Sidney Coleman

/ 18 Comments

coleman.jpg Very sad to report that Sidney Coleman passed away yesterday. Sidney, a professor at Harvard, was one of the greatest theoretical physicists of recent times. He doesn’t share the name recognition among the general public that some of his contemporaries have — he was always more interested in the deep underlying principles of quantum field theory than in any particular model of the universe — but no student of high-energy physics could help but be deeply influenced by his thinking, both through his research and his famous Erice lectures. He was an invaluable resource when I was a grad student at Harvard, both through his quantum field theory course and through many hours spent in his office pestering him with specific questions. At my wedding just a couple of months ago, some of the happy-memory-sharing involved trading our favorite Sidney quotes; “Modesty forbids me but honesty compels me” was my personal choice.

Sidney’s papers were not like anyone else’s. One of his classic quotes, from a paper with de Luccia on “Gravitational Effects on and of Vacuum Decay“:

The possibility that we are living in a false vacuum has never been a cheering one to contemplate. Vacuum decay is the ultimate ecological catastrophe; in the new vacuum there are new constants of nature; after vacuum decay, not only is life as we know it impossible, so is chemistry as we know it. However, one could always draw stoic comfort from the possibility that perhaps in the course of time the new vacuum would sustain, if not life as we know it, at least some structures capable of knowing joy. This possibility has now been eliminated.

Plenty of people aspire to be profound and playful at the same time; Sidney could pull it off, and had the technical chops to back it up.

Sidney had been sick for the last few years. In 2005 there was a conference in his honor, which arguably featured the greatest concentration of physics talent in recent memory; I wasn’t there, but Jacques Distler blogged a bit about it.

Physics will be a little bit duller without him.

Sidney Coleman Read More »

18 Comments

Science Scenesters

/ 14 Comments

Old Media, in the form of the New York Times, catches on to the Cafe Scientifique phenomenon that Mark and I have blogged about before. Under a variety of different monikers, the idea of gathering people in a bar to learn about science and have an engaging conversation is apparently catching on all over.

The spirit of “Mr. Wizard’s World” has now reached an audience that can legally drink. The same late-night revelers who spent their high school and college years plodding through mandatory science classes are now gathering voluntarily to listen to presentations on principles of string theory or how orbitofrontal cortexes work — as long as it takes place far from the fluorescent lights of classroom.

Science groups for young professionals who don’t wear white coats, like the year-old Secret Science Club at Union Hall, are cropping up in bars and bookstores all over the country, from Massachusetts to Montana.

“If you have a certain type of job, after a while that part of your brain starts to deteriorate,” said Amy Lee, 25, who works at an Internet startup and was attending her second Secret Science Club meeting. “You want to use it again. Plus, there’s alcohol.”

About 50 groups, with names like Science on Tap and Ask a Scientist, have formed in the last four years. There are three in New York City alone. Each month, they invite scientists, usually professors at nearby universities, to lecture on topics as varied as mass extinctions and frog mating calls. Anywhere from 50 to 100 people, none of whom wear pocket protectors, show up for an evening of imbibing hard science along with hard liquor.

The article exhibits a sense of bemusement that people could find all this sciencey talk interesting, and chooses to play up the less lofty angles.

Some science club attendees come more for the social benefits than for academic pursuits.

“I figure it’s a great way to meet like-minded singles,” said Lisa Dorenfest, 45, a project manager at an investment bank who was at Café Scientifique at Rialto, a restaurant and bar in downtown Manhattan. “If I do meet someone, lucky me. If not, I’m still entertained.” At the meeting, she offered to share her handout with a nice-looking actuary.

That’s okay; the great thing about science is that we can be lofty and earthy at the same time. The important thing is a shared passion for learning about the world.

“There’s a reason kids are into this stuff,” Ms. Mittelbach said. “A guy told me that when one of the speakers started talking about life on Mars, he started crying. They can shake us to our core. I like being a little scared. I like hearing that we may be hit by an asteroid.”

Science Scenesters Read More »

14 Comments

Garrett Lisi’s Theory of Everything!

