h-H comments on Open Thread: March 2010 - Less Wrong

5 Post author: AdeleneDawner 01 March 2010 09:25AM

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Comment author: h-H 04 March 2010 01:33:22AM *  4 points [-]

while not so proficient in math, I do scour arxiv on occasion, and am rewarded with gems like this, enjoy :)

"Lessons from failures to achieve what was possible in the twentieth century physics" by Vesselin Petkov http://arxiv.org/PS_cache/arxiv/pdf/1001/1001.4218v1.pdf

Comment author: arundelo 04 March 2010 02:36:51AM 2 points [-]

Neat find! I haven't read all of it yet, but I found this striking:

It was precisely the view, that successful abstractions should not be regarded as representing something real, that prevented Lorentz from discovering special relativity. He believed that the time t of an observer at rest with respect to the aether (which is a genuine example of reifying an unsuccessful abstraction) was the true time, whereas the quantity t of another observer, moving with respect to the first, was merely an abstraction that did not represent anything real in the world. Lorentz himself admitted the failure of his approach:

The chief cause of my failure was my clinging to the idea that the variable t only can be considered as the true time and that my local time t must be regarded as no more than an auxiliary mathematical quantity. In Einstein's theory, on the contrary, t plays the same part as t; if we want to describe phenomena in terms of x , y , z , t we must work with these variables exactly as we could do with x, y, z, t.

This reminds me of Mach's Principle: Anti-Epiphenomenal Physics:

When you see a seemingly contingent equality - two things that just happen to be equal, all the time, every time - it may be time to reformulate your physics so that there is one thing instead of two. The distinction you imagine is epiphenomenal; it has no experimental consequences. In the right physics, with the right elements of reality, you would no longer be able to imagine it.

Comment author: wnoise 04 March 2010 01:57:21AM *  2 points [-]

I generally prefer links to papers on the arxiv go the abstract, as so: http://arxiv.org/abs/1001.4218

This lets us read the abstract, and easily get to other versions of the same paper (including the latest, if some time goes by between your posting and my reading), and get to other works by the same author.

EDIT: overall, reasonable points, but some things "pinging" my crank-detectors. I suppose I'll have to track down reference 10 and the 4/3 claim for electro-magnetic mass.

Comment author: Mitchell_Porter 04 March 2010 04:50:49AM *  3 points [-]

overall, reasonable points

I disagree. I think it's a paper which looks backwards in an unconstructive way. The author is hoping for conceptual breakthroughs as good as relativity and quantum theory, but which don't require engagement with the technical complexities of string theory or the Standard Model. Those two constructions respectively define the true theoretical and empirical frontier, but instead the author wants to ignore all that, linger at about a 1930s conceptual level, and look for another way.

ETA: As an example of not understanding contemporary developments, see his final section, where he says

While string theory has extensively studied how the interactions in the hydrogen atom can be represented in terms of the string formalism, I wonder how string theory would answer a much simpler question – what should be the electron in the ground state of the hydrogen atom in order that the hydrogen atom does not possess a dipole moment in that state?

I don't know what significance this question has for the author, but so far as I know, the hydrogen atom has no dipole moment in its ground state because the wavefunction is spherically symmetric. This will still be true in string theory. The hydrogen atom exists on a scale where the strings can be approximated by point particles. I suspect the author is thinking that because strings are extended objects they have dipole moments; but it's not of a magnitude to be relevant at the atomic scale.

Comment author: wnoise 04 March 2010 06:48:02AM 3 points [-]

Of course he looks backwards. You can't analyze why any discovery didn't happen sooner, even though all the pieces were there, unless you look backwards. I thought the case study of SR was quite illuminating, though it goes directly counter to his attack on string theory. After getting the Lorentz transform, it took a surprisingly long time to for anyone to treat the transformed quantities as equivalent -- that is, to take the math seriously. And for string theory, he says they take the math too seriously. Of course, the Lorentz transform was more clearly grounded in observed physical phenomenon.

I completely agree he doesn't understand contemporary developments, and that was some of what I referred to as "pinging my crank-detectors", along with the loose analogy between 4-d bending in "world tubes" to that in 3-d rods. I don't necessarily see that as a huge problem if he's not pretending to be able to offer us the next big revolution on a silver platter.

Comment author: Cyan 04 March 2010 02:43:30AM *  2 points [-]

the 4/3 claim for electro-magnetic mass

Wikipedia points to the original text of a 1905 article by Poincaré. How's your French?

Comment author: wnoise 04 March 2010 03:02:43AM 2 points [-]

Thanks. It's decent, actually, but there's still some barrier. Increasing that barrier is changes to physics notation since then (no vectors!).

Fortunately my university library appears to have a copy of an older edition of Rohrlich's Classical Charged Particles, which may help piece things together.

Comment author: Cyan 04 March 2010 03:26:46AM *  2 points [-]

Petkov wrote:

Feynman [wrote], ”It is therefore impossible to get all the mass to be electromagnetic in the way we hoped. It is not a legal theory if we have nothing but electrodynamics” [13, p. 28-4]; but he was unaware that the factor of 4/3 had already been accounted for [10]).

It's worth noting that Feynman's statements are actually correct. According to Wikipedia, the problem is solved by postulating a non-electromagnetic attractive force holding the charged particle together, which subtracts 1/3 of the 4/3 factor, leaving unity. Petkov doesn't explicitly say that Feynman is wrong, but his phrasing might leave that impression.

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