Friday, December 31, 2004
Reacting to the impossible
I grew up outside Philly, so naturally I watched a lot of Fat Albert, which has now been made into a movie. (An awful one, apparently, but that's to be expected.) The cartoon kids from the TV series are swept through a rip in spacetime connected through little Doris' TV set, to re-appear as live characters in the real world. (I guess they figured out how to violate the null energy condition.)
Roger Ebert, reviewing the movie, raises a question:
And I was wondering, as I always do with plot devices like this, why the human characters deal so calmly with the appearance of toons. Yes, Doris is surprised when the Fat Albert gang pops through her TV set, but isn't that event more than just ... surprising? Isn't it incredibly amazing? When the laws of the physical universe as we know them are fundamentally violated, shouldn't it be for more earthshaking purposes than to cheer up Doris?Okay, I know this one. Yes, it is incredibly surprising. It's surprising ("it" meaning the appearance of cartoon characters in the real world) because it would never happen. Trust me on that, I'm a scientist. So, it's hard to reliably answer the question "How would someone react if they saw cartoon characters come to life?" because the hypothesis is contrary to possibility. If we're going to make movies in which Fat Albert squeezes through the TV and into our bedroom, it's okay to pass through a brief period of modest surprise before we move onto the wacky hijinks, because the only possible realistic response would involve an hour and a half of stunned disbelief, possibly enlivened by a descent into stark raving madness. Which would be, at minimum, quite a different movie, not really Cosby material at all.
And on that note, let's wish everyone a happy 2005. It can't help but be an improvement over its predecessor.
Thursday, December 30, 2004
Efficacy of prayer
Chris C. Mooney mentions something that certainly surprised me -- the NBA's New Orleans Hornets begin each home game with a prayer. Not just the team, the whole arena -- the prayer is read over the loudspeakers by someone standing at center court. Since the Hornets are not a government institution, they certainly have a right to hold a prayer, but it seems obnoxious, as there are certainly plenty of non-religious people, or devotees of different religions, in the crowd for each game.
Apparently New Orleans is the only NBA franchise to have a prayer before each game. Among other things, the prayers ask for success for the Hornets and the NFL's Saints. This gives us a nice chance to check on how useful it is to ask for divine intervention. Here are the current NBA standings:
Goodness, all that praying doesn't seem to be helping very much. Where is God-Man when you need Him?PhoenixSuns 24 4 .857
Wednesday, December 29, 2004
Can moral reasoning convince anyone of anything important?
Richard Posner, guest-blogging for Brian Leiter (here and here, with an introduction by Leiter here), lives up to his image as a practical, hard-headed guy. He basically says that people have fixed ideas of right and wrong, and all the philosophical pondering in the world isn't going to change their minds. And thank goodness, by his lights:
[T]he sort of political discussion in which political philosophers, law professors, and other intellectuals engage is neither educative nor edifying; I also think it is largely inconsequential, and I am grateful for that fact. I think that what moves people in deciding between candidates and platforms and so on certainly includes facts (such as the collapse of communism -- a tremendous fact), as well as a variety of "nonrational" factors, such as whom you like to hang out with --I think that's extremely important in the choice of a political party to affiliate with. When a brilliant philosopher like Rawls gets down to the policy level and talks about abortion and campaign financing and the like, you recognize a perfectly conventional liberal and you begin to wonder whether his philosophy isn't just elaborate window dressing for standard left liberalism.Over at Crooked Timber, Jon Mandle gives what I think is a good response:
But Rawls's approach to moral reflection -- and what he would count as a compelling reason -- s quite different. Moral reflection is not about devising arguments to get other people to switch over to the position that you already hold. It is to help you figure out where you should be.Actually I think that Mandle is conceding a bit too much. He is basically saying that the role of philosophy is to help us sort out our personal moral beliefs, even if there is little hope for convincing anyone else to change their minds. That seems a little too defeatist. Convincing other people is difficult, but it does sometimes happen, and sometimes even for good, rational reasons. It doesn't necessarily happen -- even two perfectly rational people may disagree about matters of morality, whereas they better not disagree on the solutions to a certain differential equation -- but it can happen, and it's worth trying.
The point is that there are no fixed moral truths upon which we can all agree with metaphysical certitude, but there nevertheless are pre-existing feelings that each of us has about what is right and what is wrong (basically Rawls' provisional fixed points). Some of these feelings might even be opinions that we might want to think of as conclusions of arguments rather than axiomatic starting points, but they are nevertheless the launching-points for our moral reasoning. The job of moral philosophy is to sort them out and shoot for some kind of consistency. But, even though these points are not given as fixed external truths (and might arise from random formative events, religious influences, or even biological predispositions), we are fortunate enough that different people do not have completely non-overlapping ideas to begin with. Most of us have a great deal in common in our moral beliefs, even if we can't achieve perfect unanimity.
It's this degree of overlap ("consensus" would probably be too strong a word) that allows us to make some progress in reasoning with each other. And I would claim that careful philosophizing can help us come to better degrees of agreement, as well as helping us to rationalize our individual moral judgments. It happens all the time that two or more people agree on some basic truths, but end up disagreeing on some specific policy conclusions; in such cases, academic philosophy can be helpful. It's certainly completely unfair to imagine that the work of someone like Rawls is just an elaborate justification for a pre-existing set of random beliefs; the starting points for Rawls are very similar to those of most modern welfare-state liberals, so it's not surprising that they generally end up at the same conclusions, although Rawls' will be much more thoroughly thought-out and internally consistent. Philosophy isn't impossible or useless, it's just hard.
