## Various and Sundry

• Via my Columbia colleague at Mathematics Without Apologies, a documentary about Perelman that I was unaware of.
• I learned something yesterday about another math department colleague, Mikhail Khovanov: he has games called Ringsanity and Ringiana available as apps.
• Took a quick look at a Stephon Alexander’s new book The Jazz of Physics, which is now in bookstores. While I enjoyed reading some of his account of his career in theoretical physics, I’m afraid that his two main topics, jazz and models of the big bang, both are things that pretty much leave me cold. For those with more interest in either topic, you probably should take a closer look.
• I’m sorry to see that there’s some sort of fight developing over Grothendieck’s papers. A shame.
• Previous attempts to figure out what “ER=EPR” is supposed to mean have left me baffled. Trying to read Susskind’s write up of his IAS lectures on the topic hasn’t helped, I’m afraid.

Update
: Mikhail Khovanov tells me that Ringiana for Android can be found here. It was developed jointly with Nikolay Gromov.

He also comments that “Thompson groups V and T act on the states of Ringiana and Ringsanity, correspondingly. These groups were the first two infinite, finitely-presented, simple groups discovered by mathematicians.”

Posted in Uncategorized | 8 Comments

## Starshot

I don’t know what this is about, but Stephen Hawking and Yuri Milner are here in New York today, with a press conference downtown scheduled at noon, supposedly to announce a mysterious new space exploration initiative, to be called Starshot. There’s also evidently some sort of Columbia connection, with a reception scheduled up here. More later, when we find out what this is all about. Last year there was a Hawking/Milner announcement of Breakthrough Listen and Breakthrough Message, projects related to communication with alien civilizations.

Update: Livestream will be available here.

Update: According to this source (and Google translate…), this is a project to send a small space probe to Alpha Centauri.

Update: “Breakthrough Starshot” is a $100 million research program, hoping to develop (ultimate cost of order$10 billion) very small probes attached to light-sails, pushed towards Alpha Centauri by ground-based lasers (a “Silicon Valley approach to spaceflight”). The claim is that such things could travel at a significant fraction of the speed of light, get there in 20 years or so. One thing I’m not seeing is how you get a signal back to earth.

Update: They have a website here, there’s a story at the New York Times here, at Scientific American here.

One thought about this is that if you really could accelerate probes this way with lasers, sending them out to solar system planets in days would seem to be a more interesting application.

Update: A more detailed story is here.

Posted in Uncategorized | 37 Comments

## Local Debates

I noticed that tomorrow (Tuesday, April 5) evening here in New York City there will be not one, but two debates involving theoretical physicists:

• At 7 pm the American Museum of Natural History will host the 2016 Asimov Debate, with this year the topic Is the Universe a Simulation?. You can watch a livestream at that site.

I confess that if this were a few days earlier, I would be convinced it was definitely a joke. But, it seems not, that instead this “has become a serious line of theoretical and experimental investigation among physicists, astrophysicists, and philosophers” and that it’s a “provocative and revolutionary idea”. One thing this is not is new. Nearly nine years ago it got a lot of media attention, and I wrote about it here (and here, where quite possibly my Message to Our Overlords kept them from turning us off). Sadly, the “blink” feature of html no longer seems to be supported, so the red text there won’t blink. Maybe it annoyed the overlords and they had it turned off.

• Much further downtown, at the New York Academy of Sciences, at the same time there will be a panel discussion on a much more sensible and interesting topic What Does the Future Hold for Physics: Is There a Limit to Human Knowledge?. Also at 7 pm, livestream here.

If I’d been asked (actually I was asked, and then unasked, a rather mystifying situation) for my views on this, I’d make the point that there’s no way to know what the limits will be to human understanding of physical laws. It has however become all too clear what the danger is of what will happen when we reach those limits. Instead of prominent theorists frankly admitting “we don’t know”, there will be an attempt to sell the story to the public that theorists have a wonderful, successful theory which describes everything, which sadly has the unfortunate feature of not making any falsifiable predictions. The string landscape/multiverse scenario now is being very aggressively sold as exactly this kind of endpoint to physics, to a large degree by people unwilling to admit the failure of string theory-based unification. There’s a very real danger that this will enter the textbooks, and that we will in our lifetimes see the end of fundamental physics as a human endeavor. The limit we will have hit will be due not to the nature of our minds, but instead the nature of our sociology.

I suppose one other way of seeing if we’ve reached the end of physics would be if physicists started spending their time debating things like whether we live in a simulation. Oh, wait…

Update
: At the NYAS evidently there was some discussion of the multiverse, with the audience told “The multiverse hypothesis is no more speculative than the universe hypothesis”.

