“No.”

A: Hey, what’s up? You’re looking a little anxious these days.

B: I know. We’re getting close to the romance deadline.

A: The romance deadline?

B: Yeah, in a couple of days I have to decide who I’ll be going out with for the next five years or so.

A: Oh, right, I forgot. Have you decided between boyfriend and girlfriend?

B: I’ve thought about it a lot, and I definitely want a girlfriend.

A: That’s cool. But don’t you worry that the standards are higher if you say you want a girlfriend? I’ve heard that boyfriends are much easier.

B: I heard that, too. But girls are what I’m really passionate about.

A: Couldn’t you just get a boyfriend first, and then switch if you don’t like it?

B: Some people try that, but it can be awkward. Better to just be honest about your intentions from the start.

A: Fair enough. So did you get any acceptances?

B: Yeah, two different women have agreed to date me. Cindy and Alyssa. But I have to choose one.

A: Hey, that’s great that you go two offers. Have you made a choice yet?

B: Well, I had coffee with Alyssa, and we really hit it off — she’s beautiful, and charming, and laughed at my jokes. I definitely think we would get along well over the next few years. I met Cindy, too; she’s a knockout, and clearly very talented, but there wasn’t as much of a spark there.

A: That can happen. So are you going to choose Alyssa?

B: I’m tempted, but the thing is — Cindy’s US News ranking is much higher.

A: Her what?

B: Every year, US News puts out rankings of boyfriends and girlfriends. Now, Alyssa is a solid top-20 girlfriend, but Cindy is top five! I’m really worried I’d be making a mistake by passing up the opportunity to go out with Cindy. Everyone has heard of her.

A: That sounds a little weird to me. How do they come up with these rankings?

B: Nobody knows, really. But everyone takes them very seriously. Still, I keep hoping that the NRC will update their boyfriend/girlfriend rankings soon. Those are supposed to be much more scientific.

A: NRC?

B: The National Romance Council.

A: But look, you seem to have really hit it off with Alyssa. Who cares that US News ranks Cindy higher? The concept of a “boyfriend/girlfriend ranking” just doesn’t make sense — what matters is how well you personally get along with them, not some pseudo-objective measure of excellence.

B: It’s easy to say that, but this is a big decision. I’m really worried that, ten years from now when I’m ready to get married, my prospective spouse is not going to be nearly as impressed that I went out with Alyssa than if I had gone out with Cindy.

A: Come on, it’s five years of your life that we’re talking about here. Your chances of eventually being happily married would seem to be a lot better if you choose someone you’re likely to be happy with right now.

B: You’re right, I know. Well, I hope Cindy won’t be disappointed. I don’t think she’s used to being turned down.

A: Don’t worry. I’m pretty sure she’ll get over it.

One beautiful Fall day seventeen years ago I wandered into an office and my life profoundly changed. I was an undergraduate at Princeton, and was looking for a thesis advisor. Jadwin Hall was an intimidating place. Plenty of names familiar from my textbooks. Nobel laureates scattered about. And we were expected to just barge into their offices, and ask to work with them.

One office door was always open. As you walked by you could peek in, and see its occupant hard at work. Hunched over his notebook, scribbling away. Or standing by his bookcase, deep in thought. Most often at the blackboard, chalk in hand. This was John Archibald Wheeler, one of the legends of modern physics. He did foundational work on quantum mechanics, collaborating with Niels Bohr on some of the earliest work in nuclear fission. He invented the S-matrix. He played important roles in both the Manhattan project (atomic bomb) and the Matterhorn project (Hydrogen bomb). He made major contributions to general relativity, co-authoring with Charlie Misner and Kip Thorne the bible of the field. He was legendary for his way with words, coining such terms as wormholes, quantum foam, black holes, and the wave function of the Universe (the Wheeler-DeWitt equation). He trained generations of students; one of his first was Richard Feynman.

Fortunately, being a relatively clueless 20-year old, I was only dimly aware of these things. I was interested in gravity and cosmology, and I had heard Wheeler knew a thing or two about such topics. So I waltzed in, and asked if he had any projects I could work on. I staggered out of his office four hours later, laden with books, a clearly defined project in my hands. For the ensuing two years I spent essentially every weekday with Wheeler. Each morning I would rush over to his office, always to be greeted the same way: “What’s new?” I would have been up late the night before, desperately trying to find something interesting with which to answer that question. We would then spend hours working together, going over my results, scrutinizing my calculations, poring through the literature, brainstorming new ideas. Wheeler gave me a direct and personal introduction to the joys of research. We would break for lunch, and walk up to the faculty club. I often had trouble keeping up with him. He would always take the stairs (”No time to wait for an elevator!”). He would hook his arm into the banisters, and swing around, practically leaping from one flight to the next. This was 1990; Wheeler was 79 years old.

