Pagina-afbeeldingen
PDF
ePub

tive space, according to which not only the light but also the relative space is deflected, and when deflected causes effects on light. In this case the cause of the observed deflection of light would be not merely some influence of the sun, but a dislocation of the relative space. But in his prediction his theory contained only a causa cognoscendi, not a causa fiendi, of the deflection of light. Moreover, as pointed out in your columns (page 8) of this morning, by Mr. E. Nevill, F.R.S., there are other causes which would produce such a deflection. Perhaps it is a pity that, when it was clear that the facts occurred under the influence of the sun, the discussion was not adjourned for further inquiry concerning things far more obvious to observation than relative space, before bringing into question the reputation of Newton, who was President of the Royal Society for the last twenty-five years of his life and raised the Society to the acme of its fame. However, the Royal Society, having once broached the question, has challenged the learned world to decide whether Newton or Einstein is to be taken as the authority on space, time, motion, and the spatial universe.

According to Newton's theory of space, stated in the Scholium appended to the definition with which he starts his Principia, absolute true and mathematical space without relation to anything external always remains similar and immovable; whereas relative space is any movable measure of that space, which is defined by our senses by means of its situation towards bodies-e. g. the measure of a space by means of its situation towards the earth; and this relative space is vulgarly taken for immutable space, but is absolutely mutable. According to Einstein, on the other hand, no space is absolute and immovable, but all space is relative and movable.

The two theories differ little about relative space. Newton certainly would not have denied that, when

light is deflected, the relative space of that light is deflected with it. Indeed, it is universally true that everything spatial which moves carries its space with it, except so far as its extension is changed during its passage. The earth, for example, as it revolves round the sun, carries its space with it. Similarly, the light transmitted from a star carries its space with it; if by the influence of the sun it is deflected it has its space also deflected, and if it arrives at the earth deflected it brings its space to the earth also deflected. Newton and Einstein agree then in the commonplace that the relative space of anything movable is movable; and the only difference is that Newton would certainly not have agreed that light could be deflected by the deflection of its relative space, because he knew that space is not a force.

So far, then, Einstein has not overthrown Newton; and Newton has advanced the doctrine of relative and movable space in a rather better way than Einstein. But the real issue begins when we ask ourselves whether Einstein is right in rejecting the absolute, true, and mathematical space which Newton regarded as immovable. Is space nothing but relative and movable? The answer is that, whenever anything spatial is moved from place to place, it moves in a containing space which does not move with the thing moving, but remains unmoved and indifferent to the things moving about within it. For example, if I go in a train from Weymouth to Oxford, carrying my own relative space with me, the whole space containing those two places and the interval between them is unaffected by my journey, indifferent to the rest or movement of all the bodies on the way, and so far unmoved; otherwise the journey might start from Weymouth, but would never end at Oxford. Similarly, when light moves from a star, is deflected under the influence of the sun and finally arrives at the earth, then,

1

besides all these relative spaces, these spatial things moved within a space containing stars, sun, and earth, and so far unmoved by any of the motions of the various bodies contained by it. Relative spaces and motions of bodies are always included in a containing space. We may add that their relative times are also included in a containing time. We may also propose a new definition of motion within containing space and during containing time. Motion is a change of anything spatial, from place to place within a containing space from moment to moment during a containing time.

Professor Einstein has neglected containing space which itself unmoved contains the motions of relative spaces. But, it will be said, a containing space is only relatively immovable; for example, the containing space between Weymouth and Oxford, though unmoved by bodies between these places, moves with the earth and its relative space round the sun. True; but containing space has no limit, because one containing space is contained in another; and, as it becomes more and more extended, becomes unmoved on a larger and larger scale. The earth, all other planets, and the sun itself are and perform all their movements in the one containing space of the solar system. The solar system and all other stars are in the one containing space of the stellar system; and finally, the stellar system and the ether which occupies the intervals between all ponderable bodies and their corpuscles are included within the containing and pervading space, which includes all bodies whatever, and their relative spaces, and is in fact no other than the extended universe. It is this all-embracing space of the extended universe, which Giordano Bruno said is infinite, and Newton called absolute space, not only unmoved but immovable; for if there could be any space beyond this space, this space would not be all containing and infinite

space. Hence the following passage in Newton's Scholium:

'Now no other places are immovable but those that from 'infinity to infinity do all retain the same given position to one another, and on this account must ever remain un'moved, and do thereby constitute what I call immovable space.

Sir, I feel confident that, if the learned men of our day will condescend to study the geometry of the Greeks, adopted and improved by Sir Isaac Newton, they will conclude that space is the all-containing extension of the spatial universe; that Professor Albert Einstein's theory of space is deficient because he has neglected the fact that all motion is from place to place in containing space; that his prediction and the observations of the total eclipse of May 29 have corrected Newton in an important detail concerning the deflection of light; but that neither Einstein nor anybody else has destroyed Newton's theory of space. On the contrary, his distinction between absolute and relative space is one of the achievements which have raised him to the eminence which he has long deserved in the history of science. Weymouth, November 17, 1919.

II. ABSOLUTE SPACE AND TIME

FROM The Times, APRIL 5, 1921.

The correspondence initiated by your Scientific Correspondent on March 29, and continued by Professors Fleming and Wildon Carr, seems to evince a somewhat hesitating confidence in the theory of relativity. As then on Nov. 22, 1919, at the outset of the discussion on this subject, you kindly published a letter from me to the effect that Sir Isaac Newton was right in contending that space and time are not only relative, but also absolute, perhaps, now that The Theory of Relativity has been published by Professor Einstein, and in an authorized translation by Dr.

Lawson, I may be allowed to make some critical remarks on the subject, and to defend my belief that space is the extension and time the duration of the universe.

In Chapter III, on Space and Time in Classical Mechanics, Professor Einstein asks what is meant by motion in space, and this is his answer:

[ocr errors]

We entirely shun the vague word space, of which we must acknowledge we cannot form the slightest conception, and we replace it by motion relative to a rigid body of reference.' He takes as an example the motion of a stone thrown out of the window as relative to a railway carriage moving and to an embankment at rest. Hence your Scientific Correspondent says by way of approval that space is only a relation between pieces of matter. He might have gone farther back to Leibniz, who, having defined space as a relation of coexistence and time as a relation of succession, may claim to be the chief founder of the theory of relativity.

The objection to this treatment of space and time is that, so far as it is true, it is not the whole truth. What is true is that all finite bodies, resting or moving, are related as either coexistent or successive, as well as otherwise. What is false is that space and time can be defined in this way of Leibniz, or that space can be dismissed in the way of Einstein from the definition of motion. A stone, a carriage, and an embankment, in order to be coexistent with each other must each be extended, and in order to succeed one another must each be enduring as well as extended. Now what is extended is space, and what is enduring is time. It follows, therefore, that every finite body, being extended and enduring, must have space and time of its own, in order that it may coexist with, or be successive to, any other finite body. Moreover, as space is essentially extension and time essentially duration, while extension

« VorigeDoorgaan »