## Thursday, August 21, 2014 ... /////

### David Gross: why do we have faith in string theory

David Gross has given lots and lots of vision talks at various string conferences but this time, in June 2014, he focused on string theory and the scientific method in his 21-minute-long vision talk:

At the beginning, he would enumerate five of his favorite talks, said that Andy Strominger's vision talk brought Gross almost to tears, and he finally concentrated on the explanations why the people in that Princeton room have faith in the theory despite some outsiders' opinions that they shouldn't.

(Paul Steinhardt, a speaker at Strings 2014 who has delivered some "strange" statements to the audience, was chosen as the only named prototype of the critics.)

String theory is a framework, not a specific theory making specific down-to-earth predictions about realistically doable or ongoing experiments that could decide about its fate, but David Gross recommended a very intelligent 2013 book by Richard Dawid, a trained physicist and a philosopher, that articulates rather nicely what the actual reasons for the competent physicists' faith in the theory are in the absence of those confirmed new down-to-earth predictions.

Incidentally, the rating and ranking of Dawid's book at amazon.com is catastrophic, especially if you compare them with some of the anti-physics tirades – a big enough piece of evidence that most laymen are just way too stupid and superficial regardless of the time some people are spending with licking these laymen's rectums. The rank that is worse than 1 million also indicates that no listener of Gross' talk has bought the book via amazon.com.

The three arguments that either instinctively or knowingly contribute to the competent physicists' faith and growing confidence in string theory are

• UEA: unexpected explanatory coherence argument. If the theory weren't worth studying, it would probably almost never lead to unexpected answers, explanations, and ways to solve problems previously thought to be independent
• NAA: no alternative argument. There's no other game in town. The argument has existed in the case of the Standard Model – in recent decades, NAA was getting increasingly important.
• MIA: meta inductive argument. String theory is a part of the same research program that includes theories whose success has already been established.
Gross has mentioned that these sentiments aren't really new. UEA has played a role for him when he became sure that asymptotic freedom in QCD was right: the asymptotic freedom idea automatically produced a bonus insight, the infrared slavery. String theory has produced dozens of similar "inevitable corollaries". He also sketches the developments that will occur soon. For example, supersymmetry is going to be observed in a few years at the LHC. (Laughter.) We're all waiting for this argument in favor of the MIA.

At the end, David Gross presented his theory of history that was especially addressed to the physicists who ever get depressed about anything. Things are always getting worse. But we know that in the long run, things are getting better. Why is it? The idea of Gross' explanation is more or less mathematically isomorphic to the "escalator", a meme about "how skeptics describe the temperature" and "what the temperature is actually doing" promoted by climate alarmist John Cook:

You see that the first derivative of the temperature is negative – the weather seems to be getting worse all the time. (The summer 2014 in Czechia has been said to be over, too.) But if you adopt these smooth monotonic decreasing pieces of the function, there are discontinuities, often or mostly positive ones, so the weather is getting better in the long run (it's sometimes called the global warming). Gross has applied the same idea to all of history. Things are getting worse but suddenly Jump, a big improvement.

Of course, Gross has made some sign errors – he counted the 2008 U.S. elections as an improvement, for example – but his overall performance was pretty good.

Unlike his predecessor and his spouse, Barack Obama doesn't even know what to do with a bucket of ice water.

#### snail feedback (19) :

The Amazon rating of Dawid's book seems to be based on two reviews that both complain about the price while neither has read the book.

No wounder no one buys his book. 90$for a 214 page...the world doesn't work like that Dawid. reader Rathnakumar said... "Dear alarmists such as Mr Holthaus, what about trying to spend another year by trying to work on yourself and fully understanding why you have been so fundamentally wrong for such a long time?" That will mean losing their lucrative jobs in the process. reader Ann said... I've been hearing a new phrase of late, 'climate weirdness'. The alarmist movement is becoming schizoid as their predictions and fears fail to materialize every which way they push them. Can't win by persuading people that everything is getting worrisomely warmer, and maybe 'change' is just too bland, so how about let's try 'weird'. The other big trope of 'save the planet' seems to be a modern replacement for 'save your soul'. Certain populations of fish probably need a rest from overly-efficient fishing, but those are specific conservation items, to be addressed point by point. On the other hand, 'saving the planet' is a vague, completely manipulative phrase used to push a policy agenda, not to promote scientific inquiry. Just as saving souls is also a policy agenda of religions. Seems to me the planet is doing fine, it's homo sapiens that are struggling with our own stupid and mean-spirited nature -- does not apply to all individuals for sure, but seems to apply to far too many. reader Robert said... These people are clearly bi-stable; it’s AGW, or Pascal’s Wager. This is a result of uncritical consumption of the Precautionary Principle, too much popular media, and a deep desire to emulate a bag of hammers. reader Luboš Motl said... Dear Mikael - and Grandfatherclock, there are things that may be gotten relatively cheaply, which may even include string theory textbooks, but there are products that are not that cheap. Chances are that if someone wants to study epistemology of string theory from the perspective of philosophy, then he will only get the rubbish if he's only willing to pay up to$30 per book. Sometimes paying \$90 is needed if someone wants to be exposed to something that is more than rubbish.