We would often work all afternoon (with the occasional interruption, the nuisance of having to leave for my class lectures). Every evening I would walk with him from Jadwin up across the full length of campus, to catch his bus. We would pass the corner of Ivy lane and Washington road, where he had scratched 137 into the concrete when they were pouring the sidewalk. We would pass Jones Hall, where he used to discuss relativity with Einstein. We would continue on through campus, crossing in front of Nassau Hall. Wheeler would insist we walk diagonally to the far gate, instead of exiting through the more convenient FitzRandolph Gate. An Undergraduate was not meant to exit FitzRandolph Gate until graduation, and Wheeler didn’t want to be responsible for what might occur were I to break tradition.

For two years I sat at the feet of the master, and I absorbed as much as I could. I learned about science, and about life. Wheeler had broad interests. We would often discuss biology, or history, or poetry. Over the ensuing years we kept in touch. We collaborated together on Wheeler’s last published paper.

Yesterday I spent a couple of hours at Wheeler’s bedside. I tried to say thank you. But it was impossible to convey how much he means to me, and how grateful I am to him. In that moment when I crossed the threshold to his office, I was embarking on a new path. I am still on that path, and every day I am grateful to him for showing me the way.

John Wheeler died this morning.

So you’re listening to a talk, and the speaker introduces a crucial step which you know — or perhaps only suspect — to be completely incorrect. What do you do? Do you raise your hand and point out the mistake? Or file it away momentarily, planning to ask them about it in private afterwards?

And does your answer change if the speaker is a senior scientist who will some day be writing you a letter of recommendation? What if it’s a fellow graduate student giving their first-ever technical seminar, and you know them to be intimidated by all these smart people in the room?

A Lady Scientist and PhysioProf have been talking about these issues. The former wonders whether there shouldn’t be some solidarity among grad students not to make each other look bad during journal club presentations, while the latter says that good perceptive critical questions are always in order.

My own attitude is pretty straightforward, and close to PP’s: it’s never impolite or out of order to ask appropriately probing questions about the material being presented at a scientific talk, regardless of the status of the speaker or the audience. It’s science, and we’re all on the same side; it doesn’t do anyone any favors to hide the truth in order to save someone’s feelings. Science is bigger than any of us, no matter how young and inexperienced or old and respected (feared) we may be. Not only should listeners feel free to ask any reasonable question of the speaker, but speakers should be honest enough to admit when they have said something that might be incorrect, rather than twisting around to find justifications for a slip-up. We’ve all made them; or at least I have.

To the extent that there is any sort of competition going on, it should not be “speaker vs. audience,” but rather “all of us vs. the natural world.” However, having staked out that absolutist position, it’s extremely important to recognize that we live in the real world. For one thing, many audience members tend to blur the distinction between “asking a good question” and “being an asshole.” There are people out there, one must admit, who tend to view seminar questions as a venue for them to demonstrate how smart they are, rather than learning about the subject matter in an open and collegial environment. There’s no excuse for that, and the guilty parties deserve to be smacked around, if only symbolically. Still, it’s no reason for the rest of us to equate hard questions with egotistical puffery, nor to soft-pedal questions that really are sincere. The biggest benefit of a talk, from the viewpoint of the speaker, would be to actually learn something from the questions and comments offered by the audience.

The other complication is that there is a competition going on, whether we like it or not. I personally don’t like it, and would vastly prefer to live in a utopia of unlimited resources where such competitions were unnecessary. But in the real world, there is a limited collection of goods — jobs especially, but other rewards of the profession — and a large number of people competing for them. And that competition never turns off. Academics are always judging each other, inevitably, and will use those judgments when it comes time to recommend or hire or give prizes to each other. So a real seminar is not simply a value-neutral examination of the facts; it’s a social milieu, in which interactions have real consequences.

Which is not to say that we should ever shy away from asking hard questions. But there are different ways to ask hard questions, and there’s nothing wrong with choosing the tone in which such questions are asked to match the occasion. Graduate students giving their first seminars need to learn that they will get asked tough questions, and that it’s okay — it’s not a devastating critique of their worthiness as scientists, it’s simply part of the process to which we are all ultimately subject.

