Another day in the life

Here at Cosmic Variance we occasionally grant the gawking masses a brief glimpse into the glamorous and sexy world of the professional physicist. So, for those of you keeping score at home, I just did a quick count: in the last 24 hours I have sent 35 emails. Sadly, I have received 54 emails, so it looks like I’m still falling behind. (No, this doesn’t include spam — I usually get between 100 and 150 of those per day, but I do have a very good spam filter.)

Update: sorry, in counting messages received I only accounted for those I had either answered or saved, not those I had simply deleted. So, add another 31 messages, for a total of 85 non-spam messages received.

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The graceful-exit problem

There’s an old physics joke about the stages of the reception of a new idea: first it’s considered to be wrong, then it’s considered to be trivial, before finally people are claiming that it was their idea first. Some of our more colorful colleagues have even mastered the art of claiming all three at once!

The question of whether or not we should expeditiously withdraw from Iraq seems to be working through the stages of this joke. Hilzoy at Obsidian Wings points to an especially amusing example. Joe Biden (who, I think people on all sides can agree, is a craven opportunist if ever there was one) writes an editorial calling for a timetable for withdrawal. Right-wing hacks in the blogosphere and elsewhere jump all over the poor Senator, questioning his manhood and patriotism. Meanwhile, the White House congratulates Biden for coming up with a plan that was remarkably similar to their own. A slight communication problem for the ordinarily tightly-run noise machine.

The obvious next step: a joint Nobel Peace Prize for George W. Bush, Abu Musab al-Zarqawi, and Saddam Hussein.

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We are not alone

Brian Leiter points to a short essay by John Perry about his colleagues in philosophy, and excerpts this scene:

[A] thought about this wonderful and interesting group of people, my philosophical colleagues. I have a very distinct memory of arriving at the Eastern Meetings of the American Philosophical Association some years back, when they were held at a hotel in Baltimore. The meetings began just after a National Football League playoff game had been played in that city, and the previous occupants of the hotel seemed to be mainly people connected with this game. Since I was flying from the west coast, and had to attend some meeting or other in the early afternoon of the first day, I arrived the night before most of the other participants. I was able to watch the amazing transformation that took place as the football crowd checked out and the philosophy crowd checked in. The NFL people were large, some very large, most quite good-looking, confident, well-dressed, big-tipping, successful-looking folk; the epitome of what Americans should be, I suppose, according to the dominant ethos. We philosophers were mostly average-sized, mostly clearly identifiable as shabby pedagogues, clutching our luggage to avoid falling into unnecessary tipping situations. We included many bearded men— some elegant, some scruffy— all sorts of interesting intellectual looking women; none of the philosophers, not even the big ones and the beautiful ones, were likely to be mistaken for the football players, cheerleaders, sportscasters and others who were checking out. The looks from the hotel staff members, who clearly sensed that they were in for a few days of less expansive tipping and more modest bar-tabs, were a mixture of curiosity and apprehension. The talk, as philosophers recognized each other and struck up conversations, was unlike anything that ever had been or would be heard in that hotel lobby: whether there are alternative concrete possible worlds; whether there is anything in Heidegger not better said already by Husserl; whether animals should be eaten; not to mention topics that aroused truly deep passions, mostly related to proper names.

What a wonderful group of people, I thought, and how wonderful, and lucky, that the world has managed to find a niche for us. Even if philosophy had no real intellectual content at all — was as silly as astrology or numerology certainly are, or as I suspect, in dark moments, that certain other parts of the university are— it would still be wonderful that it existed, simply to keep these people occupied. Especially me. What would I be doing without this wonderful institution? Helping people in some small town in Nebraska with their taxes and small legal problems, I suppose, and probably not doing it very well.

It would take very little to apply this to physicists (or scientists, or academics more generally) as well as philosophers. We tend not to bring up Heidegger, but we do argue about alternative possible worlds all the time.