Unexpected explanatory coherence (UEC), no alternative argument (NAA), meta-inductive argument (MIA): of the three the first and the third strike me as the more important and the fact that they are both true has multiplicative as opposed to merely additive effect. Indeed, in their absence the no alternative argument (NAA) would look like special pleading, not unlike what we see among modern academic economists who employ calculus and other advanced mathematical techniques on the grounds that otherwise their discipline would scarcely exist. Or as Strominger put it more amusingly near the end of his talk, string theory is the only student in the class and if she fails the school will have to close its doors.

Anyway, I hope I can find a cheap copy of that book.

Hope you are right, for sure, Motl. But I can't think of a single scientific advance since the start, that by human creativity alone, with no checks, no corrections; just gorgeous little brains dreams dreamin', and got it right and produced the revolution.
If objective discovery was possible in that fashion it would have been going on speckled through history as isolated events of gorgeous creativity. Instead of what it is; a single event, comprising many components and straddled through time and space, consistently exponential in way of progress.
It seems that we need something else, not of dreams, to keep the even keel. Hope you're right though.

I have a review request for you to register, Motl, if you'll allow me. Only should it interest you naturally. But would you kindly consider the currently outside but getting noticed on an increasingly regular basis, human origins theory of a hybridization event involving apes and pigs.
If you do, please watch for the knee jerk; particularly alluring I should think, anything to push the ape pig love imagery.
But read the evidence for it. And the negatives attached to the incumbent assumption. Which explains nothing. l
Please do...I think that from a purely scientific perspective, the guy knock down has what should be the leading theory of our origins.

here it is

http://www.macroevolution.net/human-origins.html#.U-dMdCUg_IU

Dear Lubos,
I know which books you are talking about. But over the years with the help of this blog and some text books and also video lectures of institutes such as perimeter I feel that I do not need such a book so urgently anymore. In fact as somebody else pointed out if you could write such a (less philosophical) book as a reply to those other books and bring it on the market for 30 dollars or so I think it will be a big hit. In fact I would feel honoured to do some correction reading or perhaps the translation to German etc.

LOL. I was reading his name as "Hothaus" (house=haus in German) and thought the thing was an Onion spoof...no such luck.

"no alternative argument (NAA)"
What exactly are the reasons why string theory is the "only game in town", distinguishing it from all other approaches like loop quantum gravity, CDT, asymptotically save gravity, conformal gravity, just to name a few of them ?
The strange thing about this argument is that Gross says that string theory is not actually a theory but rather a framework, which would imply that it is the only framework (approach) to quantum gravity available. This doesn't make sense to me.

There was an extensive discussion between Smolin and Dawid in Sabine’s blog about it.

BTW have you seen this?

http://blogs.scientificamerican.com/cross-check/2014/08/21/quantum-gravity-expert-says-philosophical-superficiality-has-harmed-physics/

Observe the derogatory tone when he refers to String theory. It is frustrating really.

And since LQG is not a unified theory he tries cunningly enough to downgrade the importance of the quest for it.

There is no alternative to String theory as a unified framework of all fields and interactions (although in my opinion it is the only consistent theory of QG too so there is no alternative in that respect either).

A difference is that string theory 100% works while LQG and all the other "stuff" you mention 100% fails to work.

Lubos,
thanks a lot. This first hand feature list really helps to follow the debates.

Are you then characterizing string theory in terms of it being the most promising by far of what there is?
If that is so, the difficulty - maybe - is whether the criteria should be that, or a benchmark standard for science to be operable.
In the past, the absence of sufficient standard theory has generally resulted in science waiting for a sufficient standard to emerge before proceeding.
Every understood with Newton's theory the conception of a force in gravity was unsatisfactory. Newton backed it off to god, and science waited 300 years for a standard to come along.
So that's my question if you've the time. Does String theory meet the scientific standard? Absent predictions it feels like it would be hard to answer in affirmative.
Thanks