By the way, Posner of course has his own blog with Gary Becker. (Funny that the University of Chicago, generally way behind the curve in anything involving computers, would be so rife with good blogs.) He also authored a one-week diary for Slate, which is both inspirational and depressing. I would be happy to accomplish in any given week what that man does in a typical day.
Tuesday, December 28, 2004
The earthquake in southern Asia is having a devastating impact, with over 44,000 dead from the quake itself and the ensuing tidal waves. The seismic shift has moved some islands more than twenty meters, and possibly shortened the day by as much as three microseconds.
If you'd like to donate to the victims, World Vision is sending food and survival kits to families affected by the disaster.
Update: a more comprehensive list of ways to help is at the Command Post.
Monday, December 27, 2004
Moses only wrote one book
An article in the Duluth News Tribune recreates the atmosphere at the Arrows of Time meeting I went to recently. One of the things it doesn't mention is the dinner-table reminiscences of the late Sidney Morgenbesser. I had never heard of Morgenbesser, but two of the participants knew him well -- Steve Savitt was his Ph.D. student, and David Albert was a close friend of his at Columbia.
Morgenbesser was a philosopher who was known for making a profound impression on his students and colleagues; you can read some personal remarks at 3quarksdaily (also here and here). There are clearly a good number of favorite anecdotes about his dry Jewish humor, as several of the stories told around dinner in Minnesota are reproduced in the New York Times. He is less well-known to those who didn't meet him personally, as he was notorious for publishing very little. He managed to have an important impact through his interactions with others, rather than by systematically expounding a particular system of thought.
Of course, there are figures throughout history who managed to make a splash without having an impressive publication record; Socrates and Jesus come to mind. But they were fortunate enough to have Plato and St. Paul put their words (or some possibly-distorted reflection thereof) onto paper; who knows how history might have been different if they didn't have such prolific acolytes. Even in the recent history of physics, there are good examples of people who wrote very little and then managed to come up with big ideas when it counted; Ken Wilson's ideas about the renormalization group and Alan Guth's inflationary universe are good examples.
It's hard to compare across generations, but I suspect that brilliant-but-reticent geniuses have a harder time getting hired as professors today than they did a few decades ago. It just seems that the competition for jobs is a little more fierce, and among the candidates for any one position there will always be someone who looks brilliant and also publishes a lot. You can hardly blame departments for being short-sighted if they tend to hire people who write papers, for the simple reason that most people are not quiet geniuses. For every Morgenbesser, there are a dozen others who show promise but will end up just taking up office space for the next thirty years as a tenured faculty member. It's a shame, of course, as there are people who are great to have as colleagues and mentors in a department, even if they don't publish very much. But, short of doubling all of the budgets so that we can hire more people, I don't know of any better way than the system we have.
Update: Steve Savitt informs me that Morgenbesser was his undergraduate advisor, not his Ph.D. advisor. His Ph.D. advisor was Jean van Heijenoort, who was Leon Trotsky's private secretary before going into academia. Another colorful life.
Friday, December 24, 2004
Christmas every 88 days
A few years old, but worth sharing: NASA interviews Santa.
In just a few hours the Jolly Old Elf will brush the fireplace ash out of his beard, don his famous red suit, and begin the serious work of delivering presents all over the world. It's a job he's done in the same way for a long, long time, but times may be changing. As humans and space probes travel to other worlds, the possibility of Christmas on other planets can no longer be ignored, and the prospect of delivering presents throughout the solar system is, well, turning Santa's hair white.Read on to get the big news: Santa is made of tachyons!
Wednesday, December 22, 2004
Wasn't the truth good enough?
So I'm poking around the internet, looking for reviews of my book. (Still time to order it for Christmas!) And I come across this page, with the following enthusiastic collection of quotes:
"I can only recommend Spacetime and Geometry: An Introduction _ to General Relativity. Special thanks to Addison Wesley which produced it. Recently I have got Spacetime and Geometry: An Introduction _ to General Relativity, it is very cool. I can only recommend this item. This way I imagined Spacetime and Geometry: An Introduction _ to General Relativity. Spacetime and Geometry: An Introduction _ to General Relativity is very cool, it is worth all the money Addison Wesley wants for this product. Spacetime and Geometry: An Introduction _ to General Relativity was a very nice present when I got it on 20 June, 2003. I was surprised that Spacetime and Geometry: An Introduction _ to General Relativity was so nice, Addison Wesley really knows how to please customers."Impressive indeed, except ... who thanks the publisher for the appearance of a book? And on closer inspection, it's especially interesting that they were pleased to receive their copy in June 2003, since I remember quite clearly that I was feverishly writing Chapter Nine during that time. The actual book didn't appear until October.
It's perfectly clear that these people just make stuff up! They're like Bill O'Reilly talking about Christmas!
Speaking of which, I'm off for the week, so don't expect any blogging. Merry Christmas to everyone, especially you ornery atheists out there.
Tuesday, December 21, 2004
Why didn't I think of this first? If you want to teach about intelligent design, you will have to decide which of the designers you should highlight. And, despite what you might read in comic books, there are a lot more designer-based theories of creation than science-based ones. Apostropher points to a helpful list of the Top Ten Intelligent Designs:
Here's something a few people have mentioned to me: the Pirelli Relativity Challenge. The tire company is sponsoring a prize of 25,000 Euros to "the best multimedia work that explains special relativity theory to the layperson." By "multimedia" they apparently mean a web-based animation, using Flash or some such thing. My total lack of animation skillz prevents me from entering, I'm afraid. If anyone is interested, the deadline is March 31, 2005.