Update: Clara Moskowitz at Scientific American has a report from the AMNH debate. At least there is one participant I agree with:

And the statistical argument that most minds in the future will turn out to be artificial rather than biological is also not a given, said Lisa Randall, a theoretical physicist at Harvard University. “It’s just not based on well-defined probabilities. The argument says you’d have lots of things that want to simulate us. I actually have a problem with that. We mostly are interested in ourselves. I don’t know why this higher species would want to simulate us.” Randall admitted she did not quite understand why other scientists were even entertaining the notion that the universe is a simulation. “I actually am very interested in why so many people think it’s an interesting question.” She rated the chances that this idea turns out to be true “effectively zero.”

One thing I’ve noticed about these kinds of things: they often feature physicists going on about mathematics, but mathematicians are never invited…

Update: The Asimov debate is available here, the NYAS one here.

Posted in Multiverse Mania | 66 Comments

## Is String Theory Scientific?

Among the various April Fool’s things on the web, the most subtle one I’ve found is by the people at James Madison University, who are advertising an April 1 event discussing the question of Is String Theory Scientific?

Part of the joke surely is Betteridge’s Law or Hinchcliffe’s Rule, which assure us that that answer to the question is “No”.

Update: Among today’s other April Fool’s efforts, Kyle Cranmer updates an oldie but goodie, supersplit supersymmetry.

Update: Another April 1 effort, this one an essay on the multiverse by Robert Lawrence Kuhn. Kuhn claims that the majority of cosmologists disagree with George Ellis about the problems with the multiverse, and that Andrei Linde (with Steve Weinberg agreeing with him) represents the consensus viewpoint. Very funny.

Update
: INTO THE MULTIVERSE: God’s Voice in String Theory is labeled March 31, but surely it too is an April 1 effort.

Posted in Multiverse Mania, Uncategorized | 6 Comments

## Short Items

A few short items:

• Beams are back in the LHC. You can follow what is going on here real-time, or here for details of this year’s beam commissioning. Physics runs scheduled to start last week of April.
• There’s a wonderful interview with John Baez in two parts, here and here.
• For news of US HEP, take a look at the HEPAP presentations as they appear here. Reports from the LHC experiments are scheduled for April Fool’s Day.
• In the last month the omnipresent Nima Arkani-Hamed was giving talks at the David Gross Fest (video here, nice comments about Gross at the beginning, presentation here), a series of lectures in Trieste (see here), and a colloquium talk at Fermilab.

In the FNAL talk Arkani-Hamed advertises a “Modern S-matrix program”, based on recent work on amplitudes. He’s a reliable source for what the conventional wisdom is among the most influential people in the field, and he has this to say about the current situation (right at the end of the talk):

String theory killed QFT, then QFT killed string theory back, now QFT is king. We’re in a situation where most people think QFT is king and string theory a derivative thing in some limits.

His own opinion is that we need “something else”, neither QFT nor string theory, but he doesn’t know what it is.

• I seem to have missed this paper on String theory and general methodology (arxiv version here) when it came out quite a few years ago. At the time the authors felt that

the majority has not been convinced [by criticisms of string theory] and they continue to believe that string theory is the right way to go.

I’m not sure if the authors had any data to back that up, curious if anyone would still make this claim now. Arkani-Hamed seems to think the majority opinion has changed, with QFT killing string theory.

• For some interesting talks at one of the few conferences not featuring Arkani-Hamed, see the Nambu Memorial Symposium.
• I was sorry to hear recently that Rudolf Haag passed away back in January. For a short biography, see here. For an earlier posting linking to an autobiographical piece, see here. His book Local Quantum Physics is well worth reading. For a discussion of perhaps his most famous result, Haag’s theorem, see here.
• Multiverse mania shows no signs of slowing down, with a long BBC article here. Despite the length of the article, the author doesn’t seem to have been able to locate anyone who could add a note of skepticism amidst the usual thick layers of hype.

