valleys and plains created through matter on a space-time surface.
The presence of matter or energy might momentarily shift the direction of the river,
but overall the river's course was smooth: It never abruptly ended or jerked backward.
However, successors like Kurt Gödel or Louis Tamburino showed that the river of
time could be smoothly bent backward into a circle. Rivers, after all, have eddy
currents and whirlpools. In the main, a river may flow forward, but at the edges there
are always side pools where water flows in a circular motion.
English Special Topic
________________________________________________ Matura 30.09.2000,
8C
Time
Marcus Meisel
Marcus.Meisel@blackbox.at
__________________________________________
, 30.09.2000
page 9
2) Relativity of Time
Newton's laws of motion put an end to the idea of absolute position in space. The
theory of relativity put an end to the idea of absolute time, so any observer can work
out precisely what time and position any other observer will assign to an event,
provided he knows the other observer's relative velocity. (they are related)
Nowadays we use just this method to measure distances precisely, because we can
measure time more accurately than length. In effect, the meter is defined to be the
distance travelled by light in vacuum in 0.000000003335640952 seconds, as
measured by a caesium clock. So, we must accept that time is not completely
separate from and independent of space, but is combined with it to form an object
called space-time. (more later)
The Beginning
I want to know how God created this world. I am not
interested in this or that phenomenon. I want to know His
thoughts, the rest are details.
Albert Einstein
•
Einstein's Start
When Einstein was born, Newton's theory led to absurd results for the
movement of light, leading him to postulate the relativity of time and to set the speed
of light as the highest one possible.
Early on in physics, scientists invented an ether to explain the characteristics of light.
But Michelson and Morley proved this idea ultimately wrong. This led Einstein to the
idea that neither space nor time are fixed. His theory of relativity has been proved
often since, as an example with the help of pulsars, and turned out to be right. The
speed of light being the absolute top causes time dilatation effects, which allow us to
observe myons. But this effect also causes the twin paradoxon, which is absolutely
possible on closer examination, and it puts an end to a definite present.
•
The Twin Paradoxon
This paradoxon is one of the best known world-wide. It describes twins, one
staying on earth the other twin making a journey in a rocket travelling with a velocity
near the speed of light. They were exactly the same age when the brother departs but
when he comes back after 50 years, the brother that stayed is older than the one that
went with the rocket. For the one that lived on earth all the time, 50 years had gone
by, whereas for the other one in the rocket, just 5 or 10 or 13 years had passed.
(dependent on the velocity he travelled)
It is not that the one in the rocket lived 50 years and got only 13 years older; He lived
just 13 years in the rocket. For him and all the watches on board only 13 years
passed. And for his brother and all the watches placed on earth 50 years passed.
Both of them are right.
English Special Topic
________________________________________________ Matura 30.09.2000,
8C
Time
Marcus Meisel
Marcus.Meisel@blackbox.at
__________________________________________
, 30.09.2000
page 10
That time is not a constant but dependent on the velocity of the system in which it is
measured, is an assumption of Albert Einstein. Meanwhile there are very exact
atomic clocks that proof his assumption as true.
Einstein's idea was that if the speed of light appeared the same to every observer, no
matter how he was moving, another factor has to be variable, what led him to the
theory of relativity. And this factor is the velocity with which time goes by, to say, time
itself. Out of this thought follows that clocks, carried by different observers, would not
necessarily agree.
Seen from an observer outside of the moving system, this interesting effect in the flow
of time is called time dilatation. The nearer to the speed of light you get, the slower
time goes by.
If an object moves with 100% lightspeed, time would stand still; and the mass would
get infinite. That is the reason why travelling with speed greater than the one of light is
impossible. The spaceship would have to get through the barrier of infinite mass and
no time passing by, the so-called light barrier. The second problem is the slightest
problem for the person travelling in the rocket. For his point of view the flow of time is
constant all the journey long! He just would not find the same persons he left when he
comes back. They will all be dead since millions of centuries.
So if one does not like his century, travelling near the speed of light would offer a
realistic possibility to jump into the next without a worth mentioning loss of time.
In this respect the advertisement slogan of Swatch, now seen from another
background, gets a completely new meaning:
"Time is what you make of it!"
It's all Relative
Both Aristotle and Newton believed in absolute time. That is, they believed
that one could unambiguously measure the interval of time between two events, and
that this time would be the same whoever measured it, provided they used a good
clock. Time was completely separate from and independent of space. This is what
most people would take to be the common-sense view. However, we have had to
change our ideas about space and time. Although our apparently common-sense
notions work well when dealing with things like apples and planets that travel
comparatively slowly they do not work at all for things moving at or near the speed of
light.
•
Einstein
Einstein had worked as a patent officer in Berne, in Switzerland, to earn a
living and pay for his academic work while he wrote up his ideas about the laws of
physics. In doing this he was rapidly becoming known as the visionary scientist of his
time. His first major work was published in 1905, the first of two Theories of Relativity.
It is called special Relativity; and the later theory, published in 1915, is called General
Relativity. The fundamental postulate, we recall from our time at school, was that the
laws of science should be the same for all freely moving observers, no matter what
their speed. Both deal with the way an observer and the event he or she observes are
related; Special Relativity essentially spells out what happens when there is a
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Time
Marcus Meisel
Marcus.Meisel@blackbox.at
__________________________________________
, 30.09.2000
page 11
constant movement linking the event and the observer, and General Relativity brings
in gravity. It also suggests what happens as the speed of any movement increases or
decreases. The idea included also the speed of light: all observers should measure
the same speed of light, no matter how fast they are moving. This simple idea has
some remarkable consequences which I will describe later on.
•
Day-to-Day Experiences
They are both still very difficult theories to understand fully, but they are
nevertheless widely acknowledged as the ideas which placed Einstein on the
scientific world stage. Einstein did not set out specifically to explain the nature of time
or the universe, but his theories inevitably interested many scientists, because he was
in effect rewriting the laws of physics which had been left unchallenged since the time
of Newton.
Einstein argued that the laws of physics must be the same, from whatever position
they happened to be observed. This idea stemmed from the insight that the same
event can appear different to two different observers, depending on their relative
positions.
Several day-to-day examples have been suggested to help illustrate the point. One
that most of us have experienced at some time or another is when two trains stop
alongside each other in a railwaystation. You can be sitting on one train, looking out
of the window at the other train, when it seems to move off. For a second or two you
are not sure whether it has in fact started to move, or whether it is your own train
which is moving off. All you know is that one train must be moving relative to the
other; hence Relativity.
Now imagine a situation where one observer is on board a train another is on a
railway station platform as the train rushes by. A cup on a table in front of the man on
the train will appear to stay 60 centimetres in front of him. So, from his point of view, it
will not be moving. However, to the man on the platform who watches the passing
carriage windows, the cup will be seen to rush past at great speed as the train hurtles
through the station.
•
A Clue
Einstein's great insight was that the laws of physics had to be rewritten in
such a way that the laws of motion would be recognised as being consistent. They
would have no account for related concepts such as acceleration and momentum,
which were involved in these apparently different views of the cup. And this meant
understanding the nature of time and space, and how they affect things.
After all, what causes two different views of the cup are the different positions of the
observers relative to the cup in time and space. One is travelling through time and
space alongside the cup, so that its relative position is always 60 centimetres in front
of him; it stays in his field of vision as long as they are both travelling through time
and space in an identical fashion. The other observer is, by comparison, stationary in
time and space relative to the moving cup, so that it comes into and moves out of his
field of vision in a very short time.
•
The Solution
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Time
Marcus Meisel
Marcus.Meisel@blackbox.at
__________________________________________
, 30.09.2000
page 12
Einstein developed mathematical equations to describe these kinds of
relationships. Taken together, they defined the nature of time and space; and they
had momentaneous consequences for cosmologists. To begin with, it emerged that
time and space were mathematically one and the same thing. And, as a
consequence, Newton's explanation of gravity had to be totally revised, accurate as it
seemed to be.
But more to this in the next chapter about 'Space and Time'.
•
Light
Contemporary physics states that no object should be able to travel faster
than the speed of light
c = 299'792'458 metres per second.
Although the value of c appears enormous when compared with conventional
travelling speeds, it suggests a limit which renders a practical realisation of interstellar
travel improbable. Whereas another planet in our solar system is reachable within
minutes or at least hours at the speed of light, a journey to the nearest star system
Alpha Centauri would already demand a travelling time of several years (4,2 Light-
years). Surely, the question remains: Are faster-than-light speeds possible? At the
present time most scientists believe that the correct answer should be "no". However,
it has to be emphasised that there is no definite proof for this claim. Actually, whether
superluminal speeds are possible in principle depends on the real structure of the
space-time continuum. (more later)
Einstein's Dreams
1
This book shows what would happen if time was no longer an arrow but
anything else. There are several examples of different kinds of appearances of time
like being like a stream of water, a circle or even parted in regions where in each time
runs at a different speed.
•
Plot
It is a fiction book, endearingly short, airy and irrational, in simple and
beautiful language. The science is gentle and it is cast in language to bring the flush
of envy to any one of the many famous writers alive today who has coaxed himself
into the delusion that scientists cannot write. It is a celebration of a world in which
1
"Einstein's Dreams" was written by Alan Lightman, who was born in Memphis, Tennessee, in 1948 and was
educated at Princeton and at the California Institute of Technology. He has written for Granta, Harper's, The
New Yorker, and The New York Review of Books.
His previous books include "Time Travel and Papa Joe's Pipe ", "A Modern-Day Yankee in a Connecticut
Court ", "Origins ", "Ancient Light ", "Great Ideas in Physics ", and "Time for the Stars ".
"Einstein's Dreams " is his first work of fiction. He teaches physics and writing at the Massachusetts Institute
of Technology and currently directs the MIT programme in writing and humanistic studies.
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Time
Marcus Meisel
Marcus.Meisel@blackbox.at
__________________________________________
, 30.09.2000
page 13
time does not march brutally through people's lives, but rather skips and gambles,
forever quirky and unpredictable. Lightman is exploring fiction's deep space, taking us
further than we are used to being taken.
The setting of the story is located in Berne, in Switzerland.
In this book Alan Lightman describes the dreams of Albert Einstein, a young patent
clerk had between 14th April 1905 and 28th June 1905. Although the characters and
situations in this book are entirely imaginary and bear no relation to any real person or
actual happening, it is a breathtaking synthesis of science and imagination.
One witnesses Einstein's dreams of new worlds: extraordinary visions of the effect on
people's lives when the direction and the flow of time changes to circular or flows
backwards, slows down or takes the form of a nightingale.
In all dreams there are given examples, of how life changes when time is different,
and most of them play in Berne, the city Einstein used to live.
The whole book is a flashback that starts after Einstein has finished his work. He
reflects back on his time of creating the new theory of time. This ends two hours later.
In those two hours Einstein reflects on the past several months, where he had many
dreams about time. The book describes some of the dreams and tells the reader that
those have taken hold of his research.
Out of many possible natures of time, imagined in as many nights, one seems
compelling. Not that the others are impossible. The others might exist in other worlds.
•
Results
The result of all those dreams was the special theory of relativity. It was a
completely new point of view. Although it cost Einstein a lot of energy, he believed
that it was worth it. The picture of time that got its final shape while it was dreaming,
was so obvious, so clear to him. Other people might also have such visions, but
Einstein had the ability to write it down as a physical concept.
New Findings
•
Consequences
The essence of Einstein's equations is that the matter and energy content of
an object determines the amount of curvature in the surrounding space and time.
•
Faster than Light
The question whether the speed of light is a true physical limit has no definite
answer yet. It depends on the real structure of space-time. If there is an absolute time
preserving causality (by preventing time-travel paradoxes), then faster-than-light
speeds - and even faster-than-light travel - are possible, at least in principle. On the
other hand, if superluminal processes are to be discovered, then absolute time will
probably have to be reintroduced in physics. Although the theory of special relativity
states against absolute time and superluminal phenomena, it does it not by proof, but
only by assumption.
Are there indications that absolute time and faster-than-light processes
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Time
Marcus Meisel
Marcus.Meisel@blackbox.at
__________________________________________
, 30.09.2000
page 14
exist ? My opinion is "yes" !
The theory of relativity does not make faster-than-light moving completely impossible,
it only forbids the crossing of the light barrier, thus principally allowing tachyons that
always move faster than light, but are not manipulatable by us. Based on the
equivalency principle and the Doppler effect Einstein concluded that also gravity
influences light, putting an end even to sub-atomic perpetuum mobiles.
Another example where particles can travel faster than light is given in the quantum
theory. There exists a phenomenon called the tunnel effect. It turned out that it is
impossible to measure the length of the tunnelling time. Some other experiments also
showed that one cannot determine which way a photon has taken in an experiment.
The photons even seemed to communicate to each other faster than light! Quantum
theory therefore proposes the concept of multiple realities.
General Relativity
•
A Solution
In 1949, Einstein was concerned about a discovery by one of his close
colleagues and friends, the Viennese mathematician Kurt Gödel. Gödel found a
disturbing solution to Einstein's equation that allowed for violation of the basic tenets
of common sense: His solution allowed for certain forms of time travel. For the first
time in history, time travel was given a mathematical foundation.
If one followed the path of a particle in a Gödel universe, eventually it would come
back and meet itself in the past. He wrote, "By making a round trip on a rocket ship in
a sufficiently wide curve, it is possible in these worlds to travel into any region of the
past, present, and future, and back again."
His solution let time bend into a circle, called a closed timelike curve (CTC).