A common technique to help students ease into the responsibility of giving talks is to have students-only seminars where the faculty are not permitted. The motivation for such things is admirable, but ultimately I don’t think they are a good idea. (As a disgruntled senior colleague once said, “Sometimes I learn something from listening to the students.”) Breaking down the barriers between “faculty” and “students,” and beginning to think of everyone as “researchers” and “colleagues,” should be an important goal of graduate school. It can all be intimidating at first, but it’s ultimately beneficial to learn to treat these artificial hierarchies as administrative annoyances, not natural categories.

The most successful graduate students are the ones that start thinking of themselves as colleagues right away. Go to the seminars, sit in the front, ask good questions, participate in the informal discussions afterward. It’s a big universe out there, and we’re all struggling to understand it, and working together is our only hope.

Funny thing about energy: it’s conserved! At least when the spacetime background is time-translation invariant, which is a very good approximation here in the Solar System. We bring you this reminder because a knowledge of basic physics can occasionally be helpful when formulating public policy.

In particular, biofuels (such as ethanol) and hydrogen are not actually sources of energy — given the vagaries of thermodynamics, it costs more energy to create them than we can get by actually using them, as there will inevitably be some waste heat and entropy produced. Almost all of the useful energy we have here on Earth comes ultimately from nuclear reactions of one form or another — either directly, from nuclear power plants, or indirectly from fusion in the Sun. There is of course direct solar power, but even fossil fuels and biofuels are simply storage systems for energy that can be traced eventually back to sunlight. The question is, what is the best way of capturing and using that sunlight — where “best” is going to be some interesting function of cheapest, cleanest, most easily transportable, and most sustainable.

People seem to be gradually catching on to the fact that biofuels are an especially wasteful and dirty energy storage system. Paul Krugman devoted a column the other day to how ethanol is a boon to Archer Daniels Midland, but terrible for the world’s food supply. (We told you the Farm Bill was a travesty.) And Time has published a cover story on the “Clean-Energy Scam.”

Propelled by mounting anxieties over soaring oil costs and climate change, biofuels have become the vanguard of the green-tech revolution, the trendy way for politicians and corporations to show they’re serious about finding alternative sources of energy and in the process slowing global warming. The U.S. quintupled its production of ethanol–ethyl alcohol, a fuel distilled from plant matter–in the past decade, and Washington has just mandated another fivefold increase in renewable fuels over the next decade…

But several new studies show the biofuel boom is doing exactly the opposite of what its proponents intended: it’s dramatically accelerating global warming, imperiling the planet in the name of saving it. Corn ethanol, always environmentally suspect, turns out to be environmentally disastrous. Even cellulosic ethanol made from switchgrass, which has been promoted by eco-activists and eco-investors as well as by President Bush as the fuel of the future, looks less green than oil-derived gasoline.

As an uneducated guess, I would imagine that in the medium run the world will have to turn to (Earth-based!) nuclear power for its energy needs. In the longer run, solar will be the way to go, although the amount of solar power we can reasonably collect here on Earth is somewhat limited. We’ll likely have to solve the problem of how to efficiently beam power down from orbit, after which we can build big million-square-kilometer solar power collectors in space. Not in my lifetime, I would bet.

Eventually the Sun will run out, of course. But there are other Suns. In the even longer run, once all of the stars have run out and we are all virtual processes running on a computer, perhaps we can tap into the Hawking radiation from the supermassive black hole at the galactic center. Once that is gone and the universe has settled into empty de Sitter space, we’ll be in thermal equilibrium. At that point there’s probably little hope, no matter what optimists like Freeman Dyson might tell you.

Trevor Paglen has written a fun book, peeking discreetly into the “black world” of secret military projects by reproducing the patches worn by workers on the projects. The patches are surprisingly artful and whimsical, often invoking wizards and dragons to heighten the aura of mystery. Here is a typical example:

In this case, the motto has proven accurate, as Paglen was unable to figure out what unit was associated with the patch. Probably has nothing to do with pornographic movies, but you never know.

The staging areas for many of the secret operations are in the Southwest U.S., including the Area 51/Groom Lake facility where conspiracy theorists are convinced that the government is harboring alien technology from the crash at Roswell. Which, as you might imagine, makes for great source material for the patches. This one comes from the 509th Bomb Wing, in charge of the B-2 Stealth Bomber — the 509th used to be based in Roswell, although it has now moved to Missouri.

“Gustatus Similis Pullus” translates from Latin as “Tastes Like Chicken.” Get it? “To Serve Man?” If not, there is a subtle knife and fork on the patch just to drive home the message.

Other times, the emphasis on secrecy is more overt. This patch is from the 22nd Military Airlift Squadron, which would fly C-5’s to deliver classified aircraft from aerospace plants in Southern California to testing facilities around the country.

