Comments on: Weighty Spin

By: Mike M

Mike M — Tue, 29 Apr 2008 13:18:52 +0000

The only problem with asking a famous physicist is that he is unlikely to have ever traveled anywhere sufficiently relativistically to be in with a shot of whipping his ruler out to measure Lorentz contraction. Surely, more productive to seek the views of a cosmic ray muon, whom you would never have met at all if he hadn’t just “directly” measured the Lorentz contraction of the Earth’s atmosphere as it flew past him.

By: Neil B.

Neil B. — Mon, 28 Apr 2008 21:58:52 +0000

Well Mike et al, maybe we can gracefully wrap this one as follows: First, again, I was referring simply to whether Lorentz contraction had been “directly” measured in the strictest way as a matter of historical interest, not whether it needed to be to warrant our belief, whether practical or not, etc. Claims per se shouldn’t be harried over extraneous matters; such matters should be made as side points. As for whether interferometer measurements should count as “direct”: Sure, once we are assured of the Einstein postulate about light speed constancy. But as I said, the null result of the MM experiment could of course in principle have derived from Galilean behavior of light propagation. So, accepting interferometer results depends on “auxiliary assumptions”, warranted as they may be. It could be a matter of semantics in philosophy of science whether that can be called “direct,” maybe we can just say it’s a judgment call depending on how anal retentive one is.

In any case, here’s a quote from one of the top physicists in the field. He supports my position exactly and the situation hasn’t changed since then:

“It is an amazing fact that there does not seem to exist any direct or simple experimental verification of the Lorentz-Fitzgerald contraction. There is no reason whatever to doubt that the effect exists, precisely as called for by theory. So far, nevertheless, the difficulties – (1) of securing an object of appreciable length that moves with a speed comparable to that of light and, (2) of determining two events, one at either end, which are simultaneous for the observer – have proved insuperable. This very fundamental conclusion of the theory awaits actual proof.”

Albert Shadowitz, Special Relativity, 1968, p. 168 of Dover paperback.

By: Mike M

Mike M — Sun, 27 Apr 2008 17:50:57 +0000

It’s a shame that neither you nor Neil actually read what I wrote. If you had, you would see that I likened the requirement that one “directly” measure Lorentz contraction (a thing most people believe to be true) using a meter rule (a completely impractical way to make such a measurement) to testing the hypothesis that the Moon is not made of cheese (a thing most people believe to be true) “directly” by tasting it (a completely impractical way to make such a measurement).

Personally, I am happy to accept the measurements of spectrometers, etc, as the more appropriate way to measure the composition of the Moon and hence show directly that it doesn’t taste of cheese, just as I am prepared to accept interferometric measurements of distance as the appropriate way to measure directly the very small effects of Lorentz contraction in the laboratory.

The fact that no-one has used a meter rule to do so may well be true, but it is entirely uninteresting as using a meter rule to measure such a distance is no more “direct” a measurement than using interferometry, just as the fact that no-one has actually tasted Moon rock may well be true, but is uninteresting because tasting Moon rock is no more “direct” a measure of its cheesiness than using a mass spectrometer.

Was that spelled out explicitly enough this time?

By: andy

andy — Sun, 27 Apr 2008 15:59:43 +0000

hey Mike, maybe you should go and check for yourself if the moon is made of cheese. that would dissuade you of many things to believe in.

By: Neil B.

Neil B. — Sat, 26 Apr 2008 00:55:03 +0000

Heh – I said good argument, that’s what I was waiting to hear from anyone else. I’m not sure you’d know if it was rare for me to get that general point, whether intro- or extro- spection is the best spin on it.

By: Mike M

Mike M — Thu, 24 Apr 2008 21:19:13 +0000

I think we have a case here of people just wanting to keep on pounding their original line out of misguided stubbornness, vanity, or whatever even after a good argument has been made against their perspective. This is as unhealthy as it is dismayingly commonplace.

I congratulate you on a rare moment of insightful introspection.

By: Neil B.

Neil B. — Thu, 24 Apr 2008 20:37:29 +0000

PS – Of course you also forgot the theoretical basis for LC being good, but me just saying “We haven’t’ measured it directly” (and I keep saying, I don’t give a damn that we haven’t, I believe in it too but just want that admitted), versus the poor theoretical basis for saying the Moon is made of green cheese. So now are you going to argue with that too, just so you don’t have to ever concede to anyone?

By: Neil B.

Neil B. — Thu, 24 Apr 2008 20:35:04 +0000

Mike, the kind of physical-chemical analysis done of Moon rocks is of course “direct” – it doesn’t require human taste buds, good grief. I’ve made my case to the extent that any fair observer would concede the issue. I think we have a case here of people just wanting to keep on pounding their original line out of misguided stubbornness, vanity, or whatever even after a good argument has been made against their perspective. This is as unhealthy as it is dismayingly commonplace.

“What we’ve got here is a failure to communicate!” – the Boss from Cool Hand Luke

By: Sam Thornton

Sam Thornton — Thu, 24 Apr 2008 20:06:36 +0000

In exploring some links related to this article, I was brought by the commodious vicus of internet recirculation to a series of articles on fusion energy technology. Turns out the science and the basic engineering were solved in October 2006 by a Navy R&D project led by now deceased scientist, Dr. Robert Bussard, former Asst. Director of the Atomic Energy Commission. Although October 2006 marked the breakthrough, it also marked cancellation of the project by the Bush Administration, which needed the insignificant amount of further engineering development money for the Iraq War. Here's a link to a video of a talk about the project Dr. Bussard delivered to Google employees before he died. Here's a link to an interview he gave about the technology. How about it, Cosmic Variance? An article on this would be great.

By: Mike M

Mike M — Thu, 24 Apr 2008 10:04:44 +0000

I agree that no-one has ever done that experiment, because measuring such tiny differences is impractical using something as crude as a meter rule . Equally, no-one has ever demonstrated that the Moon is not made of cheese by seeing what Moon rock tastes like. After all, that’s certainly the direct way of doing it, and using mass spectrometers, chromatographs, etc, well that just leads to an indirect inference that the Moon doesn’t have at least a slightly cheesy flavor. Fortunately, it is in the nature of science that we accept such inference when the “direct” way of doing something is impractical.