Some news from all over:
- The problem with a short in the LHC seems to have been resolved (one can follow progress here), looks like they’ll be ready to inject a beam in a few days. Also looks like they’re not likely to spend their Easter Sunday doing this, so, maybe it will be next Monday?
- Cambridge has finally gotten around to choosing a new Lucasian professor (the last two were Michael Green and Stephen Hawking). Michael Cates will take the position July 1.
- Grothendieck’s death last year was sad to hear about, but a positive result is that the Grothendieck Circle is back in the business of making available resources concerning his work. There’s a comment at the top of the website that
With the agreement of Grothendieck’s family, the work of the Circle to bring Grothendieck’s unique story and writings to the public has resumed.
- There was a workshop this past month devoted to Mochizuki’s work, but I haven’t found anyone who knows what happened there. Minhyong Kim has taken to trying to write about Mochizuki’s ideas on MathOverflow, see here.
- The Toronto Star has a long article about Langlands.
- At the KITP this week a new program on quantum gravity is starting. This month’s Scientific American has a Joe Polchinski cover story on Burning Rings of Fire. Maybe some of the KITP talks will be enlightening, but the small amount of time I’ve spent trying to follow the past two years of debate on this has just left me mystified, struggling to see how the very general framework people seem to be working in can possibly lead to a resolution of the questions they’re concerned with.
- Frank Wilczek has a speculative article about Physics in 100 years. A commenter here suggests comparing it to Wilczek’s version of nearly fifteen years ago. The last fifteen years have not been kind to Wilczek’s hopes for vindication of SUSY or SUSY GUTs, but he’s not giving up yet. It will be interesting to see what his reaction will be if the next fifteen years are equally discouraging.
I do very much like one thing in the new version, the section about possible unification of ideas of quantization and of symmetry, where he speculates:
Quantization and fundamental symmetry will not appear as separate principles, but as two aspects of a deeper unity.
That’s pretty much one of the main motivations of the book I’m writing (see here).
Update: There are rumors going around tonight that there’s been a hoax perpetrated on the arXiv, something like the Sokal hoax. This has to do with an hep-th posting entitled Riding Gravity Away from Doomsday, which has appeared under the name of a very prominent string theorist, Ashoke Sen, winner of the $3 million Milner Fundamental Physics Prize. What I’m hearing is that no one can believe that Sen could possibly have seriously written something this silly, so it must be some sort of hoax. Speculation is that the hoax could have been carried out to make the hep-th moderators look bad, by showing that they’ll agree to anything, no matter how absurd, if it invokes the Landscape and the multiverse. Some think that Sen’s account must have been hacked and then used to post the nonsense paper, others think that Sen himself is behind the hoax, having had enough of the Landscape business. I’ll update this as more information becomes available.
Update: At least some papers on the arXiv still are serious.
Update: Beams are back in the LHC, successfully circulated at 450 GeV on Easter Sunday (live blog here). Next step, ramp up to 6.5 TeV.
I think maybe Tuesday. Monday is a big holiday in Europe – Easter Monday.
Yaay for the LHC getting fixed so easily!
My opinion on the Sen piece FWIW: Honestly I don’t get the hoopla about it. I’m not sure it’s anything like Sokal. First of all it’s an “essay” for some random competition, not a journal paper. Second, supposing the typical eternally inflating multiverse paradigm is true I can’t spot any obvious flaw in Sen’s (or the author’s if it really wasn’t Sen) reasoning, which follows as an almost trivial consequence of the assumptions. Please correct me if I’m wrong. The essential message is to spread the human race out so as to avoid vacuum decay bubbles as much as possible. He does some very crude dimensional analysis in support of this that doesn’t go very far in terms of building a concrete model. If there is silliness in this it seems to stem from the starting assumptions, not anything in the essay itself.
So: silly premise? Yes, if you think the eternally inflating multiverse is silly (as I do).
Absurd title? Definitely. Pure, shameless click-bait.
Sokal-esque hoax? Not convinced.
Worth getting worked up about? Nah. Nothing to see here. Move along. If he tries to get it published in Nature or promoted as some major breakthrough then maybe start an outcry…
April Fools’ Day?
If Sen’s account was hacked I doubt this would last more than a minute on the arXiv. He is not a sarcastic person and tends to be kind and differential to other’s work, even when he doesn’t find it so useful. So I doubt this is a hoax. My guess is that it is what it appears to be: a lightweight, fun article intended for general readers.
Why he decided this would be appropriate for posting on the arXiv I don’t know. Perhaps he just wanted it to be available to general readers on the internet.
Text such as: “The situation looks pretty bleak, particularly since we have no control on when and where such a doomsday bubble may form! Nevertheless there is a course of action that could save some of our descendants from this catastrophe. The essential idea is simple; we must spread out as fast as possible, establishing civilizations on dfferent worlds in different parts of the universe, so that even if some of us are hit by the catastrophe, the others may survive.”
is either a joke, or the worst kind of crackpot crap. Let’s not pretend that it’s respectable to write things like this. It isn’t. No real physicist would write this. As far as know, travel to “other worlds” is a physical impossibility, and always will be. It’s all fine and good to oversimplify, but it is dishonest and irresponsible, especially in a popular essay, to claim as a solution something simply ridiculous.