“NOYFB,” in case you were wondering, stands for “None of your fucking business.”

The comments on Sean’s post below brought to mind a conversation I had long ago. I had been a postdoc at the Carnegie Observatories, which was a research foundation funded by donors. We were having a meet-n-greet with the folks who had given money to the institute — showing them the machine shop, the offices, etc. I was sitting down with one of the more elderly donors, who announced, “Women’s lib killed the public school system.”

When I picked my jaw off the floor, I encouraged him to expand on his thesis, and found that he wasn’t completely nuts. Back in the day, women of brains, talent, and ambition had two acceptable career options: nursing, and teaching. If I had been born 50 years earlier, I would not have a PhD in astrophysics. Instead, I would probably have grown up to be a school teacher, just like my grandmother. It didn’t have to pay that well, since really, what would have my other options have been? Not law school, not physics, not mechanical engineering, not finance. Today, the brightest women have far more options beyond teaching, and while some still teach, the vast majority of us work in other fields. The salaries in teaching remain low, as for many fields that have been dominated by women, guaranteeing that teaching is not as competitive with other career options available.

To clarify, I don’t 100% buy the premise that the public school system is a disaster. My dad was a public high school teacher, I went to urban public schools, and my daughter is in the public schools. Are there problems and failures? Sure. But I don’t accept that all public schools or schools systems are “bad”. Even if I’m not teaching in one.

One of the most bizarre aspects of the United States is how we organize public education at the elementary and secondary levels. For mysterious historical reasons, we leave all of the important decisions — from curriculum and testing to financing and bus routes — in the hands of local school boards. 130,000 of them, all told. The result, predictably enough, is screaming chaos. Not only do we have haphazard ideas about what to teach and how to judge how well it’s been taught, but the dispersal of resources makes economies of scale impossible, so we don’t put anything like the appropriate amount of effort into developing new techniques and training our teachers.

And it shows. Matt Miller has written a compelling article in The Atlantic, documenting how our screwy system — unique, apparently, in the developed world — has utterly failed to give our children the educations they deserve.

The United States spends more than nearly every other nation on schools, but out of 29 developed countries in a 2003 assessment, we ranked 24th in math and in problem-solving, 18th in science, and 15th in reading. Half of all black and Latino students in the U.S. don’t graduate on time (or ever) from high school. As of 2005, about 70 percent of eighth-graders were not proficient in reading. By the end of eighth grade, what passes for a math curriculum in America is two years behind that of other countries.

This dismal failure might at least be explicable if it served some misguided egalitarian impulse, but it doesn’t. This map, from Miller’s article, shows the spending per pupil on a county-by-county basis; the poorest counties spend less than $7,500 per student, while the rich ones are over $17,500. (Click for larger version.)

Is there any theory behind the idea that students should getter significantly better or worse educations based on the county in which they are born? This isn’t an issue of private vs. public; it’s a public service, paid for by taxes, just like Medicare or national defense. But we finance public education by combination of state and local revenues, rather than through the national government.

Faced with such a patently misguided system, the most common calls for reform involve the imposition of some sort of national standards, such as those featured in the No Child Left Behind Act that has lately been foisted on our schools. In principle, national standards are a great idea; in a sensible system, however, they be the last of a series of necessary reforms. It’s like a team that hires a new football coach, who addresses the team on the first day of practice by saying “Here’s the system: we’re going to win all of our games!” Without an actual playbook, appropriate equipment, and some strategy, exhortations to do better aren’t going to achieve any tangible results.

It’s obvious what is needed: a basic national curriculum that is shared by all schools, with a set of requirements that leave room for creativity and innovation by individual districts within the overall framework. (There is no reason why American math classes should be two grade levels behind European math classes.) Plus, crucially, an overhaul of the financing system so that resources are distributed fairly. Those are just the minimal reforms that every sensible person should be able to agree on; after those are implemented, we can return to our regularly scheduled debates about school choice and bilingual education. Apparently the problem is that conservatives hate “national” and liberals hate “standards,” and both are afraid of the teachers’ unions. So we should all be able to compromise and do the right thing! As Miller says, “We started down this road on schooling a long time ago. Time now to finish the journey.”

Fewer people are probably familiar with F. Scott Fitzgerald’s short story “The Curious Case of Benjamin Button” than they are with the reversed-time novels by Martin Amis, Kurt Vonnegut, or Lewis Carroll. But don’t worry, you will be!

In this case, the protagonist is born as an old man who grows younger with time, eventually dying as a baby. His father, not to mention the hospital staff, are somewhat nonplussed at his birth.