Update: A lot of data on recent DOE funding trends is available here and here. From FY 13 – FY 17, theory funding is down %20 at universities, 2% at labs. A bit over $20 million/year is now being spent by the DOE on HEP theory and computational research. For the most recent round of reviews, 23 groups were funded, and of these two were ones not previously funded, with two previously funded turned down. Posted in Uncategorized | 9 Comments ## Two Book Reviews Blogging has been light here, trying to finish a complete draft of the book I’m working on, this should be done very soon. Here are a couple all-too-short reviews of books with some relation to math or physics. ## A Doubter’s Almanac The main character of Ethan Canin’s new novel A Doubter’s Almanac is a mathematician, one who solves a great problem early on in his career (as a graduate student in Berkeley, then a faculty member at Princeton). It’s a beautifully written work, with a remarkably convincing portrayal of a talented young mathematician struggling with a difficult problem and making his way through life. I wouldn’t have guessed that anyone who hadn’t lived and worked in this kind of environment would be able to describe it so realistically.There are only a couple false notes in the many details of the part of the story set in academia. In particular, I don’t think anyone would consider a “subchairmanship” to be much of an inducement, even at Princeton, and they don’t give Abel Prizes to young geniuses. Besides getting the details right, the characters come up with some quite insightful remarks about mathematics, including some that deal with the way talent and immersion in a mathematical problem may alienate one from the rest of the humanity. While I greatly enjoyed the first half of the book, I have to admit that the later part held less interest, turning away from academia to a long story of family relations and the ravages of alcoholism. Not at all an upbeat book, if that’s what you’re looking for, but I can’t think of another novel as good that so deeply engages with some aspects of mathematics and the mathematical life. ## Black Hole Blues Janna Levin’s Black Hole Blues has just been published, with excellent timing for anyone who wants to know more about the story of LIGO and its first observation of gravitational waves. The main strength of the book derives from her interviews with some of the people crucial to building LIGO (in particular Kip Thorne and Rainer Weiss). Together with research and other interviews she has put together a rich version of the history of the project and the roles of the three physicists (Drever, Thorne and Weiss) whose vision and dedication made it successful. LIGO has been a very long term project, with its beginnings going back 40 years. It’s remarkable that it didn’t get abandoned or defunded at some point, with the NSF playing a very important role in supporting the project over many years. Drever, Thorne and Weiss will likely soon be the recipients of all sorts of well-deserved honors and prizes (I’d bet on this year’s Breakthrough Prize and probably the Nobel too). I was sad to learn that this is coming too late for one of them, Ronald Drever, who is ill and suffering from dementia. The physics of LIGO has a bright future, it’s great to have the story told of the people who made it happen. Posted in Book Reviews | 8 Comments ## Number Theory News • Andrew Wiles is the recipient of this year’s Abel Prize. I have to confess that I found this surprising, since I assumed he’d already won this. His work in general and specifically the work that led to the proof of Fermat’s Last Theorem is on any reasonable list of the top few achievements in mathematics in recent decades. If you haven’t seen the documentary about the FLT proof, you really should, it was a BBC Horizon show in the UK, Nova here in the US, transcript here. I’d heard and Nature confirms that Wiles has for quite a while now been working quietly on the BSD Conjecture, maybe some day there will be another very dramatic moment in the subject, and another documentary. • Erica Klarreich at Quanta has the story of a surprising new result about prime numbers from Kannan Soundararajan and Rober Lemke Oliver. They have found that, given a prime number with a certain last digit, there are different probability for the last digit of the next one (among the various possibilities). This violates usual assumptions that such things are in some sense “random”, indicating just how subtle this “randomness” is. For more details, there’s an excellent blog post from Terry Tao. This might be a good time to point out that people sometimes complain about the quality of coverage of scientific advances aimed at non-experts. From what I’ve seen in recent years, the coverage of mathematics advances has been of extremely high quality, with this story a good example. • April 29 is the release date for The Man Who Knew Infinity, a film about the life of Ramanujan. It’s based on a great biography and a fascinating story. I hope this turns out better than the similar situation with the film about Turing. Update: It turns out that an astronomer, Chung-Ming Ko, had already a while ago done some calculations showing non-randomness in the last digits of primes, see here. The new paper has been updated to refer to that. Reports about the Ramanujan film are that they took great pains to get the mathematics right, with Ken Ono and Manjul Bhargava working extensively on the film. Posted in Uncategorized | 20 Comments ## The Ultimate Simplicity of Everything There’s a wonderful interview with Perimeter Institute director Neil Turok here, entitled The Ultimate Simplicity of Everything, and done for a Canadian radio program. Turok discusses his point of view on whether we’re at “the end of physics”, and I’m very much in agreement with what he has to say: I think what people are sort of expressing is that we haven’t had a big revolution in physics. String theory was hoped for to be that revolution in the 1980s but it hasn’t really panned out in the sense that it hasn’t given a single prediction. Instead it’s given us a huge collection of theories where, if you like, there’s no overarching theory to tell which particular version of string theory is the one that describes the world. It’s almost self-destructed, I would say because it turned out to be not just one theory but this vast collection of theories which could all give different descriptions of the world. So I think that sort of theoretical catastrophe, as I view it — meaning the logical pursuit of quantum mechanics and relativity over a hundred years was tremendously successful at some level but finding its own successor theory, it hasn’t been successful. I think that is also laying the ground for some sort of revolutionary change in the sense that we basically will have to go back to the founding principles. It looks like the founding principles of modern physics — quantum theory and relativity — have played out and they have not given us the answers we need. And so we have to go back and question those founding principles and find whatever it is, whatever new principle will replace them. So matching these great puzzles posed by the observations are equally great puzzles in our fundamental theories. And so that is just a wonderful thing to contemplate in itself. I mean, partly people become very pessimistic and say, oh my god, I’ve devoted 50 years of my life to studying this incredibly technical and difficult theory and now I find it’s blown up in my face, it’s not giving any predictions at all…and so some people talk about the multiverse where the universe would be wild and chaotic on large scales and almost anything you could imagine would actually exist somewhere in the universe. I mean, this is literally a scenario which became very popular among a category of physicists, that there is a multiverse out there. Yet the evidence is exactly the opposite. That, as we look around us, things could not be simpler. There’s no evidence for chaos on large scales in the universe. It’s totally the opposite. It’s pristine, elegance, minimalism is all we see. So, I think this is a very, very exciting time to be doing theory. The challenge is enormous. The clues are enormous. We’re waiting and we’re preparing and we’re encouraging people to take radical leaps. Posted in Uncategorized | 10 Comments ## This and That A few short items: • Nature has an editorial this week summarizing the situation with the 750 GeV possible diphoton bump. It mentions a new paper analyzing related data (the number of theory papers on this as a function of time). The paper is called A Theory of Ambulance Chasing, and claims that looking at a large collection of similar fads producing theory papers, the high-level behavior of the HEP theory community can be well summarized by a model that requires only two parameters to fit the data. • If you’re at Stanford tomorrow and a fan of multiverse mania, you can go hear Alexander Vilenkin talk about The Universes Beyond the Horizon. According to the Stanford PR for this Despite the similarities between Vilenkin’s theory and the Wikipedia summary of the film Interstellar, many scientists have hope for the multiverse theory. Stanford physics faculty members seem to have innovative ideas about the scientific method, with one of them quoted as claiming Once a reasonable idea comes, you can never say it’s wrong. which I guess could be taken as some sort of motto for research into string theory and the multiverse. • CERN is running a series of articles about the Theory group there, first one is here. • Norbert Bodendorfer has a nice new blog about loop quantum gravity and related topics. • The Templeton Foundation has mercifully stopped giving huge financial prizes to people for dubious attempts to bring religion and science together. I hadn’t even realized they had already given out this year’s Templeton Prize, which went to a British Rabbi. Among the many things they fund is a recent$1.1 million grant for this project on the philosophical implications of quantum gravity. They will hold a summer school this year (with Amanda Peet and Carlo Rovelli, that should be fun), and there’s a Youtube channel.