There will probably be a bunch of similar stunts, associated with the World Year of Physics in 2005. (Another site here -- I think the latter is more US-based.) It's the anniversary of Einstein's "Miraculous Year," in which he had no fewer than three amazing breakthroughs: an understanding of Brownian motion in terms of atomic theory, an understanding of the photoelectric effect in terms of light quanta, and the ultimate formulation of special relativity. Of course, his best breakthrough was ten years later, when he came up with the ultimate formulation of general relativity. Plenty of room for more celebrations then.
Monday, December 20, 2004
What we know, and don't, and why
Reporting now from a rustic lodge deep in the forests of Minnesota, where a motley collection of physicists and philosophers have gathered to talk about the Arrows of Time. My job is of course to let people know that we have an explanation for the apparently low entropy of our observable universe. Once you have that, there are still a number of interesting questions, but I think that the cosmo-thermodynamic arrow is the origin of all the rest.
Actually the collection is not so motley; there are some very smart people here in the woods, including one Nobel laureate, Tony Leggett. The other night we shared the lodge with the holiday party of a local real estate firm, and let me tell you something: women swoon for Nobel prizewinners. Even (especially?) ones as gentle and soft-spoken as Tony. Trust me on this.
Physicists have a lot to learn from philosophers (and vice-versa). I learned something (or think I did) about the psychological arrow of time from David Albert. As you know (since even those who haven't been reading the blog from the start have gone back and combed through all the archives), I have previously mentioned the idea that the thermodynamic arrow of time -- the fact entropy is very small in the past, and tends to grow on purely statistical grounds -- is responsible for the fact that we can remember the past but not the future. But why is that exactly?
It's a tricky argument, and I'm still not sure I understand it correctly. But the basic idea hinges on the consistency of different hypotheses about what was going on in the far past. In particular, imagine a situation where we have three things: 1) a memory of receiving a new sweater for Christmas last year, 2) detailed knowledge of the laws of physics, and 3) complete ignorance about the initial conditions of the universe, i.e. a hypothesis that all conditions consistent with our current macroscopic state are equally likely. (Our macroscopic state is really everything we think we know about the present universe, including positions and properties of the macroscopic objects in it; but this knowledge is compatible with a huge number of microstates, which would correspond to a specification of the properties of each and every elementary particle comprising these objects.) Can we conclude, from these three pieces of information, that we probably did receive a sweater? No; in fact, it turns out to be incredibly unlikely. That's because, of all the ways we could have a memory of receiving the sweater, most involve very high-entropy conditions in the past, out of which we and our memory have appeared very recently as a random fluctuation. Random fluctuations of order from disorder are very rare; however, there are many many more ways to be disordered than to be ordered, so the number of ways to achieve order is dominated by trajectories that come from disorder, not trajectories that come from greater order. So if we really believe that all possible past configurations are equally likely, our "memories" are utterly unreliable.
What saves us from such a psychologically devastating situation is that this set of beliefs is cognitively unstable. That's because we used our knowledge of the laws of physics (not to mention the rules of logic, probability, and so forth) to reach this conclusion. But the reason why we believe these laws is that we have memories of experiments that count as evidence for them -- but these memories are completely unreliable! So we have no reason to think that we actually understand the laws of physics. Thus, this set of beliefs is self-undermining; if we hold it, we conclude that we have no reason to hold it.
The way out is to change our initial set of assumptions. We simply replace the assumption that any past configuration is equally likely with the "past hypothesis" -- the idea that the early universe is in a very special state (or one of a small number of special states) with very low entropy. This simple hypothesis removes from consideration all of the thermodynamically unlikely (but very numerous) possible histories in which we and our memories of Christmas past are just fluctuations from the surrounding chaos. Given that we have a memory of receiving a sweater, and that the universe began in a highly ordered state, it is quite likely that we actually did receive a sweater.
The lesson that we are supposed to learn from this is that the past hypothesis is a crucial part of our understanding of how the world works -- it has the status of a law of nature. In the picture that Jennie Chen and I have suggested of a universe in which our observed patch is just a small part of a bigger ensemble, this hypothesis is local and contingent, but still reasonable. There are other parts of the bigger universe which are close to thermal equilibrium, where the past hypothesis wouldn't be appropriate. But in regions of thermal equilibrium you won't have living beings, much less reliable memories.
David Albert is also known for being perhaps the sole respectable person to appear in the movie What the #$*! Do We Know?, a docu-drama about quantum mechanics and consciousness. (I haven't actually seen the movie, but Peter Woit has. FYI, "#$*!" is usually pronounced as "bleep", but more colorful renderings are allowed.) The movie was made by crackpots, who want to argue that consciousness and quantum mechanics are inextricably intertwined, to the extent that we can literally change reality by appropriately focusing our mental states. David was asked by the producers to sit for an extended interview about the mysteries of quantum mechanics, and he innocently agreed. After five hours of filming, in which he patiently explained to them that their views were completely crazy, they chopped up the footage into short sounds bites of quotes like "Yes, that's an important question," and interspersed them throughout the film. David is on record as saying that his views were dramatically misrepresented by the movie. Another lesson learned: if anyone wants to get you on film, you have to establish that you trust them not to twist your words against themselves.
Sunday, December 19, 2004
All of Bob Park's What's New is good this week. I'm on the road again, so I'll just cheat by reproducing this (you're welcome to subscribe yourself).
WHAT'S NEW Robert L. Park Friday, 17 Dec 04 Washington, DC
Friday, December 17, 2004
By James Weldon Johnson.
