james_nicoll ([info]james_nicoll) wrote,
@ 2007-11-19 10:18:00
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Speaking of dogs at the opera
Everyone seems to be exited about Garrett Lisi's An Exceptionally Simple Theory of Everything but I don't have the background to understand it or its implications.

Warning: pdf

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Pshaw!
[info]tsm_in_toronto
2007-11-19 04:11 pm UTC (link)
They all laughed at me when I came up with my Grand Unified Theory of Small Partial Hypotheses ... laughed at me, I say! They said I was MAD! Fools! I'll show them [evil cackling laughter, as Tesla coils zap away in the background ...]

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Re: Pshaw!
[info]james_nicoll
2007-11-19 04:13 pm UTC (link)
Well, at least Lisi's model can be tested, which is more than one can say for a lot of the string theories.

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Re: Pshaw!
[info]bpholden
2007-11-20 12:12 am UTC (link)
Well, at least Lisi's model can be tested, which is more than one can say for a lot of the string theories.

Really? How can it be tested? I mean, has anyone calculated anything from it yet?

The only new number I have seen, on page 26, is that the cosmological constant should be up there with the Higgs, which is ridiculously large as compared to what we measure. (Overpredicting the cosmological constant has a long tradition.)

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[info]andrewducker
2007-11-19 04:16 pm UTC (link)
Bst description I've seen so far is this:
http://science.slashdot.org/comments.pl?sid=362251&cid=21373411

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[info]kowh
2007-11-19 04:49 pm UTC (link)
Another take on it: http://arstechnica.com/news.ars/post/20071117-upon-further-review-surfers-new-theory-of-everything-severely-deficient.html

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[info]mrbankies
2007-11-19 05:10 pm UTC (link)
Interesting. Seems fair and unbiased.

When this first broke, I read an article (no idea where, lost the link) where part of what was being discussed in the bashing of Lisi's approach was that there would be criticism towards it that would be politically motivated - ie string theorists criticizing Lisi's work because it wasn't string theory.

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[info]derekl1963
2007-11-19 08:45 pm UTC (link)
Fair and unbiased? The blog article they link to is from a string theorist. Emphasizing that he is a surfer, then giving a backhanded apology at the end by blaming someone else? The guy they thank for providing the meat of the post explaining how Lisi must be a crank because a string theorist doesn't like him, and because he is 'outside of the mainstream'?

I have no dog in this fight, but I'd hate to see what you consider 'unfair and biased'.

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[info]mrbankies
2007-11-19 09:51 pm UTC (link)
well, first off I'll state that I didn't know the article was written by a string theorist. When I said 'unfair and biased' it didn't seem to me that he wasn't just bashing the guy for something to do, and was at least attempting to give Lisi's ideas a fair shake. I push bits for a living and am nothing remotely approaching a physicist. My understanding of theoretical physics amounts to a) it's a theory, and b) they're trying to prove something that's way above my head.

Personally, I'd like to see Lisi's work be validated. It also doesn't surprise me that he's being put down because he's a surfer with a pHd in physics rather than a physicist who likes to surf.

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[info]kowh
2007-11-19 10:27 pm UTC (link)
At the moment the main criticism of it should really be that it hasn't been peer reviewed. What he does with his time otherwise is irrelevant.

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[info]mmcirvin
2007-11-20 02:16 am UTC (link)
I generally like Chris Lee's articles on the physics beat, and the heuristic of not trusting New Scientist is sound, but I think he dropped the ball here, albeit in a very understandable way given the oddities of this case.

After I saw that on Ars Technica, I wondered if I had just been had, and went back and looked at Lisi's paper again to see if the kinds of elementary mathematical errors claimed (adding scalars to vectors and such) were really there, and I couldn't find them, though I could see places where you might think they were there if you weren't used to the kind of notation that field theorists use. On the other hand, it's quite possible that I'm missing something.

