By the end of the nineteenth century scientists were faced with a contradiction in physics that seemed to throw into question all of Newtonian physics, including Newton’s first law of motion, based on Galileo’s principle of relativity.
It was Einstein who successfully resolved these contradictions into an entirely new physics at the turn of the twentieth century, laying the basis for an entirely new cosmology.
One of the great questions of the late nineteenth century was what medium light waves travelled through. Termed aether, this medium was thought to be an absolute frame of reference, a medium that was stationary with respect to the universe. A large number of experiments were conducted to try to detect it.
Scientists thought that, if light was transmitted through the aether at a definite speed, as the earth moved in its elliptical orbit through the same medium, the speed of light from a particular source should appear to vary over the course of twelve months.
For instance, imagine a distant star that the earth happens to travel first towards and then away from as it orbits the sun each year. As the earth travels towards the star, meeting the starlight from the star, Newtonian physics supposes that the starlight will appear to be travelling faster than six months later, when the earth’s orbit takes it speeding away from the same starlight.
The same measurement conducted as the earth rushed away from the starlight should find the speed of light to be slower, because the star light was catching up the earth – like the difference between a head-on collision and a bump from behind. The car speeds may be the same but the consequences of a head on collision are far worse. Newton’s theory suggests a difference of roughly sixty kilometres per second between these two measurements.
In 1887, Albert Michelson and Edward Morley conducted a famous experiment to detect the aether. But they failed to measure any difference in the speed of light travelling from any direction, irrespective of the motion of its source. Their ‘null result’ was shocking and unexpected. The aether did not appear to exist but, more importantly, the experiment confirmed what James Clerk Maxwell’s theories seemed to suggest: that light propagated at the same speed irrespective of any motion, either of the source or the measuring device.
Light appeared to break Galileo’s principle of relativity. It refused to obey Newtonian physics. The speed of light is invariant regardless of the motion of the observer or the light emitting source – for instance, light does not appear to us to go faster if it emerges from a star moving rapidly towards us or slower from a star receding from us. Light from a star is red-shifted if a star is moving away from us, and blue shifted if it is moving towards us, because the wavelength of the light is lengthened towards the red end of the spectrum or shortened towards the blue. The length of the light waves change, but the speed that the waves travel through space remains the same. The speed of light is not relative to the motion of any frame of reference. Light always appears to be going at the same speed to all observers – that is to say, to all measuring devices, all frames of reference.
The experiment, and many others like it since, established as objective fact this peculiarity of the motion of light, which simply did not fit in to the seemingly orderly and common sense Newtonian view of the world. Needless to say, Woods does not recognise this seminal failure of Newtonian physics.
As a result of many experimental results, but particularly the 1887 Michelson and Morley experiment which was far more accurate than any made before, Einstein commented:
Prominent theoretical physicists were therefore more inclined to reject [Galileo’s] principle of relativity, despite the fact that no empirical data had been found that were contradictory to this principle. (Relativity, p19)
In 1903, the physicist Hendrik Lorenz produced an equation, termed the Lorenz transformation, which offered a mathematical expression for measuring motion based on the results of the Michelson-Morley experiment, taking this aberrant behaviour of light as its basis. The unusual result of this equation was that length shortens in the direction of motion and time slows too – a result Lorenz was not at all happy about. Einstein adopted the Lorenz transformation, but rejected the undetectable aether, for which there was no evidence.
By 1905 Einstein had pieced together the theory of relativity, which could explain the null result of Michelson-Morley. He was able to derive the Lorenz transformation equation directly from considerations based on rejecting two false assumptions made by Newtonian physics in relation to Galileo’s principle of relativity. For Newtonian science, motion was relative, but the motion of objects took place on a stage which was assumed to be comprised of absolute space and time. Einstein re-examined Galileo’s principle of relativity, and removed these assumptions.
Let us return to the train and the pedestrian of Einstein’s popular exposition of relativity, written in 1916. The train is one frame of reference, which is moving with respect to the other, the footpath on the embankment, where a pedestrian watches a stone fall from a window of the train.
We must note again in passing – what should by now be obvious to the reader – that the notion of an ‘observer’ (the pedestrian in this case), is a common technique used in scientific literature to communicate in accessible form the physics which, in scientific terms, may be expressed by a measurement taken from the stated system of coordinates (frame of reference), and so forth. There is no requirement for an actual observer – the truth of both Galileo’s results and those of Einstein remain valid even if no human being ever walked the earth. It is not necessary for Woods to sarcastically object: “Presumably, if there is no observer, there is no time!” (p215) The presumption is wrong and absurd.