And God stepped out on space,One of the things you hear all the time about the Bible, even from non-believers, is what a great work of literature it is. When people say things like that, exactly what book have they been reading? Parts of the Bible are well-written and/or interesting, but it's mostly boring, stilted, repetitive, and contradictory -- exactly as you would expect from an edited collection assembled by committees working under powerful political pressures. Wouldn't the Genesis story be much better if it had been written, for example, in the cadences of an African-American folk preacher, as above?
James Weldon Johnson was a remarkable person. Among other achievements, he was the first leader of the National Association for the Advancement of Colored People who was an actual colored person. Could you imagine any contemporary national political organization being led by a poet?
And the punchline is: Johnson was an agnostic. Amen to that, brother.
Thursday, December 16, 2004
Brian Leiter has a quote from the blog of Lawrence Velvel, who is the Dean of the Massachusetts School of Law:
[W]hile I have always been in favor of diversity of viewpoints on a faculty, and our own faculty ranges from very liberal to quite conservative -- although we see no need to hire the right wing kooks who seem to be taking over the world -- I have lately begun to wonder about the intellectual diversity argument. The right wing has taken over the government, radio, part of television, a significant part of the newspaper world, and certain religiously based universities. Having taken over much of the world, is it really necessary that they be given a major voice in universities too? They’ve done pretty well without a major foothold at lots of universities. Why give these nuts still more power?That's an astonishingly stupid comment, especially from the Dean of a law school. (Leiter characterizes the quote as "memorable.") The problem is the gentle glide from "conservative" to "right wing" to "nuts." I would hope that, even in these times when liberals are incredibly frustrated at the damage that the nuts in power are doing to our country, we are able to acknowledge that being conservative doesn't automatically make you nuts (even if the examples are depressingly numerous). We honestly do need intellectual diversity in universities, and there is no question that such diversity should include conservative viewpoints. I don't have to agree with people who believe in a strict constructionist interpretation of the Constitution, or were in favor of the war in Iraq, or think that an unfettered free market would ultimately benefit people in poverty -- but I certainly want people who believe those things to be present at my university, just as I think cosmologists should explore both inflation and the ekpyrotic universe. We're supposed to be in favor of the free interplay of ideas, remember?
Don't get me wrong -- there is a line to be drawn, and it's not always obvious where to draw it. Physics departments should consider people who work on both string theory and loop quantum gravity, but needn't bother with astrologers. Biology departments don't need to hire creationists, and no departments need to hire racists, fascists, misogynists, anti-Semites, and so on. But you can sincerely believe that affirmative action is harmful to minorities without being racist. There can be policy disagreements about extremely difficult questions among legitimate scholars working in good faith. We don't need to go out of our way to hire more conservatives as professors -- we should hire people who are smart and make real contributions, and some of them will end up being conservative. As a liberal, I am idealistic enough to think that (at least in the context of universities) our ideas will win out through the simple force of reason, not because we give in to the right wing's paranoid fantasies and start explicitly excluding competing views.
How not to run a world
Found this a while ago on Arts & Letters Daily, but it's still worth mentioning. An interview with Timothy Garton Ash on the relationship between the Bush administration and Europe.
IDEAS: You met with President Bush at the White House in May 2001. How did that come about?I'm always skeptical about comparing different generations, as nobody has an unbiased view. But from Roosevelt and Churchill to Bush and Blair one does detect a certain diminution of sophistication.
By the way, I can strongly recommend The Magic Lantern, a compelling and highly personal account of the overthrow of Communism in Eastern Europe. Garton Ash was friends with leaders of the revolutions in Poland, Hungary, Czechoslovakia, and East Germany, and spent 1989 traveling from capital to capital and reporting back on the historic events as they occurred.
Wednesday, December 15, 2004
I have nothing unpredictable to say about Alabama judge Ashley McKathan, who has gone a step beyond the usual loopiness of Alabama judges and had the Ten Commandments embroidered on his robe. Ed Brayton says what needs to be said. But I did the gritty blogo-journalistic legwork to surf through the internets and find a picture! From the Andalusia Star News.
I hope they don't mess around with McKathan. If a judge intentionally flouts the highest law of the land, his butt should be on the unemployment line the next day.
Flying the coop
First from Majikthise, later from Julian Sanchez, Grammar.police, and Matthew Yglesias, we hear about Antony Flew's theistic waverings. Flew, a philosopher well-known for his atheism, has apparently "converted" to a kind of deism, where he acknowledges the possibility of an Aristotelian Unmoved Mover, although he explicitly rejects the idea of a caring, interventionist God.
Two disclaimers. First, I had barely heard of Flew before the current dust-up, so I'm certainly not an expert on his views. Second, who cares? A change of heart on the part of any single individual doesn't change the status of an argument. If a religious leader like John Paul II, or Pat Robertson, or Ayatollah al-Sistani were to suddenly embrace atheism, it would be interesting on a personal-history, People-magazine kind of level, but I wouldn't hold it up as a reason for anyone else to become an atheist. I'm more interested in good arguments on either side.
