Smolin's Response to review by Joe Polchinski

[marcus]

Stick to the book. Where in the book does he talk about this?

..I don't think other members should be required to duplicate your library to participate in this...

I think we know where we stand with you now. The topic is an exchange between Polchinski and Smolin about the latter's book, which I gather most of us venturing to comment here have read. You seem unfamiliar with it.

Your bickering constitutes a useless distraction, have to put you on ignore, sorry.

 

[josh1]

I've repeatedly tried to engage the people in this thread on it's topic. But rather than taking me up on it and putting their money where their mouth is, they post one personal attack on me after another.

I think we know where we stand with you now.

Where is that exactly? In strong disagreement with whoever you meant by "we"?

...have to put you on ignore...

What you'll really do is what you always do which is to respond to my posts only in exchanges with other members but never with me. This kind of provocative behaviour is against the PF posting guidelines and I shall be reporting all such posts.

On the other hand, perhaps you really mean it, in which case I expect my opinions in relation to your posts will meet no opposition, at least from you. But whatever the case, one way or another, as with everyone else, you will be held accountable for your posts.

 

[f-h]

All we ever hear about here are the problems with string theory and the “successes” of lqg.
[\QUOTE]

Where do you hear that? At the University where I studied (one of the top Universities in Germany) some people were roughly aware of the existence of LQG. But you certainly didn't hear about it's successes. The only speaker during my time there who spoke about LQG was Herman Nicolai.

On this forum? Yes. I think that's simply because there's a much larger deficit for this then for String Theory.

Or do you complain that Smolins point are not reported fairly and sensationalized in the media? In other words, are you answering to Smolins points or to the media image of Smolins points?

The latter is what Woit got famous for. He spends most of his time fighting the media image of String Theory.

smolin said that the time limit he had in mind was something like ten years. So if you haven’t produced a theory that makes predictions etc by then, you should move on. Thus smolin says that time has run out for string theory. But does he say anything about LQG? Nope. This lack of balance looks even more hypocritical when you look at the relative complexity of string theory versus lqg.

LQG as used here is not a theory it's a conglomerate of vaguely related or philosophically sympathetic theories. The original LQG ideas are today mostly pursued by Thiemann, most everone else has moved and tried different ideas and theories.

You are also ignoring the fact that LQG was pursued for ten years by a very small number of people, and that new results (not revolutions, incremental results) chipping away at theproblems have been and are coming.

The complexity of String THeory seems to me to be purely mathematical, compared to that, the approaches pursued in the LQG community are varied and physically/philosophically much more sophisticated.

You say that the majority of QG people are convinced that by searching these mathematical complexities they will eventually (incidentally?) arrive at the physical subtlties. Correct? But is there any evidence of that?

And that is an appealing thing in LQG, and the reason I chose to study it. If you look at the things Carlo Rovelli for example has worked on, these insights (relational formulations, local particle concepts, etc.) will by neccesity play a role in the final theory. They arise out of a straightforward combination of GR and QM!

Much of the LQG type research is pursued in this spirit. So in fact the time spans have been much shorter.
And it is this spirit that I think Smolin is asking for. Instead of looking for physics in the mathematical complications of one particular approach, as fascinating as they may be, it might be prudent to look at other approaches to do physics. Or at least acknowledge them.

What has become clear again is that you have not at all investigated the spirit and ideas of the LQG community. I have until this post refrained from commenting on String Theory because I do not have the knowledge in the field to judge it scientifically. By neccesity this is the case for all beginning researchers. We have to go by the arguments that have been made to us.

Therefore my ire at your intial post josh. Your double standard circular logic (study it and you will see) and the refusal to take other ideas serious and deeply study them are irritating. And you will have to accept that the consensus that String Theory is the most promising road to QuantumGravity is not universal, that it's something people can seriously disagree about.

From there on maybe we can have a discussion about WHY different backgrounds in physics lead to different perspectives on the promise of different approaches.

 

[f-h]

Gee the tone of the discussion sure got more civil while I was typing that...

 

[marcus]

a lot of that is really well expressed f-h, material for a good essay
I will pull out some exerpts to look at

LQG as used here is not a theory it's a conglomerate of vaguely related or philosophically sympathetic theories. The original LQG ideas are today mostly pursued by Thiemann, most everone else has moved and tried different ideas and theories.

... LQG was pursued for ten years by a very small number of people, and ... new results (not revolutions, incremental results) chipping away at the problems have been and are coming.

... purely mathematical, compared to that, the approaches pursued in the LQG community are varied and physically/philosophically much more sophisticated.

You say that the majority of QG people are convinced that by searching these mathematical complexities they will eventually (incidentally?) arrive at the physical subtleties. Correct? But is there any evidence of that?

...an appealing thing in LQG, ... If you look at the things Carlo Rovelli for example has worked on, these insights (relational formulations, local particle concepts, etc.) will by necessity play a role in the final theory. They arise out of a straightforward combination of GR and QM!

there are other good points too, I just want to take a careful look at these (which aren't part of any local quarrel, they stand on their own interest)
I've served as an editor---sometimes for pay sometimes as volunteer if I liked the article---in technical/scientific writing.
If you ever want some volunteer editing on an overview piece like this---ask me. I might say no, but could well say yes.
the thing I get is clarity and personal honesty, and a strategic point of observation: as a PhD student in the midst of rapidly changing situation.

I like the combination you say "physical/philosophical". At some points in physics history a fully physical intuition was required to also be philosophical and deal with questions like how do we know and what is an observer and what is space actually, what is time?. E.g. the intuition underlying 1905-1915 revolution was not just physical but depended on being able to ask philosophically sophisticated questions and follow out the consequences. You already know all this and can say it your own way better but I put it in for other readers.