More importantly, it’s the second paragraph that hits home. How fortunate we are to live in a time and place where society is sufficiently robust and diverse as to put aside a bit of its resources in order to foster a tiny group of people whose professional duty it is to think deeply about the secrets of the universe. I am reminded of the dedication page in the most poetic general relativity textbook ever written, Gravitation by Misner, Thorne and Wheeler:

We dedicate this book
To our fellow citizens
Who, for love of truth,
Take from their own wants
By taxes and gifts,
And now and then send forth
One of themselves
As dedicated servant,
To forward the search
Into the mysteries and marvelous simplicities
Of this strange and beautiful Universe,
Our home.

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Obscure films

Since we’re doing holiday frivolities here, let me point to a post by Tony Galluci at milkriverblog, who is collecting nominations for the best film that too few people know about. I’m not very good at these games, since I only catch on to quality small films once twenty other people recommend them to me, at which point I can’t really claim that too few people know about them.

So, at the risk of being insufficiently obscure, I’ll nominate Vanya on 42nd Street as a dramatically under-appreciated film. In this movie we have:

  1. A play by Anton Chekhov,
  2. adapted by David Mamet,
  3. directed (in rehearsal) by Andre Gregory,
  4. filmed by Louis Malle,
  5. performed by an amazing cast featuring Julianne Moore, Wallace Shawn, Larry Pine, and several other New York theater regulars.

Happily, these raw materials come together into an amazing whole. We start with a play that has the typical Chekhovian layerings of meaning and mood, and embed it in a film that follows seamlessly from the actors arriving at the theater into beginning their rehearsal (one of the jolts of the movie is when you realize the play has already begun and you hadn’t noticed). We alternate between being drawn in completely to Chekhov’s dialogue and being pushed out by reminders that these are actors performing a play; the juggling act could have fallen flat, but all the different balls are kept artfully in air. It’s not such an obscure film, but I can still push it as under-appreciated.

Forced to slightly greater obscurity, I’ll vote for Gazon Maudit (French Twist). A completely hilarious film that starts as your typical frustrated-housewife-falls-for-lesbian-truck-driver picture, and then takes, unsurprisingly, a twist. Americans could never have made this movie — certain things the French will always do better.

Nominations? I’m sure people can out-obscure me without much trouble.

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A Brief History of Disbelief

Abbas Raza at 3 Quarks Daily, just before kindly linking to my martini post, mentions a recent BBC documentary, Jonathan Miller’s Brief History of Disbelief. Not sure how I will ever get to see it, but it sounds great; very similar in spirit to the Moments in Atheism course I taught with Shadi Bartsch some time back. The synopses look about right:

Shadows of Doubt
BBC Two
Monday 31 October 2005 7pm-8pm
Jonathan Miller visits the absent Twin Towers to consider the religious implications of 9/11 and meets Arthur Miller and the philosopher Colin McGinn. He searches for evidence of the first ‘unbelievers’ in Ancient Greece and examines some of the modern theories around why people have always tended to believe in mythology and magic.

Noughts and Crosses
BBC Two
Monday 7 November 7pm-8pm
With the domination of Christianity from 500 AD, Jonathan Miller wonders how disbelief began to re-emerge in the 15th and 16th centuries. He discovers that division within the Church played a more powerful role than the scientific discoveries of the period. He also visits Paris, the home of the 18th century atheist, Baron D’Holbach, and shows how politically dangerous it was to undermine the religious faith of the masses.

The Final Hour
BBC Two
Monday 14 November 7pm-8pm TBC
The history of disbelief continues with the ideas of self-taught philosopher Thomas Paine, the revolutionary studies of geology and the evolutionary theories of Darwin. Jonathan Miller looks at the Freudian view that religion is a ‘thought disorder’. He also examines his motivation behind making the series touching on the issues of death and the religious fanaticism of the 21st century.

I’m happy to see Baron D’Holbach in there, although a little surprised that Hume’s name wasn’t featured more prominently. And it’s too bad that he discounts the role of scientific discoveries; my own theory is that the mechanics of Galileo and Newton was actually much more influential in the development of atheism than people tend to believe.