Sadly, Flew's arguments seem really bad, even back when he was an avowed atheist. Here is an interview he did a few years back, trying to put to rest previous rumors that he had found God. In the interview he draws a conventional distinction between "positive atheism" and "negative atheism" -- the former being the claim that God does not exist, and the latter (which is [was] Flew's position) simply holding that there is no evidence for God, but there also aren't any disproofs of His existence, so we can't be sure one way or another. I have to say, even though this is an extremely common position (some of my best friends are negative atheists), it makes no sense. Is there any other question about the universe for which we say, "Well, there's no evidence for it, but I can't absolutely rule it out, so I'll keep an open mind"? Bertrand Russell raised the question of the existence of an exquisite tiny china teapot in orbit around the planet Saturn. We have no firm evidence that there is no such teapot, you see, even though there is also no reason to believe in it. Should we really keep an open mind? (Hint: no. When there is no need for something, no evidence for it, and it unnecessarily complicates our description of the universe, it's okay to simply not believe in it.)
The reasons for Flew's recent change of heart are even worse. Essentially, he has bought into the modern, cosmology-based argument from design. (Here's a recent interview with Gary Habermas, and a short essay by Richard Carrier at the Secular Web.) Despite the fact that the big news here is Flew's change of mind on the existence of God, the interview doesn't go into details about his reasoning, preferring to jump right to some theological implications; but it's a fairly common argument. There are basically two pieces of evidence from modern cosmology that purportedly provide reasons to believe in God: the mysterious creation event at the Big Bang, and the fine-tuning of parameters of nature in order to allow for intelligent life. The idea is that invoking an omnipotent Creator helps to explain these otherwise puzzling features of our universe.
Which is just ridiculous. For one thing, it doesn't "explain" anything; if I tell you ahead of time that there exists an omnipotent Creator, but you didn't know anything about our actual universe, you wouldn't be able to use that "theory" to say anything useful about how the universe would work. You couldn't derive the existence of the Big Bang, much less the particle content of the Standard Model.
Second, there isn't anything that needs explaining. The Big Bang event is something that we don't yet claim to understand, but that's just how science works; we understand more and more, but not everything at once. There is no reason to believe that the Big Bang won't eventually be understood as part of a comprehensive bigger picture. (I mean, if even I can come up with scenarios like that, it can't be that hard.)
And the fine-tuning argument isn't any better. The claim is that we find laws of physics that seem delicately arranged to allow for the existence of life. Of course, it is quite unclear that there is anything here to explain, even in principle; if conditions in our universe didn't allow for the existence of life, we wouldn't be around to argue about it. But one might still argue that the God hypothesis provides a greater economy of explanation than simply listing the numbers that describe our universe, despite the fact that it requires the introduction of an entirely new metaphysical category. One would be wrong. For one thing, it is far from obvious that there is any significant amount of fine-tuning going on. It's true that small changes in physical parameters would result in a very different universe; but nobody really knows what that universe would look like, or if it would be able to support some form of intelligent life. (People occasionally claim to know, but don't believe them.) And if someday the state of the art allows us to quantify a significant degree of fine-tuning, there are perfectly naturalistic explanations available, in the context of the anthropic principle. We might not like the anthropic principle, but our distaste is based on the fact that it's more fun for scientists if there is a unique kind of universe in which we can live, not because it isn't a plausible explanation.
Finally, if God really did provide an explanation for the parameters we observe, we should be able to use this explanation ("God arranges the universe in the simplest possible form consistent with our existence") as a good old-fashioned scientific theory, and start making predictions. What would God have chosen as the mass of the Higgs boson, for example? Would God make use of low-energy supersymmetry breaking? Why are there three generations of fermions? Why is the proton lifetime so long, and why are flavor-changing neutral currents so small? If you're going to claim explanatory power, you'd better be able to explain things.
In reality, the temptation to believe in God arises from a combination of wishful thinking and a loss of nerve -- the fear that there are some features of reality that will never admit of a conventional scientific explanation, despite the historical reality that such fears have always proven groundless. Just as Darwin killed off the biological argument from design, physicists will eventually kill off the cosmological one. The universe we actually observe is elegant, preposterous, extravagant, and generally quite thrilling; no need to sully it with superfluous pieces of pseudo-explanatory baggage.
Monday, December 13, 2004
Our simple little universe
Plane trips are great. You have time to think about all sorts of random things that you would never get to if you had a working internet connection. I wanted to write about cosmology and the argument from design, but I got sidetracked into thinking about how complicated our current universe is, at least those aspects that are relevant to human existence. The mass of the top quark, for example, doesn't affect your life very much, unless you are a high-energy physicist (and we can ignore them for the moment).
So let's imagine we are given the basic set-up of the standard models in particle physics and cosmology -- the gauge groups and representations of the particles, a cold dark matter candidate, the dimensionality and signature of spacetime, a flat homogeneous and isotropic universe with a scale-free spectrum of adiabatic fluctuations. These are the fundamental discrete facts that describe the framework of our universe. But within that framework, there are a number of parameters, which we could imagine taking on all sorts of values. How much information is required to specify those values?
We can easily list the continuous parameters that matter to human life: the masses of the electron and up and down quarks, the QCD scale, the Fermi constant, Newton's constant of gravitation, the fine-structure constant, the amplitude of density perturbations, and the densities of baryons, dark matter, and vacuum energy. So I count eleven parameters -- really only ten, since only dimensionless ratios of mass scales matter -- each of which needs to be specified to three significant digits or fewer. A number expressed to three significant digits in decimal notation requires about ten bits (210 = 1024), so ten such numbers requires about one hundred bits of information. And there you have it, our whole universe. Or at least, the statistical properties of our branch of the wavefunction of the universe. It wouldn't be enough information to predict, for example, how long it will take the Cubs to win the World Series.
Have I missed anything important? Some of these numbers (in particular, the quark masses) aren't even known to three significant figures. But other numbers that could in principle be derived from them (like the masses of the neutron and proton) are known quite well, and are pretty important to the way the universe looks.