The criticism he links to is not just from any string theorist, it's from Lubos Motl, who is...how shall I put this...well-known to be strident in his criticisms of any approach to unification other than string theory, as well as on...many other subjects.

As for the paper itself, from my semi-educated perspective, it seems like there are a bunch of interesting ideas in there but the theory isn't fully fleshed out. It would be a serious exaggeration to pronounce some sort of Holy Grail achieved. On the other hand, it's not just crackpot nonsense. As I've said elsewhere, it seems more crackpotty than it is because the author is something of an outsider and uses chatty prose and lots of colorful diagrams in a way that is uncharacteristic of this kind of paper. But he's not what Martin Gardner would call a "hermit scientist"; he's building on established work.

Of course, it's getting a lot of public attention both because Theories of Everything are sexy and because of the author's personal story. It's the old thing Richard Feynman used to grumble about when he was described as the bongo-playing physicist, that he didn't understand why, in the papers, playing the bongos humanized him but doing physics didn't.

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[info]mayaknife
2007-11-20 11:33 am UTC (link)
The criticism he links to is not just from any string theorist, it's from Lubos Motl

When you compare Lisi's calm, friendly and thoughtful posts to Motl's ad hominem vitriol, the latter comes out looking like the crank.

Although I can't understand more than a word in 10 of Lisi's paper I do like how he handles his critics. He admits that this is just the very tip of a theory and that it's gotten so big (e.g. those massive calculations that someone else here mentioned) that he's opened it up to see if others can help.

I also think that the title of the paper is somewhat off-putting for those who don't understand the double-pun it contains.

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[info]armb
2007-11-19 05:22 pm UTC (link)
Nor me, but the animated pictures are pretty.
Incidentally, if you were a bright 11 year old whose father had finally got around to cancelling his New Scientist subscription and made vague noises about teaching you to use an RSS aggregator instead, where would you be looking for science news?

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[info]kowh
2007-11-19 07:32 pm UTC (link)
I find http://arstechnica.com/journals/science.ars to be a decent news and first critical reaction source.

For a slightly different focus, http://www.aip.org/pnu/ is often quite interesting. It's focused on physics, but often reports on novel developments from other disciplines. As it's aimed at those with a scientific background it may be a bit too technical, but because it doesn't assume that you're familiar with the particular specialties involved it's usually fine for the interested armchair scientist as well.

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[info]sharp_blue
2007-11-19 08:23 pm UTC (link)
UnNews's coverage seems shockingly close to the real news story. The scary thing is that almost the whole paragraph by Lubos Motl at the end is made up of things he actually said, and not really taken out of context either.

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[info]derekl1963
2007-11-19 08:51 pm UTC (link)
The implication is that the much sought 'theory of everything' may not be as complicated as everyone thought. (I.E. the road not taken.)

Much of the criticisim to date seems to come from a) the string theory community whose rice bowl will be well and truly shattered if this turns out to be true (or even a start down the path), and b) folks who object to the producer of the theory not fitting the 'button down mind' stereotype of the physicist.

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[info]mindstalk
2007-11-19 11:14 pm UTC (link)
Seems like it trades the complication of multiple dimensions, hard to calculate, for the complication of an extremely complicated symmetry group, hard to calculate.

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[info]derekl1963
2007-11-20 12:47 am UTC (link)
But in making that trade you get something valuable - testable predictions, and give away something nearly valueless - untestable theories.

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[info]mmcirvin
2007-11-20 02:28 am UTC (link)
Yeah, and with this kind of approach you always have the problem that a lot of arbitrariness gets not so much eliminated as swept under the rug by sticking it into the symmetry-breaking Higgs sector.

Also, it has the characteristic that a lot of papers on this sort of thing have, that it's being advertised as unifying gravity with the other forces, when it doesn't really even claim to make a stab at solving all the problems of quantizing gravity--it just has some degrees of freedom and a thing in its Lagrangian that look like general relativity. So even if it turned out to be correct, there would be a lot of work left before you could honestly say "Einstein's dream has been achieved!"

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