Also interesting was this quote from the interview with the director, Richard Denton:

BBC Four: Were you surprised to find the first American presidents were so sceptical about religion?
RD: I was incredibly struck by their quotations – these guys wouldn’t even get considered as candidates if they said anything like that now. And I was depressed by that because it made me feel that we have not made a great deal of progress since the Age of Enlightenment. If anything, we’re going backwards at the moment.

Ain’t it the truth.

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Three and I'm under the table

It’s unusual, in this muddy imperfect world of ours, that we have the ability to conjure up perfection when the moment calls for it. Thank goodness, then, for the martini.

A simple enough thing: mix four parts gin and one part dry vermouth into a cocktail shaker over ice. Shake, and strain into a martini glass. (No need to rush; a tiny bit of dilution from the melting ice can help bring out the flavor.) Garnish with an olive or two. Simplicity is often a grace of perfection. Enjoy before dinner after a long day of solving equations, or later at night between sets at a smoky jazz club.

Really we should just stop there, and returning to our regularly scheduled string-theory-and-God blogging. But it is not in human nature to accept perfection in an appreciative stillness; we have to go mucking around, trying to make it even better. And thank goodness, or some enterprising bartender never would have invented the martini in the first place. Alas, mucking more often leads to tragedy than to triumph, and some wheat/chaff separation is in order.

martini The martini’s perfection is deceptive because of its near-inevitability. Every aspect of the cocktail manifests its individual degree of perfection, so we are hardly surprised (that is, not as much as we should be) when it all comes together so elegantly. Gin, originating in the Low Countries and elevated to iconic status in Britain, forms the foundation of this quintessentially American drink. The basic white grain spirit is enlivened by the slightly exotic flavors of juniper and other botanicals. It’s everything you want in a foundation: solid and agreeable, perfectly transparent without being empty or boring. Dry vermouth, a fortified wine that is quite acceptable as a separate aperitif, but only reaches toward divinity in its role as a secondary ingredient against the gin. And the olives, suggesting a touch of the Eastern Mediterranean, adding a worldly spiciness and lush green roundness to the austerity of the cocktail.

But the experience of a martini extends beyond the ingredients. We have, most obviously, the glass: a perfected artistic form, functional as well as attractive, borrowed shamelessly (and understandably) for a myriad of lesser purposes. We have also the mixing procedure itself; a proper metallic cocktail shaker is one of those accessories that is worth investing in. There is a myth going around, if you hang out on the wrong street corners, that shaking will “bruise” the gin. Rubbish, of course. But go ahead and stir if you like — you can avoid tiny bubbles that may cloud your drink, but you’ll miss out on the sensual pleasure of the act of shaking itself.

Now, let it never be said that I am a fundamentalist. A little deviation from orthodoxy can be a good thing. Indeed, replacing the traditional toothpick with an artistic metal pick can add a touch of class to the presentation. If you’d like to experiment with whimsical modifications of the traditionally-shaped glass, be my guest, although you’re operating at your own risk. It’s occasionally fun to use olives stuffed with blue cheese or garlic or — my favorite — a bit of jalapeno pepper. Heck, you could even replace the olives with a twist of lemon, although at that point you risk sacrificing taste for visual impact (a completely unnecessary compromise, in this instance).

But there are some roads that we have no good reason to walk down, and two of them have become all too well-traveled: dryness and vodka. Original martini recipes called for nearly equal proportions of gin and vermouth, and only later did experimentation reveal that a much smaller proportion of vermouth made for a more successful drink. Four-to-one is about right, although there is room for variations in taste. But this worthy discovery has devolved into a pointlessly macho competition about whose martini is the driest. Bartenders now regularly splash vermouth into their shakers and then pour it out before adding the gin, leaving behind a helplessly thin coating of the original spirit. The next step is to simply pour chilled gin into your glass while doing a Google image search for “vermouth.” There is a name for the resulting drink: it’s called “gin.” It’s not a cocktail, it’s just a straight spirit, one step removed from doing shooters of grain alcohol. The success of the martini comes from the symbiotic mixture of different spirits, as Fareed Zakaria has persuasively argued.