There are a lot of other parameters, of course, both in particle physics and in cosmology: masses of neutrinos and the heavier fermions, CP-violating angles, amount of isocurvature perturbations, and so on. But all these numbers have values that are safely removed from our everyday lives; we could change them by quite a lot and you'd never know. For a look at what might happen if you really messed around with different parameters, see Robert Cahn's The eighteen arbitrary parameters of the standard model in your everyday life (postscript). You wouldn't want to live in a world where the muon was the lightest charged lepton.
Of course it would be nice to have something even more economical -- maybe even just one number! But still, it's interesting that it takes so little information to specify the workings of our universe. As a homework problem, look up the actual values and turn them into a hundred-digit binary number. It would make a nice T-shirt.
Update: I realized I was a little too optimistic about expressing each number with just ten bits. Even if the number of significant figures is only three, you still need to keep track of the overall size of the number; i.e., if you want to express 2.85x10-16, you need to encode the -16 as well as the 2.85. So a few more bits will be necessary, but not very many; perhaps 15 bits per parameter.
Sunday, December 12, 2004
Time to move someplace dry?
From Patridiot Watch, via Pandagon: the strategic missile defense that is supposed to make us safe from nuclear catastrophe won't work in the rain.
WASHINGTON (Reuters) - The first flight test in nearly two years of a planned U.S. missile-defense shield has been scrapped two days in a row this week because of bad weather, the Pentagon said on Friday.Sorry for the long excerpt, but it's just all so good. The finest comedy minds of our generation couldn't make this look any more ridiculous than it already does.
Our session here at Irvine was this morning, it went fine. Everyone seemed to buy into the ideas of dark matter and dark energy, but really wanted them to have interactions. Well, so do I.
Now we're having a great session on music and computers. Increasingly, computers are incredibly useful tools for working musicians -- not just as synthesizers of different sounds, but as aids to composition. A program called Band-in-a-Box will take the chords that you give it, and basically create an arrangement of backing instruments in the style of your choice. Belinda Thom is telling us about her work on something even more ambitious -- a program that will allow the computer to improvise along with you in real time as you play. The idea is that the computer will "listen" to your phrases, get the idea, and come up with an appropriate riff to play back to you. She showed some simple examples that were not in real time -- you type in a transcription of, say, Charlie Parker soloing on Mohawk, and the computer comes up with its own solo. It sounds okay, actually.
This is an incredibly sophisticated problem in artificial intelligence. When you hear some sounds, how does the computer deal with them? Before even worrying about improvisation, you need to deal with how the computer understands the music. How to turn a time-stream of audio data into something comprehensible? How, for example, should the computer group sets of "related" notes into discrete phrases? The work is by no means a priori -- they collect lots of data on how people actually hear real pieces of music, which is not always the same for different people. Is there an inherent "musical grammar" in human beings, as a Chomskian would suggest that there is an inherent linguistic structure?
Again, I'm not an expert in this field, so I can't do justice to the details. But here's a tiny example of the kind of thing that goes on. Imagine giving the computer a head start by explicitly breaking up the music into bars (information that it wouldn't actually have in real time). Then the computer can characterize each bar according to several different tests, to determine what "style" the music is being played in. By examining real pieces of music, you learn interesting things about the way that real human beings play. For example, it's common to use scales as the basis for improvisation. A scale is characterized by a subset of the twelve notes in an octave; but there is actually more information than that, since not every note is played equally often. So the computer can make a histogram of which notes are being played in a given bar, to help it determine which scale is being improvised on.
Okay, it will never replace the real thing. But who knows, computers might help train a new generation of young lions. And if we learn something about how people think in the process, it's all good.
Friday, December 10, 2004
Live from Irvine
If you're wondering why posts from the last few weeks are lacking a certain, you know, "substance," it's because I've been traveling like crazy. Right now I'm in Irvine, California, at the National Academy of Sciences ("Home of Studies that are Increasingly Ignored"), for a Japanese-American Frontiers of Science meeting. They bring together young (-ish) scientists from the two countries, in various fields, to share the wonders of their research. The good news is that they have wireless internet all over the place. So we're livebloggin', baby!
Except that, not being an expert in the talks, I can't really report accurately what we are hearing. This morning we heard about the geological (areological?) history of Mars, especially as it was influenced by the presence of water. There is very good reason to believe that Mars used to be filthy with the stuff, so we'd like to know where it all went. The Earth could someday end up like that.
Right now we are hearing an extremely amusing talk on cloning by Teruhiko Wakayama. His group was the second to clone mammals; they cloned multiple generations of mice shortly after the first mammalian clone, Dolly the sheep. Clones should be boring -- they're just genetic duplicates of the parent, just as twins are duplicates of each other. But there's more to life than genetics! It turns out that clones tend to be overweight and die young, on average. You might think that the cloning process had somehow messed up the DNA. But, interestingly, when the clones have offspring via ordinary sexual reproduction, they come out perfectly normal! Here I am far outside my expertise, but the point seems to be that the expression of the genetic information is somehow disrupted by the cloning process, but the children of the clone are okay.
(The one thing I remember from a similar meeting last year is that female clones are effectively not genetic copies of their parents. Each individual uses the same amount of genetic information, but the X chromosome has more information than the Y. So the men (XY) use all the information they have, but the women (XX) will randomly turn off some fraction of the data in their X chromosomes while they are still embryos. There are something like 250 possible outcomes. So, for example, you can clone a female cat, but the kittens will all have different colorings.)
