THE LEADING EDGE by Phillip E. Johnson
Out from the Ether
Sometime in the 1990s, I read Einstein's Cosmos by theoretical physicist Michio Kaku, which described Einstein's science in the context of events in his life. Particularly fascinating was Kaku's account of the state of physics in the decade prior to 1905, when Einstein's Special Theory of Relativity set the discipline in a new direction.
When nineteenth-century physicists learned that light traveled through space in waves, they assumed that the waves must travel in a medium, just as ocean waves travel in water. Physicists called this hypothetical medium "ether," and, according to Kaku, attributed bizarre properties to it. The ether became an almost mystical substance. It was supposed to be absolutely stationary, weightless, invisible, with zero viscosity, yet stronger than steel. Then, in 1887, physicists Albert Michelson and Edward Morley performed a brilliantly designed experiment to determine the properties of ether by observing its effect on a beam of light.
Scientists believed that, as the earth moved through the ether in its orbit around the sun, it generated an "ether wind." It seemed to follow that a light beam that traveled in the direction of the earth's motion would travel faster than a beam moving at a right angle to the earth's direction of motion.
To test this hypothesis, Michelson and Morley designed an experiment in which an apparatus split a light beam into two parts, one moving in the same direction as the earth and the other moving across that path. When mirrors reflected the two beams back to the starting point, they should have been out of sync, with a resulting interference pattern. To the scientists' astonishment, they found that, no matter in which direction they pointed the apparatus, there was no interference, indicating that the two beams always moved at the same speed.
Kaku explained what this meant:
A Quick Fix
This analysis of the dilemma left by the unexpected result of the Michelson-Morley experiment misrepresents Copernicus's conclusion: while the astronomer did write that the earth moves around the sun, he did not say that there is "nothing special" about the location of the earth; some scientists have simply assumed that this philosophical doctrine is implied by his conclusion that the earth is a planet that moves like other planets.
Nevertheless, I found it remarkable to read that, as late as 1887, it seemed that a stationary earth might be worth considering. No physicist actually did consider that possibility, as far as I know—possibly because it would be intolerably humiliating to science, and would imply that the hated Catholic Church might have been correct in disputing Galileo's endorsement of the heliocentric theory.
Instead, established scientists tried to explain the baffling Michelson-Morley result by giving new properties to the ether. The Dutch physicist Hendrick -Lorentz and the Irish physicist George Fitzgerald postulated that the earth, in its passage through the ether, was physically compressed by the ether wind; thus, the apparatus measuring the light beam traveling in the same direction as earth would also be slightly compressed.
The ether, which already had the near-mystical properties of being invisible, non-compressible, extremely dense, and so on, now had one more property: it could mechanically compress atoms by passing through them. This would conveniently explain the Michelson-Morley result. In this picture, the speeds of the two light beams were different, but you could neither observe nor measure the difference, because every time you tried, the measuring apparatus would shrink in the direction of the ether wind by precisely the right amount.
Lorentz and Fitzgerald independently calculated the amount of shrinkage, yielding what is now called the Lorentz-Fitzgerald contraction. Michio Kaku reports that neither Lorentz nor Fitzgerald was pleased with this result, sensing that they had only provided a "quick fix" to patch up a fading system of Newtonian mechanics.
An Elegant Theory
The world of physics was in need of a theory that would clear up the problems left by the Michelson-Morley experiment in a way that constituted a great advance for science, rather than a retreat or quick fix. Einstein provided that theory in 1905, with his Special Theory of Relativity, and soon the obscure patent-office clerk became recognized as a giant of science. Kaku explains,
Then, writes Kaku, in a "masterful stroke,"
It seems strange that a formula, the Lorentz-Fitzgerald contraction, devised as an ad hoc quick fix to prop up a fading ether theory, should persist after science had turned to an elegant theory providing a new picture of space and time. This persistence makes me wonder how much the scientists really needed relativity.
I have heard that many scientists working today with quantum mechanics do not trouble themselves about whether their theory describes "the way things really are," as long as its equations provide correct answers to the problems that concern them. I wonder what the effect would have been if physicists had taken that attitude in 1905.
Like everyone else, I stand in awe of Einstein's achievements. Even so, I suspect that his words will not be science's last on the speed of light. This is partly because I find the logic of special relativity opaque and confusing. But I also find it hard to accept that the universe has an absolute speed limit, particularly when that limit is derived from a principle called relativity.
I suppose that my fascination with Einstein stems at least in part from my understanding that science is not a static body of established facts, but a dynamic process of speculation and investigation that undergoes periodic revolutions. These revolutions are sometimes sparked not by highly credentialed members of the inner group of established experts, but by an outsider, like a patent-office clerk, who insists on challenging the assumptions that influential scientists hold.
In that vein, I like to imagine that imagination itself is often the most neglected of scientific virtues, and that the best scientists are those who want to give unfashionable ideas a fair hearing, and thus a fair chance to change the world's thinking.
When I re-read Einstein's Cosmos this spring, I was struck by Kaku's story of how Einstein went through an intense period of religious devotion at age 11, which he dropped abruptly after concluding that the biblical miracles were incompatible with science. Kaku writes:
That seems a strange mixture of ideas. If the universe contains whole realms beyond the reach of science, why should the Bible's miracles be judged by the conventions of early-twentieth-century science? And isn't the human mind, including the mind of Einstein, with powers that go far beyond anything needed for survival and attracting mates in the wild, a miracle in itself?
Phillip E. Johnson is Professor of Law (emeritus) at the University of California at Berkeley. He is the author of Darwin on Trial, The Wedge of Truth, The Right Questions (InterVarsity Press), and other books challenging the naturalistic assumptions that dominate modern culture. He is a contributing editor of Touchstone.
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“Out from the Ether ” first appeared in the July/August 2012 issue of Touchstone. If you enjoyed this article, you'll find more of the same in every issue.
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