“There was a young lady named Bright
Whose speed was faster than light;
She set out one day
In a relative way
And returned home the previous night.”
(A. Buller, Punch, 19 December 1923)

As with quantum mechanics, relativity has been seized upon by those who wish to introduce mysticism into science. “Relativity” is taken to mean that we cannot really know the world. As John Desmond Bernal explains:

It is, however, equally true that the effect of Einstein’s work, outside the narrow specialist fields where it can be applied, was one of general mystification. It was eagerly seized on by the disillusioned intellectuals after the First World War to help them in refusing to face realities. They only needed to use the word ‘relativity’ and say ‘Everything is relative’, or ‘It depends on what you mean’.[40]

This is a complete misinterpretation of Einstein’s ideas. In point of fact, the very word “relativity” is a misnomer. Einstein himself preferred the name invariance theory which gives a far better idea of what he intended – the exact opposite of the vulgar idea of relativity theory. It is quite untrue that for Einstein, “everything is relative”. To begin with, rest energy (that is, the unity of matter and energy) is one of the absolutes of the theory of relativity. The limiting speed of light is another. Far from an arbitrary, subjective interpretation of reality, in which one opinion is as good as another, and “it all depends how you look at it,” Einstein “discovered what was ‘absolute’ and reliable despite the apparent confusions, illusions and contradictions produced by relative motions or the action of gravity.”[41]

The universe exists in a constant state of change. In that sense, nothing is “absolute” or eternal. The only absolute is motion and change, the basic mode of existence of matter – something that Einstein demonstrated conclusively in 1905. Time and space, as the mode of existence of matter are objective phenomena. They are not merely abstractions or arbitrary notions invented by humans (or gods) for their own convenience, but fundamental properties of matter, expressing the universality of matter.

Space is three dimensional, but time has only one dimension. With apologies to the makers of films in which it is possible to “go back to the future”, it is only possible to travel in one direction in time, from the past to the future. There is no more danger of a spaceman returning to earth before he was born, or of a man marrying his great grandmother, than there is of any of the other amusing but idiotic fantasies of Hollywood. Time is irreversible, which is to say, every material process develops in only one direction – from the past to the future. Time is merely a way of expressing the real movement and changing state of matter. Matter, motion, time and space are inseparable.

The shortcoming of Newton’s theory was to regard space and time as separate entities, one alongside the other, independent of matter and motion. Up till the 20th century, scientists identified space with a vacuum (a “nothing”), which was seen as something absolute, that is, always and everywhere the same, changeless “thing”. These empty abstractions have been discredited by modern physics, which has demonstrated the profound relation between time, space, matter and motion. Einstein’s relativity theory firmly establishes that time and space do not exist in and of themselves, in isolation from matter, but are part of a universal interrelation of phenomena. This is conveyed by the concept of the integral and indivisible space-time, of which time and space are seen as relative aspects. A controversial idea here is the prediction that a clock in motion will keep time more slowly than one that is stationary. However, it is important to understand that this effect only becomes noticeable at extraordinarily high speeds, approaching the speed of light.

If Einstein’s general theory of relativity is correct, then the theoretical possibility would exist in the future of travelling unimaginable distances through space. Theoretically, it would be possible for a human being to survive thousands of years into the future. The whole question hinges upon whether the changes observed in rates of atomic clocks also apply to the rate of life itself. Under the effect of strong gravity, atomic clocks run slower than in empty space. The question is whether the complex interrelations of molecules that constitute life can behave in the same way. Isaac Asimov, who knew a thing or two about science fiction, wrote:

If time really slows down in motion, one might journey even to a distant star in one’s own lifetime. But of course one would have to say good-bye to one’s own generation and return to the world of the future.[42]

The argument for this is that the rates of living processes are determined by the rates of atomic action. Thus, under strong gravity, the heart will beat more slowly, and the brain impulses will also slow down. In fact, all energy diminishes in the presence of gravity. If processes slow down, they also take longer in time. If a space-ship were able to travel close to the speed of light, the universe would be seen flashing past it, while for those inside, time would continue as “normal”, i.e., at a much slower rate. The impression would be that time outside would be speeded up. Is that correct? Would he in fact be living in the future, relative to people on earth, or not? Einstein seems to answer in the affirmative.

All kinds of mystical notions arise from such speculation – for example about hopping into a black hole and entering another universe. If a black hole exists, and that is still not definitely proven,* all that would be at the centre would be the collapsed remains of a gigantic star, not another universe. Any real person who entered it would be instantly torn apart and converted into pure energy. If that is what is considered as passing into another universe, then those who advocate such ideas are most welcome to make the first excursion! In reality, this is pure speculation, however entertaining it may be. The whole idea of “time-travel” inevitably lands one in a mass of contradictions, not of dialectical but of the absurd variety. Einstein would have been shocked at the mystical interpretation of his theories which involve notions such as shuttling back and forth in time, altering the future, and nonsense of that sort. But he himself must bear some responsibility for this situation because of the idealist element in his outlook, particularly on the question of time.

Let us grant that an atomic clock at a high altitude runs faster at high altitudes than on the ground, because of the effect of gravitation. Let us also grant that, when this clock returns to earth, it is found to be, say, 50 billionths of a second older than equivalent clocks which had never left the ground. Does that mean that a man travelling in the same flight has equally aged? The process of ageing is dependent upon the rate of metabolism. This is partly influenced by gravitation, but also by many other factors. It is a complex biological process, and it is not easy to see how it could be fundamentally affected either by velocity or gravitation, except that extremes of either can cause material damage to living organisms.

If it were possible to slow down the rate of metabolism in the way predicted, so that, for example, the heart-beat would slow to one every twenty minutes, the process of ageing would presumably be correspondingly slower. It is, in fact, possible to slow down metabolism, for example, by freezing. Whether this would be the effect of travelling at very high speeds, without killing the organism, is open to doubt. According to the well-known theory, such a relativistic space-man, if he succeeded on returning to earth, would come back after, say 10,000 years, and to pursue the usual analogy, would presumably be in a position to marry his own remote descendants. But he would never be able to return to his “own” time.

Experiments conducted with subatomic particles (muons) indicate that particles travelling at 99.94 per cent of the speed of light extended their life by nearly thirty times, precisely as predicted by Einstein. However, whether these conclusions can be applied to matter on a larger scale, and living matter in particular, is an issue that remains to be seen. Many serious mistakes have been made by attempting to apply the results derived from one sphere to another, entirely different, area. In the future, space-travel at very high speeds – maybe one-tenth of the speed of light – may become possible. At such speed, a journey of five light-years would take fifty years (though according to Einstein, it would take three months less for those travelling). Will it ever be possible to travel at the speed of light, thus enabling human beings to reach the stars? At this moment in time, such a prospect seems remote. But then, a hundred years ago – a mere blink in history – the idea of travelling to the moon was still confined to the novels of Jules Verne.

  1. Bernal, J. Science in History, pp. 527-8.

  2. Calder, N. op. cit., p. 13.

  3. Asimov, I. op. cit., p. 359.

  4. suggests that black holes do exist, and are to be found at the center of galaxies. Their massive gravitational attraction appears to be what holds galaxies together. For obvious reasons, little is known about this phenomenon. However, it is clear that at the heart of black holes there is an enormous concentration of matter. See Alan Woods’ introduction to the second edition.