Miscellany

The cat is out of the bag about Stephen Hawking’s new ideas about black holes. Preposterous regulars were in on the ground floor, of course. We can now speculate somewhat more intelligently about what the ideas actually are, since the abstract for his talk (next week at the GR17 conference in Dublin) is online:

The Euclidean path integral over all topologically trivial metrics can be done by time slicing and so is unitary when analytically continued to the Lorentzian. On the other hand, the path integral over all topologically non-trivial metrics is asymptotically independent of the initial state. Thus the total path integral is unitary and information is not lost in the formation and evaporation of black holes. The way the information gets out seems to be that a true event horizon never forms, just an apparent horizon.

(For more scoop see Not Even Wrong, Smijer, By the Way, and this thread on sci.physics.research.)

It seems as if our initial skepticism might be accurate: even if Hawking’s proposal is ultimately judged to be a fantastic breakthrough, it won’t catch on right away. The Euclidean path integral approach to quantum gravity, which Hawking has been instrumental in developing, is not generally thought to be the most promising approach. One never knows, and it might eventually turn out to be on the right track, but it’s not very popular in the quantum-gravity community.

Let’s try to explain what is going on. Quantum mechanics tells us that the world is described by wave functions, which give the probability for getting a certain result when we make an observation. A path integral is just a certain way of calculating the wave function. Invented by Richard Feynman, the path-integral approach says that we should attach a certain contribution to every possible path the system can take from one configuration to another, and then sum all of these contributions; the result is the wavefunction for being in the final state, given the initial state we started with. Often this sum (the path integral) is hard to do, and a convenient mathematical trick is to allow the time coordinate to be imaginary; this purely formal manouver turns four-dimensional spacetime into a four-dimensional space (no direction is singled out as “timelike”), and the integral turns out to be much easier to do. In gravity, we would like to sum over all the possible geometries of spacetime itself. So “Euclidean quantum gravity” tells us to calculate the wave function for the geometry of three-dimensional space at some fixed time by summing over all the possible four-dimensional geometries that connect to that spatial geometry.

The problems with this approach include: nobody knows what number to attach to each geometry in the sum, nobody knows how to do the integral, and nobody knows how to interpret the result. Significant problems, in other words. Optimists like Hawking think that they can describe a certain set of approximations in which the path integral makes sense; string theorists, on the other hand, would generally say that the path integral is nonsense if you don’t include the fundamentally “stringy” aspects of spacetime on ultra-small scales. In the absence of direct experimental data, we have to judge how well the ideas hang together in their own right; at the moment, Euclidean quantum gravity seems to have serious issues, and hasn’t scored many notable triumphs.

Hawking now seems to be saying that the path integral for black holes can help us understand how information that we thought had disappeared into the singularity can actually be lurking close to the horizon, so that it can eventually influence the outgoing Hawking radiation, and thus allow information to be recovered by the evaporating black hole. He’ll be met with serious skepticism in the physics community, but let’s wait to see how it washes out.

Of course, he’ll also be met with serious awe by the media. This can drive other physicists crazy. I often find myself explaining to non-physicists that Hawking is not the very best theoretical physicist out there, but simultaneously defending his reputation to my fellow physicists. It’s probably safe to say that Hawking was the leading researcher in theoretical gravitational physics in the second half of the twentieth century, and arguably since Einstein; but gravitational physics was not where the action was during that time (it was in particle physics and quantum field theory). A lot of physicists hurry to point out that Hawking is not doing the most influential work in quantum gravity these days; but the truth is that most sixty-year-old physicists aren’t doing the most influential work in their fields, even if they don’t have serious neurological disorders. Like anyone else who has made fantastic contributions, Hawking has earned respect for new ideas he might have, but the ideas themselves will be judged on their own merits.

Okay, can we stop doing this? Where by “this” I mean grasping at any opportunity to ridicule the behavior of Jenna and Barbara Bush, simply because they are the children of our disastrously bad President. And no, the fact that they are campaigning for their father doesn’t make their private lives fair game. If you want to critique their ability as campaigners, or suggest that they have implausible policy views, go right ahead. But to titter about stories of the Bush twins’ bar exploits is tawdry, demeaning, and completely unnecessary.

I would make a distinction that is rather fine, but seems valid: in the context of pure gossipy dirt-dishing (like the original Times article that the Barbara Bush story came from, or nearly every story in Wonkette), I have no objection to mean-spirited snarkiness. That’s the point of those kinds of stories. But when we indiscriminately mix this trash in with serious political disagreements, we are stooping lower than there is any need to stoop. Here we have an administration that has produced so many fiascos that there is increasing talk of “outrage fatigue“; what is the point of muddying the waters with jabs at the personal lives of the President’s kids? There are real things to complain about without following people into bars hoping they’ll embarrass themselves.

