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Ernst Mach

Newton s most basie distinction with respect to spacc rested on h' ontological mind-matter dualism. Apparent spacc was mcntal nul relative.^2C Physical spacc was of two kinds, absolute and rclative, nei ther of which was mcntal or in any way expcricnccablc (i._c„ _Con sciously noticcable). Our understanding of physical spacc camc from in-fcrcncc based on sensory and ideational cvidcncc.

Absolute physical spacc had the qualitics of cxtcnsion, duration, and penetrability. It was immovablc and apparendy unboundcd.*⁷ It was also unchanging cxccpt that its penetrability varied with respcct to the strength of gravitational and magnetie forccs cxcrciscd through it by physical objeets.

Rclatiuc physical spacc was a part of absolute physical spacc as dc-termined by physical coordinates. If the physical coordinates moved in absolute spacc whilc retaining their positions relative to one another, then one could speak of a relatirc physical spacc moving along with them or changing its position with respect to absolute spacc as a whole.²⁸

Absolute physical place was merely that part of absolute physical spacc which a materiał body or particie occupicd.²⁵*

Relatire physical place was the same part within the contcxr of one or morę relative physical spaccs.^3Cł

Absolute physical limę was another nnme for cqually fiowing, un-disturbablc duration, which was neither defincd by or contingcnt on any particular means of mcasuremenr.³¹ Indced, it should continuc un* affccted even if thcrc wcrc no materia! objeets in the universe, much less measuring instruments or people to use them.

Relatiie physical limę was a measurc of duration as determined by some means of motion like the hands of a clock.³²

Absolute physical rest was the continuancc of a body in the same absolute physical place.³³ lioth this kind of rest and absolute physical place tacitly assumed measuremeni from the borders of the universc, if the univcrsc had borders, and if the universe had no borders then from the limits of the dctectablc universe treated as if thosc limits con* stituted an inclusivc border.

Relatwe physical rest was the continuancc of a body in the same rela-tivc physical place.³⁴

Absolute physical motion was defincd in two different ways: first, as “the translation of a body from one absolute place into another”;

Theorelical Physict

and sccond, »> what was "neither gcncratcd nor altcred but bv ^ forcc imprcsscd upon the body movcd."^M    3

Rchlwt physical molion was also defincd in two different wavs-first, as tlić translation of a body from one rclative place into another-and sccond, as a kind of molion which may be “gcncratcd or ahered without any forcc impressed upon the body.”³®

Let mc attempt to clarify what Newton most likcly mcant hv tk* terms “rclative” and “absolute.”

1.    “Rclativc" mcant measurablc from a local pcrspcctivc in physical spacc and timc, and “mcrcly rclativc” mcant uncauscd and/or not mcasurcable from the “fixcd stars" or the borders of the univcrsc.

2.    “Absolute” mcant: first, what something had to be "in itself" to satisfy all measurements from all pcrspcctives; sccond, what something was as mcasurable from the most distant stars or from the borders of the univcrsc; and third, what something was as madę by God or as movcd or changcd by physical agents possessing inertial mass, gravitational mass, or somc other kind of efficicnt forcc.^3T

3* Everything “absolute” had numerous “rclativc" charactcristics, but not vicc vcrsa. Neither “absolute” nor “relative” physical referents could literally be sensed or noticed. Things “in themselvcs” had both intcrnal and external relations. Physical relations were not ob-servable. Ali relations were not causal relations. Exact measure-ment did not imply observability, and neither implied the causal dependcncc of physical objeets on measurcment or sensory obser-vation.³⁸

IV

George Berkeley anticipated a number of Mach’s cńticisms of Newton^ ideas. Mach admitted that he read Berkeley, but Mach, who was usually very conscientious in giving sources for his ideas, did not men-tion Berkeley in connection with these particular criticisms. Hence, it might be both unfair and wrong to assert that Mach took or dcvcloped his criticisms from Berkeley. Nonctheless, the similarity in many of these criticisms does seetn to justify relabeling some of our cxprcssions. We should probably speak about the "Berkelcy-Mach criticism of mass” and the “Berkelcy-Mach Principlc."

The analyses of Karl Popper and lohn Myhill into the similarities

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