•
The Trojan Horse
Einstein's equations, in some sense, were like a Trojan horse. On the
surface, the horse looks like a perfectly acceptable gift, giving us the observed
bending of starlight under gravity and a compelling explanation of the origin of the
universe. However, inside lurk all sorts of strange demons and goblins, which allow
for the possibility of interstellar travel through wormholes and time travel. (more later)
The price we had to pay for peering into the darkest secrets of the universe was the
potential downfall of some of our most commonly held beliefs about our world - that
its space is simply connected and its history is unalterable.
•
Questions
But the question still remained: Could these CTCs be dismissed on purely
experimental grounds, as Einstein did, or could someone show that they were
theoretically possible and then actually build a time machine?
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3) Space and Time
Because of the non-existence of an absolute rest, the lack of an absolute position in
space and time is explained !
A Brief History of Time
2
"A Brief History of Time" is a book that tries to explain the main theories of
today physics in a quite "non-technical" language so everybody can understand them.
This book starts at the beginning of science with the Greek philosopher Aristotle and
goes on until the youngest theories about our universe like the superstring-theory
which needs 10dimensions.
We go about our daily lives understanding almost nothing of the world. We give little
thought to the machinery that generates the sunlight that makes life possible, to the
gravity that glues us to an Earth that would otherwise send us spinning off into space,
or to the atoms of which we are made and on whose stability we fundamentally
depend. Except for children, few of us spend much time wondering why nature is the
way it is; where the cosmos came from, or whether it was always here; if time will one
day flow backward and effects precede causes; or whether there are ultimate limits to
what humans can know. Was there a beginning of time? Could time run backwards?
Is the universe infinite or does it have boundaries? These are just some of the
questions considered in an internationally acclaimed masterpiece which begins by
reviewing the great theories of the cosmos from Newton to Einstein, before diving into
the secrets which still lie at the heart of space and time.
This book tries to answer at least some of these questions that can be answered
now. To get some answers we can only follow the theories of Stephen Hawking,
which are very good explained in his best-seller.
Sinking into space-time
•
Einstein
As I already mentioned, Einstein developed mathematical equations to define
the nature of time and space. These equations had momentous consequences for
cosmologists. To begin with, it emerged that time and space were mathematically one
and the same thing. And, as a consequence, Newton's explanation of gravity had to
be totally revised, accurate as it seemed to be. Einstein argued that two objects do
not directly attract each other as Newton has thought; rather, each of the two objects
2
"A Brief History of Time" was written by Professor Stephen Hawking, who was born in Oxford, Great
Britain, on 8
th
January 1942.
He studied physics at Oxford University and went on to pursue his graduate studies at Cambridge. In his early
twenties he was diagnosed as having ALS (Amyotrophic Lateral Sclerosis), known in the UK as Motor Neurone
Disease. He holds Newton's chair as Lucasian Professor of Mathematics at Cambridge and is widely considered
to be the greatest scientific thinker since Newton and Einstein. In 1989 he received an Honorary Doctor of
Science degree from Cambridge University and was made a Companion of Honour.
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affects time and space, and any gravitational effects are a consequence of this. That
was the moment when he found out that space and time are warped.
•
The Universe as a Sheet
If this concept is difficult to grasp, imagine a heavy object (such as a cannon
ball), representing the sun, being placed in the middle of a taut rubber sheet [{
einfügen Bild in files }], creating a cone-shaped dent all around it - rather reminiscent
of the surface of a vortex of swirling water rushing down a plunge hole.
Einstein argued that whenever something heavy bent space-time like this, it would
naturally affect the path of anything lighter travelling nearby. So a smaller ball
representing the Earth or one of the other planets could be rolled across the stretched
rubber sheet representing space-time, towards the dent around the cannon ball sun.
If it was travelling too slowly, it would fall directly into the dent and quickly reach the
surface of the sun (just like Newton's apple falling to the surface of the Earth). If it
was travelling too fast, it would have its path deflected towards the cannon ball sun,
but would only dip into the dent then climb out of the other side, before continuing on
its journey. But at just the right speed, the small planet ball would be going fast
enough not to fall right into the dent, but too slowly to escape it completely. With
nothing else to stop it or slow it down, it would find its level on the 'side' of the dent in
space-time, rather like a motorcycle stunt rider going round and round the 'wall of
death'. It would have found its static orbit around the sun.
•
Einstein as Idol
The mathematical formula of Einstein could apart from even describe the
orbit of Mercury, what was not possible with Newton's rather simpler equation. This
was impressive evidence that Einstein's theory was correct, or at least an
improvement on Newton's explanation of gravity. It was natural for physicists to begin
to think: if it fits in with Einstein's theories, it is probably going to be true.
•
Dynamic Space and Time
It was while studying these equations of Einstein's that Lemaître, a priest and
Belgium's most famous astronomer, discovered something which really excited him.
One of the consequences of Einstein's maths was that the universe was not static; it
was dynamic.
It is simply enough to see why. If time and space are 'dented' by anything with mass,
then, as one body passes another, it will be drawn closer to it.
If the universe is static, then all objects will eventually be drawn to each other; all
mass will congregate together at the bottom of the largest dent in space and time.
This was the same problem which had worried Newton when he came up with his
theory of gravity; how could all the matter in the universe still be widely spread out
after billions of years? Why hadn't it been pulled together by gravity into one
conglomerate lump? But, whereas Newton's idea had confined itself to the attraction
of objects, Einstein's theory involved the mathematics of how space and time change
when an object with mass affects them. Thus Newton's system had no way for the
coming together of all objects to be avoided but Einstein's maths did. Einstein needed
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space and time to be able to change in the presence of mass. So space and time had
to be dynamic, rather than static.
Consequently, space-time, and so the universe, could not remain still; and if it had to
change it could only really get bigger or smaller. Hence it ought to be gently
expanding or contracting.
•
Gravitational Effects
It is gravity that governs and shapes the large-scale structure of the universe
and thus even time.
The laws of gravity were incompatible with the view held until quite recently that the
universe is unchanging in time: the fact that gravity is always attractive implies that
the universe must be either expanding or contracting.
According to general theory of relativity, there must have been a state of infinite
density in the past, the big bang, which would have been an effective beginning of
time. (Scientists today generally agree on an age of the universe of about 13 billion
years.)
Similarly, if the whole universe recollapsed, there must be another state of infinite
density in the future, the big crunch, which would be an end of time. Even if the whole
universe did not recollapse, there would be singularities in any localised regions that
collapsed to form black holes. These singularities would be an end of time for anyone
who fell into the black hole.
In every case there are certain locations in space that effect time, seen from an
different, innocent, and independent observer.
•
Solutions?
Schwarzschild calculated a solution to Einstein's equations where the time
dilatation is infinite from a certain radius on, out of which evolved the idea of black
holes. Wheeler found out that Schwarzschild´s solution included a singularity, but also
proved its possibility. (The first black hole was found in 1964 in the system Cygnus X-
1.)
Hubble proved the even expanding of space, which allowed to calculate the Big Bang.
Einstein therefore introduced a new term into his theory of relativity, the “cosmic
term”, which he later thought of as his biggest error, because it would have caused
the universe to become unstable.
In the search for “theories of everything”, which try to unite relativity and quantum
mechanics, the possibility of a cosmic term returned.
•
A Unifying Theory
When scientists like Stephen Hawking combine quantum mechanics, with
general relativity, there seems to be a new possibility for him that did not arise before:
that space and time together might form a finite, four-dimensional space without
singularities or boundaries, like the surface of the earth but with more dimensions. It
seems that this idea could explain many of the observed features of the universe,
such as its large-scale uniformity and also the smaller-scale departures from
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homogeneity, like galaxies, stars, and even human beings. It could even account for
the arrow of time that we observe.
At the end of A Brief History of Time Stephen Hawking concludes that, if we do
discover a complete theory that could describe everything, its basic principles and
implications should in time be understandable by everyone. And once we all
understand the true nature of the universe, we all, philosophers, scientists and just
ordinary people, can take part in the discussion of the question of why it is that we
and the universe exist. Should we ever resolve this question, he suggests, it will be
'the ultimate triumph of human reason - for then we would know the mind of God'.
Perhaps, for many of us, that challenge will seem a step too far. There are millions of
us who have never before got close to discovering the nature of the universe. We
may just have not tried; more likely we were convinced that it was beyond our limited
capacity to understand.
But I think that our opinion is changing. Changing towards knowing more and more
about the world and universe we live in. And that is the reason for me to belief that in
no way research in this field will find a sudden end.
Already Yogi Berra said :
“It ain’t over till it’s over”
•
Dreams
I think that these concepts will come to seem as natural to the next
generation as the idea that the world is round. Imaginary time is already a
commonplace of science fiction. But it is more than science fiction or a mathematical
trick. It is something that shapes the universe we live in.
An example of how the human race could cope with the progress made in all scientific
directions is given in Star Trek. It shows how much we know already and how much
we will be able to do with our knowledge in the near future.
•
The Physics of Star Trek
3
It is a popular science book, trying to tell most modern science in a simple
language. " The Physics of Star Trek" is a book to be read many times as long it is
up-to-date with our time (till we cross the milky ways of our and other galaxies). It
offers a lot of exotic science to anyone who wants to make a small investment of
imagination. Perhaps accidentally, Krauss also does a useful job in explaining some
important physics, using Star Trek as a pop culture example: the physics of Newton,
Einstein and Stephen Hawking all figure in the highly successful analysis. It is a book
on physics, but it is written in such a spirit of fun, it might even make you want to
watch Star Trek. This book is fun, and Mr. Krauss has a nice touch with a tough
subject. Krauss is smart, but speaks and writes the common tongue.
3
"The Physics of Star Trek" was written by Lawrence M. Krauss. He is Ambrose Swasey Professor of
Astronomy and Chairman of the Department of Physics at Case Western Reserve University. He is the author of
two acclaimed books, Fear of Physics: A Guide for the Perplexed and The Fifth Essence: The Search for Dark
Matter in the Universe, and over 120 scientific articles.
He is the recipient of several international awards for his work, including the Presidential Investigator Award,
given by President Reagan in 1986. He lectures extensively to both lay and professional audiences and frequently
appears on radio and television.
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In this entertaining book the physics professor Lawrence Krauss looks at how the
imaginary science of the Star Trek universe stacks up against the real thing. Krauss
speculates on the possibility of alien life, touching on whether any kind of life is such
an improbable phenomenon.
There are impressively clear explanations of difficult and up-to-date concepts in
information theory, quantum mechanics, particle physics, relativity, mechanics and
cosmology. The book goes where not even the show's laudable tradition of scientific
evangelism has gone before.
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4) To Build a Time Machine
The First Thoughts
•
Change Time
Since ever, humans wanted to change the past and know about the future.
Just to know the results of a bet of tomorrow today or to mend a decision, made in the
past.
Since it was not possible for scientists to build machines to look or travel through
time, it was the duty of science fiction authors to speculate about possible ways, how
a time machine would look and work like.
•
The Time Machine
4
It is a science fiction novel about the Victorian future which is more than a
fantastical yarn. It raises chilling questions about progress, social orders, so called
civilisation and the ultimate fate of the world. It tells the story from the present until
the end of our sun-system, a cold, almost lifeless earth with a dying sun.
Wells wrote this novel mainly because Charles Darwin published and proved his
theory of Evolution, which was the greatest scientific rumpus since the trial of Galileo.
It is a story about evolution brought to the reader as an adventure of an old scientist,
who has invented a time machine. Although Wells doesn’t tell the reader the names
of the Victorian scientist and the Narrator, he creates a personal relationship with the
reader, which is very difficult and proves again that H.G.Wells is one of the best
writers.
The Time Traveller lives in a house in London, in Richmond. In the cellar he has his
laboratory, his workshop. The Time Traveller shows his disbelieving dinner guests a
device he claims is a Time Machine.
He tries to convey his dinner guests that he found a machine to interrupt the floating
time stream an though have the possibility to move through time as one wants.
In real time a week later the dinner guests visit the Time Traveller again, but instead
of a settled old man they find him raged, exhausted and garrulous. The tale he tells is
of the year 802,701 AD of life as it is lived on exactly the same spot, what once had
been London. He has visited the future, he has encountered the future -race -elfin,
beautiful, vegetarian, helpless, leading a life of splendid idleness.
4
Herbert George Wells, "The Time Machine" was written by H.G.Wells,who was born in Bromley, Kent in
1866, to a working class family.His mother worked as a maid and housekeeper.
After working as a draper’s apprentice and pupil-teacher, he won a schoolarship to the ”Normal School of
Science” in South Kensington, where he began to write.The first published work appeared in May 1887 in the
Science Schools Journal -”A Tale of the Twentieth Century”. After his studies he worked in poverty in London as
a cramer and published his first book ”A Textbook of Biology” (1893), which was to remain in print for over
forty years. Wells had been in print as a professional writer, since 1891 when the F
OTNIGHTLY
R
EVIEW
published
his article ”The Rediscovery of the Unique”. He lived on his writing in those times. But not until he published his
first novel ”The Time Machine” (1895) did his literary career start.
H.G.Wells died in London, on 13
th
August 1946 at the age of 79 years, after having survived the First and
Second World War.
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But this is not the only race, these are not our only descendants. In the tunnels
beneath the new Eden there lurks another life form.
The end of the book is open because the Time Traveller disappears in front of the
eyes of the Narrator and hasn’t come back for three years although he said he’ll need
only half an hour for his journey.
•
Time Travel
Can we go back in time?