• Chris Quigg has an interesting overview of the future of HEP physics. I particularly like his emphasis on the questions

How are we prisoners of conventional thinking?

and

Might we have misunderstood the hierarchy problem, and so need to reframe it? Perhaps it is time to ask whether the unreasonable effectiveness of the standard model (to borrow a turn of phrase from Eugene Wigner) is itself a deep clue to what lies beyond.

Posted in Uncategorized | 7 Comments

## Multiverse Observed, South of Glasgow

It turns out the multiverse does exist, just off the A76, 25 miles north of Dumfries in Scotland. It’s called the Crawick Multiverse and is now open 10 am to 4 pm. Admission is 5 pounds, but parking is free.

For more details, see this story, which explains about the huge mounds, and that

There’s also a mound where mudstone slabs trace a spiral path up to the top that represents the multiverse. Along the way, some of the slabs are carved out to symbolise other potential universes where different physical laws apply.

The idea seems to be that

the park is a modern take on Neolithic monuments such as Stonehenge, which paid tribute to the movements of the Solar System – but this time the focus is on the latest advances in physics, such as chaos theory and the idea of parallel universes.

so while Stonehenge was designed to last forever and show that a primitive people understood about the solar system, this is going to show our descendants that 21st century humans knew about the multiverse.

Since it is well known that the LHC is our best chance of figuring out if multiverses exist, it seems that the people at CERN have agreed to have the same person build something like this there. This should ensure that when any future generations excavate the LHC site, they will get some idea of its purpose, and marvel at how much progress the human race made after the Neolithic era.

Update: Another observation of a multiverse, this one in Trieste.

Posted in Multiverse Mania | 18 Comments