Materialism versus idealism: Einstein’s Relativity

Materialism versus idealism: Einstein’s Relativity 

BY MARTIN ZARROP, from Bulletin Vol. 7 No. 15

AT THE END of the 19th century, many scientists considered that there was very little that could be added to their basic body of theoretical physics. 

The fundamental theories of Newton in mechanics and gravitation had served the bourgeoisie well. The development of capitalism signified a huge step forward in mankind’s productive forces and his knowledge of the world in which he lived. 

The truth of Newton’s theories - verified daily in a million ways within every factory machine - seemed unassailable. Surely here was unconditional and absolute truth - the divine word of God, revealed to man through his profits? 

Even the development of the theories of electricity and magnetism by Faraday and Maxwell in the 19th century could scarcely disturb the calm. 

The universe, including man, was conceived as a system of tiny, indivisible particles, moving under their mutual interactions - either gravitational or electromagnetic in nature - and subject to the laws of Newton and Faraday-Maxwell. 

In other words, the universe was qualitatively finite at the atomic level. 

AS one eminent scientist of the day said - everything is perfect apart from ‘two small clouds’. 

The "small" clouds to which he referred led in 1900 to Planck’s quantum theory and in 1905 to the special relativity theory of Einstein! 

The theoretical and practical implications of their work challenged everything that had been considered fixed and settled. Together they dealt a heavy blow against the old conceptions of the nature of matter, space and time. 

The purpose of mechanics is to describe how bodies change their position in space with time. 

What is meant by the terms "position", "space" and "time"?

By position we mean "position relative to some rigid body of reference"; for ex- ample, we may fix the position of an aeroplane by a measurement of longitude, latitude and height. Here the reference frame is attached rigidly to the earth. 

With the advent of space travel, it will become more convenient to use one attached to the sun or even the galaxy. In other words, we are dealing with the spatial relationships of real, material bodies. 

For Newton, "it is the non-material space between the bodies which is basic: ‘Absolute space, in its own nature, without relation to anything external, remains always similar and immovable’ (‘Mathematical Principles of Natural Philosophy’ - 1687)."

Absolute space is therefore conceived of as a canvass (reference frame) against which bodies move without interaction. 

Absolute time 

Newton’s view of absolute time is consistent with this: 

"Absolute, true, and mathematical time, of itself, and from its own nature, flows equably without relation to anything external, and by another name is called duration."

Time is related here to the ticking of some cosmic clock, rather than emerging as a quantitative measure of the development of material processes. 

Until the end of the last century, the question: "Where is the absolute frame of reference?" or, equivalently, "How fast is the earth moving relative to absolute space?" was not decisive as far as scientific practice was concerned. 

In the first place, the earth’s rotation has a negligible effect on most terrestrial scientific activity and therefore a reference frame, fixed to the earth, proved as adequate as the elusive absolute frame. 

Secondly, no constant velocity of the earth relative to absolute space can be detected by any experiment. 

This is embodied in the principle (not the theory) of relativity which can be stated as follows: 

"The result of an experiment performed on a station platform is the same as the result obtained in a train moving along a straight track at constant speed." 

For example, an observer on the train who releases a stone from his hand sees it fall to the floor in a straight line, just as if he were standing on the platform. 

Of course, an actual platform observer would see the train observer’s stone travel in a curve, a parabola. Coupled with the relativity principle is the theorem of Galileo concerning the addition of velocities. This simply states that a man walking at five miles per hour along the corridor of a train travelling at 60 mph appears to be moving at 65 mph to an outside, stationary observer. Such a "commonsense" result could hardly be questioned - or could it?

Conflicted

  After 200 years of Newtonian supremacy, the develop- ment of electromagnetism pro- duced a law that conflicted with Newton and Galileo. 

It was shown by Lorenz that the speed of light is always the same (in a vacuum), whether or not the light-emitting body is moving. 