Like the protagonist in H.G. Wells's The Time Machine, can we spin the dial of a
machine and leap hundreds of thousands of years to the year 802,701? Or, like
Michael J. Fox, can we hop into our plutonium-fired cars and go back to the future?
The possibility of time travel opens up a vast world of interesting possibilities. With
time travel, we could go back to our youth and erase embarrassing events from our
past, choose a different mate, or enter different careers; or we could even change the
outcome of key historical events and alter the fate of humanity.
For example, in the climax of Superman, our hero is emotionally devasted when an
earthquake ravages most of California and crushes his lover under hundreds of tons
of rock and debris. Mourning her horrible death, he is so overcome by anguish that he
rockets into space and violates his oath not to tamper with the course of human
history. He increases his velocity until he shatters the light barrier, disrupting the
fabric of space and time. By travelling at the speed of light, he forces time to slow
down, then to stop, and finally to go backward, to a time before Lois Lane was
crushed to death.
This trick, however, is clearly not possible. Although time does slow down when you
increase your velocity, you cannot go faster than the speed of light ( and hence make
time go backward ) because special relativity states that your mass would become
infinite in the process. Thus the faster-than-light travel method preferred by most
science fiction writers contradicts the special theory of relativity.
Einstein himself was well aware of this impossibility.
Most scientists, who have not seriously studied Einstein's equations, dismiss time
travel as poppycock, with as much validity as lurid accounts of kidnappings by space
aliens. However, the situation is actually quite complex.
To resolve the question, we must leave the simpler theory of special relativity, which
forbids time travel, and embrace the full power of the general theory of relativity,
which may permit it. General relativity has much wider validity than special relativity.
While special relativity describes only objects moving at a constant velocity far away
from any stars, the general theory of relativity is much more powerful, capable of
describing rockets accelerating near supermassive stars and black holes. The general
theory therefor supplants some of the simpler conclusions of the special theory. For
anyone who has seriously analysed the mathematics of time travel within Einstein's
general theory of relativity, the final conclusion is, surprisingly enough, far from clear.
Proponents of time travel point out that Einstein's equations for general relativity do
allow some forms of time travel. They acknowledge, however, that the energies
necessary to twist time into a circle are so great that Einstein's equations break down.
In the physically interesting region where time travel becomes a serious possibility,
quantum theory takes over from general relativity.
Einstein's equations state that the curvature or bending of space and time is
determined by the matter-energy content of the universe. It is, in fact, possible to find
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configurations of matter-energy powerful enough to force the bending of time and
allow for time travel.
However, the concentrations of matter-energy necessary to bend time backward are
so vast that general relativity breaks down and quantum corrections begin to
dominate over relativity. Thus the final verdict on time travel cannot be answered
within the framework of Einstein's equations, which break down in extremely large
gravitational fields, where we expect quantum theory to become dominant. But
quantum corrections, in turn, may actually close the opening of the wormhole, making
travel through the gateway impossible.
•
Introducing a New Theory
This is when the ten dimensional hyperspace theory can settle the question. Because
both quantum theory and Einstein's theory of gravity are united in ten dimensional
space, scientists expect that the question of time travel will be settled decisively by
the hyperspace theory. But wormholes and dimensional windows which could be used
for time travel might only be understood completely when one incorporates the full
power of the hyperspace theory.
Because of this reason it will take some time until enough scientists can research in
this direction and decide whether these wormholes are physically relevant or just
another crazy idea.
However, the most bizarre consequence of wormholes is that physicists can not only
show that wormholes allow for multiply connected spaces, but that they allow for time
travel as well. This is the most fascinating, and speculative, consequence of multiply
connected universes. (more later)
Problem: Time Travel
•
Logical Paradoxon
If what one does could be predicted, then the fact of making that prediction
could change what happens. It is like the problems one would get into if time travel
were possible. If you see what is going to happen in the future, you could change it.
But that action would change the odds. One only has to see Back to the Future to
realise what problems could arise.
•
The Risks of Time Travel
The peculiar risk lies in the possibility of the time traveller finding some
substance in the space which he, or the machine, occupies. As long as the traveller
travels through time at a high speed, this scarcely matters, but to come to a stop
would involve the jamming of him, molecule by molecule into whatever lies in his way.
That would result in a far reaching explosion and would blow him and the apparatus
out of all possible dimensions into the 'Unknown'.
Here one could raise the question weather air or water is also a substance which
leads to an explosion or if these substances are exceptions because of their low
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density. Another interesting case that could happen would be if a feather is just gliding
through the air, exactly at the place in space where the time traveller stops. When he
stops and the feather is exactly under his nose, he will sneeze. When he stops and it
is there where his lounges are, he will cough it up. But what will happen when the
feather is there where his leg or head is going to be?
Avoidable but risky problems are also posed by time paradoxes, but more to this later
on.
Another risk is that you never know the exact situation in which you stumble in
stopping the machine. At your destination a suddenly appearing earthquake could
surprise and kill you without giving you a chance to flee through time in the last
moment.
In the movie Time Cop one of the greatest risks is described very vivid. The same
object cannot exist in the same place, at the same time! It would erase itself out of the
universe. From that time on it would stop to exist as matter.
But already while the time traveller is making or entering the machine, he has to
accepted these possibilities as unavoidable risks, some of the risks a time traveller
has to take.
•
Time Paradoxes
To understand the problem with time travel, it is first necessary to classify the
various paradoxes. In general, most can be broken down into one of two principal
types:
1. Meeting your parents before you are born
2. The man with no past
The first type of time travel does the most damage to the fabric of space-time
because it alters previously recorded events. For example, remember that in Back to
the Future, our young hero goes back in time and meets his mother as a young girl
his age, just before she falls in love with his father. To his shock and dismay, he finds
that he has inadvertently prevented the fateful encounter between his parents. To
make matters worse, his young mother has now become amorously attracted to him!
If he unwittingly prevents his mother and father from falling in love and is unable to
divert his mother's misplaced affections, he will disappear because his birth will never
happen.
The second paradox involves events without any beginning. For example, let's say
that an impoverished, struggling inventor is trying to construct the world's first time
machine in his cluttered basement. Out of nowhere, a wealthy, elderly gentleman
appears and offers him ample founds and the complex equations and circuitry to
make a time machine. The inventor subsequently enriches himself with the
knowledge of time travel, knowing beforehand exactly when stock-market booms and
busts will occur before they happen. He makes a fortune betting on the stock-market,
horse races, and other events. Decades later, as a wealthy, ageing man, he goes
back in time to fulfil his destiny. He meets himself as a young man working in his
basement, and gives his younger self the secret of time travel and the money to
exploit it. The question is: Where did the idea of time travel come from?
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•
My Favourite
My favourite time travel paradox is one of the second type. It was cooked up
by Robert Heinlein in his classic short story All You Zombies--.
A baby girl is mysteriously dropped off at an orphanage in Cleveland in 1945. "Jane"
grows up lonely and dejected, not knowing who her parents are, until one day in 1963
she is strangely attracted to a drifter. She falls in love with him. But just when things
are finally looking up for Jane, a series of disasters strike. First, she becomes
pregnant by the drifter, who then disappears. Second, during the complicated
delivery, doctors find that Jane has both sets of sex organs, and to save her life, they
are forced to surgically convert "her" to a "him." Finally, a mysterious stranger kidnaps
her baby from the delivery room.
Reeling from these disasters, rejected by society, scorned by fate, "he" becomes a
drunkard and drifter. Not only has Jane lost her parents and her lover, but he has lost
his only child as well. Years later, in 1970, he stumbles into a lonely bar, called Pop's
Place, and spills out his pathetic story to an elderly bartender. The sympathetic
bartender offers the drifter the chance to avenge the stranger who left her pregnant
and abandoned, on the condition that he join the "time travellers corps." Both of them
enter a time machine, and the bartender drops off the drifter in 1963. The drifter is
strangely attracted to a young orphan woman, who subsequently becomes pregnant.
The bartender then goes forward 9 months, kidnaps the baby girl from the hospital,
and drops off the baby in an orphan age back in 1945. Then the bartender drops off
the thoroughly confused drifter in 1985, to enlist in the time travellers corps. The
drifter eventually gets his life together, becomes a respected and elderly member of
the time travellers corps, and then disguises himself as a bartender and has his most
difficult mission: a date with destiny, meeting a certain drifter at Pop's place in 1970.
The question is: Who is Jane's mother, father, grandfather, grandmother, son,
daughter, granddaughter, and grandson? The girl, the drifter, and the bartender, of
course, are all the same person.
And the reason why it is my favourite is because it makes your head spin, especially if
you try to untangle Jane's twisted parentage. If You draw Jane's family tree, we find
that all the branches are curled inward back on themselves, as in a circle. You will
come to the astonishing conclusion that she is her own mother and father! She is an
entire family tree unto herself.
Creating the Impossible?
Special warpings of space-time would make time travelling possible. In
warped space-time also wormholes are possible, although all current models require
exotic matter, to say imaginary matter, to generate negative pressure and so negative
gravity.
•
Theoretical Basis
Using Einstein's equations, it is perfectly possible to predict changes to the
shape of space and time which would affect us in ways we have so far found no way
to experience - like time warps.
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Most people imagine the universe to be a bit like an ever-inflating balloon, with us
somewhere inside it. But perhaps the balloon is hardly inflated at all, and is instead a
loose and flexible bag. Perhaps we are inside a universe where time and space can
be so bent and flexed that the balloon can be folded back on itself. Eventually two
parts of the outer skin could somehow get close enough to each other to be linked by
wormholes - strange tunnels through space and time through which we might one day
be able to move from one end of the universe to the another.
•
Multiply Connected Universes
Multiply connected is the opposite to simply connected what means, that our windows
and doorways are not entrances to wormholes connecting our home to a far-away
universe.
Although the bending of our universe in an unseen dimension has been
experimentally measured, the existence of wormholes and whether our universe is
multiply connected or not is still a topic of scientific controversy.
Many physicists, who once thought multiply connected spaces in which regions of
space and time are spliced together, are now seriously studying multiply connected
worlds as a practical model of our universe.
These models are the scientific analogue of Alice's looking glass. When Lewis
Carroll's White Rabbit falls down the rabbit hole to enter Wonderland, he actually falls
down a wormhole.
One can visualise a wormhole as the tube between two sheets of paper, connected
through holes.
If you fall into the wormhole, you are instantly transported to a different region of
space and time. Only by retracing your steps and falling back into the wormhole can
you return to your familiar world.
•
Time Travel and Baby Universes
Although wormholes provide a fascinating area of research, perhaps the most
intriguing concept to emerge from this discussion is the question of time travel.
Wormholes may connect not only two distant points in space, but also the future with
the past.
Since travel through the wormhole is nearly instantaneous, one could use the
wormhole to go back in time. Unlike the machine portrayed in H.G.Wells's The Time
Machine, however, which could hurl the protagonist hundreds of thousands of years
into England's distant future with the simple twist of a dial, a wormhole may require
vast amounts of energy for its creation, beyond what will be technically possible for
centuries to come.
Another bizarre consequence of wormhole physics is the creation of "baby universes"
in the laboratory. We are, of course, unable to re-create the Big Bang and witness the
birth of our universe. However, a few years ago some physicists of the
Massachusetts Institute of Technology shocked many physicists, when they claimed
that the physics of wormholes may make it possible to create a baby universe of our
own in the laboratory. By concentrating the intense heat and energy in a chamber, a
wormhole may eventually open up, serving as an umbilical cord connecting our
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universe to another, much smaller universe. If possible, it would give a scientist an
unprecedented view of a universe as it is created in the laboratory.
One could then find out how the starting conditions of a universe look like; if time is
already one of those conditions or if it is just a product, created by chance.
•
Evading the Light Barrier
When Carl Sagan wrote a novel called Contact, he wanted to make his book
as scientifically accurate as possible and though wrote to the well known physicist Kip
Thorne weather there was any scientifically acceptable way of evading the light
barrier.
Sagan's request piqued Thorne's intellectual curiosity. A serious request that
demanded a serious reply. Fortunately, because of the unorthodox nature of the
request, Thorne and his colleagues approached the question in a most unusual way:
They worked backward. Normally, physicists start with a certain known object and
then solve Einstein's equation to find the curvature of the surrounding space.
However, Thorne and his colleagues started with a rough idea of what they want to
find. They wanted a solution to Einstein's equations in which a space traveller would
not be torn apart by the tidal effects of the intense gravitational field. They wanted a
wormhole that would be stable and not suddenly close up in the middle of the trip.
They wanted a wormhole in which the time it takes for a round trip would be
measured in days, not millions or billions of earth years, and so on. In fact, their
guiding principle was that they wanted a time traveller to have a reasonably
comfortable ride back through time after entering the wormhole. Once they decided
what their wormhole would look like, then, and only then, did they begin to calculate
the amount of energy necessary to create such a wormhole.
They did not care if the energy requirements were well beyond twentieth-century
science. To them, it was an engineering problem for some future civilisation actually
to construct the time machine. They wanted to prove that it was scientifically feasible,
not that it was economical or within the bounds of present-day earth science.
Much to their delight, they soon found a surprisingly simple solution that satisfied all
their rigid constrains. It was not a typical black hole solution at all. They christened
their solution the "transversible wormhole," to distinguish it from the other wormhole
solutions that are not transversible by spaceship.
They were so excited by their solution that they wrote back to Sagan, who
incorporated some of their ideas in his novel. (and this year in the identically named
film Contact.)