/ 241 Comments

Garrett Lisi has a new paper, “An Exceptionally Simple Theory of Everything.” Many people seem to think that I should have an opinion about it, but I don’t. It’s received a good deal of publicity, in part because of Lisi’s personal story — if you can write an story with lines like “A. Garrett Lisi, a physicist who divides his time between surfing in Maui and teaching snowboarding in Lake Tahoe, has come up with what may be the Grand Unified Theory,” you do it.

The paper seems to involve a novel mix-up between internal symmetries and spacetime symmetries, including adding particles of different spin. This runs against the spirit, if not precisely the letter, of the Coleman-Mandula theorem. Okay, maybe there is a miraculous new way of using loopholes in that theorem to do fun things. But I would be much more likely to invest time trying to understand a paper that was devoted to how we can use such loopholes to mix up bosons and fermions in an unexpected way, and explained clearly why this was possible even though you might initially be skeptical, than in a paper that purports to be a theory of everything and mixes up bosons and fermions so casually.

So I’m sufficiently pessimistic about the prospects for this idea that I’m going to spend my time reading other papers. I could certainly be guessing wrong. But you can’t read every paper, and my own judgment is all I have to go on. Someone who understands this stuff much better than I do will dig into it and report back, and it will all shake out in the end. Science! It works, bitches.

For a discussion that manages to include some physics content, see Bee’s post and the comments at Backreaction.

Garrett Lisi’s Theory of Everything! Read More »

241 Comments

High-Energy Spam Filter

/ 2 Comments

Monica Dunford, at the US/LHC Blog, has a great metaphor: thinking of the “trigger” in a particle detector as a spam filter. The trigger, you will remember, is the combination of hardware and software that works to separate potentially interesting events from boring old background. If my rough numbers are anywhere near right (experts should chime in if not), the LHC will create about a billion collisions per second, and only about 100 of them will actually get stored on hard disk. Doesn’t sound like much, but we’re talking about a megabyte of data per event, so you’re writing a gigabyte to disk every ten seconds. Just not practical to keep every piece of data, so the trigger makes some snap judgments about what events are fun (like the simulated supersymmetric ATLAS event below) and which are just the usual workings of the Standard Model.

atlantis_susy.jpg

The spam-filter analogy is pretty apt: you’re being deluged with data, and most of it is irrelevant, and you can’t afford to look at all of it individually. So you have to come up with some automated system that decides what to keep and what to toss out. And of course you have exactly the same concern that you would have with any spam filter: the worry that you’re tossing out interesting stuff! You don’t want any job offers to get lost amidst the ads for C!al1$.

A great deal of work, therefore, goes into deciding what the trigger should keep and what it should toss out. Perhaps that helps explain the graph in a previous post of Monica’s:

atlas_events.jpg

That would be “meetings as a function of time,” in case it wasn’t obvious. Over 4500 scheduled meetings in 2007, and that’s just for the ATLAS collaboration. The other general-purpose LHC experiment, CMS, has a similar graph, but they only had about 1000 meetings. Whether it is a tribute to their greater efficiency or a mismatch in accounting procedures remains an open question.

High-Energy Spam Filter Read More »

2 Comments

200 Lashes

/ 51 Comments

That’s the punishment you get in Saudi Arabia for being a woman and riding in a car with a man who is not in your family. Oh, after your gang rape. (Via Feministing.)

A court in the ultra-conservative kingdom of Saudi Arabia is punishing a female victim of gang rape with 200 lashes and six months in jail, a newspaper reported on Thursday.

The 19-year-old woman — whose six armed attackers have been sentenced to jail terms — was initially ordered to undergo 90 lashes for “being in the car of an unrelated male at the time of the rape,” the Arab News reported.

But in a new verdict issued after Saudi Arabia’s Higher Judicial Council ordered a retrial, the court in the eastern town of Al-Qatif more than doubled the number of lashes to 200.

A court source told the English-language Arab News that the judges had decided to punish the woman further for “her attempt to aggravate and influence the judiciary through the media.”