To see the significance of this, let us speed the train up to one mile per second and attach a lamp to the front. As the speed of light is 186,000 miles per second (mps), the outside observer should see the beam travelling at 186,001 mps. 

However, according to the new law, he actually measures a velocity of 186,000 mps! The impossibility of resolving this contradiction within the philosophical framework laid down by Newton constituted one of the "small clouds" that marred the scientific horizon until 1905. 

In overcoming this impasse, Einstein embarked on an examination of space and time measurements from a materialist standpoint. 

Both absolute space and absolute time are rejected, together with the old law of addition of velocities. Einstein concludes that "every reference- body has its own particular time." 

The nonsensical statement that 186,000 mps equals 186,001 mps is now made meaningful by rendering it concrete: 186,000 miles per train-second equals 186,001 miles per platform second. Time as measured on the moving train moves’ more slowly than it does on the stationary platform. 

Expressed in this way, the problem seems to have been resolved through sleight of hand. However, Einstein shows in a simple experiment how relative time-scales are linked to the relative motion of the observers.

How do two observers, in motion relative to each other, synchronize their clocks? 

Suppose that the stationary clock ticks once every second and with each tick emits a flash of light. An observer moving away at constant velocity adjusts the ticks of his clock to correspond to the arrival of the light signals. 

"Discrepancy"

Because of the motion each consecutive signal has further to travel before being detected. 

Therefore, a second for the moving observer is greater than a second for the stationary observer. 

There is no way in which the ‘discrepancy’ can be detected, because such detection would presuppose the existence of a process transmitting faster than light. 

Such a process has not as yet been discovered and certainly could not be described by the theory of relativity in its present form. 

Einstein’s theory led to a reformulation of the laws of mechanics - a more precise reflection of objective reality. However, this did not mean that Newton’s laws were not "true" and could be scrapped. The development of quantum theory and relativity revealed the conditional and limited nature of Newtonian theory and, in so doing, enriched our understanding of it. 

Provided that we remain outside the atomic domains (distances of the order of a millionth of a centimetre) and deal with speeds which are small compared with the speed of light, then classical theory suffices.

For example, even for a train moving at 1 mps, that is, 3,600 miles per hour, the difference in the hour is only a fiftieth of a second. 

Practically, relativistic effects only become important (on earth) in the realm of elementary particles, which can attain velocities comparable with that of light because of their infinitesimal masses. 

The theory of relativity reveals time and space as a unity inextricably linked with material processes. 

It not only embraces the gains made by Galileo and Newton, but reveals new qualities of matter. 

Probably the most important is that mass and energy become interchangeable - mass can give rise to energy and vice versa. 

This is the principle behind the creation of new fundamental particles and the possibility of nuclear oblivion. 

We can understand this in the following way.

A force acting on a body produces an acceleration, which (according to Newton) will, after a time, give the body a speed greater than that of light. 

Relativity theory rules this out by ‘automatically’ increasing the mass of the body with speed and, therefore, making it more and more difficult to accelerate. 

It is in this way that there emerges the famous formula: E=mc^2 (energy equals mass, multiplied twice by the speed of light). 

The attack on Einstein came mainly from those who praised this achievements. At all costs the materialist core of his theory had to be obscured, along with Einstein’s continuity with and break from Newton. 

No longer true 

Dr Hermann Bondi, in his book "The Universe at Large", has this to say: 

"In spite of the enormous number of cases where Newton’s theory has been correct, it is no longer regarded as true in any sense; but we know from its close agreement with Einstein’s theory that, except for a few very small details, (!) Newton’s theory will give the same answers as Einstein’s."

"As Newton’s theory is much simpler mathematically, we go on using it as a useful tool of astronomical work, not as something we believe true in any sense of the word" (pp. 19-20). 

Here empiricism runs rife. Physical theories are collections of facts, devoid of all qualitative aspects or reducing them to "a few small details." 

If it works, use’ it - if it doesn’t, it isn’t true. 