•
Inside Out
Scientists are not quite sure what happens inside a black hole. There are
solutions of the equations of general relativity that would allow one to fall into a black
hole and come out of a white hole somewhere else. A white hole is the time reverse
of a black hole. It is an object that things can come out of but nothing can fall into.
The white hole could be in another part of the universe. This would seem to offer the
possibility of rapid intergalactic travel. The trouble is it might be too rapid. If travel
through black holes were possible, there would seem nothing to prevent you from
arriving back before you set off. You could then do something, like kill your mother
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before you were born. You must then cease to exist. But if you cease to exist, you
could not have gone back and killed your mother. But if you didn't kill your mother,
then you have not ceased to exist. To put it another way: if you exist, then you cannot
exist, while if you don't exist, you must exist.
This is the most famous paradox to be found in both science fiction and physics. (It
belongs to the first type)
Perhaps fortunately for our survival ( and that of our mothers), it seems that the laws
of physics do not allow such time travel. What seems to happen is that the effects of
the uncertainty principle would cause there to be a large amount of radiation if one
travelled into the past. This radiation would either warp space-time so much that it
would not be possible to go back in time, or it would cause space-time to come to an
end in a singularity like the big bang or the big crunch. Either way, our past would be
save from evil-minded persons.
But the best evidence that time travel is not possible, and never will be, is that we
have not been invaded by hordes of tourists from the future.
But, are we alone?
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I) Conclusion
Why it matters
I
n what sense do these issues matter? Why shouldn't we ignore the view from nowhen, and
go on in physics, philosophy, and ordinary life just as we always have? After all, we cannot
actually step outside time, in the way in which we can climb a tree to alter our viewpoint. Isn't
it better to be satisfied with the viewpoint we have?
We cannot step outside time, but we can try to understand how the way in which we are
situated within time comes to be reflected in the ways in which we talk and think and
conceptualise the world around us. What we stand to gain is a deeper understanding of
ourselves and of what is external to us. This is a reflective kind of knowledge: we reflect on
the nature from the standpoint from within, and thereby gain some sense, a sense-from-
within, of what it would be like from without.
If the reflexivity were viscous the whole project would be self-defeating, but is it vicious? Our
understanding seems to be enhanced, not overturned. With each advance comes a new
picture of how the world would look like from nowhere, and a new appreciation of the limits
of our own standpoint.
Our culture has been as surely shaped by the miracles of modern physics as it has by any
other human intellectual endeavour. And while it is an unfortunate modern misconception
that science is somehow divorced from culture, it is, in fact, a vital part of what makes up our
civilisation. Our explorations of all dimensions of the universe, represent some of the most
remarkable discoveries of the human intellect, and it is a pity that they are not shared among
as broad an audience as enjoys the inspiration of great literature, or painting, or music.
The campaign for a view from nowhen is a campaign for self-improvement, and not a
misguided attempt to do the impossible. It promises only to enhance our understanding of
ourselves and our world, and not to make us gods.
A proof for this kind of argumentation is the increasing number of still present a new
question: Why is the future so different from the past? Why does the past affect the future
and not the other way round? The universe began with the Big Bang - will it end with a 'Big
Crunch'?
To try to answer these questions we adopt some "world picture." Each answer and each
new theory we humans find, lets us feel that mankind could bring the world totally under his
control. But until now, none of the known theories results in a completely determined picture
of our universe.
This paper presents an innovative and controversial view of time and
contemporary physics. I especially pondered on time in space, the paradoxes of
time and time travel to throw a fascinating new light on some of the great
mysteries of the universe and to give all the readers the opportunity to look at
the world from a fresh perspective.
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II) Glossary
big bang: The singularity at the beginning of the universe.
big crunch: The singularity at the end of the universe.
black hole: A region of space-time from which nothing, not even light, can escape, because
gravity is so strong.
Chandrasekhar limit: The maximum possible mass of a stable cold star, above which it
must collapse to a black hole.
cosmological constant: A mathematical device used by Einstein to give space-time an
inbuilt tendency to expand.
event: A point in space-time, specified by its time and place.
field: Something that exists throughout space-time, as opposed to a particle that exists at
only one point at a time.
general relativity: Einstein's theory based on the idea that the laws of science should be the
same for all observers, no matter how they are moving. It explains the force of gravity in
terms of the curvature of a four-dimensional space-time.
grand unified theory: A theory that unifies the electromagnetic strong and weak forces.
imaginary time: Time measured using imaginary numbers.
light cone: A surface in space-time that marks out the possible directions for light rays
passing through a given event.
light-second (light-year): The distance travelled by light in one second (year).
no boundary condition: The idea that the universe is finite but has no boundary (in
imaginary time).
primordial black hole: A black hole created in the very early universe.
quantum mechanics: The theory developed from Planck's quantum principle and
Heisenberg's uncertainty principle.
singularity: A point in space-time at which the space-time curvature becomes infinite.
space-time: The four-dimensional space whose points are events.
special relativity: Einstein's theory based on the idea that the laws of science should be the
same for all freely moving observers, no matter what their speed.
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III) Bibliography
Nr.
Titel
Autor
Publishing Company
1)
A Brief History of Time
Stephen W.
Hawking
Rowohlt
2)
The Time Machine
H. G. Wells
Everyman - JM Dent
3)
Einstein's Dreams
Alan Lightman
Sceptre
4)
Hyperspace, a scientific odyssey
through the 10th dimension
Michio Kaku
Oxford University
Press
5)
Black Holes and Baby Universes
Stephen W.
Hawking
Bantam Books
6)
Time’s Arrow and Archimedes’
Point
Huw Price
Oxford University
Press
7)
The Physics of Star Trek
Lawrence M. Krauss Flamingo
8)
Why aren't Black Holes Black?
Robert M. Hazen
Anchor Books
9)
Stephen Hawking's Universe
David Filkin
BBC
10)
Multimedia Encyclopedia CDv1.5 Encyclopedia
Software Toolworks
11)
Encarta 95 CD
Lexicon
Microsoft
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V) Bookreports
i) Einstein's Dreams
page 30
ii) The Time Machine
page 37
iii) A Brief History of Time
page 45
iiii) The Physics of Star Trek
page 61
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Marcus Meisel,8C
Einstein's Dreams
by Alan
Lightman
Author:
"Einstein's Dreams" was written by Alan Lightman, who was
born in Memphis, Tennessee, in 1948 and was educated at Princeton and at
the California Institute of Technology. He has written for Granta,
Harper's, The New Yorker, and The New York Review of Books.
His previous books include "Time Travel and Papa Joe's Pipe ", "A
Modern-Day Yankee in a Connecticut Court ", "Origins ", "Ancient Light
", "Great Ideas in Physics ", and "Time for the Stars ".
"Einstein's Dreams " is his first work of fiction. He teaches physics and
writing at the Massachusetts Institute of Technology and currently directs
the MIT programme in writing and humanistic studies.
Published :
It´s a Sceptre Book, published by Hodder and Stoughton
in Great Britain in 1994. It was first published in Great Britain in 1993 by
Hodder and Stoughton, a division of Hodder Headline PLC.
Type of book:
It is a fiction book, endearingly short, airy and irrational,
in simple and beautiful language. It is an accomplished first novel and a
beautiful book. The science is gentle and it is cast in language to bring the flush
of envy to any one of the many famous writers alive today who have coaxed
themselves into the delusion that scientists cannot write. "Einstein's Dreams " is
the sort of book to be read many times and hored and treasured for bleak times
and empty spaces.
" A joy to read. It is a celebration of a world in which time does not march
brutally through people's lives, but rather skips and gambols, forever quirky and
unpredictable" - The Times
"Original, beautifully written... light, amusing, fresh... a bit of scintillating
intellectual daring" - The Observer
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"Lightman is exploring fiction's deep space, taking us further than we are used
to being taken. It is payful, poignant, intimate... cool, languid, intelligent and
quotable.Lightman writes movingly and with great precision"-The Sunday
Times
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Subject:
The setting of the story is located in Bern in Switzerland.
In this book Alan Lightman describes the dreams of Albert Einstein, a
young patent clerk, which he had between 14th April 1905 and 28th June
1905. Although the characters and situations in this book are entirely
imaginary and bear no relation to any real person or actual happening, it is
a breathtaking synthesis of science and imagination.
One witnesses Einstein's dreams of new worlds: extraordinary visions of
the effect on people's lives when the direction and the flow of time changes
to circular or flows backwards, slows down or takes the form of a
nightingale.
The whole book is a flashback that starts after Einstein has finished his
work. He reflects back on his time of creating the new theory of time. This
ends two hours later. In those two hours Einstein reflects on the past
several months, where he had many dreams about time. Most of the dreams
take place in Berne, where Einstein lives, while he is dreaming. So in each
dream a typical situation out of everyday life of the dream persons, is
described. The book describes some of the dreams and tells the reader that
those have taken hold of his research.
Out of many possible natures of time, imagined in as many nights, one
seems compelling. Not that the others are impossible. The others might
exist in other worlds.
The most important persons:
Einstein:
a young, 26 years old patent clerk in Berne, dreaming about
time while he is discovers a new theory of time. Already this year, he has
completed his Ph.D. thesis, finished one paper on photons and another on
Brownian motion. The current project actually began as an investigation of
electricity and magnetism, which, Einstein suddenly announced one day,
would require a reconception of time.
Besso:
a close friend to Einstein. They have known each other since their
student days in Zürich, and still meet to talk and dine. He is married.
a typist:
she has already typed several of his personal papers for him in her
spare time. She likes Einstein.
Plot synopsis:
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It is six o'clock in the morning and Einstein has
finished with his new theory of time, which he will mail to the German
journal of physics that day. It cost him a lot of strength and energy, but
now he has finished. But not completely. While he waits for the typist in
the patent office in Berne he works in, he begins to reflect on the dreams he
had.
14th April 1905
Suppose time is a circle, bending back on itself. The world repeats itself
precisely, endlessly. Every movement and thought, every flapping of a
butterfly's wing, each touch, each smile, every kiss, every birth and every
word will be repeated an infinite number of times. But how would humans
living in such a world know that nothing is temporary, that everything
happened and is going to happen again and again?
There are some few people in every town, who, in their dreams, are
vaguely aware that all has occurred in the past. These are the people with
unhappy lives who fill up the vacant streets with their moans at night. They
are unable to rest because they have the knowledge that they cannot change
a simple action or mistake they or anyone else has made.
16th April 1905
In this world time is like a flow of water. Now and then, some cosmic
disturbance will cause a rivulet of time to turn away from the mainstream,
to make connection backstream.
When this happens, birds, soil, people caught in the branching tributary
find themselves suddenly carried to the past. Persons who have been
transported back in time are easy to identify because of their fear that any
change they make in the past, could have drastic consequences for the
future.
There is an example given, of such a traveller from the future. She huddles
in a corner, creeps across the street and cowers in another darkened spot.
For if she makes the slightest alteration in anything, she may destroy the
future. Like kicking up dust while she crossed the street just as Peter
Klausen is making his way to the apothecary in Berne on Spitalgasse this
afternoon of 16
th
April 1905. Klausen hates to have his clothes sullied. If
dust messes his clothes, he will stop and brush them off, regardless of
waiting appointments. If Klausen is sufficiently delayed, he may not buy
the ointment for his wife, who has been complaining of leg aches for
weeks. In that case, Klausen´s wife, in a bad humour, may decide not to
make the trip to Lake Geneva .
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And if she does not go to Lake Geneva on June 23rd, 1905, she won´t meet
a Catherine d'Épinay walking on the jetty of the east shore and will not
introduce Mlle. d'Épinay to her son Richard. In turn, Richard and Catherine
will not marry on 17th December 1908, will not give birth to Friedrich on
8th July 1912. Friedrich Klausen will not be father to Hans Klausen on
22nd August 1938, and without Hans Klausen the European Union of 1979
will never occur.
The woman from the future knows the Klausen story and a thousand other
stories, waiting to unfold, dependent on the birth of children and the
movement if people in the streets.
19th April 1905
In this world time has three dimensions, like space.
Just as an object may move in three perpendicular directions,
corresponding to horizontal, vertical, and longitudinal, so an object may
participate in three perpendicular futures. Each future moves in a different
direction of time.
Each future is a real one. At every point of decision the world splits into
three worlds, each with the same people but with different fates for these
people. In time, there are an infinity of worlds.
24th April 1905
There are two times at the same time. There is a mechanical time and there
is a body time. The first is like a pendulum that swings back and forth,
regularly and without anything disturbing it. The second wriggles like a
bluefish in a bay. It makes up its mind as it goes along.
All people who are convinced that mechanical time does not exist, never
look at a clock. They eat when they are hungry, sleep, whenever they want
and go to their jobs, whenever they wake from their sleep. The others live
like machines, they think their bodies don´t exist. They rise at seven a.m.,
eat their lunch at noon, supper at six, and make love between eight and ten
at night.
You can live in either time, but not in both times. Each time is true, but the
truths are not the same.
26th April 1905
This is an odd world. Everybody lives on Dome, the Matterhorn, Monte
Rosa, and other high ground. No one would buy or build a home
elsewhere.
And all this because some time in the past, scientists discovered that time
flows more slowly the further from the centre of the earth. The effect,
produced by the rotation of the earth , is minuscule, but it can be measured
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with extremely sensitive instruments. Once the phenomenon was known,
the people got anxious to stay young and moved to the mountains. To get
the maximum effect, they have constructed their houses on stilts.
Height has become status. In time people have forgotten the reason why
higher is better. Nevertheless, they continue to live on the mountains. They
tolerate cold, thin air and discomfort for staying younger.