Terry Teachout has a nice reflection on the social disapprobation that accompanies an unseemly regard for the artistic and intellectual side of life (especially for children). I have nothing deep to add, except that his mention of a hypothetical waitress who could quiz him knowledgeably on what he was reading reminded me of this well-known math joke:

The first mathematician says to the second that the average person knows very little about basic mathematics.

The second one disagrees, and claims that most people can cope with a reasonable amount of math.

The first mathematician goes off to the washroom, and in his absence the second calls over the waitress.

He tells her that in a few minutes, after his friend has returned, he will call her over and ask her a question.

All she has to do is answer: `one third x cubed’.

She repeats `one thir — dex cue’? He repeats `one third x cubed’.

Her: `one thir dex cuebd’? Yes, that’s right, he says.

So she agrees, and goes off mumbling to herself, `one thir dex cuebd…’.

The first guy returns and the second proposes a bet to prove his point, that most people do know something about basic math. He says he will ask the blonde waitress an integral, and the first laughingly agrees.

The second man calls over the waitress and asks `what is the integral of x squared?’.

The waitress says `one third x cubed’ and while walking away, turns back and says over her shoulder `plus a constant’!

Okay, it’s not very funny if you don’t know much calculus (the waitress was giving a more precisely correct answer than the mathematicians had any right to expect, demonstrating that they were both handicapped by inaccurate stereotypes). But I noticed something else: looking for a copy of the joke through Google, the version I just transcribed is only the second-most-popular version. More popular is the following:

Two mathematicians were having dinner in a restaurant, arguing about the average mathematical knowledge of the American public. One mathematician claimed that this average was woefully inadequate, the other maintained that it was surprisingly high.

“I’ll tell you what,” said the cynic. “Ask that waitress a simple math question. If she gets it right, I’ll pick up dinner. If not, you do.”

He then excused himself to visit the men’s room, and the other called the waitress over.

“When my friend returns,” he told her, “I’m going to ask you a question, and I want you to respond ‘one third x cubed.’ There’s twenty bucks in it for you.” She agreed.

The cynic returned from the bathroom and called the waitress over. “The food was wonderful, thank you,” the mathematician started. “Incidentally, do you know what the integral of x squared is?”

The waitress looked pensive, almost pained. She looked around the room, at her feet, made gurgling noises, and finally said, “Um, one third x cubed?”

So the cynic paid the check. The waitress wheeled around, walked a few paces away, looked back at the two men, and muttered under her breath, “…plus a constant.”

You see the difference? In the first version, with which I was familiar, I always imagined that the waitress was having fun teasing the mathematicians, and walked away smiling. But in the second version it’s clear she is just pissed off and grumbling. Now it seems much less funny to me, although obviously a lot of people prefer this version.

It’s amazing what psychological insights you can reach just be wandering through the web with Google as your only guide. The internet isn’t anything weird and scary, it’s just a window into our brains. Okay, that is pretty scary.

Another young mind enters the community of scholars. Congratulations to Eugene Lim, who just finished successfully defending his Ph.D. thesis, and is now an official doctor. Preposterous readers may know Eugene from his occasional appearance in the Comments, under the nom de blog “Your Hardworking Student.” Eugene is only the second Ph.D. student I’ve had, so I’m still fumbling around a bit, but hopefully my inexperience as an advisor didn’t scar him too badly.

Eugene’s thesis work was about the gravitational effects of vector fields that violate Lorentz invariance by picking out a preferred direction in spacetime. We have one joint paper coming out soon, and he has a longer single-author paper, so I’ll give more details about the research when they are ready. The basic story is surprisingly short and sweet: the vector field acts to change the measured value of the gravitational constant, but in different ways in different circumstances, so you can actually place interesting limits on its magnitude by comparing different experiments.

In the fall Eugene will be heading to Yale to take up a postdoctoral research position. Good luck!

This weekend I saw the first Godzilla movie, in the restored original Japanese version. The Godzilla universe is as complicated and internally inconsistent as they come, but the first movie (1954) was an interesting allegory about the hazards of nuclear weapons. Shot in stark black and white, the movie tells the story of a prehistoric monster who is brought back to life by H-bomb testing and proceeds to terrorize coastal Japan and Tokyo in particular. The original American theatrical release was heavily bowdlerized, both removing some of the harsher scenes of irradiated children (Godzilla was highly radioactive) and splicing in scenes of Raymond Burr as an American journalist. I haven’t seen the American version in a long time (ever? there are so many Godzilla movies it’s hard to keep track), but I suspect the Japanese version is both more coherent and dramatically compelling.