I think it has to be a joke. The joke is to see if he wins the contest submitting complete garbage.
To understand Sen’s paper, use Occam’s razor !
There is a trivial interpretation: today is April 1st ….
Ha, ha. All you commentators were successfully
sent into April by Peter.
Truly funny April fools’ day joke, Peter ;-).
Sen’s article is in hep-th instead of pop-ph, I’m sure it will be moved. It’s just some kind of popular, quasi sci-fi essay (not paper) for a general audience. Lighten up.
https://indico.cern.ch/category/6386/ is not open anymore.
Too bad. Public news is still available here:
I think that the article grates because, as our host frequently points out, hep theory is becoming subject to Poe’s law. I suspect the same sort of paper would have been considered all in good fun in, say, 1995.
On Sen: April 1st?
Yes, the update about Sen was written very late last evening, I’ve just restored comments that pointed this out. Unfortunately all evidence seems to be that this isn’t actually a hoax…
I had a great laugh with that article. Ashoke Sen could make some money writing sci-fi plots for TV series.
Am I missing something here? The arxiv lists Sen’s paper as Submitted on 27 Mar 2015. Surely that’s not sufficently close to April 1st.
Are you Statler or Waldorf? 🙂
What do you make of this paper?
I gather the claim is that in some approximation, in some class of string vacua, you can’t get a positive CC 4d spacetime. The subject of “string vacua” is an infinitely complex one, I don’t see that this changes the situation much. Their conclusion I guess is that many arguments about string vacua “should be viewed with caution”, and on this I can’t disagree with them…
It’s interesting you have Langlands right after Mochizuki, who was quite fed up with Langlands program.
The Star article on Langlands is pretty entertaining. He sounds like quite an interesting character.
6.5 GeV is unlikely to be interesting… I believe you mean 6.5 TeV! 🙂
Thanks physics grad, fixed.
I keep making that mistake…
Prof. Sen has given an update on his website about this: http://www.hri.res.in/~sen/
Thanks! It’s interesting to see that Sen denies any connection to eternal inflation and the multiverse, and yet devotes the concluding section to arguing for investigation of the string theory landscape. I guess this is logically consistent, but it gives up on “statistical predictions”, and, going forward, I don’t see any plausible argument that you could ever use the string theory landscape to predict anything.
The Sen paper seems to mirror the plot of Schild’s Ladder by Greg Egan, some of the hardest of hard sci-fi.
I loved it, but actual physicists may be angered by it, I don’t know 🙂
Actual physicist here who thinks Schild’s Ladder was pretty darn good. Much better, in fact, than the vast majority of sci-fi (confession: I do like Star Trek, though for sentimental reasons more than anything). I’ll grant it’s certainly not to everyone’s taste, but I think you’d have to be stubbornly, boringly hard-nosed to be unwilling to suspend disbelief over Egan’s departures from reality as we know it (or speculate it to be). He at least goes to extraordinary lengths to ensure the internal consistency of his fictional universes.
I wonder if he’s serious in proposing that this scheme to delay extinction via vacuum decay, through a crash program of cosmic fecundity and settlement, offers an important incentive to study the string landscape. That is the sort of thought you see in impassioned Internet discussions by transhumanists at their most extreme, who often don’t understand why our whole civilization isn’t already mobilized around some Promethean agenda like “ending death”. I have personally had at least one discussion with someone anxious to know if string theoretic cosmology could allow “information processing” to continue forever.
Such speculations (and obsessions) make the plot of the film Interstellar seem conservative by comparison, to put it politely.
My reading was that you only need a doubling time just faster than the vacuum decay rate, so in ordinary terms you don’t need anything like a “crash program of cosmic fecundity and settlement” (though I love the phrase — thanks!).
Fun speculations aside, I don’t understand how anyone can really worry about these things. I mean, even if we were all very confident string theory was a complete, consistent and unique theory of physical phenomena and we had the whole landscape mapped out, who’s to say that one of our fundamental assumptions isn’t slightly wrong? Maybe nature doesn’t admit a complete, consistent and unique theory. Maybe in a hundred billion years God comes in, says “nice experiment that one, moving on” and everything vanishes in a puff of thought. Who’s to say? In the infinite future there is an infinite amount of time for things to go wrong. You have to assign literally zero prior probability to anything you want to avoid. Not good Bayesianity.
Nah. String landscape/multiverse doesn’t predict anything so exotic as closed timelike curves. Only random configurations of chaotic events which, on casual inspection, look like closed timelike curves. 😉
Not that I want to start a flamewar here but “travel to other worlds” isn’t impossible. It’s impractical. Those are different adjectives.
The essay posted under the name Ashoke Sen is actually by Ashoke Sen.
He clarifies his essay in his website:
haha, I was amazed at that anyone could make a comparison to the “Sokal Hoax” for this innocent and fun little essay.
Come on Peter Woit – you have not too bad standards, the update about the Sen publication was well below what is expected