28th April 1905
Time is visible in all places. Clock towers, wristwatches, church bells
divide years into months, months into days, days into hours, hours into
seconds, each increment of time marching after the other imperfect
succession.
In this world a second, is a second. Time is equal for all, it´s an infinite
ruler.
Time is absolute. A world in which time is absolute, is a world of
consolation. For while the movements of people are unpredictable, the
movement of time is predictable.
3rd May 1905
Consider a world in which cause and effect are erratic.
Sometimes the first precedes the second, sometimes the second the first.
Or perhaps cause lies forever in the past while effect in the future, but
future and past are entwined.
It is a world of impulse. It´s a world of sincerity. It´s a world in which
every word spoken speaks just to that moment, every glance given, has
only one meaning, each touch has no past or no future, each kiss is a kiss
of immediacy.
4th May 1905
In this world, time does pass, but little happens. Just a s little happens from
year to year, little happens from month to month, day to day.
If time and the passage of events are the same, then time moves barely at
all. If time and events are not the same, then it is only people who barely
move. If a person holds no ambitions in this world, he suffers
unknowingly. If a person holds ambitions, he suffers knowingly, but very
slowly.
8th May 1905
The world will end on 26th September 1907. Everyone knows it. In Berne,
it is just as in all cities and towns. One year before the end, schools close
their doors. Why learn for the future, with so brief a future?
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One month before the end, businesses close. What need is there for
commerce and industry with so little time left? People are not afraid . They
sit and sip coffee and talk easily of their lives. What is there to fear now?
One day before the end the streets swirl in laughter. Neighbours who have
never spoken greet each other as friends. What do their past stations
matter? In a world of one day they are equal.
One minute before the end of the world everyone in Bern gathers on the
grounds of the Kunstmuseum. No one moves. No one speaks.
In the last seconds, it is as if everyone has leaped off Topaz Peak, holding
hands. The end approaches like approaching ground. Cool air rushes buy,
bodies are weightless. The silent horizon yawns for miles. And below, the
vast blanket of snow hurtles nearer and nearer to envelope this circle of
pinkness and life
.
There are a lot more dreams described, and in each dream time has a
completely different character and behaviour.
Here are some other examples:
Each village is fastened to a different time and this is because the texture of
time is not smooth but it happens to be sticky.
In another dream the passage of time brings increasing order. If time is an
arrow, that arrow points toward order.
This book is about the things in life, life, and the humans living in the
world. But not only a simple description of their places , behaviours or
themselves, it is a description of what happens to them if time has another
appearance as we know it.
If there is a world with a centre of time, the time would stand still in the
centre. The further one moves away, the faster time goes by. Or imagine a
world without any time at all. There would be only images.
A world without memory, as a world in which time flows not evenly but
fitfully also occurs in Einstein's dreams. As a consequence of the fitful
flow of time, the people receive fitful glimpses of their future.
In another dream all the buildings are built on wheels and race through the
cities. Instead of standing still they move fast. Everybody is fixed on speed
and this only because some time in the past scientists discovered that time
passes more slowly for people in motion. Thus everyone travels at a high
velocity, to gain time.
In other worlds the time runs backwards, or the lifetime is compressed to
the space of one turn of the earth on its axis, or that time is a sense some
people have, and some not.
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There are some interludes between these chronologically ordered dreams in
which the real time and though Einstein's actions in real live, like meetings
with his best friend Besso are described. In such meetings they talk about
Einstein's progress with his work, but the reader also gets a glimpse of
Einstein's lifestyle in Berne.
Other dreams are about worlds where people live forever, or that time is
not a quantity but a quality so that it exists but cannot be measured, or
about a world without future where no person can imagine the future.
In another dream, time is a visible dimension which everybody is able to
use like all the other dimensions in space, or in another world, time is not
continuos, its a local phenomenon. This world is split up in zones of time.
In another dream there is a world where every moment of time is
determined.
Other examples of the behaviour of time in the worlds of Einstein's dreams
are a world in which time is like the light between two mirrors, a world of
countless copies, or a world in which time is a nightingale. For everyone
who catches a nightingale, time stands still.
This was the last dream of Einstein before he finished his "Special Theory
of Relativity".
Ideas, opinions and comments:
This is my favourite book. As I read the book the first time, I was able to
understand the meaning of everything what was written, but as I read it
the second time, I could enter the plot and really live in the thoughts of
Einstein. It was such a fantastic and extraordinary experience, to be
relaxed and excited the same time while reading this book. I truly can
recommend this book to any person who want's to get a short but deep
insight in the thoughts of a genius. It will be an enlarging experience.
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Marcus Meisel,7C
The Time Machine
by H.G.Wells
Author:
"The Time Machine" was written by H.G.Wells, who was
born in Bromley, Kent in 1866, to a working class family. His mother
worked as a maid and housekeeper.
After working as a draper’s apprentice and pupil-teacher, he won a
scholarship to the ”Normal School of Science” in South Kensington, where
he began to write. The first published work appeared in May 1887 in the
Science Schools Journal -”A Tale of the Twentieth Century”. After his
studies he worked in poverty in London as a cramer and published his first
book ”A Textbook of Biology” (1893), which was to remain in print for
over forty years. Wells had been in print as a professional writer, since
1891 when the F
ORTNIGHTLY
R
EVIEW
published his article ”The
Rediscovery of the Unique”. He lived on his writing in those times. But not
until he published his first novel ”The Time Machine” (1895) did his
literary career start.
H.G.Wells died in London, on 13
th
August 1946 at the age of 79 years,
after having survived the First and Second World War.
Published :
It´s an E
VERYMAN
Book, published by J.M.Dent, and
edited by John Lawton in 1995. It was first published on paperback by
J.M.Dent in Everyman’s Library 1935.The first publication as book was
1895 by Heinemann in Britain and in the USA by Holt.
Type of book:
It is a science fiction novel about the Victorian future
which is more than a fantastical yarn. It raises chilling questions about
progress, social orders, so called civilisation and the ultimate fate of the
world. It tells the story from the present until the end of our sun-system, a
cold, almost lifeless earth with a dying sun.
Wells wrote this novel mainly because Charles Darwin published and
proved his theory of Evolution, which was the greatest scientific rumpus
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since the trial of Galileo. Although the theory shocked society, and Wells
had created another ”prove” with ”The Time Machine”, he got positive
critics like:
”The Time Machine - considered by the majority of scientific readers to be
Mr. Wells’s best work” - Nature Magazine.
”The Time Machine - A new thing under the sun” - The Daily Chronicle.
Subject:
It´s a story about evolution brought to the reader as an
adventure of an old scientist, who has invented a time machine. Although
Wells doesn’t tell the reader the names of the Victorian scientist and the
Narrator, he creates a personal relationship with the reader, which is very
difficult and proves again that H.G.Wells is one of the best writers.
The Time Traveller lives in a house in London, in Richmond. In the cellar
he has his laboratory, his workshop, where he invents a miniature and a
full- size time machine. The Time Traveller shows his disbelieving dinner
guests a device he claims is a Time Machine.
In real time a week later the dinner guests visit the Time Traveller again,
but instead of a settled old man they find him raged, exhausted and
garrulous. The tale he tells is of the year 802,701 AD of life as it is lived on
exactly the same spot, what once had been London. He has visited the
future, he has encountered the future -race -elfin, beautiful, vegetarian,
helpless, leading a life of splendid idleness.
But this is not the only race, these are not our only descendants. In the
tunnels beneath the new Eden there lurks another life form.
The end of the book is open because the Time Traveller disappears in front
of the eyes of the Narrator and hasn’t come back for three years although
he said he’ll need only half an hour for his journey.
The most important persons:
The Time Traveller:
He is an old but lively grey-eyed man who
usually has a pale face. He is very learned and wise. The Time Traveller is
as reliable as all inventors of new things that weren’t proved properly. He
thinks un- happily of the Advancement of Mankind, and sees in the
growing pile of civilisation only a foolish heaping that must inevitably fall
back upon and destroy its makers in the end.
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The Narrator:
He is one of the most constant guests of the Time
Traveller. He is a young man, who believes the Time Traveller because of
the things he saw ( the flowers, the Time Traveller disappearing). But he
also has his own point of view of the future. For him future is still black
and blank - is a vast ignorance, lit at a few casual places by the memory of
the Time Traveller’s story.
A Psychologist:
He always tries to destroy a theory with facts that are
universally accepted.
A Medical Man:
He is a very realistic thinking man. He trusts his eyes
but doesn’t make premature decisions.
A Provincial Mayor:
He doesn’t really understand the matters of
science, but tries hard to do so.
Filby:
He is an argumentative person with red hair.
A Very Young Man:
Smokes cigars, is very young and gullible
A Journalist:
He thinks the same as the Editor.
A Editor:
He believes that the Time Traveller is only an old man who
made ”telling fantastic stories” to his aim.
A Silent Man:
plays his part perfectly. Silent in action and sound.
The Eloi and the Morlocks:
Those were the two species that resulted
from the evolution of man. Those two were now in the year 802,701 AD
sliding down towards, or had already arrived at, an altogether new
relationship. The Eloi who were the Upperworld people, might once have
been the favoured aristocracy, and the Morlocks, their mechanical servants.
But that had been long ago. The Eloi, like Carlovingan kings, had decayed
to a mere beautiful futility. They still possesed the earth on sufferance,
since the Morlocks, subterranean for innumerable generations, had come at
last to find the daylight surface intolerable.
In contrast to the Upper-worlders, to whom fire is a novelty to watch and
play with, the Morlocks fear any light because their eyes were that sensible
that they could see under the surface of earth.
Weena:
One of the Eloi women. She fell in love with the Time Traveller
because he saved her life. Weena had the oddest confidence in the Time
Traveller. She followed him everywhere he went and tried to delight him
when he got upset. The Eloi feared the darkness like the Morlocks the light
but nevertheless Weena followed the Time Traveller into the darkness.
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After one week queer friendship for about a week, during a journey, the
Time Traveller and Weena got attacked by Morlocks and Weena died.
All characters are only related to one another because of their meetings
with the Time Traveller.
Plot synopsis:
The action of the book plays in two main settings. One is the house of the
Time Traveller in the Victorian age. The other one is on exactly the same
place, on an area from Richmond until Wimbledon (in London), but in the
year 802701, where everything but-physical rules-has changed. The action,
if one sees it in the perspective of the Time Traveller, is strictly
chronological, but in the view of all other involved persons in real time, the
action has a long and exact foreshadowing.
The novel is gradually built up. It starts with an open beginning, where the
Time Traveller, Provincial Mayor, Very Young Man, Psychologist, Filby
and the Narrator discuss the existence and nature of a fourth dimension.
The Time Traveller explains, that he found out that the fourth dimension,
time, is only another dimension of space. He also tries to convey to the
dinner guests that man is only able to move in two dimensions without
technical help (like a balloon as technical help for the third dimension,
heighth). He compares time with some sort of gravitation which limits our
movements up or down. The Timetraveller visualises with that example, if
it is like that, that it is possible, with technical help, to interrupt the floating
time stream, or even move through time as one wants. To prove that to his
guests, he experiments with a miniature time machine and shows his guests
his lifework, the full-size version of the nearly completed Time Machine.
After a week real time, the Psychologist, Medical Man, Journalist, Editor,
Silent Man and Narrator gather at the Time Traveller’s. As they can’t find
him, they start to eat dinner. When he suddenly appears, dishevelled and
lame, he washes himself, eats dinner and begins his story.
There is one disruption in the tale of the Time Traveller in chapter seven
while he puts the flowers of Weena on the table. This should be a
significant sign for the reader that there were two actions at the same time.
And that the Time Traveller is only telling a story which is told like a very
long direct speech. Except for that very long direct speech the whole book
is narrated like a diary by the Narrator who is not named.
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”At ten o’clock this day, real time,...” the Time Traveller begins his hardly
believable story about his journey. He tells about his sensations as he
travelled through time, that one gets a bit sick of it, that years pass like
seconds for him,... and he tells about the risks of time travelling.
The peculiar risk lies in the possibility of him finding some substance in
the space which he, or the machine, occupies. As long as he travels through
time at a high speed, this scarcely matters, but to come to a stop would
involve the jamming of him, molecule by molecule into whatever lies in his
way. That would result in a far reaching explosion and would blow him
and the apparatus out of all possible dimensions into the Unknown.
But already while he was making the machine, he accepted it as an
unavoidable risk, one of the risks a man has to take.
When continuing the story, the Timetraveller says that when he halted, he
saw some creatures, friendly, smiling, human, vegetarian, but degenerated.
Their behaviour was comparable to children’s, not to adult’s. He says that
he had dined with the creatures he met and comments on their nature and
way of life. Eg. that they spoke a very sweet and liquid tongue. They didn’t
know what fear during sunshine was, their hair, which was uniformly curly,
came to a sharp end at the neck and check, their mouths were small, with
bright red, rather thin lips and their eyes were large and mild,... etc.
The Time Traveller considers how the world of his own time could have
changed to that in which he finds himself after the journey. After dinner he
discovered that his machine had disappeared. He met Weena. In the early
dawn of one night he caught a glimpse of creatures other than those he first
met and concluded that there were two distinct peoples, those who lived
above ground, and those who existed below.
Convinced the under-world creatures which he named Morlocks had
hidden his machine, the Time Traveller descended to their underground
caves but had to escape, empty- handed.
