Not much time for blogging at the moment, with one reason that I’ll be giving a talk at Rutgers on Wednesday, and need to get that prepared. A few quick items:
- As some commenters have mentioned here, talks from the recent Munich conference (discussed here) are now available. From the little time I’ve found to look at them, I think Rovelli’s is the talk that makes the point about all of this most worth making, with Massimo Pigliucci good at explaining the wider implications.
While interesting comments on the talks are encouraged, for reasons that I can’t explain publicly, discussion here of the Polchinski contribution is not welcome. - Besides watching Gordon Kane in Munich on string theory predictions, he also has a paper about this out now.
- Congratulations to Bert Kostant on the award of the 2016 Wigner Medal. Kostant has been one of the major figures over the years in developing many deep ideas about the intersection of mathematics and physics, as well as a leading figure in the algebraic approach to Lie algebras and their representations.
- A lot of mathematicians and physicists want you to use TurboTax.
- Steven Weinberg’s sensible opposition to guns in UT Austin classrooms has gotten a lot of media attention (for instance here). Of the many obvious reasons why this is a bad idea, he correctly points out that it may well make it difficult for UT to recruit faculty.
Update: A commenter points out that more videos from the Munich conference are available here.
Update: John Horgan has a wonderful interview with the remarkable and ubiquitous Sabine Hossenfelder. Highly recommended.
Update: For news from the LHC, see last week’s Chamonix LHC performance Workshop. From the summary, the goal is about 30 inverse fb of pp collisions this year.
This place contains more videos from the conference: https://videoonline.edu.lmu.de/en/wintersemester-2015-2016/7475
I went through Kane’s talk.
It is not the first time he mentions Newton’s law or the Schroedinger equation and then claims that their predictions are analogous (in methodology) to string theory (slides 9 and 10). He says that in both cases (Newton or Schroedinger) you have to propose the force or the Hamiltonian and then see if they work with the experiment. In ST one provides the compactification scheme and then see if it works too – and so they are analogous in methodology.
I think Kane is missing a very simple fact that disqualifies his analogy. The point is that for both Newton and Schroedinger theories we know what are the elementary constituents interacting and we know what is their interaction (whether it is electromagnetic, gravitational or any other know interaction). In principle we could write corresponding potentials for all the interacting constituents and so there is no guess work about the Hamiltonian to which Kane is referring. In Newton or Schroedinger equations there is in principle no room for proposing the potentials unless one is considering some effective potential due to complexity of the system considered. However exact potential are solutions of concrete equations (e.g. Maxwell) which have been tested experimentally many times.
On the other hand in ST one starts with guesses about the compactification schemes and ends up in theories that has never been verified. There is no analogy here, I’m surprised he is bringing this up.
Other thing that surprises me in his talk is slide 17 where he claims that “Gravity, YM theories, gauge fields,…. – all are prediction of and evidence for ST”. He is certainly confusing a prediction with the postdiction – you cannot predict something that has been already discovered, but I hear many STheorists making this error.
I’m afraid that they’ve failed to adequately explore the parameter space – the free version last year started concealing the information that it won’t do self-employment tax (without buying the premium version) until late in the exercise.
I would have appreciated Kane putting references for all the claims in his paper. If it was Wikipedia, there would have been a good many [citation needed] tags. Also, are any of the ‘incorrect predictions’ he refers to due to himself?
Kane did mention Lee Smolin and Peter at the 6 minute mark in the presentation. Sounded like he has some major disagreements with them.
I was really surprised the organizers chose Kane as a speaker. His point of view doesn’t really have anything to do with the “post-empirical” topic of the conference. His idea seems to be to do conventional empirical science, making distinctive falsifiable predictions. The innovation is to just ignore it when they get falsified. He just puts out a new paper or new edition of a book, replacing the falsified ones with new ones, repeating as necessary.
Looking forward to reading your perspective on your book 10 years on (if slides are available). Will there be e.g. a second edition with a new preface?