On Sunday I'll be giving a talk on cosmology, along with Hitoshi Murayama and Naoshi Sugiyama. Still need to decide what I will talk about. Tomorrow I might skip the talks and go Xmas shopping.
No, not -symmetry. Nor -string, nor -nova, nor -conductor. Good old-fashioned super-hero, as promised previously.
As you see, my superhero identity involves atoms and mysterious energy fields of some kind; only makes sense, as I work in the same building as Enrico Fermi did. Presumably these fields would be detectable in fifth-force experiments some day.
As a bonus, "Mr. H" sends along a familiar physicist in fighting garb:
He's pretty buff, for an old guy. Go make your own!
Thursday, December 09, 2004
Looking for astronomers
A friend of Preposterous points us to the following announcement in the American Astronomical Society electronic newsletter:
___________________________________________________________If anyone gets selected, I want a cut of all proceeds.
While I was in Sweden, everyone was naturally excited about the upcoming Nobel Prize lectures. As you know, the Physics prize was given to David Gross, David Politzer, and Frank Wilczek for the discovery of asymptotic freedom (the phenomenon by which the force between quarks becomes weaker, rather than stronger, at short distances). All of the laureates give lectures on their work, although occasionally someone will wander off topic -- Einstein won the prize for the photoelectric effect, but talked about general relativity in his lecture.
So people were quite curious about David Politzer's scheduled talk, which had the provocative title "The Dilemma of Attribution." Now the lectures have apparently been given, but I can't find any indication of what Politzer talked about; does anyone know? Eventually the talks will appear online, but that hasn't happened yet; the news articles give every indication of being written before the events they describe.
In other news, we're talked a lot about the idea of sending robots to service the Hubble Space Telescope. They could never do as good a job as an ordinary manned servicing mission, but NASA administrator Sean O'Keefe seems set on the idea. Now a National Academy of Sciences study has come out strongly in favor of a manned shuttle mission. We'll see if it makes any difference.
Wednesday, December 08, 2004
Evolution of Iraq
From Tony Auth.
Tuesday, December 07, 2004
Entropy in Beantown
I'm in Boston right now, having given an arrow-of-time talk at Tufts this afternoon. No time to blog, as I am obligated to rush around taking advantage of the delights here in the Hub. In particular, no time to follow Majikthise's suggestion and make a picture of myself as a superhero. (Usually I'm pretty easy to convince on things like that.) But if anyone else wants to take a crack at it, I'd be curious to see how they come out; the best ones that people sent me I will post here. Categories include: superhero avatars of yourselves, of me, or of famous physicists. Villains are also acceptable. (More examples here.)
Monday, December 06, 2004
Why three dimensions of space just aren't enough
The second issue of symmetry has just come out. symmetry is a magazine about particle physics and related fields, jointly published by Fermilab and SLAC. It takes the place of their individual house magazines, and looks like a significant upgrade. The editor is David Harris, who hopefully will get back to blogging once things are running smoothly! This issue includes a good article about the status of inflation, including its connection to string theory.
Another interesting little note was the histogram of citations to the original paper by Oskar Klein on the idea of extra dimensions (Kaluza-Klein theory), reproduced at right. The data are from the SPIRES literature database at SLAC, a fanastic service that makes it a cinch to see who cites what papers in high-energy physics and related fields. (Kind of like google scholar, but years ahead of their time.) You can see that there is a peak in the early 80's, and another one that we're in the middle of right now. These reflect well-defined movements in high-energy theory. In the early 80's, the idea of grand unification of the three forces of particle physics (strong, weak, and electromagnetic) had been pretty well investigated, and people were eager to get gravity into the game. In this spirit, KK theory was resurrected, but now in the context of supersymmetry, which has a natural home in eleven dimensions of spacetime.
The movement toward KK theory was squelched by the rise of string theory; the string bandwagon was launched in 1984 when Michael Green and John Schwarz showed that you could cancel certain annoying "anomalies" (quantum-mechanical effects that can destroy classical symmetries), and (almost) everyone dropped 11-dimensional supergravity to work on string theory. Of course, string theory naturally lives in ten dimensions, so the compactification of the extra dimensions is just as important in string theory as it ever was in KK theory; but there are so many other things going on that it made sense to think of strings as a new beginning, and references to the original Kaluza-Klein papers dropped off.
More recently, the string duality revolution showed that there really wasn't a big difference between ten-dimensional superstring theory and 11-dimensional supergravity; they are each versions of one more comprehensive (and still ill-understood) theory, M-theory. But that's not the reason for the uptick in citations to Klein in the late Nineties; it's because of the phenomenological idea of brane worlds and large extra dimensions, led by the papers from Arkani-Hamed, Dimopoulos and Dvali and Randall and Sundrum. These were inspired by work on D-branes in string theory, since it was in that context that people took seriously that we might live on a brane and be unable to escape into the "bulk" in which it was embedded. But the details of string theory aren't intimately connected to those models (and the idea of being stuck to a brane goes back to earlier work by Rubakov and Shaposhnikov).
The idea that modern theories of quantum gravity imply the existence of extra dimensions was the subject of my talk at the Philosophy of Science Association meeting last month. I've finally turned my slides into a pdf file, for anyone who'd like to check them out. Unfortunately the figures didn't always convert smoothly, so at times you will have to imagine the presence of a string or quark where no image is present. All part of the challenge of modern physics.
Sunday, December 05, 2004
The Weary Blues
By Langston Hughes.
Droning a drowsy syncopated tune,You can also listen to the poem read by the author, with music by Leonard Feather.