But that action was not useless. From that moment on he knew that the
Morlocks feared light and the Eloi, like he named the upperworlders,
feared the dark. He considered the relationship between the two races and
realised that the once- subservient Morlocks now dominated the Eloi. So
he took Weena to explore a large place , which had been a museum in
former times.
During the journey Weena put some flowers into his pocket. While he tells
the story he puts the flowers onto a table in his smoking room. After a short
break he continues and says that it was further than he thought. With the
darkness approaching, his and Weena’s fear of Morlocks grew. They
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spended the night in safe. In the ruined museum the Time Traveller found
matches, camphor and a metal bar to use against the Morlocks as a weapon.
As the Time Traveller and Weena returned from the museum, they were
forced by tiredness to rest in a forest. Although the Time Traveller had set
fire to the trees to fend off the Morlocks, the two were attacked and Weena
disappeared which gave the Time Traveller a keen stab of pain directly into
his heart. The Morlocks, however, were blinded by the raging fire.
On the next day the Traveller returned to the Eloi and found his time
machine in a trap of the Morlocks, but he escaped through time. He went
on into the future. During his journey he recognised that the changing of
day and night got more slowly although he drove at a constant speed,
which could only mean, that the earth was spinning more and more slowly.
He also saw that the sun got bigger. When he stopped, he discovered a cold
and almost lifeless earth with a dying sun. That shocked him that much,
that he returned immediately into his own time, where he was greeted with
scepticism.
As the Narrator visits the Time Traveller on the next day again, he, the
Time Traveller disappears with a camera in his Time Machine.
In the Epilogue the Narrator reflects on what might have befallen the Time
Traveller, he also considers his own view of the future, as black and blank
as ever.
Ideas, opinions and comments:
This book is very interesting because since I was in Kindergarten, I
wanted to build a Time Machine, so I really could easily identify with
the Time Traveller, as an excellent scientist and inventor. I really
enjoyed that science fiction novel because it is not that unrealistic,
how time works and what will happen to our earth. I think many
writers of science fiction novels have gathered material from the
fairy- land of science, and have used it in their construction of
literary fabrics, but none have done it more successful than
H.G.Wells.
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Marcus Meisel,8C
A Brief History of
Time
by Stephen W.
Hawking
Author:
"A Brief History of Time" was written by Professor Stephen
Hawking, who was born in Oxford, Great Britain, on 8
th
January 1942.
He studied physics at Oxford University and went on to pursue his
graduate studies at Cambridge. In his early twenties he was diagnosed as
having ALS (Amyotrophic Lateral Sclerosis), known in the UK as Motor
Neurone Disease. He holds Newton's chair as Lucasian Professor of
Mathematics at Cambridge and is widely considered to be the greatest
scientific thinker since Newton and Einstein. In 1989 he received an
Honorary Doctor of Science degree from Cambridge University and was
made a Companion of Honour.
Published :
It´s a Bantam Books Book, published by Bantam Press. It
was first published by Bantam Books in 1988. "A Brief History of Time"
remained on The New York Times best-seller list for fifty-three weeks; and
in Britain, as of February 1993, it had been on The Sunday Times list for
205 weeks. (At week 184, it went into the Guinness Book of Records for
achieving the most appearances on this list.) The number of translated
editions is now thirty-three.
Type of book:
"A Brief History of Time" is a book that tries to explain the main
theories of today physics in a quite "non-technical" language so everybody can
understand them. Stephen also explains also the basics to these theories so that
the reader has to know almost nothing about physics to understand them. This
book starts at the beginning of science with the Greek philosopher Aristotle and
goes on until the youngest theories about our universe like the superstring-
theory which needs 10dimensions.
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The book is divided into 11 chapters and 3 epilogues about Einstein, Newton
and Galileo Galilei. There is also a glossary that explains the main technical
verbs that are used in this book.
" This book marries a child's wonder to a genius intellect. We journey into
Hawking's universe, while marvelling at his mind " - Sunday Times
Subject:
We go about our daily lives understanding almost nothing of the
world. We give little thought to the machinery that generates the sunlight that
makes life possible, to the gravity that glues us to an Earth that would otherwise
send us spinning off into space, or to the atoms of which we are made and on
whose stability we fundamentally depend. Except for children few of us spend
much time wondering why nature is the way it is; where the cosmos came from,
or whether it was always here; if time will flow backward one day and effect
precede causes; or whether there are ultimate limits to what humans can know.
Was there a beginning of time? Could time run backwards? Is the universe
infinite or does it have boundaries? These are just some of the questions
considered in an internationally acclaimed masterpiece which begins by
reviewing the great theories of the cosmos from Newton to Einstein, before
delving into the secrets which still lie at the heart of space and time.
This book tries to answer this question, but a lot of these questions can not be
answered now and so we can only follow the theories of Stephen Hawking,
which are very well explained here.
The most important persons:
Albert Einstein:
He is a German-born American physicist and Nobel
laureate, best known as the creator of the special and general theories of
relativity and for his bold hypothesis concerning the particle nature of
light. He is perhaps the most well-known scientist of the 20th century.
Einstein was born in Ulm on March 14, 1879. At the age of 12 he taught
himself Euclidean geometry.
In 1902 he secured a position as an examiner in the Swiss patent office in
Bern. After 1919, Einstein became internationally renowned. He accrued
honours and awards, including the Nobel Prize in physics in 1922, from
various world scientific societies. His visit to any part of the world became
a national event.
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When Hitler came to power, Einstein immediately decided to leave
Germany for the United States. He took a position at the Institute for
Advanced Study at Princeton, New Jersey. Einstein died in Princeton on
April 18, 1955.
He often said, only the discovery of the nature of the universe would have
lasting meaning.
Galileo Galilei:
Galileo was born near Pisa, on February 15, 1564. He
was a Italian physicist and astronomer, who, with the German astronomer
Johannes Kepler, initiated the scientific revolution that flowered in the
work of the English physicist Sir Isaac Newton. Born Galileo Galilei, his
main contributions were, in astronomy, the use of the telescope in
observation and the discovery of sunspots, lunar mountains and valleys, the
four largest satellites of Jupiter, and the phases of Venus. In physics, he
discovered the laws of falling bodies and the motions of projectiles. In the
history of culture, Galileo stands as a symbol of the battle against authority
for freedom of inquiry.
In 1589 he became professor of mathematics at Pisa. Only the Copernican
model supported Galileo's tide theory, which was based on motions of the
earth. He discovered mountains and craters on the moon. He also saw that
the Milky Way was composed of stars. By December 1610 he had observed
the phases of Venus, which contradicted Ptolemaic astronomy and
confirmed his preference for the Copernican system.
He died in 1642.
Sir Isaac Newton:
He was born on January 4, 1643 at Woolsthorpe,
near Grantham in Lincolnshire. He was an English mathematician and
physicist, considered one of the greatest scientists in history, who made
important contributions to many fields of science. His discoveries and
theories laid the foundation for much of the progress in science since his
time. Newton was one of the inventors of the branch of mathematics called
calculus. He also solved the mysteries of light and optics, formulated the
three laws of motion, and derived from them the law of universal
gravitation.
Later, in the summer of 1661, he was sent to Trinity College, at the
University of Cambridge. Newton received his bachelor's degree in 1665.
He received his master's degree in 1668.
Newton is probably best known for discovering universal gravitation,
which explains that all bodies in space and on earth are affected by the
force called gravity. He published this theory in his book Philosophiae
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Naturalis Principia Mathematica in 1687. This book marked a turning point
in the history of science. Newton died in 1727.
Plot synopsis:
In the introduction Stephen Hawking explains that
he left out all but one equation, the most famous
E
mc
=
2
found by Albert
Einstein because someone told him every equation would halve the sales of
the book. He also describes how he got help from friends, who donated a
communication programme and a speech synthesiser to him, which in
combination with a small personal computer mounted on his wheelchair,
allows him a better communication than before he lost his voice.
In the beginning Hawking tells an anecdote on how a well-known scientist
once gave a public speech on astronomy and in the end an old lady got up
and said that he´d talked rubbish, because in reality the world would be a
flat plate supported on the back of a giant tortoise that stands on the back
of another tortoise and so on. He points out that most people would find
this picture rather ridiculous, but why do we think to know better?
Only recent breakthroughs in physics suggest answers to our questions
about the history of the universe, which may seem as obvious as the earth
orbiting our sun, or as ridiculous as a tower of tortoises. Only time
(whatever that may be) will tell.
The Greek philosopher Aristotle was the first to point out that earth was a
round sphere. Nevertheless the Greek still believed in the earth being the
stationary centre of the universe. This idea was elaborated by Ptolemy into
a complete cosmological model, which was generally accepted and adopted
by the Christian church as the picture of the universe that was in
accordance with the Scriptures, for it had the great advantage that it left
lots of room outside the sphere of the fixed stars for heaven and hell.
A simpler model suggesting that the sun was stationary at the centre and
the earth and the planets moved in circular orbits around the sun, was
proposed by Nicholas Copernicus. Nearly a century passed before this idea
was taken seriously by two astronomers, the German, Johannes Kepler and
the Italian, Galileo Galilei. Galileo observed the moons of Jupiter with a
just invented telescope, which was the deathblow to the old theory. An
explanation was provided only much later, in 1687, when Sir Isaac Newton
published his "Philosophiae Naturalis Principia Mathematica", probably
the most important single work ever published in the physical sciences. In
there, he postulated the law of universal gravitation and developed the
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complicated mathematics needed to analyse the motions of planets and
calculus.
The beginning of the universe has been discussed long then, because
according to religious traditions the universe started at a finite, and not
very distant time in the past. Nowadays we take it for granted that we live
in a lacy spiral disk galaxy and that there are many other galaxies more or
less like it in the universe. But early in our century not everyone accepted
this picture.
It was the American astronomer Edwin Hubble who, in the 1920s, showed
that there are indeed many galaxies besides our own. It was Hubble again
who showed that distant galaxies, wherever you look, are all moving away
from us. In other words, the universe is expanding. The most helpful way
to think of the expansion of the universe is not as things rushing away from
one another but as space between them swelling. Imagine a balloon with
dots on its surface being inflated. When the balloon swells, the dots move
apart.
This discovery finally brought the question of the beginning of the
universe into the realm of science. If galaxies move apart from each other,
they used to be much closer together at some moment in the past, ten or
twenty thousand million years ago. They all have been in exactly the same
place. All the enormous amount of matter in the universe packed in a single
point, infinitely dense and infinitesimally small. Such a situation is called
the "big bang". One may say that time had a beginning at the big bang, in
the sense that earlier times simply would not be defined.
But this is not the only possible history of an expanding universe.
The second chapter describes the non-existence of absolute rest and
therefore the lack of an absolute position in space and time.
The fact that light travels at a finite, but very high, speed ( 186,000 miles
per second) was first discovered by the Danish astronomer Roemer. He
measured the motion of Jupiter and the eclipses of its moons. A better
theory of the locomotion of light did not come until the 19
th
century when
the British physicist Maxwell managed to unify the partial theories that till
then had been used to describe the forces of electricity and magnetism.
Maxwell's theory predicted that radio or light waves should travel at a
certain fixed speed. In order to fit Newton's theories he introduced a
substance called "ether" that was present also in empty space.
Finally in 1905 Albert Einstein came to the conclusion that the whole idea
of an ether was unnecessary, providing one was willing to abandon the idea
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of absolute time. Based on this Einstein worked out first the special, then
the general theory of gravity, presenting the famous equation
E
mc
=
2
and
the law that nothing can travel faster than the speed of light.
The theory of relativity describes that any observer can work out precisely
what time and position any other observer will assign to an event, provided
he knows the other observer's relative velocity. Nowadays we use just this
method to measure distances precisely, because we can measure time more
accurately than length. In effect, one meter is defined to be the distance
travelled by light in 0.000000003335640952 seconds, as measured by a
caesium clock.
So, we must accept that time is not completely separate from and
independent of space, but is combined with it to form an object called
"space-time".
Einstein spent several years attempting to find a theory of gravity that
would work with what he had discovered about light and motion at near
light speed. In 1915 he introduced the theory of general relativity where he
thinks of gravity not as a force acting between two bodies but in terms of
the shape, the curvature, of four-dimensional space-time itself. In general
relativity, gravity is the geometry of the universe. According to Einstein
the curvature is caused by the presence of mass. Every massive body
contributes to the curvature of space-time. Things going "straight ahead" in
the universe are forced to follow curved paths. Imagine a heavy object,
such as a cannon ball, representing the sun, being placed in the middle of a
taut rubber sheet, creating a cone-shaped dent all around it.
Einstein argued that whenever something heavy bent space-time like this, it
would naturally affect the path of anything lighter travelling nearby. If you
now try to roll a smaller ball representing the Earth or one of the other
planets across the stretched rubber sheet representing space-time, it will
certainly change direction slightly when it meets the dent caused by the
cannon ball sun.
It will probably do more than that: it may describe an ellipse and roll back
in your direction. Something like that happens as the earth tries to continue
in a straight line past the sun. The sun warps space-time as the canon ball
warps the rubber sheet. The earth’s orbit is the nearest thing to a straight
line in warped space-time. At just the right speed, the small planet ball
would be travelling fast enough not to fall right into the dent, but too
slowly to escape it completely. With nothing else to stop it or slow it down,
it would find its level on the 'side' of the dent in space-time.