I guess the book has aged reasonably well; whilst a lot of things have changed in the last decade, a lot of things have stayed the same.
andrew,
I think the argument of the book has aged very well, with evidence for it now stronger than when it was written (most dramatically, no SUSY at the LHC). Main developments since then have been the discovery of the Higgs (expected, but I was hopeful that it might turn out to behave in an unexpected way), multiverse-mania, and, personally, I’ve learned a lot more about mathematics, which would change how I’d write some of the book if I were to do it again.
I’m trying to finish my textbook the next few months, and then want to pursue a bunch of ideas that have been on hold while I work on the textbook. Spending time on popular writing isn’t something I want to do much of, but perhaps I should write some kind of piece about the “string wars”, ten years later.
Slides from the Rutgers talk will be available.
https://videoonline.edu.lmu.de/en/node/7494
In her talk Sabine Hossenfelder has a brilliant interpretation of how the Multiverse theories are born.
It starts at 8:22 in the video.
She basically argues that in any physical reality with any set of physical laws where intelligent beings get to think about their physical laws, there will always be unobservable/unmeasurable factors that will prevent them from coming up with a complete set of axioms to represent the theory of everything.
Then eventually their physicists, after long struggle, will always come up with a theory that will group all the unobservables/unmeasurables into a framework that will just be a version of the Multiverse.
OK, this isn’t physics, so delete if necessary; but I applaud Weinberg’s stance at UT; the mere thought of a disgruntled student in a classroom is very disturbing for the lecturer; would he be breaking the law if he refused to teach after an anonymous threat, for instance?
This has to be on the outer fringes of state insanity.
I’m not a physicist myself, but it seems to me that the No Alternative Argument would be more appropriately named Proof By Lack of Imagination.
The idea of grading people who might want to discuss their grades while carrying a weapon is fairly scary. It shouldn’t take a Nobel laureate to see that.
On a more delightful / depressing note: Kane writes that Witten discovered M-Theory in 1995. How amazing! I was only aware of him conjecturing the existence of an M-Theory in the same year, but I totally missed that he also made the next step! And in such timely fashion!
“The idea of grading people who might want to discuss their grades while carrying a weapon is fairly scary. It shouldn’t take a Nobel laureate to see that.”
So how do you know they don’t carry an illegal gun now? To get a CCW permit you must go through training, background checks and other obstacles. Seems to me these students are more vetted then others which you know nothing about.
But then most people are scared of what they don’t understand.
Sorry, but I’ll cut off further debate about the advisability of having armed students in one’s classroom. Nothing anyone says here is likely to affect most people’s opinion that this is obviously crazy. I am curious to know if it will have an effect on UTs ability to hire faculty.
Peter,
I read Kane’s paper, but I am not an expert in ST and cann’t follow his arguments and claims.
Supeficially, the paper looks “scientific” and sound – what is your opinions about it?
Miki,
Kane makes a complicated argument, involving a lot of different assumptions. As explained above, he has a long history of doing this, making “predictions” which are falsified time and time again. I don’t see any point to spending time understanding the details of the latest ones.
Thanks for the LHC news links.
Can anyone explain the long technical stops that coincide with year’s end?
Why would the world’s most expensive machine be turned off and then have to go through 4 weeks of recommissioning every year? I realize some maintenance is required but it seems such a long time to be idle.
**start silly comment**
I am hoping that the answer is not that the people working there want long vacations, but if that is the case I wonder if the many people on this site that complain about finding HEP jobs, might be willing to replace those people at 80% of their salary and keep the machine up.
**end silly comment**
its really easy to accelerate particles from your keyboard, a lot harder from
an actual accelerator
Off-topic, but perhaps of interest, is a New Yorker piece by Lawrence Krauss on the waste of money that is the Breakthrough prizes:
http://www.newyorker.com/tech/elements/do-the-new-big-money-science-prizes-work
I hope that your Rutgers talk becomes available!