Of course the production quality was not what we are used to these days, nor was the general pacing. To a contemporary audience, this movie seems awfully relaxed, even in the scene where Godzilla is stomping trains and power lines in downtown Tokyo. Part of this is the difference between Japanese and American sensibilities, but much of it is simply the passage of time; those early James Bond films seem just as lethargic. And it’s easy to recognize when a tiny model is being destroyed by waves rather than a full-size town. (Probably much of our ability to tell the difference can be traced to physics — the relative timescales associated with various actions change with respect to each other as a function of length scale. Someone should write a paper about this.) The one effect that remains unmatched is the sound that Godzilla makes; even in the horrible but high-tech 1998 American version, they were unable to create an equally impressive Godzilla sound from scratch and had to stick with the original.

Science plays an ambiguous role in the movie. Obviously, technology is implicated in the original horror of the H-bomb that brings Godzilla to life. Later, the elderly paleontologist is portrayed as heartbroken that there are plans to kill Godzilla (who has been happily rampaging through Tokyo) rather than attempt further study — a standard, although not very complimentary, stereotype of scientists. But at the end, it is a lonely researcher working in his basement laboratory who invents the weapon that ultimately destroys Godzilla — the Oxygen Destroyer, which kills all aquatic life in a wide radius around where it is activated. So science has terrible consequences, but we have no other recourse when we need to address our serious problems. Of course, yet another misunderstanding of how science works leads to the final plot twist, when the lonely researcher (who had been permanently scarred by an atomic blast) commits suicide after the Oxygen Destroyer is used, so that this terrible power cannot fall into the wrong hands. In the real world, if a well-funded group of dedicated scientists have just seen something demonstrated, they will figure it out for themselves before too long. There are no true secrets when it comes to science and technology; the interesting discoveries will all eventually be made, regardless of what any one person chooses to share.

Good news for all you jazz lovers out there: The Great Divide, a new CD from tenor master Von Freeman.

As I’ve previously mentioned, Von is a Chicago legend. Eighty-one years young, he is still blowing as hard as ever. His style owes much of its allure to the ability to absorb many different influences, from Coleman Hawkins to Lester Young to Gene Ammons to Charlie Parker to John Coltrane to Ornette Coleman, and mix in something absolutely unique. For a quick demonstration, run out and buy his 1981 album Young and Foolish. Go to track one, “I’ll Close My Eyes,” and skip right ahead to the 9:11 mark. For the next two and a half minutes you’ll hear one of the most amazing sax solos ever committed to CD. A true solo, the rest of the band sitting out, that stretches from manic bebop phrases to near-dissonant growling, only to suddenly and sharply caress the original melody in startling epiphanies, bringing the audience to a state of near-riot. And that is the true genius: to experiment and test the limits of the music while remaining consistently and compellingly beautiful. (Don’t take my word for it, read the reviews.)

Along with his musical gifts, Von is famous for his generous spirit and mischievous humor. Best of all, he’s extremely accessible, at least if you’re in Chicago. Von and his quartet play the second Saturday of every month at Andy’s downtown, and every single Tuesday at the New Apartment Lounge on 75th Street, in an atmosphere at once informal, authentic, and genuinely welcoming. You will never find music of this caliber for such a low cover charge (zero dollars). Later in the evening, striving young musicians from throughout the city take part in a spirited jam session. (For a lively discussion of the Chicago music scene, opening with an amusing account of the vibe at the Apartment, check out Waking Up in Chicago by British journalist Claire Hughes.) This Tuesday (the 13th) there will be a party to celebrate the new CD; Von will also be playing later this week at the Green Mill and in Millennium Park.

Von’s fans will tell you that the only reason he hasn’t become as well-known as the usual roster of saxophone legends is that he never moved to New York to pursue a recording career, preferring to stay home and play gigs. Whatever the explanation, Chicagoans are truly fortunate to have such a master in their midst.

As a theoretical physicist, you come to cherish those very few moments when a new idea makes everything snap into place. In politics it almost never happens, so we should be even more grateful. One such idea has been hit upon by John McKay’s wife: George W. Bush doesn’t want to be President any more. He’d be just as happy to lose. It all makes sense now. He never really wanted to be President in the first place; he only ran because God told him to. But he was never happy about it; more like a reluctant Orestes being egged on by Apollo to do all those nasty things.