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The speed of light in space time can be seen like the ripples that spread out
on the surface of a pond when a stone is thrown in. The ripples spread out
as a circle that gets bigger as time goes on. If one thinks of a three-
dimensional model consisting of the two-dimensional surface of the pond
and the one dimension of time, the expanding circle of ripples will mark
out a cone whose tip is at the place and time at which the stone hit the
water. Similarly the light spreading out from an event forms a three-
dimensional cone in the four-dimensional space-time. This cone is called
the future light cone of the event. In the same way we can draw another
cone, called the past light cone, which is the set of events from which a
pulse of light is able to reach the given event.
Einstein’s theory predicts that not only planets, also Photons are affected
by the warp of space-time. If a light ray is travelling from a distant star and
its path takes it close to our sun, the warping of space-time near the sun
causes the path to bend inward towards the sun for a few degrees. Perhaps
the path of light bends in such a way that the light finally hits the earth.
Our sun is too bright for us to see such starlight; except during an eclipse
of the sun.
If we see it then and do not realise the sun is bending the path of the stars
light, we would get the wrong idea about which direction the beam of light
is coming from and where that star actually is in the sky. Astronomers
make use of this effect. They measure the mass of objects in space by
measuring how much they bend the paths of light from distant stars. The
greater the mass , the greater the bending.
Einstein made the revolutionary suggestion that gravity is not a force like
other forces, but is a consequence of the fact that space-time is not flat, as
had been previously assumed: it is curved, or warped, by the distribution of
mass and energy in it. Roger Penrose and Stephen Hawking showed that
Einstein's general theory of relativity implied that the universe must have a
beginning and, possibly, an end.
Chapter three begins with the observation that even fixed stars in fact
change their position, and all visible to us are concentrated in one band,
which we call the Milky Way. Our modern picture of the universe dates
back to Hubble, who demonstrated that ours was not the only galaxy.
There were in fact many others, with a lot of empty space between them.
We live in a galaxy that is about one hundred thousand light-years across
and is slowly rotating. The stars in its spiral arms orbit around its centre
about once every several hundred million years. Our sun is just an
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ordinary, average-sized, yellow star, near the inner edge of one of the spiral
arms.
The characteristics of a stars, we get by observing the spectra, which not
only tells us the temperature, but also the elements it consists of.
Friedmann started with two assumptions in his model: 1
st
: The universe
looks much the same in whatever direction you look (except for nearby
things like our Solar System and the Milky Way); 2
nd
: The universe looks
like this from wherever you are in the universe.
Friedmann’s first assumption is fairly easy to accept. The second isn’t. We
do not have any scientific evidence for or against it.
From these two ideas alone, Friedmann showed that we should not expect
the universe to be static. In fact, in 1922, several years before Edwin
Hubbell's discovery, Friedmann predicted exactly what Hubble found! In
1965 two American physicists at the Bell Telephone Laboratories in New
Jersey, discovered the microwave background of the universe and thereby
proved Friedmann´s theories.
Although Friedmann found only one, there are in fact three different kinds
of models that obey Friedmann´s two fundamental assumptions. In the first
which Friedmann found, the universe is expanding too slowly so that the
gravitational attraction between the different galaxies causes the expansion
to slow down and eventually to stop. The galaxies then start to move
toward each other and the universe contracts until the big crunch. In the
second kind of solution, the universe is expanding so rapidly that the
gravitational attraction can never stop it, though it does slow it down a bit.
Finally, there is a third kind of solution, in which the universe is expanding
only just fast enough to avoid recollapse. However, the speed at which the
galaxies are moving apart gets smaller and smaller, although it never quite
reaches zero. Because of insufficient measuring methods and some
uncertainty about dark matter we cannot exactly figure out which
Friedmann model describes our universe. All the Friedmann solutions have
the feature that at some time in the past, the distance between neighbouring
galaxies must have been zero. At that time, which we call the big bang, the
density of the universe and the curvature of space-time would have been
infinite. Because mathematics cannot really handle infinite numbers, this
means that the general theory of relativity (on which Friedmann´s solutions
are based) predicts that there is a point in the universe where the theory
itself breaks down. Such a point is an example of what mathematicians call
a singularity.
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In 1965 the British mathematician and physicist Roger Penrose discovered
the existence of black holes, which also contain singularities.
The idea, that stars may end up and can become a black hole, is based on
the gravitational effect of mass. Imagine a star that has ten times the mass
of the sun. The star’s radius is about 3 million kilometres, about five times
that of the sun. Escape velocity is about 1,000 kilometres per second. Such
a star has a life span of about a hundred million years. On one side the sun
has to fight against gravity: the attraction of every particle in the star for
every other. On the opposing side is the pressure of the gas in the star. This
pressure comes from heat released when hydrogen nuclei in the star collide
and merge to form helium nuclei what is called the fusion process. The
heat makes the star shine and creates enough pressure to resist gravity and
prevent the star from collapsing.
For a hundred million years this balance is held. Then the star runs out of
hydrogen that it could convert into helium. Some stars then convert helium
into heavier elements, but that gives them only a short reprieve.
When there’s no more pressure to counteract gravity, the star shrinks. As it
does, the gravity on its surface becomes stronger and stronger because the
mass gets more and more compressed. It won’t have to shrink to a
singularity to become a black hole. When the 10-solar-mass star’s radius is
about 30 kilometres, escape velocity on its surface will have increased to
300,000 kilometres per second, the speed of light. And out of these facts
rises the definition of a black hole: When light can no longer escape the
star is a black hole.
Stars with less than 8 solar masses probably don’t shrink all the way to
form black holes. Such stars are then called brown dwarfs. The limit,
beyond that a star can become a black hole, is called the "Chandrasekhar
limit".
Whether our star goes on shrinking to a point of infinite density or stops
shrinking just within the radius where escape velocity reaches the speed of
light, gravity at that radius is going to feel the same, as long as the star’s
mass doesn’t change. Escape velocity at that radius is the speed of light
and will stay the speed of light. Such a border of a black hole is called
"event horizon". Light coming from the star will find escape impossible.
Nearby beams of light from distant stars may curl around the black hole
several times before escaping or falling in.
A black hole, with its event horizon for an outer boundary, is shaped like a
sphere, or if it is rotating, a bulged-out sphere, a convex lens. The event
horizon is marked by the paths in space-time of rays of light that hover just
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on the edge of that spherical area, not being pulled in but unable to escape.
Gravity at that radius is strong enough to stop their escape, but just not
strong enough to pull them back in. We can't see them because the photons
of those rays can’t escape from that radius, they can’t reach our retina.
General relativity predicts the existence of singularities, but in the early
1960s only a few took this prediction seriously. Until Hawking and
Penrose showed that if the universe obeys general relativity, a star of great
enough mass undergoing gravitational collapse must form a singularity.
Hawking realised that if he reversed the direction of time so that the
collapse became an expansion, everything in the theory would still hold. If
general relativity tells us that any star which collapses beyond a certain
point must end in a singularity, then it also tells us that any expanding
universe must have begun as a singularity therefore as a Friedman model.
With newly developed mathematical techniques and other technical
conditions from the theorems that singularities must occur, Penrose and
Hawking at last proved that there must have been a big bang singularity
provided only that general relativity is correct and the universe contains as
much matter as we observe. It is perhaps ironic that now, having changed
his mind, Hawking actually is trying to convince other physicists that there
was in fact no singularity at the beginning of the universe - as you will see
later, it can disappear once quantum effects are taken into account.
The fourth chapter begins with the theory of determinism proclaimed by
the French scientist the Marquis de Laplace at the beginning of the 19
th
century.
To avoid that a hot object, or body, such as a star, must radiate energy at an
infinite rate, the German scientist Planck suggested in 1900 that light, X
rays, and other waves could not be emitted at an arbitrary rate, but only in
certain packets that he called quanta. 1926 another German scientist,
Heisenberg, formulated his famous uncertainty principle. In order to
predict the next position and velocity of a particle, one has to be able to
measure its present position and velocity exactly.
This led Heisenberg, Schrödinger, and Dirac to reformulate mechanics into
a new theory called quantum mechanics, based on the uncertainty
principle. It predicts a number of different possible outcomes and tells us
how likely each of these is. Quantum theory also led to the theory of wave-
particle duality.
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The fifth chapter deals with elementary particles and the forces of nature.
Just thirty years ago, it was thought that protons and neutrons were
elementary particles, but experiments in which protons were shot on one
another at high speeds had shown that they were in fact made up of smaller
particles which were named quarks. There are different types of quarks:
there are thought to be at least six "flavours", which we call: up, down,
strange, charmed, bottom, and top. Each flavour comes in three "colours",
red, green, and blue. These colours and names are just a creative invention
of physicist, quarks are much smaller than the wavelength of visible light
and so do not have any colour in the normal sense.
A proton or neutron for instance, is made up of three quarks, one of each
colour. We can create particles made up of the other quarks, but these all
have a much greater mass and decay very rapidly into protons and
neutrons.
The wave-particle dualism leads to a characteristic of particles, called spin.
Since particles have no well-defined axis, the spin really tells us what the
particle looks like seen from different directions. A particle of spin 0 is like
a dot: it looks the same from every direction. A particle of spin 1 has to be
turned round a full revolution to look the same, a particle of spin 2, half a
revolution. But there are particles that do not look the same if one turns
them through just one revolution: you have to turn them through two
complete revolutions! Such particles are said to have spin ½. All the
known particles in the universe can be divided into two groups: particles of
spin ½, which make up the matter in the universe, and particles of integer
spin which give rise to forces between the matter particles. The matter
particles obey what is called Pauli´s exclusion principle. This was
discovered in 1925 by an Austrian physicist, Wolfgang Pauli.
There exist just four groups of force-carrying particles. You can sort them
according to the strength of the force they carry and the particles with
which they interact. These four are: gravitational force, electromagnetic
force, weak nuclear force, and strong nuclear force. The last three are
combined into what is called a Grand Unified Theory (GUT), but these
contain a number of parameters whose values cannot be predicted from the
theory. That's the reason why this theory is not the ultimate theory up to
now.
Till 1956 it was believed that the laws of physics obeyed each of three
separate symmetries called C, P, and T. The symmetry C(charge) means
that the laws are the same for particles and antiparticles. The symmetry
P(parity) means that the laws are the same for any situation and its mirror
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image (the mirror image of a particle spinning in a right-handed direction is
one spinning in a left-handed direction). The symmetry T(time) means that
if you reverse the direction of motion of all particles and antiparticles, the
system should go back to what it was at earlier times; in other words, the
laws are the same in the forward and backward directions of time.
However, in 1964 two Americans, J. W. Cronin and Val Fitch proved this
believe to be wrong.
The sixth chapter gets a little bit more practical and explains the mystery of
black holes. In 1969 the term "black hole" was put into the world by the
American scientist John Wheeler as a graphic description of an idea at least
two hundred years old. Roemer´s discovery that light travels at a finite
speed meant that gravity might have an important effect on it, following the
wave-particle duality of quantum mechanics. However, a consistent theory
of how gravity affects light did not come along until Einstein proposed
general relativity.
The possible final states are "white dwarfs", neutron stars or black holes.
Chandrasekhar had shown that the exclusion principle could not halt the
collapse of a star more massive than the Chandrasekhar limit, but the
problem of understanding what would happen to such a star, according to
general relativity, was first solved by a young American, Robert
Oppenheimer. He found that at this singularity the laws of science and our
ability to predict the future would break down.
Anybody who remained far enough away of the black hole would not be
affected by this failure of predictability, because neither light nor any other
signal could reach him from the singularity.
There are some solutions of the equations of general relativity in which
occur so-called "wormholes". These are "highways" of transport through
space. You can get from one region of the universe to another in no time at
all. This would offer great possibilities for travel through space and time,
but unfortunately, it seems that these solutions may all be highly unstable.
The extra attraction of a large number of black holes could also explain
why our galaxy rotates at the rate it does: the mass of the visible stars is
insufficient to account for this. We also have some evidence that there is a
much larger black hole, with a mass of about a hundred thousand times that
of the sun, at the centre of our galaxy.
As in the case of Cygnus X-1, a very possible candidate for a black hole,
the gas will spiral inward and will heat up. It will not get hot enough to
emit X-rays, but it could account for the very compact source of radio
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waves and infrared rays that is observed at the galactic centre. It is thought
that similar but even larger black holes, with masses of about a hundred
million times the mass of the sun, occur at the centres of quasars. Matter
falling into such a supermassive black hole would provide the only source
of power great enough to explain the enormous amounts of energy that
these objects are emitting.
As the matter spirals into the black hole, it would make the black hole
rotate in the same direction, and though producing a magnetic field like
that of the earth. Very high energy particles would be generated near the
black hole by the in-falling matter. The magnetic field would be so strong
that it could focus these particles into jets ejected outward along the axis of
rotation of the black hole. Such jets are really observed in a number of
galaxies and quasars.
The seventh chapter is about light rays in the event horizon. If the rays of
light that form the event horizon can never approach each other, the area of
the event horizon might stay the same or increase with time but it could
never decrease - because that would mean that at least some of the rays of
light in the boundary would have to be approaching each other. In fact, the
area would increase whenever matter or radiation fell into the black hole.
The nondecreasing behaviour of a black hole's area was very significant for
the behaviour of a physical quantity called entropy, which measures the
degree of disorder of a system. It is a matter of common experience that
disorder will tend to increase if things are left to themselves.
This idea combined with the second law of thermodynamics, leaded to a
fatal law. If a black hole has entropy, then it ought also to have a
temperature! But a body with a particular temperature must emit radiation
at a certain rate. This radiation is required in order to prevent violation of
the second law. So black holes ought to emit radiation. But by their very
definition, black holes are objects that are not supposed to emit anything. It
therefore seemed that the area of the event horizon of a black hole could
not be regarded as its entropy.