– is 30 inverse fb of pp collisions this year enough data to
1- decide on 750GEV diphoton excess
2-determine if natural SUSY exists or rule it out
3-incease bounds on gluino masses
4-determine if LSP neutralino dark matter exists ?
@SteveB-
Here’s a rundown of what they did for commissioning last year: http://lhc-commissioning.web.cern.ch/lhc-commissioning/2015/2015-comm-plan-schedule.htm
This doesn’t look like an excuse for a vacation to me.
Part of the answer is electric utility rates, especially during peak holiday periods. A better answer is from Fred P. It’s typically a mad scramble to get everything installed on schedule. The correct question to ask is “how do they get so much done with so little down time?” But the best answer is “ask someone at CERN (or SLAC, Fermilab, etc.) how do they manage to do as much as they do within the limited downtime available?”
SteveB:
It’s the world’s most complicated machine. Four weeks a year of maintenance would be a miracle. However, the period you’re talking about, the ‘recommissioning period’, isn’t so much maintenance as ‘the process of turning the LHC on’. The LHC doesn’t run during the winter season because fuel costs are higher then and the budget is limited. During this time, the physicists and engineers do maintenance and upgrades. Then in the spring, they turn on and tune all the subsystems in their proper order so that they can have collisions in the summer and fall.
* I wonder if the many people on this site that complain about finding HEP jobs, might be willing to replace those people at 80% of their salary and keep the machine up.*
Those are theory jobs they were talking about. Putting theorists in charge of LHC maintenance would be a bit like giving a dentist a scalpel and asking him to perform brain surgery. Maybe you’ll get a discount, but you probably won’t get the desired effect.
Steve B,
the LHC being the “world’s most expensive machine” is off by at least an order of magnitude.
The total cost of the LHC is about $9 billion.
Just for reference: The total cost of the ISS is $150 billion. The cost of a single CVN-78 Class Aircraft Carrier is close to $10 billion. (And the R&D cost for the F35 plane was a staggering $320 billion).
Even looking at physics alone, the LHC is not the most expensive machine. The cost estimate for ITER is >$15 billion and the current projection for the Webb telescope is $8.8 billion.
Nilay,
Thanks for pointing that out. I pretty much agree with Krauss, although I think the standard “instead support young people who are just entering the field” alternative he suggests is problematic. The problem I see (especially in theoretical physics) is not that good young people can’t get postdocs, but that there are so few permanent jobs for them. It would be a great idea for the math/physics community to try and convince Milner and Zuckerberg to stop giving these large personal awards, and instead endow permanent positions in the name of the honoree.
30 inverse fb
1. yes
2. no (or, maybe, yes, since it is already ruled out).
3. yes
4. no (you can always push the mass up higher).
In case anyone is interested in some technical details, here is a fairly good short summary of the model Kane and his collaborators have been working on where you can read about some of the assumptions and how much connection to M-theory it actually has: https://ncatlab.org/nlab/show/G2-MSSM
2. no (or, maybe, yes, since it is already ruled out).
are you saying the result of first run @ 8 TEV is enough to rule out TEV-scale SUSY?
30 inverse fb,
If susy is supposed to be “natural”, it really is supposed to show up at the weak scale (100 GeV), and the current bounds on superpartners rule that out. You can claim if you want that there is just some fine-tuning, so the superpartners are at higher mass, even push them up above the point the LHC will see them in this run.
As for “TeV-scale susy”, depends exactly what that means. There are different bounds on different superpartners, best bounds on the strongly interacting ones, which already have to be above a TeV, but if you think a few TeV is “TeV-scale”, that’s not yet ruled out.
Clara Moskowitz, on page 14 of the February 2016 Scientific American, in an article on XENON1T tells us “WIMPs are a prediction of superstring theory”. Little did I know!
Anonyrat,
She just doesn’t mention that no WIMPs are also a prediction of superstring theory…