Vodka, of course, is a perfectly enjoyable spirit in its own right. It should be served as cold as possible, in shot glasses, alongside black bread and earthy Slavic accomaniments like caviar and pickles. The thing about vodka is that, in its purest form, it is basically tasteless. This makes vodka an excellent backdrop for all sorts of flavorings, which is why flavored vodka is so popular. (You’ll never walk into a liquor store and see flavored gin — at least, I hope not.) But it makes it useless for a martini, especially a dry one. Gin, dry vermouth, and olives all taste like something, and it is the miracle of those tastes working together that creates a transcendent cocktail.

And now we’ve come right up to the point where my inner cranky old man takes over from the face of youthful libertinism that I present to the world. Because, from replacing gin with vodka, it’s a short step to the multiple horrors foisted on the drinking public that appear on “martini lists” in many of our finest establishments. Look, you can drink whatever you want. And I have nothing against color or sweetness for its own sake. But if you mix together a concoction involving any sort of Kahlua or Frangelico or raspberry liqueur — call it what you want, but it’s not a martini. It doesn’t matter that it involves alcohol and is served in the traditional martini glass. It’s a mixed drink, but it’s not a martini. Just because you stick a tail on a watermelon, don’t make it a pig.

See, I like to think that words have meanings. And the word “martini” has a perfectly good referent — the above-discussed cocktail, worldwide symbol of elegance and sophistication. And this martini has certain qualities. And none of these qualities involves “fruitiness” or “sweetness.” Sorry. Martinis are astringent, challenging, an acquired taste of limitless reward. They are not fluorescent concoctions redolent of high-fructose corn syrup. Don’t get me wrong; some of these drinks can be quite enjoyable. I recently went to the Raw Bar here in Chicago and sampled the “Barry White martini,” which was appropriately dark and satiny and certainly not a martini. At Aquitaine in Boston I had something called the “Icicle,” made from Icelandic vodka and ice wine with a frozen grape — also enjoyable, also not a martini. Why use a perfectly precise word when you really mean something else?

sidecar The most successful non-martini cocktails take the lessons of the martini and use them in innovative ways. My personal favorite is the sidecar: three parts cognac, one part each Cointreau (orange liqueur) and lemon juice, decorate with a lemon twist. You can even put sugar on the rim without doing violence to the basic conception of the drink. Sidecars are a little sweet, but the fundamentally robust nature of the cognac provides an effective counterweight, and this would never be accused of being a frivolous drink. (Edging toward frivolity, we have the “between the sheets”: equal parts cognac, Cointreau, lime juice, and white rum, served with a twist. But it’s good, I have to admit.)

manhattan Still, the cocktail that in some ways is the most impressive is the Manhattan: three parts bourbon, one part sweet (red) vermouth, dash of bitters and a splash of cherry juice, served with a Maraschino cherry. You can see the basic similarity to the martini template: robust foundational spirit, secondary aperitif-oriented spirit, colorful garnish. But the martini, composed of ingredients of individual perfection, was destined to succeed. Meanwhile, the fact that the Manhattan works at all is a minor miracle. Its ingredients are individually barbaric — I mean, bourbon? cherry juice? — that work together in an impressive high-wire act, the coarseness of the bourbon playing off the sickly sweetness of the cherries. When it succeeds, it’s a feat worthy of our admiration.

These cocktails don’t try to sully the worthy martini name by pretending to be what they’re not; they succeed on their own terms. I’m even prepared to grant a place to the much-maligned Cosmopolitan (vodka, Cointreau, lime juice, cranberry juice), unless you try to call it a martini. The Sex in the City gals needed to be drinking something light and colorful — the transparent severity of a true martini would have undermined the mood.

Happy holidays. And if you can find a bartender that does right by you, tip well. You’ll feel good about yourself, and your status will be elevated in the eyes of persons of whatever sexual identification and preference you hope to impress.