But calculations showed that black holes in fact emitted radiation. The
spectrum of the emitted particles was exactly that which would be emitted
by a hot body, and the black hole was emitting particles at exactly the
correct rate to prevent violations of the second law.
So there occurred a new question: How is it possible that a black hole
appears to emit particles when we know that nothing can escape from
within its event horizon? The answer, quantum theory tells us, is that the
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particles do not come from within the black hole, but from the "empty"
space just outside the black hole's event horizon.
What we think of as "empty" space cannot be completely empty because
that would mean that all the fields, such as the gravitational and
electromagnetic fields, would have to be exactly zero. There must be a
certain minimum amount of uncertainty, or quantum fluctuations, in the
value of the field. One can think of these fluctuations as pairs of particles
of light or gravity that appear together at some time, move apart, and then
come together again and annihilate each other. These particles are virtual
particles like the particles that carry the gravitational force of the sun:
unlike real particles, they cannot be observed directly with a particle
detector, but their indirect effects, like small changes in the energy of
electron orbits in atoms, can be measured. And those measurements agree
with the theoretical predictions with a high accuracy.
Heisenberg's uncertainty principle also predicts that there will be similar
virtual pairs of matter particles, such as electrons or quarks. In this case
one member of the pair will be a particle and the other an antiparticle. Out
of the reason that energy cannot be created out of nothing, one of the
partners in a particle/antiparticle pair will have positive energy, and the
other partner negative energy. The one with negative energy is condemned
to be a short-lived virtual particle because real particles always have
positive energy in normal situations. It must therefore seek out its partner
and annihilate with it. Normally, the energy of the particle is still positive,
but the gravitational field inside a black hole is so strong that even a real
particle can have negative energy there. If a black hole is present, it is
possible for the virtual particle with negative energy to fall into the black
hole and become a real particle or antiparticle. In this case it no longer has
to annihilate with its partner. Now there are two possibilities what could
happen: The second partner could also fall into the black hole and
disappear forever, or it might also escape from the black hole as a real
particle or antiparticle. To an observer at a distance, like us humans, it will
appear to have been emitted from the black hole. And this is the radiation
we can observe.
Because of this radiation, the black hole therefore reduces its mass, very
slowly, but it does.
Moreover, the lower the mass of the black hole, the higher its temperature.
So, as the black hole loses mass, its temperature and rate of emission
increase, so it loses mass more quickly. What happens when the mass of
the black hole eventually becomes extremely small, is not quite clear, but
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the most reasonable guess is that it would disappear completely in a huge
final burst of emission, equivalent to the explosion of millions of H-bombs.
The eighth chapter is about the origin and fate of the universe as general
relativity predicts it and when quantum effects are taken into account.
Hawking first gives us an opportunity to think about the role the church
had played in the picture of the universe, and then goes on with new
theories science has uncovered.
We don´t yet have a complete and consistent theory that combines quantum
mechanics and gravity, but we are fairly certain of some features that such
a unified theory should have.
One is that it should incorporate Feynman´s proposal to formulate quantum
theory in terms of a sum over histories. In this approach, a particle does not
have just a single history, as it would in a classical theory. Instead, it is
supposed to follow every possible path in space-time, and with each of
these histories there are associated a couple of numbers, one representing
the size of a wave and the other representing its phase. The whole thing
works with probabilities of the sums of waves, associated with every
possible history that a particle has.
To avoid technical problems, one must add up the waves for particle
histories that are not in the "real" time that you and I experience but take
place in what is called imaginary time. Imaginary time may sound like
science fiction but it is in fact a well-defined mathematical concept. There
are special numbers, called imaginary, that, unlike ordinary numbers, give
negative numbers when multiplied by themselves. So for the purposes of
the calculation of Feynman's theory, one must measure time using
imaginary numbers, rather than real ones. This has an interesting effect on
space-time: the distinction between time and space disappears completely.
A second feature that we believe must be part of any ultimate theory, is
Einstein's idea that the gravitational field is represented by curved space-
time. When we apply Feynman´s sum over histories to Einstein's view of
gravity, the analogue of the history of a particle is now a complete curved
space-time that represents the history of the whole universe.
In the classical theory of general relativity, there are many different
possible curved space-times, each corresponding to a different initial state
of the universe. If we knew the initial state of our universe, we would know
its entire history!
Similarly, in the quantum theory of gravity, there are many different
possible quantum states for the universe. Again, if we knew how the
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Euclidean curved space-times in the sum over histories behaved at early
times, we would know the quantum state of the universe now and in the
future.
In the classical theory of gravity, which is based on real space-time, there
are only two possible ways the universe can behave: either it has existed
for an infinite time, or else it had a beginning at a singularity at some finite
time in the past. In the quantum theory of gravity, a third possibility arises.
Because it is possible for space-time to be finite in extent and yet to have
no singularities that formed a boundary or edge. Space-time would be like
the surface of the earth, only with two more dimensions.
The ninth chapter discusses the arrow of time and its direction. There are at
least three different arrows of time. First, there is the psychological arrow
of time. This is the direction in which we feel time passes, the direction in
which we remember the past but not the future. Then, there is the
thermodynamic arrow of time, the direction of time in which disorder or
entropy increases. Finally, there is the cosmological arrow of time. This is
the direction of time in which the universe is expanding rather than
contracting.
Chapter ten speculates about the unification of physics. To remove
infinities, one uses a process called renormalization, but this leads to many
errors conflicting with observation. The introduction of "supergravity"
caused problems, too. So, in 1984 there was a change of opinion in favour
of string theories. In these theories the basic objects are not particles,
which occupy a single point of space, but things that have a length but no
other dimension, like an infinitely thin piece of string. These strings may
have ends or they may join with themselves in closed loops. A particle
occupies one point of space at each instant of time. Thus its history can be
represented by a line in space-time, the "world-line". A string, on the other
hand, occupies a line in space at each moment of time. So its history in
space-time is a two-dimensional surface called the world-sheet. Any point
on such a world-sheet can be described by two numbers: one tells the time
and the other the position of the point on the string.
But, string theories seem to be consistent only if space-time has either ten
or twenty-six dimensions, instead of the usual four. The suggestion is,
therefore, that the other dimensions are curved up into a space of very
small size.
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The eleventh, final chapter, tries to draw a conclusion. The history of
science (and time) is once again briefly summed up, and Stephen Hawking
ends with the hope of finally gain understanding of everything that
happens in our universe.
Ideas, opinions and comments:
I liked this book very much, for it is one of the very best I´ve
ever read. Stephen Hawking points out the most complicated scientific facts in
an easily understandable and very fascinating way. This book will attract the
interest of any reader, and probably everyone willing to think about it will have
no problems to understand it.
At the end I just want to mention that Stephen's book has sold 8 million copies
world-wide and familiarised a whole generation with complex but intensely
exciting scientific theories. I think that he has a very good ability to explain
complicated things in an easy understandable way. I really loved to read this
book and I can only strongly recommend this book to anyone!
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Marcus Meisel,8C
The Physics of
Star Trek
by Lawrence M. Krauss
Author:
"The Physics of Star Trek" was written by Lawrence M.
Krauss. He is Ambrose Swasey Professor of Astronomy and Chairman of
the Department of Physics at Case Western Reserve University. He is the
author of two acclaimed books, Fear of Physics: A Guide for the Perplexed
and The Fifth Essence: The Search for Dark Matter in the Universe, and
over 120 scienific articles. He is the recipient of several international
awards for his work, including the Presidential Investigator Award, given
by President Reagan in 1986. He lectures extensively to both lay and
professional audiences and frequently appears on radio and television.
Published :
It´s
a
Flamingo
Book,
published
by
HarperCollinsPublishers in 1997. It was first published in the USA by
Basic Books, a division of HarperCollinsPublishers in 1995.
It was first published in the UK by HarperCollinsPublishers in 1996.
Type of book:
It is a popular science book, trying to tell most modern
science in a simple language.
" The Physics of Star Trek" is a book to be read many times as long it is up-to-
date with our time (till we cross the milky ways of our and other galaxies). It
offers a lot of exotic science to anyone who wants to make a small investment
of imagination. Perhaps accidentally, Krauss also does a useful job in
explaining some important physics, using Star Trek as a pop culture example:
the physics of Newton, Einstein and Stephen Hawking all figure in the highly
successful analysis.
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It is a book on physics, but it is written in such a spirit of fun, it might even
make you want to watch Star Trek.
"Always enlightening... this book is fun, and Mr Krauss has a nice touch with a
tough subject... Krauss is smart, but speaks and writes the common tongue." -
New York Times Book Review
" Entertaining and fascinating" - Manchester Evening News
" A brilliant book" - Cambridge Evening News
" Highly recommended" - SFX
Subject:
This entertaining book from the popular professor for physics and
astronomy at the Case Western University, Cleveland, Ohio deals with the
physical backgrounds of Star Trek and looks at how the imaginary science
of the Star Trek universe stacks up against the real thing. Krauss speculates
on the possibility of alien life, touching on whether any kind of life is such
an improbable phenomenon.
There are impressively clear explanations of difficult and up-to-date
concepts in information theory, quantum mechanics, particle physics,
relativity, mechanics and cosmology. The book goes where not even the
show's laudable tradition of scientific evangelism has gone before.
The most important persons:
This book is about science from the past through the present into the
future. Because of this enormous frame of time it is not possible to give a
brief description of every important scientist or character of the Star Trek
series.
Plot synopsis:
In the foreword famous Lucasian Professor and one-time
Star Trek guest star Stephen Hawking points out that the main purpose of
science fiction is to expand the imagination of all people. He says that
"Science fiction suggests ideas that scientists incorporate into their
theories". Star Trek literally takes us “where no one has gone before”, and
the science fiction of today may become the science of tomorrow.
In the first four chapters the author takes us on a guided tour through the
history of physics, always with an eye on some Star Trek adventures that fit
to this special part of physics.
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He starts with seventeenth-century mathematician and physicist Isaac
Newton, continues with Albert Einstein and Stephen Hawking until he
finally reaches Trek's 24
th
century, with Data as the temporary end of
knowledge. A main objective of these first four chapters is faster-than-light
travel, called "warp drive" in Star Trek. Lawrence M. Krauss notices that
the authors of Star Trek had a brilliant imagination with the word “warp”,
because for almost all scientists warping space seems to be the only
possibility to move faster than light.
His next objective is the transporter, probably one of the most fascinating
technics in Star Trek. At the beginning he asks the question of whether to
transport atoms or Bits, because this has never become clear in Star Trek
until today. A big problem in dematerialising a man would be how to get
rid of the body. Following Einstein's famous equation E
mc
=
2
, the atoms
of only one man would transform to the energetic equivalent of about one
thousand hydrogen bombs. On the other hand, the energy needed to
dematerialise someone is gigantic, because to convert matter into energy
you have to heat it up to about 1000 billion degrees like in a fusion-reactor.
To "save" a human body on a hard disk of a computer you need to save the
position, kind and movement of every single atom in that moment. If you
try to remember only the position, you would need about 10
28
Kilobytes of
RAM for the storage of a single human. Another question that rises at this
point is if the "soul" of someone is, or would be transported too. In
addition, Heisenberg's uncertainty principle also sets limits for just
scanning somebody. Based on this, Krauss considers a transporter to beam
someone, is nearly impossible to realise.
Another problem for the Enterprise is the energy she needs to survive and
move through the universe. The engines of the Enterprise are constructed
to use anti-matter to produce energy. But the huge amounts needed are
much more than we can today even imagine to produce. One very
informative detail of this book is to reveal the formula for dilithium
crystals: 2<5>6 dilithium 2<:>1 diallosilikat 1:9:1 heptoferranid. These
dilithium crystals are the most important part in a warp drive, and it seems
that the theoretical method could work with today's understanding of
nuclear physics.
The next part of the Enterprise the author examines is the so-called
"holodeck". Though three dimensional touchable holograms are possible,
but this device suffers from the same problems as the transporter, the
almost infinite memorycapacity it would need.
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A very interesting chapter is the one about the possibility of extraterrestrial
life, one of the most important points in Star Trek. It´s a pity that this one
allows only speculations until we have the first contact to any kind of
species of another planet (also in our own solar system).
Near the end the author tells us about perspectives of modern physics in
connection with Star Trek, which is very interesting for somebody with
knowledge on these issues.
The last chapter then reveals the ten biggest mistakes in the history of Star
Trek. This starts with the fact that it is absolutely silent in space, and goes
on with the second fact, that an event horizon is a mathematical border in
which it is impossible to shoot a hole with a phaser. Other funny mistakes
are technical terms used in a wrong way. As an example, in one episode the
Enterprise is cleaned from Baryons. But the only Baryons are protons and
neutrons. If you clean a ship from them, there isn´t much left... The last
error is a very specialised one, because in one episode the Neutrinos have a
wrong spin. I guess that only a few people even know what Neutrinos are.
The author ends with a quote from Gene Roddenberry: " The human race is
a remarkable creature, one with great potential, and I hope that Star Trek
has helped to show us what we can be if we believe in ourselves and our
abilities."
Ideas, opinions and comments:
I liked this book because I am very interested in physics, all the
explained theories in this book and especially the future of mankind.
I was not a Star Trek freak before I read this book and I won't get
one now, but I am sure I will watch more if I have more time.
It is generally very easy to read, but a few parts are specialised. For
that reason I would recommend a basic knowledge in physics for
reading this book.
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