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Friday, September 30, 2005

Evolutionary Ether

I am often told that, regarding the debate about some topic, the scientific community nearly universally supports one side of the debate. The implication is that the side of the debate endorsed by that amazing brain trust that is the scientific community is certainly correct and that the other side likely consists of unenlightened and misguided Neanderthals.

However, for this implication to be valid, it seems to me that it requires that when the scientific community nearly universally endorses a theory or some position in a debate, that they are always right. Conversely, if scientists have unanimously and passionately endorsed theories in the past that later turned out to be completely, absolutely wrong, it seems to me that subscribing to the scientific community's viewpoint without question, while automatically rejecting opposing viewpoints, especially when there is no absolute proof one way or the other, is not necessarily reasonable or fair.

For amusement, consider the following excerpt regarding the "luminiferous ether" from Quantum Reality: Beyond the New Physics, by Nick Herbert, pages 5-7:
In 1864 Scottish physicist James Clerk Maxwell discovered the basic equations that govern electricity and magnetism. To everyone's surprise these phenomena turned out to be two aspects of a single entity - the electromagnetic field. Today physicists are seeking for a way to unify all of nature's fields. Maxwell was the first physicist to show that the task of field unification is not futile.

A theorectical bonus which Maxwell reaped from his fusion of two fields into one was the discovery that waves in his electromagnetic field traveled at the same speed as the measured velocity of light. On the basis of this numerical coincidence, Maxwell conjectured that light, in reality, was an electromagnetic vibration at a particular frequency. The experimental production by Heinrich Hertz of low-frequency electromagnetic radiation (radio waves) which were identical in all respects save frequency to light confirmed Maxwell's bold conjecture.

All known waves vibrate in some medium (such as air or water). The medium in which light presumably travels was dubbed the "luminiferous ether." Late nineteenth-century physicists gave top priority to research into the ether's mechanical properties. Maxwell described the subject of this research in these words: "Whatever difficulties we may have in forming a consistent idea of the constitution of the ether, there can be no doubt that the interplanetary and interstellar spaces are not empty but are occupied by a material substance or body, which is certainly the largest, and probably the most uniform body of which we have any knowledge."

From light's well-known attributes one could infer many of this hypothetical ether's properties. For instance, since light travels so fast the elasticity of the ether must be enormous, millions of times more resilient than the hardest spring steel. Since light is a transverse wave - vibrating sidewise rather than back and forth - the ether must be a solid. Gases and liquids can support only back-and-forth vibrations (sound is an example), while solids transmit both kinds of vibration (earthquake waves, for example, vibrate in all directions). The fact that light vibrates only sidewise (no back-and-forth light has ever been observed) had to be explained by complex structures in the ether which suppressed altogether this otherwise natural back-and-forth vibration but which permitted sidewise vibrations to propagate with extreme rapidity.

Although the universe was filled with a transparent "glass" much harder than steel, this glass offered not the slightest resistance to the passage of material bodies. The Earth's motion was seemingly unaffected by the presence of the luminiferous ether. Some physicists proposed that the ether might act like a solid for rapid motions such as light, but like a fluid for slow motions, such as planets, in the manner of certain waxlike solids with deformation-rate dependent viscosities. In modern terms, such a hypothesis amounts to assuming that the universe is filled brim to brim with a kind of Silly Putty.

In 1887 two American physicists performed a simple experiment whose purpose was to determine the velocity of the Earth through this ever present vibrating solid. Albert Abraham Michelson and Edward Williams Motley set up a kind of optical racetrack that pitted a light beam moving north and south between parallel mirrors against an east/west beam. Depending on the direction of the "ether wind," one or the other of these beams had the track advantage and was sure to win. The result of the Michelson-Morley experiment was always a photo finish. Despite the enormous velocity of the Earth through space, a velocity that constantly changes its direction during the year, the two experimenters could detect no movement whatsoever of the luminiferous ether past the Earth.

Michelson and Morley's failure to detect the "ether wind" led physicists to propose that massive bodies such as the Earth trap the ether and carry it along with them. However, attempts to detect this "ether drag" near massive rotating bodies in the laboratory were unsuccessful. Ether drag should also distort the apparent positions of distant stars, an effect which was also noticeably absent.