But, lest you jump to conclusions, understand that it’s not only women who have to feel the occasional lash to be kept in line. It’s gay men, too!

About 50 people picketed Saudi Arabia’s embassy in London on Oct. 19 in protest against the nation’s reported floggings and executions of gay men.

On Oct. 2, two Saudi men convicted of sodomy in the city of Al Bahah received the first of their 7,000 lashes in punishment, the Okaz daily newspaper reported. The whippings took place in public, the report said.

I presume that the strong connections between totalitarian impulses, religious fundamentalism, and sexual repression have already been the subject of dozens of Ph.D. theses. There is a truly ugly part of human nature that feels a need to control the lives of others, and theocracy serves as a mechanism for amplifying those impulses into public actions.

200 Lashes Read More »

51 Comments

arxiv Find: Universal Quantum Mechanics

/ 41 Comments

A new paper by Steve Giddings, “Universal Quantum Mechanics,” arxiv:0711.0757. Here’s the abstract:

If gravity respects quantum mechanics, it is important to identify the essential postulates of a quantum framework capable of incorporating gravitational phenomena. Such a construct likely requires elimination or modification of some of the “standard” postulates of quantum mechanics, in particular those involving time and measurement. This paper proposes a framework that appears sufficiently general to incorporate some expected features of quantum gravity. These include the statement that space and time may only emerge approximately and relationally. One perspective on such a framework is as a sort of generalization of the S-matrix approach to dynamics. Within this framework, more dynamical structure is required to fully specify a theory; this structure is expected to lack some of the elements of local quantum field theory. Some aspects of this structure are discussed, both in the context of scattering of perturbations about a flat background, and in the context of cosmology.

Part of the problem in reconciling gravity with quantum mechanics is “technical” — GR is not renormalizable, by the lights of ordinary quantum field theory. But part is “conceptual” — ordinary QM takes a spacetime background as given, not as part of the wavefunction. The role of time, in particular, is a bit hazy, especially because the Wheeler-deWitt equation (the quantum-gravity version of the Schrodinger equation) doesn’t contain any explicit time parameter. Most likely, our notion of “time” makes sense only in a semi-classical context, not as part of the fundamental dynamics. Similarly, our notions of “locality” are going to have to be broadened if spacetime itself is part of the quantum picture. But the truth is that we don’t really know for sure. So it’s worth digging into the underlying principles of quantum mechanics to understand which of them rely crucially on our standard understanding of spacetime, and which are likely to survive in any sensible theory of quantum gravity. Giddings’s paper follows in the footsteps of previous work such as Jim Hartle’s Spacetime Quantum Mechanics and the Quantum Mechanics of Spacetime. (The Santa Barbara air must be conducive to thinking such deep thoughts.)

arxiv Find: Universal Quantum Mechanics Read More »

41 Comments

reCAPTCHA

/ 16 Comments

We’ve all seen CAPTCHA‘s — those distorted words that function as a cut-rate Turing test, separating humans from spambots on any number of websites.

image.jpg

This weekend I was at a Kavli Frontiers of Science meeting at the National Academies of Science office in Irvine, and one of the participants was Luis von Ahn — the guy who was responsible for inventing the CAPTCHA idea. He gave a great one-minute talk, in which he traced his personal feelings about being responsible for something that is so useful, yet so annoying.

CAPTCHA, you will not be surprised to hear, is ubiquitous. Luis figured out that the little buggers are filled out about sixty million times per day by someone on the web. So, as the inventer, he first felt a certain amount of pride at having exerted such a palpable influence on modern life. But after a bit of reflection, and multiplying sixty million times by the five seconds it might take to fill in the form, he became depressed at the enormous number of person-hours that were essentially wasted on this task.