Einstein’s considerations described here never wander from the objective to the subjective, from experimental evidence to speculative philosophy. Rather the opposite. The reader can check this by examining Einstein’s original 1905 paper, On The Electrodynamics Of Moving Bodies, at http://www.fourmilab.ch/etexts/einstein/specrel/www/ . This is the paper which proposed the theory that became known as the special theory of relativity.
Let us return to Einstein’s popular exposition. The passenger on the train drops a stone. Einstein points out that the train passenger and the pedestrian do not see the stone falling simultaneously. Here is the oversight of Galileo-Newtonian physics, inevitable in their day. Light must travel from the stone to the observers (or measuring instruments). Furthermore, the Michelson-Morley experiment had confirmed the peculiar nature of light’s propagation between the two frames of reference – the speed of light is constant and is not affected by the fact that the train is in motion.
Let us spend two paragraphs giving a slightly more detailed exposition of this question. In The Elegant Universe, Brian Greene provides an excellent example of Einstein’s crucial critique of Newtonian physics’ assumption of simultaneity, which reduces itself to this: imagine a light is switched on in the middle of a carriage of the train, at an equal distance between two passengers at either end of the carriage, one at the front, and one at the rear. The light strikes both passengers simultaneously, as measured by atomic clocks in the carriage, since the train carriage is their stationary frame of reference and light has an equal distance to travel. But the train is moving as viewed from the platform. Viewed or measured from the platform, the light appears to strike the passenger at the rear of the carriage first, because from the point of view of the platform, he is moving forwards towards the light.
Here is where the strange properties of light come in. Measured from the platform, the light has further to go to reach the passenger at the front of the carriage since the train is moving, again as measured from the frame of reference of the platform. And the speed of light remains constant no matter which frame of reference you are in (rather than having an additional speed as a result of the motion of the train, according to the observer on the station). Since the passenger at the front of the train has travelled further from the light, and the passenger at the rear has travelled towards the light, the distances the light has to travel, from the point of view of the platform, are different, and so it strikes the two passengers at different times. Simultaneous events in time in one frame of reference (the train) are not simultaneous with respect to a different frame of reference (the platform). Time and space are different on the moving train, as observed from the platform.
Newtonian assumption of absolute time exposed
After discussing this, in a key passage in his popular exposition of relativity, Einstein comments:
Now before the advent of theory of relativity it had always been tacitly assumed in physics that the statement of time had an absolute significance, i.e. that it is independent of the state of motion of the body of reference. But we have just seen that this assumption is incompatible with the most natural definition of simultaneity; if we discard this assumption, then the conflict between the law of propagation of light in vacuo [in a vacuum] and [Galileo’s] principle of relativity disappears. (Relativity, p27)
The assumption of Newtonian physics that “time had an absolute significance”, which Einstein exposes as a false assumption, is precisely that which Woods ardently defends.
Woods attacks “the subjectivist interpretation of time, which makes it dependent on (‘relative to’) an observer. But time is an objective phenomenon, which is independent of any observer.” (p215) This muddled position consists firstly of an attack on a ‘straw man’: a misrepresentation of Einstein’s relativity as a form of subjective idealism – a misunderstanding which was all too common among popular commentators in the first half of the last century. Secondly, Woods’ comments are also a clear defence of absolute time, which has no material basis. Reason in Revolt is mired in a swamp of such mistakes and misapprehensions.
Time is objective, of course, but has no meaning independent of a specific frame of reference. The modern scientific concept of time is not the “product of a definite philosophical point of view, smuggled in under the banner of ‘relativity theory’.” (p215) Rather, the idea of absolute time is an ideal which originates with Newton’s belief in god, and which was hidden in the preconceptions of the measurement of motion dating back to René Descartes. Woods is incorrect to continue: “You see, for time to be ‘real’, it needs an observer, who can then interpret it from his or her point of view.” This has no bearing on relativity, and in any case bears no relation to the viewpoint of science of the last four centuries. It is a complete misunderstanding of scientific shorthand.
|Aristotle||Absolute||Absolute||Finite||Infinite||Denied actual infinite|
|Galileo||Relative||Relative||Finite (assumed)||Infinite (assumed)||Showed paradoxes of infinite|
|Newton||Absolute||Absolute||Infinite||Infinite||God as infinite|
|Einstein||Relative||Relative||Finite*||Finite*||‘Only two things are infinite, the universe and human stupidity, and I’m not sure about the former’.|
Einstein showed that between the two frames of reference, the train and the embankment, the Lorenz transformation provided a set of equations that could relate them objectively to one another so that one could express the motion of the stone falling from the train as viewed from the embankment – in long-hand, as measured according to the frame of reference of the embankment – in a way consistent with all known physical observations, but with astonishing results.
In essence, Einstein began by returning to Galileo’s principle of relativity, but stripped of the idealist notions of time that Woods embraces. Then he entered into the equations the newly discovered enigmatic properties of the constant speed of light. The result was a new theoretical understanding of the physical nature of time and space.