On page 18, Dr Bondi is more explicit: 

"It is never any good in science to cry for the fullest information. We have never got it. One always has to do with what we have and make the best of the job in hand at the moment." 

Empirical 

In admiring Einstein, Bondi renders him superfiuous. Other physicists had approached some of Einstein’s results in an empirical way, from the standpoint of adapting Newton to the new developments in science.

This can, of course, give "the right answers" by continually avoiding theory and relying on "rules of thumb." 

The present stage of the theory of elementary particles is now coming more and .more to rely on such "rules," albeit of a very sophisticated and mathematically complex nature. 

As we have attempted to show, Einstein transcended Newton in developing physical theory from a materialist standpoint. 

The implications of his general theory and Einstein’s philosophical development will be dealt with in a further article.

 "WHAT’S the time?" 

We look at wrist watches and give the answer, confident that we are correct within an error of a few minutes. If we want to check this, we either switch on the radio, have a look at Big Ben or telephone the speaking clock. 

We would then, in fact, be referring to time as measured out by an atomic clock, driven by the process of decay of a suitable radioactive element - a process relatively unaffected by external factors, such as traffic vibrations or temperature changes, which disturb our "everyday" time-pieces. 

Even Big Ben itself runs slightly fast (except on the hour) because of the weight of its minute-hand! 

It is the extremely weak interaction of the atomic clock with its environment that gives us confidence in its "correctness." 

We seem to be approaching Newton’s absolute time which, "from its own nature, flows equably without relation to anything external." 

Such considerations make it all the more difficult to abandon the concept of absolute time and raise the question: "Do moving clocks really slow down or is this an illusion suffered by the stationary observer?" 

Firstly, time and process cannot be separated. In his "The Meaning of Relativity" (1922), Einstein insists on this: 

"In order to give physical significance to the concept of time, processes of some kind are required which enable relations to be established between different places. It is immaterial what kind of processes one chooses for such a definition of time. This holds for the propagation of light in vacuo in a higher degree than for any other process ... From all these considerations, space and time data have a physically real, and not merely a fictitious, significance." 

MATERIAL 

Einstein’s relativity, therefore, deals not with abstract time-measurements but the effect of motion on physical processes. 

We are obliged to drop the concept of the ‘impartial’ observer and to recognize that a real, materia] observer, movingwith a real, material clock, is subject to the same effect and cannot detect the relativistic changes. 

However, light signals received by a stationary observer reveal the changes. 

Although not strictly analogous, this situation arises even in classical physics. 

If we stand near a railway track, the pitch of a train whistle drops as the train goes past, while for a passenger the pitch remains constant. 

Returning to our atomic clock, experiments have shown that the process of radioactive decay is also subject to the relativistic effect. 

Such material emits charged particles which produce ‘clicks’ on a Geiger counter. 

If the material is attached to the rim of a disc which is then rotated at high speed, the average time between clicks increases during motion away from the counter, in accordance with relativity. 

So we can be confident that the launching of Big Ben into space from its Westminster pad - apart from chalking up a notable space first for Britain - would cause the clock to run slow (except for those MPs occupying the building at blastoff). 

The introduction of a material observer must not therefore be interpreted as meaning that physicists are dealing with "subjective" phenomena. Objective reality does not disappear with absolute space and time. 

Einstein himself, while developing his theories from the most searching criticism of Newton’s system, took up a Kantian position on physical theory.

On the first page of his "The Meaning of Relativity" he explains his philosophical position: "The object of all science... is to co-ordinate our experiences and to bring them into a logical system. How are our customary ideas of space and time related to the character of our experiences?"

After 1916, this outlook led him to a theoretical impasse, as we shall see later, both in the development of relativity and quantum theory. 

An individual's experiences - sense data - are taken as the main items of scientific research and the question: "What is the relationship between sense data and the real world?" is never asked or is considered meaningless. 

What is therefore placed in doubt is the existence of a material universe, independent of men and their thoughts. 