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"A New Low"

I can be as amused by a theatrical political stunt as the next guy. You want to call the Senate into closed session? Close down the government for a bit? Be my guest. (Although, as Newt Gingrich will testify, sometimes stunts can backfire.)

But then there are stunts that are so fundamentally dishonest that they make your skin crawl, and it’s hard to understand how even people who agree on the politics can ever excuse the tactics. We were just handed a classic example by House Republicans. As you’ve undoubtedly heard, Democratic Representative John Murtha, an ex-Marine and noted hawk, recently came out in favor of withdrawal from Iraq. Originally a supporter of the war, Murtha gave an impassioned speech decrying the casualties and the lack of support for our troops within Iraq itself; see video of his speech at Crooks and Liars, read the text at firedoglake. He did not shy away from pointing out that many of the architects of the conflict had managed to avoid military service in their own day.

Here is the text of the resolution sponsored by Murtha:

Whereas, Congress and the American People have not been shown clear, measurable progress toward establishment of stable and improving security in Iraq or of a stable and improving economy in Iraq, both of which are essential to “promote the emergence of a democratic government”;

Whereas, additional stabilization in Iraq by U, S. military forces cannot be achieved without the deployment of hundreds of thousands of additional U.S. troops, which in turn cannot be achieved without a military draft;

Whereas, more than $277 billion has been appropriated by the United States Congress to prosecute U.S. military action in Iraq and Afghanistan;

Whereas, as of the drafting of this resolution, 2,079 U.S. troops have been killed in Operation Iraqi Freedom;

Whereas, U.S. forces have become the target of the insurgency,
Whereas, according to recent polls, over 80 percent of the Iraqi people want U.S. forces out of Iraq;

Whereas, polls also indicate that 45 percent of the Iraqi people feel that the attacks on U.S. forces are justified;

Whereas, due to the foregoing, Congress finds it evident that continuing U.S. military action in Iraq is not in the best interests of the United States of America, the people of Iraq, or the Persian Gulf Region, which were cited in Public Law 107-243 as justification for undertaking such action;

Therefore be it Resolved by the Senate and House of Representatives of the United States of America in Congress assembled, that:

Section 1. The deployment of United States forces in Iraq, by direction of Congress, is hereby terminated and the forces involved are to be redeployed at the earliest practicable date.

Section 2. A quick-reaction U.S. force and an over-the-horizon presence of U.S Marines shall be deployed in the region.

Section 3. The United States of America shall pursue security and stability in Iraq through diplomacy.

Even if you weren’t in favor of the war originally, it doesn’t necessarily follow that you support withdrawal at this point. My own attitude is that we have completely turned Iraq upside down, and have some responsibility to help the country get back on its feet — maybe the way to do that is to remove our troops and let them sort things out for themselves, maybe it’s to stay in there and help out how we can. I honestly don’t know. But at least it’s worth some reasonable consideration, by people on either side of the issue.

House Republicans, needless to say, don’t agree. They were scared to death that a pro-war conservative Democrat would come out in favor of withdrawal, as they see poll numbers for the war plummeting. The last thing they want is an actual debate on the merits. But, rather than just ignoring the resolution, they resorted to an incredibly dishonest tactic: they had California Republican Duncan Hunter propose a new (and stupid) resolution calling for withdrawal, and then debated against it, referring to it repeatedly as “the Murtha resolution” or “the Democratic proposal.” A starkly blatant lie, meant only to discredit the Democrats as soft-headed and unpatriotic.

Here is the full text of Hunter’s resolution (via Shakespeare’s Sister):

Expressing the sense of the House of Representatives that the deployment of United States forces in Iraq be terminated immediately.

1 Resolved, That it is the sense of the House of Representatives that the deployment of United States forces in Iraq be terminated immediately.

Notice any differences between this one and the one Murtha actually proposed? No justification, “immediate” withdrawal instead of “earliest practicable date,” no talk of quick-reaction forces. It’s a farce, and Nancy Pelosi was exactly correct when she called it “a new low, even for them.”