 

[marcus]

Gee the tone of the discussion sure got more civil while I was typing that...

I noticed the decibels got lower, and maybe it got more thoughtful as well.
I want to throw out an idea that has to do with the underlying geology or plate techtonics of the situation. (not the local PF, the international science picture)

This is just speculative. I think, or maybe I should ask others do you think that the leadership in administering and funding research programs is shifting to Europe?

The whole art of directing and supporting research is, well, an art. In a long varied career I've worked for NAS (national academy on a bunch of studies advising congress and the NSF) and knew some of the people and got a feel for how the scientific establishment worked at that level. I think NSF and DOE used to be real good at allocating research support. I think NAS committees used to give real smart advice. I respect the US high science establishment the way it was several decades back---longer than I can comfortably acknowledge.

Now I am getting the feeling that Europeans have become more INSTITUTIONALLY INVENTIVE and somehow it is getting smarter than the US in how they place their bets, and how they invest their research Euros, and how they organize it.

The people I knew and heard reasoning together in DC committees would not have let the present situation happen. I can only infer that the people who have replaced them must be less perceptive and more sheep-like. Or if not, then some other key factor has changed.
QG-wise, nothing of much physical interest happening at several prestige US universities and a shift of activity and excitement to upstart Perimeter and Penn State. (Penn State?)

=======
So one of the ways I view Smolin's book is that it tries to say in MORAL terms what the Europeans seem to be figuring out on pragmatic grounds.

He distills a lesson from why science has succeeded for 400 years since Bacon, and says it is partly because of a certain (open discussion empiricist) ethic and qualities like fairness, good faith between opponents, acceptance of consensus fairly arrived at. If US scientific establishment leaders would accept these ETHICAL arguments----which sounds a little Utopian---then perhaps this would eventually translate into creative changes in policy and the flourishing of physics theory we all so wish.

And the book does present policy ideas, practical suggestions which are supported by the ethical reasoning about what has historically made science succeed.
Basically a diversified theory research portfolio with more autonomy for the postdoc with a proven track record. Funding to the proven individual regardless of what direction their research takes---support for creative individuals rather than quotas for dominant programs.

Maybe Perimeter Institute was the testtube where he arrived at these notions or demonstrated to his own satisfaction that they were right. Perimeter seems to work splendidly.

But I see the Europeans doing things like setting up the QGQG research network with John Barrett in charge (and Hermann Nicolai) and it suddenly dawned on me that they aren't doing it for moral reasons. On the contrary as I imagine it, they see that the US scientific establishment has gone stagnant in the theory department, and that this is their chance to GET AHEAD and seize the initiative from the US if they are just a little bit more alert and inventive as administrators than their US counterparts.

So it is the old sailboat race picture that comes to mind. Who has the research program administrators who are just a little bit better at reading the wind and the waves and a tiny bit better at plotting a course. And they want to see the next generation of Nobels, because they think too many have been Americans.

I hope you will tell me gently if this is completely off track.

 

[francesca]

The remarks by smolin against "group think" (or whatever) have always been made by people who think they've been unfairly marginalized and are uninteresting to me from a physics point of view.

Knowing personal histories is often worth in order to understand the development of physical ideas, to understand why we use some concepts now instead of others... as it was for Leibniz and Newton, it's now for QG and Stringy people
(well, I don't thing it would be a good analogy...)
Hystory will decide, not a truth, not a physical reality
(also because I believe that we can't have the Truth ;-)

 

[f-h]

I have no idea about structural/funding issues. I have zero experience with that side of the issue.

Overall IMO it's not at all unreasonable that String Theory should be larger then the alternative approaches. For one, the alternatives are almost all quite idiosyncratic. Two they often come from a relativist background, and GR has been smaller then Particle Theory for pretty much all of the 20th century. Due to it's Particle Theory background String Theory has a lot to say (inspirationally/technically) about Particle Physics and there'll be new data from CERN soon enough. (other QG approaches have nothing at all there)

In Europe, where I have personal experience the situation is pretty much as it should be as far as I can see. There are a couple of strong groups, vividly interacting (ESF money is helping there, it is a testimony to the fact that alternative approaches exist in a strong way that the ESF is spending money to encourage interaction between them). ST is the majority but there is a sizable minority, growing in step with it's ability to generate interesting models and toys to play with.

That's cool. We just had a very successfull completely overbooked school in Zakopane, PhD Students up and down find that these are nice problems to think about, etc... As far as I can see, all is well.

 

[Sauron]

Josh, someone told in these thread that LQG people had more insights on philosophical and intuitive physical ideas. I agree with that viewpoint.

But that´s not the point I want to rise now. The question that worries me is if string people theory would allow to publish articles in their field with that aim. I mean, many research areas in string theory look more like mathematical work in classifications of many kind of objects than a search for genuine physics (things like the K-theory for classification of branes, the langlands program, etc). I don´t think that it is not a necessary part (specially the work to clarify the landscape) but I guess that too much work is addressed towards pure mathematical and too few towards intuitive foundations.

And I don´t think that there is a good reason for that, except perhaps that many people is afraid to publish anything that could sound risked.

About the tendency on these forum of not going into the details I must say that it is not only with string theory. I have made occasionally some concrete answers about some concrete points on LQG papers and I have had no answer. But I think that the most reasonable cause for it is that people didn´t read that concrete paper (too many papers going here) and not a lack of knowledge (or simply I make stupid questions).