Being a clever guy, Luis decided to make lemonade. What we have here is a huge number of people who are recognizing words that a computer can’t make out. Luis realized that there was a separate circumstance in which you would want the computer to recognize the words, even though it wasn’t quite up to the task — optical character recognition, and in particular the problem of digitizing old texts. Apparently, before the advent of the Internet, people would store information by binding together pieces of paper with words printed on them, forming compact volumes known as “books.” In the interest of preserving the products of this outmoded technology, various efforts around the world are attempting to scan in all of those books and store the results digitally. But often the text is not so clear, and the computers don’t do such a great job at translating the images into words.

sample-ocr.gif

Thus, reCAPTCHA was born. At this point you should be able to guess what it does: takes scanned images from actual books, with which optical character recognition software are struggling, and uses them as the source material for CAPTCHA’s. The project is up and running, and can be implemented anywhere the ordinary CAPTCHA’s are used. Now, when you get annoyed at having to make out those squiggly words with lines slashed through them, you can take some solace in knowing that you’re making the world a better place. Or at least saving some books from the trash bin of history.

reCAPTCHA Read More »

16 Comments

Quirks and Quarks: Before the Big Bang

/ 65 Comments

The Canadian Broadcasting Corporation has a smart and engaging radio show, Quirks & Quarks. Yesterday’s show focused on a big question: What happened at, and before, the Big Bang? Mavens queried included Robert Brandenberger, Paul Steinhardt, Justin Khoury, and of course me (otherwise it’s somewhat less likely that I’d be blogging about it, I guess). The blurb:

The Big Bang theory of the origin of our universe is widely accepted by the physics community. The idea that our universe started out as some infinitesimally small point, which expanded out to what we see today, makes a lot of sense. Except for one small thing. That initial point, called a singularity by physicists, is a physical impossibility. According to the models we have today, the temperature of the universe at that first moment would have had to be infinite, which mathematically makes no sense. Also, the singularity doesn’t do a good job of explaining where all the matter and energy we see today in the universe came from. So, physicists are increasingly starting to look at other branches of physics to see what they can do to replace the singularity with a more reasonable proposition, one which can actually be explained by existing science.

Listen here. As we’ve talked about on this very blog, the time is right to push our understanding of the universe back before the Big Bang and ask what was really happening. Current ideas are understandably vague, but the only way to improve them is to keep exploring.

One slight clarification, to those who listen: in the interview, I give an entropy-based argument against bouncing cosmologies. That’s appropriate for the ekpyrotic universe, but not necessarily for the most recent versions of the cyclic universe. In these models, the universe never really crunches; it keeps expanding, but at some point flares back to life — particles are created without space ever contracting. Some sort of thermodynamic sleight-of-hand is still being pulled — the entropy of the whole universe rises monotonically for all of eternity, which seems a bit fishy — but the argument is somewhat different.

Quirks and Quarks: Before the Big Bang Read More »

65 Comments

Smart Women are Scary

/ 46 Comments

Via Seed, a group of economists chose to study human relationship dynamics under tightly controlled conditions: speed dating. Emphasis added.

With the obvious qualification that we’re talking here about a four-minute version of love and dating, we found that men did put significantly more weight on their assessment of a partner’s beauty, when choosing, than women did. We also found that women got more dates when they won high marks for looks from research assistants, who were hired for the much sought-after position of hanging out in a bar to rate the dater’s level of attractiveness on a scale of one to 10.

By contrast, intelligence ratings were more than twice as important in predicting women’s choices as men’s. It isn’t exactly that smarts were a complete turnoff for men: They preferred women whom they rated as smarter—but only up to a point. In a survey we did before the speed dating began, participants rated their own intelligence levels, and it turns out that men avoided women whom they perceived to be smarter than themselves. The same held true for measures of career ambition—a woman could be ambitious, just not more ambitious than the man considering her for a date.

When women were the ones choosing, the more intelligence and ambition the men had, the better. So, yes, the stereotypes appear to be true: We males are a gender of fragile egos in search of a pretty face and are threatened by brains or success that exceeds our own. Women, on the other hand, care more about how men think and perform, and they don’t mind being outdone on those scores.

Men can be such wimps sometimes.

Smart Women are Scary Read More »

46 Comments
Scroll to Top