Of course the GOP didn’t stop there; predictably, they launched an immediate ethics investigation against Murtha. If I were a principled conservative who believed in good faith that the invasion and subsequent nation-building exercise in Iraq was the best way to spread democracy and stability in the region, it would make me feel sick that these were the people representing my views in the government. As it is, I simply feel sick that these are the people running my country.

As one tiny footnote, thank goodness for blogs. Although the Murtha controversy is all over the media, nine stories out of ten are completely confused about what happened with the competing resolutions — it takes some work to find out that the resolution was proposed by Republican Hunter. (And would be nearly impossible to find the text of the resolutions if you relied on newspaper stories.) Who knows, maybe this particular cheap stunt actually had the desired effect.

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Shadowing Members of Parliament

Those Brits come up with the wackiest ideas. Intrepid young cosmologist Andrew Jaffe, at Imperial College London, is participating in a fun scheme from the Royal Society: pairing members of Parliament with scientists, who will follow them around for a few days.

Sorry I’ve been so quiet this week: I’ve just finished participating in the Royal Society’s MP-Scientist Pairing Scheme. They’ve linked 25 youngish scientists from throughout the UK with a member of Parliament, and let us “shadow” them for much of this week (as well as giving us presentations on the way science and scientists interact with the UK Parliamentary system): attending meetings, watching debates, going to the bar, generally absorbing the chaos that goes along with politics and government.

Sounds like a blast. Although I suspect that “going to the bar” doesn’t result in any martinis being served. (Not that this would ever happen in Britain, anyway; a friend relates the story of being tossed out of a London pub for trying to order a martini. Too American, apparently.)

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The Kansas School Board is right

I find myself nodding in agreement with the wisdom of the Kansas Board of Education. Not very much agreement, to be sure; the recent move to introduce official skepticism about evolution into its new public school science standards is just bad. Bad, bad Kansas.

But, amidst the bemoaning of this setback for Enlightenment values, we all had a little fun with the school board’s attempt to change the definition of science, as Risa has already pointed out. (See also John Rennie at the new Scientific American blog.) Seems that they have decided to open the door to explanations other than the purely natural — obviously, so that they can include religious (“supernatural”) explanations within a science curriculum.

But only after reading Dennis Overbye’s story in yesterday’s New York Times did I really understand what they had done. Here’s the new definition of “science”:

The changes in the official state definition are subtle and lawyerly, and involve mainly the removal of two words: “natural explanations.” But they are a red flag to scientists, who say the changes obliterate the distinction between the natural and the supernatural that goes back to Galileo and the foundations of science.

The old definition reads in part, “Science is the human activity of seeking natural explanations for what we observe in the world around us.” The new one calls science “a systematic method of continuing investigation that uses observation, hypothesis testing, measurement, experimentation, logical argument and theory building to lead to more adequate explanations of natural phenomena.”

At the risk of alienating all my friends — the school board is right. Science isn’t about finding “natural” explanations vs. “supernatural” ones; it’s about finding correct explanations, without any presupposition about what form they may take. The distinguishing feature of science isn’t in the explanations themselves, it’s in the process by which we find them. Namely, we toss out hypotheses, compare them to data, and look for the hypotheses which account for the largest number of phenomena in the simplest possible way. Simplicity here is in the sense of “algorithmic compressibility” — the number of bits, if you like, required to specify the mechanism that purports to do all this explaining.

What the Kansas school board has tried to do is to open the door for unbiased consideration of natural and supernatural explanations by a common standard — that of scientific investigation. This is just what I’ve been arguing for all along. Scientists have to get off this kick that science and religion are completely distinct magisteria that have nothing to do with each other. Quite the contrary; religion (at least in its common Western forms) goes around making claims about how the world works, and it’s perfectly appropriate to judge such claims by the same standards that we judge any other suggested hypotheses about nature.