Friday, December 03, 2004
Like a prayer
From Bob Park's What's New, a newsletter loosely affiliated with the American Physical Society:
PRAYER STUDY: COLUMBIA PROFESSOR REMOVES HIS NAME FROM PAPER. We have been tracking the sordid story of the Columbia prayer study for three years (WN 05 Oct 01). It claimed that women for whom total strangers prayed were twice as likely to become pregnant from in-vitro fertilization as others; it was published in the Journal of Reproductive Medicine. At the time we were unaware of the background of the study, but knew it had to be wrong; the first assumption of science is that events result from natural causes. The lead author, Rugerio Lobo, who at the time was Chair of Obstetrics, now says he had no role in the study. The author who set up the study is doing five years for fraud in a separate case, and his partner hanged himself in jail. Another author left Columbia and isn’t talking. The Journal has never acknowledged any responsibility, and after withdrawing the paper for "scrutiny," has put it back on the web. Nor has the Journal published letters critical of the study. Columbia has never acknowledged any responsibility. All of this has come out due to the persistence of Bruce Flamm, MD. The science community should flatly refuse all proposals or papers that invoke any supernatural explanation for physical phenomena.I'm not really sure what it means to say "the first assumption of science is that events result from natural causes," but we did know that it had to be wrong. This ground was covered a long time ago by David Hume in On Miracles:
The plain consequence is (and it is a general maxim worthy of our attention), `That no testimony is sufficient to establish a miracle, unless the testimony be of such a kind, that its falsehood would be more miraculous, than the fact, which it endeavours to establish; and even in that case there is a mutual destruction of arguments, and the superior only gives us an assurance suitable to that degree of force, which remains, after deducting the inferior.' When anyone tells me, that he saw a dead man restored to life, I immediately consider with myself, whether it be more probable, that this person should either deceive or be deceived, or that the fact, which he relates, should really have happened. I weigh the one miracle against the other; and according to the superiority, which I discover, I pronounce my decision, and always reject the greater miracle. If the falsehood of his testimony would be more miraculous, than the event which he relates; then, and not till then, can he pretend to command my belief or opinion.On the other hand, part of me says "who cares?" Certainly in theoretical physics, having published papers that are incorrect doesn't do any harm; you can just ignore them. Would many readers of the Journal of Reproductive Medicine have their opinions swayed by such a study? Or is it worth fighting to have the paper withdrawn so that it can't be used for propaganda purposes? Something tells me that, among people who thought the paper was compelling, having it withdrawn would only provide further evidence of their persecution by the Establishment.
More sexual repression!
In an ongoing effort to reach out to a younger demographic (after the depressing epiphany of last week), Preposterous continues to track the forces of reaction as they attempt to recreate a lost Puritan utopia. In this case, no claim to breaking the news: from Davos Newbies via Pharyngula and Crooked Timber, a story from the Financial Times explains why Americans can't be trusted to see Veronese frescoes shown on television. Something about naked Cupids. No word on colors or flavors.
For those readers in our older, post-giggling demographic, here's more traditional fare: NSF budget slashed, via Chris C. Mooney. I guess there's a fine line between "double the budget" and "cut by $100 million."
Thursday, December 02, 2004
Sex is fun...
... but we're not allowed to admit it. At least, not in Illinois, which remains stuck in the Midwest no matter how blue it appears on the map.
It would appear that Governor Blagojevich has decided to stop the Illinois Department of Public Health from handing out free colored and flavored condoms. (Ironically, the announcement was made on World AIDS Day.) Condoms that look and taste ordinary will continue to be handed out as usual.
Apparently the worry is that handing out condoms with color and flavor (just like quarks!) will encourage people to have sex. I cannot quite imagine how these people think a typical pick-up routine might go. "Hey baby, how'd you like to back to my place and have some safe sex? No? What if the prophylactics were ... lemon-flavored?"
Allow me to point out what these condoms would actually encourage: using condoms. The campaign on the part of certain people to prevent other people from enjoying sex has been going on as long as we've had civilization, and it's not likely to succeed any time soon. But we can continue to make it safe as well as fun.
Wednesday, December 01, 2004
This is a couple of weeks late, but still worth noting. Physicist and educator Melba Phillips passed away on November 8th at the age of 97. (Obituaries at the New York Times and Washington Post.) I didn't know anything about her personally, so everything here is stolen from the press release.
Phillips had a remarkable career. She started on a fast track, as one of J. Robert Oppenheimer's first graduate students, receiving her Ph.D. from Berkeley in 1935. The Oppenheimer-Phillips effect helped to understand the interactions of deuterons with other nuclei. But jobs were scarce during the Depression, and being female didn't make it any easier. She finally landed a faculty position at Brooklyn College in 1938. She had a strong social conscience and was politically active, helping to found the Federation of American Scientists in 1945. Her activities got her in trouble in the McCarthy era, and she ended up being fired in 1952 after refusing to testify before a U.S. Senate committee investigating alleged communist activities. Much like the Pope and Galileo, Brooklyn College eventually apologized somewhat late, in 1987; they held a symposium in her honor in 1997.
Unemployed, Phillips turned her attention to physics education; her book with Panofsky is till a standard text in undergraduate electromagnetism. From 1966 to 1967 she served as president of the American Association of Physics Teachers, which later created the Melba Newell Phillips Award in her honor.
She joined the faculty of the University of Chicago in 1962, recruited by her former student Stuart Rice. Among other accomplishments, she was responsible for the first physics course taught here to non-scientists. She retired in 1972, but remained active, serving as a visiting professor at several universities. A rich and admirable life.