Experiences become "things in-themselves", to be juggled about and fitted together in a plausible way. 

The development of Marxism has taken place precisely in opposition to such conceptions. 

In "Feuerbach and the End of Classical German Philosophy", Engels explains the relationship between thought and the real world. 

"In what relation do our thoughts about the world surrounding us stand to this world itself? Is our thinking capable of the cognition of the real world? Are we able in our ideas and notions of the real world to produce a correct re- flection of reality?...

There are those philosophers who question the possibility of any cognition, or at least any exhaustive cognition, of the world. To them, among the more modern ones, belong Hume and Kant... 

The most telling refutation of this as of all other philosophical crotchets is practice, namely, experiment and industry.

If we are able to prove the correctness of our conception of a natural process by making it ourselves, bringing it into being out of its conditions and making it serve our own purpose into the bargain, then there is the end to the Kantian ungraspable 'thing-in-itself'...

If, nevertheless, the neo-kantians are attempting to resurrect the Kantian concep- tion... this is ... scientifically a regression and practically merely a shamefaced way of surreptitiously accepting materialism, while denying it before the world." 

Einstein’s mass-energy relationship, a qualitatively new aspect of matter predicted by his special theory of relativity, received its most spectacular confirmation in the conscious construction of the first atomic weapon. 

Henceforth, no-one could disagree that Einstein’s theory (at least the special theory) was talking about "real things." 

Forty years separated the publication of Einstein’s original paper and the destruction of Hiroshima in 1945. 

In the intervening years, thousands of scientists and mathematicians worked on his theory, yet it was Einstein himself who made the next major step forward in 1916. 

It was in this year that he published his General Theory of Relativity - a theory of gravitation. 

Einstein’s re-examination of space and time, which led to the special theory, had rejected Newton’s conception of absolute space and time, yet he realized that in many ways it remained inadequate and as limited as Newtonian theory. 

SPECIAL

If "the result of an experiment performed on a station platform is the same as the result obtained in a train moving along a straight track at constant speed" - the principle of relativity in both Newton’s theory and Einstein’s special theory - the question arises: 

"Why are we restricted to a straight track or a constant speed? In other words, why are we restricted to special frames of reference?" 

Conversely, if we are restricted in this way, what determines which frames are which? 

Paraphrased, Einstein argues as follows: 

“We can think of no cause for this preference for special observers, unless we say that this isa property of space-time. In which case, we have rejected Newton’s absolute space and time for an absolute space-time which determines material processes." 

Einstein, correctly, rejected this as unscientific and demanded that the principle of relativity be extended to any observer. 

At first sight, this seems ridiculous. Surely, no-one is going to be convinced that they are still standing on solid ground when, in fact, they are riding on a roller-coaster? 

In a way, Einstein does precisely this and in so doing developed a theory of gravita- tion, in which matter and motion became inseparably linked. 

THE CONCEPTS of "mass" and "energy" are basic to any system of mechanics...but what are they? 

In the first case, it used to be said that "mass is quantity of matter." Such a definition seems circular and makes sense only if all matter were made up of identical atoms and we could simply count their number in any given body. 

One body would then have twice the mass of another if it contained twice the number of atoms. 

PHYSICAL 

However, above all, this definition in no way indicates how the concept of mass arose from man’s practice, from scientific experimentation, as a quantitative measure of a real, physical quality. 

Mass emerged as a measure of inertia, that is the property of a body to resist changes in its motion. 

It is easier to throw a pebble than to move a boulder; a lorry requires a large force to deflect it from its path, while a football changes direction hundreds of times during a soccer match. 

This property of inertia, independent of other properties, such as temperature and shape, gave rise to the concept of inertial mass. 

But if matter is essentially inert, what motivates matter - what is the "impelling power"? 

The reply of physics is - energy. This can take many forms - the thermal energy of a hot body in the process of melting or burning; the kinetic energy of a body in the process of motion; the potential energy of a wound spring driving a clock mechanism. 