While many aspects of Einstein’s special theory of relativity were soon proven, it was thirty-six years before the first experiment (1941) that measured ‘time dilation’, and sixty-six years before the definitive experiment (1971) which we discussed in the chapter, Galileo and the relativity of space. Einstein had shown that time on a moving train passes more slowly than time on the embankment, just as the Lorenz transformation seemed to imply. Einstein can assert that when measured from the embankment, “as a consequence of its motion the clock goes more slowly than at rest.” (Einstein, Relativity, p37)
The difference in the times measured in each case is so small that only if the motion of the train and clock was near to the speed of light would it be noticeable, without the aid of atomic clocks. This theory, along with the general theory of relativity, was proven experimentally in 1971 using atomic clocks on a passenger airplane. Further, the moving train appears to shorten slightly, as viewed from the embankment, since it was “shorter when in motion than at rest, and the more quickly it is moving, the shorter” it gets. (Einstein, Relativity, p35) Again, this shortening is completely beyond our experience (and so inevitably strikes us at first as a little absurd), since the train at normal speeds would shorten very considerably less than the width of an atom.
Einstein’s theory of relativity could reconcile all experimentally proven aspects of reality. Indeed, other forgotten anomalies (or contradictions) which could not be explained by Newtonian concepts of absolute space and time, such as the anomalous path of the planet Mercury, were later resolved by Einstein’s general theory of relativity which, as Woods admits, predicted Mercury’s path far more precisely on the basis of the new understanding of the warping of space-time.
The science of the atom bomb
The Lorenz transformation, adopted by Einstein, included the peculiar properties of light discovered by the Michelson-Morley experiment. In consequence, the speed of light, denoted by ‘c’ (or more precisely, the speed of light squared, c2), appears in Einstein’s equations.
Einstein followed his 1905 paper, which introduced special relativity, with a short paper in the same year that showed a formula could be derived from the equations of special relativity: the famous e = mc2 – “energy equals mass multiplied by the speed of light squared”.
Since the speed of light is determined by a distance in space over a certain time, the equation shows the complete link between energy, mass and space and time. Breathtakingly, Greene emphasises: “The combined speed of any object’s motion through space and its motion through time is always precisely equal to the speed of light.” (The Fabric of the Cosmos, p49)
Woods correctly endorses Einstein’s e = mc2, but without understanding its derivation or implication.
To common sense the mass of an object never changes… Later this law was found to be incorrect. It was found that mass increases with velocity… The predictions of special relativity have been shown to correspond to the observed facts. (p152)
Woods cannot avoid endorsing the formula that explains and gave rise to the atom bomb.
Motion through space-time affects mass-energy. The two are inextricably linked. Space and time, mass and energy, in our universe become an integral whole. It seems to follow that if the mass and energy of our universe have an origin, so does space-time, and one arrives back (on a higher level) at Aristotle’s discussion of the origins of the universe. For Aristotle, outside of the universe – where there is nothing, no universe, as reference – there is no space and time. And if the heavens are corruptible, and have come into being and will pass away, so will the space-time of our universe. (This is not to speak of causes, of a substratum from which the universe arose, but of the relationship between space-time and mass-energy in our existing universe.) Of course, Aristotle, as we have said, thought that the heavens were unchanging and not corruptible.
But Woods cannot accept that time is relative to the observer, nor understand that this is an objective, not a subjective, fact of life, an aspect, for instance, of the everyday use of satellite navigational aids. He writes:
The question is whether the laws of nature, including time, are the same for everyone, regardless of the place in which they are and the speed at which they are moving. On this question, Einstein vacillated. At times, he seemed to accept it, but elsewhere he rejected it.
Einstein, under the influence of Ernst Mach, treated time as something subjective, which depended on the observer, at least in the beginning… (p168)
Neither statement is true.
Woods pours scorn on the application of Einstein’s relativity in modern science, calling it “subjective idealism”.
[The] empty abstraction Time, envisaged as an independent entity which is born and dies, and generally gets up to all kinds of tricks, along with its friend, Space, which arises and collapses and bends, a bit like a cosmic drunkard, and ends up swallowing hapless astronauts in black holes. (p216)
But this satire rebounds on Woods. He appears to contradict himself. He endorses e = mc2 despite the fact that it is derived from a theory that he rejects and ridicules. Woods asserts that “mass increases with velocity” yet rejects the concept of the relativity of space and time which underlies this discovery. Woods appears to be unaware of the physics. The careful reader of Reason in Revolt will discern that Woods sometimes attributes the relativity of time to Einstein’s later general theory of relativity, which he denigrates, and does not recognise that it is integral to Einstein’s special relativity, which Woods associates with the formula e = mc2.