Mr. Button’s eyes followed her pointing finger, and this is what he saw. Wrapped in a voluminous white blanket, and partly crammed into one of the cribs, there sat an old man apparently about seventy years of age. His sparse hair was almost white, and from his chin dripped a long smoke-coloured beard, which waved absurdly back and forth, fanned by the breeze coming in at the window. He looked up at Mr. Button with dim, faded eyes in which lurked a puzzled question.

“Am I mad?” thundered Mr. Button, his terror resolving into rage. “Is this some ghastly hospital joke?”

“It doesn’t seem like a joke to us,” replied the nurse severely. “And I don’t know whether you’re mad or not—but that is most certainly your child.”

The cool perspiration redoubled on Mr. Button’s forehead. He closed his eyes, and then, opening them, looked again. There was no mistake—he was gazing at a man of threescore and ten—a baby of threescore and ten, a baby whose feet hung over the sides of the crib in which it was reposing.

No word of what Mrs. Button had to say about the whole affair.

Fitzgerald’s story takes a different approach to running the arrow of time backwards: Benjamin Button has experiences and memories that are completely conventional (although, for expository purposes, he is born with a full vocabulary), while his physical body ages backward.

The reason why I know everyone will be hearing about the story is that “Benjamin Button” is being made into a feature film, directed by David Fincher (Fight Club, Se7en) and starring Brad Pitt and Cate Blanchett. Major photography has been completed, and it’s currently in post-production, scheduled to be released late in 2008. Major Oscar buzz.

Leaked photos seem to indicate that the film will portray Benjamin as being born baby-sized (albeit old and wrinkly), rather than as a full grown human being. Different actors will be used to portray Button’s reverse aging at different stages of his life, while CGI effects insert Brat Pitt’s face onto each body.

As far as I know (and I’d love to hear otherwise), one of the earliest examples of literary characters with incompatible arrows of time (as opposed to a simple reversed-chronology narrative) is from Lewis Carroll (no relation), in Through the Looking Glass. When Alice first meets the White Queen, she learns that the Queen experiences time backwards.

`I don’t understand you,’ said Alice. `It’s dreadfully confusing!’

`That’s the effect of living backwards,’ the Queen said kindly:

`it always makes one a little giddy at first –

`Living backwards!’ Alice repeated in great astonishment. `I never heard of such a thing!’

` — but there’s one great advantage in it, that one’s memory works both ways.’

`I’m sure MINE only works one way.’ Alice remarked. `I can’t remember things before they happen.’

`It’s a poor sort of memory that only works backwards,’ the Queen remarked.

I agree, and I wish someone would do something about that. Carroll doesn’t emphasize this device much in the book, but does offer one classic illustration of the phenomenon.

Alice was just beginning to say `There’s a mistake somewhere-,’ when the Queen began screaming so loud that she had to leave the sentence unfinished. `Oh, oh, oh!’ shouted the Queen, shaking her hand about as if she wanted to shake it off. `My finger’s bleeding! Oh, oh, oh, oh!’

Her screams were so exactly like the whistle of a steam-engine, that Alice had to hold both her hands over her ears.

`What IS the matter?’ she said, as soon as there was a chance of making herself heard. `Have you pricked your finger?’

`I haven’t pricked it YET,’ the Queen said, `but I soon shall - - oh, oh, oh!’

`When do you expect to do it?’ Alice asked, feeling very much inclined to laugh.

`When I fasten my shawl again,’ the poor Queen groaned out: `the brooch will come undone directly. Oh, oh!’ As she said the words the brooch flew open, and the Queen clutched wildly at it, and tried to clasp it again.

`Take care!’ cried Alice. `You’re holding it all crooked!’ And she caught at the brooch; but it was too late: the pin had slipped, and the Queen had pricked her finger.

`That accounts for the bleeding, you see,’ she said to Alice with a smile. ‘Now you understand the way things happen here.’

`But why don’t you scream now?’ Alice asked, holding her hands ready to put over her ears again.

`Why, I’ve done all the screaming already,’ said the Queen. `What would be the good of having it all over again?’

Both Alice’s Adventures in Wonderland and Through the Looking Glass rely on nonsense to tell a gripping story. Reversing an individual arrow of time is sufficiently nonsensical to qualify as automatically amusing, but also provocative. Why does everyone remember the same direction of time, anyway? (Actually that one’s not hard to answer. If two systems with incompatible arrows were to noticeably interact, the one with more degrees of freedom would swamp the other one and quickly “correct” its arrow of time. No being that “remembered the future” would survive very long in the real world.)