Energy is usually represented in physics as a non- material, "something" whose endless transformations underlie all physical processes; a non-material entity whose association with inert matter is responsible for physical change. 

Marxists seek no cause external to matter in accounting for its motion. Matter is selfmotivated. Matter includes not only the quality of inertia, but also an opposite quality -  "motivity" or "impelling power" - measurements of which define quantities of energy. 

In other words, energy is the quantitative aspect of matter’s general and inherent tendency to be active. 

The dialectical unity of motivity and inertia is expressed in the numerical equivalence of mass and energy, in accordance with Einstein’s equation: energy equals mass multiplied twice by the velocity of light. 

This does not mean that mass and energy are "identical." 

Rather, motivity and inertia are dialectically opposed physical qualities, mutually transformable in accordance with Einstein’s equation. 

Transformations of inertia into motivity and vice versa take place in every chemical reaction (such as the burning process) but, in these cases, changes of mass are extremely small. 

"ANNIHILATION" 

However, within the modern particle-accelerators, the socalled "annihilation" of matter and the "materialization" of energy is commonplace and easily detectable. 

The special theory of relativity was therefore a triumph for the dialectical materialist conception of matter in motion. 

Einstein’s equation (in mathematical form) expresses the equivalence of the physical quantities, mass and energy. 

To the formalist and idealist, this exhausts the relationship - the form is taken for the content, the unity and opposition of qualities, motivity and inertia. 

In Newton’s world, particles moved in empty space acted on by forces external to them. Mass is divorced from (nonmaterial) energy. 

IMMEDIATE

In particular, astronomical bodies influence each other at a distance through the force of gravity, completely separated by empty space. 

This "action at a distance" is instantaneous. 

According to the Newtonian theory of gravitation, if I lift my little finger, I change the distribution of mass in this part of the universe and, immediately, the farthest stars change their courses in a predictable way. 

Einstein’s theory rules out instantaneous action at a distance. If the maximum speed for signals is that of light, then lifting my little finger will not affect the sun for eight minutes, the time taken for light to travel 93 million miles. 

During the eight minutes, "something" is travelling between the earth and the sun - energy. 

Empty space is therefore replaced by a real gravitational field, a region of energy. Inertia and motivity are reunited. 

However, gravity has an unusual property. If we release two unequal stones from the same height, they hit the floor at the same time. The force of gravity will differ for the two stones (that is, they have different weights), yet their accelerations are the same. 

This may be expressed by saying that the stones have different gravitational masses.

KEY 

What is surprising is that the most refined measuring techniques to date have failed to detect any difference between the gravitational mass of a body and its inertial mass.

Newton simply accepted this as a fact and talked about "mass." For Einstein, this "principle of equivalence" became the key to his general theory of relativity.

  Just as the constancy of the speed of light led to the special theory and mass-energy law, so the principle of equivalence was to lead to a general theory of gravitation. 

Einstein hoped that this would also resolve the problem of "special observers", discussed in our last article. 

Mach, at the later part of the 19th century had already put forward the proposition that such observers were naturally selected by the gravitational effects of the distribution of matter in the universe. 

In other words, we got our inertial bearings from the stars in a very real sense and this neatly explains why the "star sphere" which we see when we stargaze is fixed. 

If "Mach’s Principle" were correct, then the rotating heavens would automatically carry our "fixed" frames round with it and no one would know the difference! 

MATERIAL 

The main point about ‘Mach’s Principle’ is that it proposes a material solution to the problem of the special observer rather than attribute the phenomenon to the properties of empty space. 

This was the attraction of "Mach’s Principle" for Einstein himself, who saw it as a natural extension of his relativity. 

Yet before he could return to the special observers, they had to be discarded. Which brings us back to the rollercoaster. 

So shut your eyes, enjoy the ride and think of the principle of equivalence. Now, where are you? 

To be continued.