The thing is, if we judge popular religious vs. naturalist explanations for how the universe works by a common scientific standard, naturalism wins. Without breaking a sweat, frankly; by the beginning of the second half, we have to send in the scrubs from the bench, at the risk of being accused of running up the score. Intelligent Design, to take one obvious example, is laughably bad as a scientific hypothesis. It explains practically nothing (since it refuses to say anything about the nature of the designer, so we have no clue what such a designer would ever choose to design), while introducing a fantastic amount of new complexity in the form of an entirely distinct metaphysical category (the designer). I have no problem saying that ID is a “scientific hypothesis”; it’s just such a bad one that no sensible scientist would give it a moment’s thought if it weren’t for the massive public-relations campaign behind it.

Science doesn’t home in on naturalistic explanations by assumption; it chooses them because those are the best ones. That doesn’t mean that we have to “teach the controversy” in high schools; the number of grossly inadequate scientific theories is far larger than we could ever address in such a context. But it’s about time that we admitted that science is perfectly capable of judging supernatural claims — and finding them sadly wanting.

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Congratulations to Jennie!

This is the time of year when a lot of undergraduate students are filling out applications to graduate school. So it’s nice to be reminded that all that effort occasionally pays off. Join me in congratulating brand-new Ph.D. Jennifer Chen, who successfully defended her thesis yesterday!

Jennie’s previous work with me was on spontaneous inflation and the arrow of time, in which we tried (and even succeeded, I might claim) to answer a century-old question: why does the early universe have such low entropy? This work was briefly deemed press-worthy, and was the basis for our second-place winning essay in the Gravity Research Foundation essay competition.

For her thesis work, Jennie looked at experimental constraints on light scalar fields in the universe. We’ve never detected a fundamental scalar field, for the sensible reason that they tend to be very massive. But one possible candidate for dark energy is an extremely light scalar field (a mass about 10-40 times the mass of the electron), known as “quintessence.” Some time back I explored how you might detect a quintessence field directly through its couplings to matter, rather than indirectly through the expansion of the universe, in my paper Quintessence and the Rest of the World. Basically there are two ways to do it: looking for very weak long-range forces via 5th-force experiments (light fields always give rise to long-range forces), and looking for gradual evolution of the “constants” of nature such as the fine-structure constant.

Jennie took this idea and did a thorough job of exploring what the current data are telling us. For the 5th-force experiments, this meant exploring what the “charge” for different test masses would be, especially from the complicated effects of quarks and gluons. As particle physicists know but rarely admit, most of the mass in ordinary matter comes not from the fundamental masses of elementary particles themselves, but from the chromodynamic binding energy of quarks confined into protons and neutrons. Jennie showed that couplings to gluons and quarks would be the most significant contributor to the 5th-force effects from light scalars.

The other idea, that coupling constants could evolve over the history of the universe due to the gradual evolution of a light scalar field, has received a lot of attention recently due to claims that the fine structure constant α (characterizing the strength of the electromagnetic interaction) actually does vary. This work looks at the spacing of spectral lines in systems at high redshift, and purportedly provides evidence that α has varied by about 10-5 between today and a redshift of a few. Other studies, it should be mentioned, claim that α actually does not vary at all, and place an upper limit.

Here is Jennie’s plot of the data, with some theoretical curves (click for larger version).
alpha vs. redshift
This is the inferred value of α as a function of cosmological redshift. The points with the big error bars that lie below zero are from the group claiming to see a variation in α (the data have been binned for easier viewing). The points above those, consistent with zero, are from other groups looking at quasar spectra. The two points near the top left are interesting; the leftmost one is from the Oklo natural reactor, and the next one uses data from abundances of radioactive isotopes in meteors.

The moral is simple enough: trying to fit the data with a simple quintessence model doesn’t readily accomodate the Oklo and meteor points, much less the new quasar data. Probably α is not changing, and if it is, it’s not doing so in a way we would expect in a simple model. That’s what complicated models are for, of course. But I wouldn’t bet a lot of money on this one.

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