The man has suffered enough for the greater good. He’d be happier on his pickup truck back in Crawford. It’s really the least we can do for him, after all he’s done for us.

p.s. I do have one question. Why is considered humble to think that you’ve been chosen by God? Doesn’t that mean that you think God has chosen you personally, rather than somebody else? It’s a funny approach to humility.

Now would be a good time to brush up on our theology and morality, in preparation for the upcoming debate about the Federal Marriage Amendment. The Senate had a preview this week, as they voted 51-46 to confirm J. Leon Holmes to the Eastern District Court in Arkansas. Holmes was controversial for various reasons, including a 1997 article in which he and his wife Susan argued that it was the duty of a good Catholic wife to subordinate herself to her husband. This angered knee-jerk liberals like Edward Kennedy, who referred to the Holmes’ view as “extreme.” Kennedy was countered by Orrin Hatch, who pointed out that the argument originated in St. Paul, not in the Holmes article, and that “most everyone” in the country would vote for St. Paul over Teddy Kennedy if they were choosing from whom they should take advice about morality.

The relevant Scripture is from Chapter Five of Paul’s letter to the Ephesians, verses 22-24:

Wives should be subject to their husbands as to the Lord, since, as Christ is head of the Church and saves the whole body, so is a husband the head of his wife; and as the Church is subject to Christ, so should wives be to their husbands, in everything.

(From the New Jerusalem Bible, probably the most accurate translation.*) In all fairness, Paul attempts to be evenhanded, when in verse 28 he says

In the same way, husbands must love their wives as they love their own bodies, for a man to love his wife is for him to love himself.

Although, to be absolutely fair, we should also draw attention to Chapter Six, verses 5-6:

Slaves, be obedient to those who are, according to human reckoning, your masters, with deep respect and sincere loyalty, as you are obedient to Christ: not only when you are under their eye, as if you had only to please human beings, but as slaves of Christ who whole-heartedly do the will of God.

Most religious liberals these days would probably not go along with the ideas that wives should be subservient to their husbands, nor that slaves should be obedient to their masters. One would rather interpret these as anachronistic relics of an earlier time when our understanding of morality was less well-developed. The question is then, how do we distinguish between the anachronisms and the useful guides to behavior? Think of it this way: are there any circumstances under which your moral instincts might be in direct conflict with religious doctrine, where you would accept the Church’s teaching even though you would have come to a very different conclusion by yourself? And if not, what good exactly is the teaching as a guide to morality?

Update: I should include a footnote about the New Jerusalem Bible, as found at bible-researcher.com: “The idea that a Bible version such as this, which contains introductions and notes that presuppose the acceptance of skeptical views and modernistic theories concerning the authorship and authenticity of the books, would be suitable for all Christians, is very questionable. After fully admitting its good qualities, we must point out that the Jerusalem Bible is not in fact suitable for Christians who are in need of edification in the faith. The theological commentary and critical speculations included in this version, useful as they may be for advanced studies, are likely to have a bad spiritual effect on most readers. This is a Bible suitable only for students who are well established in the faith and capable of using it with discretion.”

Today the quotes will speak for themselves. It’s all rabid political polemic, so those of you looking for our regularly-scheduled insights into the workings of the universe will have to wait until next week.

From Chris C. Mooney, more complaints from high-level scientists about the administration’s unbelievable politicization of the scientific advisory process. From his notes on a Union of Concerned Scientists press conference:

Janet Rowley, cell biologist at the University of Chicago and President’s Council on Bioethics member. Rowley delivered what I consider a startling revelation: That her appointment to the President’s Council in 2001 was politically vetted to an inappropriate extent. In her own words, the White House personnel office asked her the following questions: “Had I voted for president Bush’s election; also, did I support president Bush’s policies.” Rowley said she “remonstrated” that these questions had no bearing on her competence to serve on the council. “The response from the White House was that this was a presidential appointment, they wanted to appoint people who supported the president,” Rowley continued.

Also links to a new report from the UCS.

From Talking Points Memo, a pointer to an article in The New Republic about the administration’s attempts to score a big coup against terror just in time for the election:

This spring, the administration significantly increased its pressure on Pakistan to kill or capture Osama bin Laden, his deputy, Ayman Al Zawahiri, or the Taliban’s Mullah Mohammed Omar, all of whom are believed to be hiding in the lawless tribal areas of Pakistan. A succession of high-level American officials–from outgoing CIA Director George Tenet to Secretary of State Colin Powell to Assistant Secretary of State Christina Rocca to State Department counterterrorism chief Cofer Black to a top CIA South Asia official–have visited Pakistan in recent months to urge General Pervez Musharraf’s government to do more in the war on terrorism. […]