To explain the failure of Michelson and Morley to detect an "ether wind," even more preposterous effects were invoked. Dutch physicist Hendrik Antoon Lorentz and Irish physicist George Francis FitzGerald independently proposed that motion through the ether resulted in a tiny contraction of all physical bodies in the direction of motion. The Lorentz-FitzGerald contraction - a kind of "ether squeeze" - could not be directly observed, because measuring rods also supposedly shrank when oriented in the ether wind's direction. The sole function of the Lorentz-FitzGerald contraction was to even the odds in the Michelson-Morley optical racetrack: the light beam that would have lost the race, by virtue of the L-F contraction would now travel a shorter path, and consequently both beams would reach the finish line at precisely the same time. This hypothetical "ether squeeze" was a desperate attempt to save appearances by loading the already peculiar ether with yet one more unusual attribute.

Although its properties grew more preposterous with each new investigation, the existence of the ether itself was never called into question. One of England's leading physicists, the eminent William Thomson, Lord Kelvin, expressed physicists' general attitude a few years after the Michelson-Morley experiment when he said, "One thing we are sure of, and that is the reality and substantiality of the luminiferous ether."

Despite physicists strong faith in the existence of the luminiferous ether, a few years after Lord Kelvin's profession of belief the ether was swept away into the junkyard of obsolete physical concepts in company with phlogiston, caloric, and the fabled philosopher's stone.
I had never heard of the luminiferous ether prior to stumbling upon the above passage and I wouldn't be surprised if you hadn't either. Scientists have no reason to go out of their way to publicize their embarrassing failures. Nonetheless, the acceptance of the luminiferous ether as fact survived for decades and was nearly universally endorsed by the scientists of that era.

The progression of knowledge demonstrated by this story is not uncommon. Theories are often constructed to explain existing data and have to be updated, modified, and/or extended as new information is discovered. For example, Darwin's theories of Natural Selection, Evolution, and Common Descent started out much simpler than they are today. Because Darwin's initial theories didn't match the fossil record, things like "punctuated equilibrium" had to be added to make the theories match the observations.

Indeed, to me, the evolution of the theories related to biological Evolution and Common Descent looks very similar to the evolution of theories concocted to explain observations related to the luminiferous ether. While I think that the theories of Evolution and Common Descent are probably more or less reflect deep reality, I have to admit that I probably would have been taken in by the luminiferous ether concept as well.

This realization has caused me to ask numerous questions. How do I know I'm right about Evolution and Common Descent when I would have been so ridiculously wrong about the luminiferous ether? How does anybody else really know? What's different this time? Why is it okay to dismiss out-of-hand those who think Common Descent is false as not even being worthy of debate? There are numerous other questions along these lines that could be asked as well.

Does anyone have any answers to these questions?

2 comments:

johnt said...

Bret, it's called following the herd. One of the reasons you have scientific breakthroughs is because everybody went along with everybody else. The claptrap about brave explorers for the truth ignores the arguments and resistance from other brave explorers. Much of the opposition to Gallileo came not from the Church,where he did have some supporters, but from the then scientific community,and this after Copernicus. Whether it's Kuhn,s paradigm shifts'Peirce's fallibilsm, or Poppers conjectures and refutations doesn't matter as much as some think. It may have been Feyerabend who said there is no single or valid overarching process. The man did write "Against Method" which I guess would place him,that book being somewhere in that chaotic mess I call a library. BTW,as you know we now have dark matter,son of Ether, to fill in for some trouble spots relating to mass and gravity. Don't know if my response is precisely connecting to your post but the bottom line is; you have a free mind,think freely. Don't worry about the new priesthood,they're to busy following the bandwagon and collecting their grants.

Bret said...

johnt,

Regarding "following the herd." I think that's partially it, but I think it's also that each incremental addition to the theories surrounding the luminiferous ether made sense. Prior to Maxwell's discovery, all waves required a medium, thus it was a small and sensible step to assume that electromagnetic waves would too. Everything else followed incrementally. In my younger days, before I became so skeptical, I would have fallen for it, not necessarily because of following the herd, but because it would've kinda made sense. That's why now, even when I "think freely" I don't necessarily assign a high probability to the conclusions I reach.

Regarding "worry about the new priesthood." The Left seems to buy their statements unquestioningly (they are, of course, part of the Left). I think that's hurting the Left badly, which in turn hurts the political discourse in the United States, which in turn hurts the country. I think that's worth worrying about.