This public pressure would be appropriate, even laudable, had it not been accompanied by an unseemly private insistence that the Pakistanis deliver these high-value targets (HVTs) before Americans go to the polls in November. The Bush administration denies it has geared the war on terrorism to the electoral calendar. […] But The New Republic has learned that Pakistani security officials have been told they must produce HVTs by the election. According to one source in Pakistan’s powerful Inter-Services Intelligence (ISI), “The Pakistani government is really desperate and wants to flush out bin Laden and his associates after the latest pressures from the U.S. administration to deliver before the [upcoming] U.S. elections.” […]

But according to this ISI official, a White House aide told ul-Haq last spring that “it would be best if the arrest or killing of [any] HVT were announced on twenty-six, twenty-seven, or twenty-eight July”–the first three days of the Democratic National Convention in Boston.

And from Political Animal (via Brad DeLong), a link to a CNN story explaining (yet!) another reason GWB is the odds-on favorite to be judged Worst President Ever:

President Bush declined an invitation to speak at the NAACP’s annual convention, the group said…. NAACP spokesman John White said Wednesday that Bush has declined invitations in each year of his presidency — becoming the first president since Herbert Hoover not to attend an NAACP convention.

It’s enough to make even a libertarian like Jacob “I’ve never cast a vote for a major-party candidate for President” Levy come out in favor of Kerry. As he says here,

This time, it seems very clear to me that the Bush Administration has failed basic tests of competence in policymaking and execution, and of trusteeship of long-term interests like alliances and trade negotiations and moral credibility. I expect to dislike an awful lot of John Kerry’s policies. But I don’t expect that kind of failure of the basic responsibilities of the office.

Hopefully enough folks in Michigan, Ohio, and Pennsylvania will follow suit (link from Balkinization.)

A recent article by Amanda Schaffer in Slate is causing physicists to sit up and take notice (see comments at Gnostical Turpitude, Quark Soup, Not Even Wrong). The article is nominally about Brian Greene’s standing in the physics community, although it doesn’t really address that question. Brian, of course, is a well-known string theorist at Columbia, but celebrated more widely as the author of The Elegant Universe and The Fabric of the Cosmos, as well as host of a NOVA special on PBS.

The real focus of the Slate article is more about the style of string theory — in the absence of detailed experimental results, are the criteria of beauty and mathematical coherence that string theorists rely on sufficient guides to doing effective physics? Interesting questions, about which I’ve previously promised to blog, but haven’t gotten around to it yet. But what about the nominal question, of someone’s standing as a physicist? It should come as no surprise that physicists, being the hard-nosed quantitative types that they are, have developed an extremely precise (and, often, wildly inaccurate) method for rating the worthiness of their colleagues, and implemented it as a web page to boot. It’s the SPIRES high-energy physics literature database, which keeps track of what articles are citing, and being cited by, other articles in physics (or at least in high-energy physics, and increasingly astrophysics and related areas). Coupled with the availability of the papers themselves (in preprint form at arxiv.org or in published form at various online journals), the ease with which one can search through literature citations has become fantastically greater over the last ten years or so. No self-respecting physicist goes to an actual library any more, much less uses a Xerox machine.

But the real fun of SPIRES is to figure out how many citations your friends have (and thus, how good they are). For example, I have about 40 papers listed, with about 2000 total citations — pretty good for an assistant professor, but by no means near the top of the list. I have no “renowned” papers (more than 500 citations), but I do have seven “famous” papers (more than 100 citations). Even that is a bit of a cheat, since two of those papers are review articles, which are cheap ways to rack up lots of citations. There are numerous caveats to this measure of one’s quality — different specialties have very different rates of citations, certain fields are not covered as well by SPIRES, it’s very hard to appropriate credit in large collaborations, not to mention the obvious fact that having a lot of citations is not the same as being a good paper — but it’s just so easy and quantitative that the citation numbers from SPIRES have become very influential.

It’s humbling to look at the citation records of the really influential people in high-energy physics. Big names in string theory do especially well in the citation game; string theorists just write a lot of papers. Cumrun Vafa at Harvard has five renowned papers and 58 famous ones; David Gross at KITP in Santa Barbara (who was an extremely successful field theorist long before he became an influential string theorist) has twelve renowned papers and 41 famous ones. In cosmology, Andrei Linde has three renowned papers and 39 famous ones; in particle phenomenology, Howard Georgi has eight renowned papers and 47 famous ones. These are just representative names; I haven’t done any systematic searches for who has the most citations. Besides, everyone knows the answer: Ed Witten has an amazing 36 renowned papers and 99 famous ones. Both prolific (over 200 papers) and profound (over 200 citations per paper). Everyone else is just playing for second place.