CV’s spam filter has been a tad bit overenthusiastic these days, so I’ve recently had to troll through the spam to retrieve misfiled comments. As expected, the spam is a morass of viagra ads and truly horrid lists of porn-related search terms (where “horrid” means “things that Dan Savage would not approve of”). But lurking in there is a new breed of affirmation spam:

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Moreover, now that they’re tired of thinking only of on-line casino gambling, spammers seem to wish to join the CV conversation:

Hey!, what made you want to write on Best Calculator Ever | Cosmic Variance? I was wondering, because I have been thinking about this since last Sunday.

I couldn’t understand some parts of this article Post: Juan Collar on Dark Matter Detection | Cosmic Variance, but I guess I just need to check some more resources regarding this, because it sounds interesting.

I am not sure that I can completely understand your comments. Would you be so kind as to expand on your reasoning a little more before I comment.

Sometimes, though, the spammers enthusiasm for our work transcends their usual respectful admiration:

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And at least among the spammers, our work is being appreciated.

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Reflecting on his earlier speech on faith at the height of his campaign, Mitt decides to stand up for atheists:

But upon reflection, I realized that while I could defend their absence from my address, I had missed an opportunity…an opportunity to clearly assert that non-believers have just as great a stake as believers in defending religious liberty.

If a society takes it upon itself to prescribe and proscribe certain streams of belief — to prohibit certain less-favored strains of conscience — it may be the non-believer who is among the first to be condemned. A coercive monopoly of belief threatens everyone, whether we are talking about those who search the philosophies of men or follow the words of God.

We are all in this together. Religious liberty and liberality of thought flow from the common conviction that it is freedom, not coercion, that exalts the individual just as it raises up the nation.

(from a speech at the “Beckett Fund for Religious Liberty’s Canterbury dinner”). He loses a lot of ground with me on the rest of the speech, where he elaborates on his earlier claim that “freedom requires religion” and argues that without religion keeping us all well behaved, the US would have descended into anarchy or facism. All the same, it’s nice to see someone tied so closely with both politics and faith demonstrating understanding of why atheists get a bit squicked out with the notion of theocracies.

UPDATE: This was recovered from before the recent site troubles. As Sean mentioned, earlier comments have been lost.

And we’re back! The blog, that is — I’m still on vacation. But we were down for about 24 hours. Plausible explanations include:

1. Mitt Romney said something nice about atheists, and God was pissed.
2. Julianne said something nice about Mitt Romney, and the universe didn’t know how to react.
3. Computers are mysterious and complicated things, and frankly nobody understands how they work.

We should be in working order, although some comments were lost — sorry about that.

Here is a clip of Dianne Reeves singing “Stormy Weather.”

I just received the following workshop announcement:

11th Birmingham-Nottingham Extragalactic Workshop - 1st Announcement

“Semi-analytic models - are we kidding ourselves?“

Refeshingly honest conference title aside, this is a terrific topic for a workshop. Semi-analytic galaxy formation models are extremely useful tools, which consist of (1) an underlying prescription for the growth of dark matter halos and (2) a set of knobs for grafting complicated baryonic physics onto those halos. The first step is well-understood analytically, and has been reliably calibrated with N-body simulations. The second step, however, contains a lot of crafty juju (how much gas winds up inside the dark matter halos? At what rate does that gas cool? How and when does that gas convert into stars? How does the formation of stars and the subsequent supernovae affect the surrounding gas? How do mergers between dark matter halos change the spatial distribution of the stars and the temperature structure of the gas?). The developers of these models are smart folks, and make reasonably well-informed assumptions about all of these baryonic processes, leading to results that are decent matches to the ensemble properties of the galaxy populations. (Note that I didn’t say “predict results” — these models are ex post facto in most usages.) However, just because the models can be tuned to produce a rough statistical match to observations in no way means that the input assumptions are correct or unique descriptions of what actually happens. Moreover, there are serious discrepancies between the models and the observed properties of very low mass galaxies — when the models are tuned to match the properties of relatively massive galaxies, they predict that the low mass galaxies are red and gas poor, whereas the observations say they’re blue and gas rich. It’s great that the community is looking at these issues head on, given the usefulness the semi-analytic galaxy models.

As you know, I’m not blogging right now — I’m taking a well-deserved vacation. But if I were blogging, I would most likely be lamenting Hillary Clinton’s decision to take up the side of ignorance in the culture war against expertise.

“There are times that a president will take a position that a broad support of quote-unquote experts agree with. And there are times they will take a position that quote-unquote experts do not agree with.”

That would be Howard Wolfson, Clinton’s communication director, speaking about the McCain/Clinton gas tax holiday proposal. The one that is so bad that a gaggle of economists have fired up a blog just to oppose it. But who cares what economists might say?

STEPHANOPOULOS: But can you name an economist who thinks this makes sense?

CLINTON: Well, I’ll tell you what, I’m not going to put my lot in with economists….

Paul Krugman gets this completely wrong. He thinks the gas tax holiday, while obviously a bad idea, is small potatoes in the big scheme of things, and all of the fuss is just an excuse to paint Hillary Clinton as evil. That’s not right. It is small potatoes, policy wise, but the fuss is being kicked up by the Clinton campaign themselves — they’re running a wide variety of ads attacking Obama for opposing the holiday, casting him as elitist and out of touch.

The gas tax holiday doesn’t help “ordinary Americans.” The supply of petroleum during the summer months is essentially fixed, and the oil companies will charge what traffic will bear. If taxes are lower, they will simply charge the same amount and pocket the difference. Clinton’s proposal includes some weird end-around in which the oil companies pay extra windfall profits taxes so that the idea is purportedly revenue-neutral; which means the whole scheme is precisely meaningless, as the same amount of tax is being paid either way.

The tragedy is that Hillary Clinton understands perfectly well that this is a stupid policy. (If you actually wanted to save people $40 over the course of the summer, you would just give them $40.) She is embracing it anyway. Her campaign is pushing it as a purely symbolic gesture, attempting to take the side of “real people” against elitist snobs with all of their “education” and “expertise” and Ivy-League degrees.

A bit later she added: “It’s really odd to me that arguing to give relief to a vast majority of Americans creates this incredible pushback…Elite opinion is always on the side of doing things that don’t benefit” the vast majority of the American people.

It’s hard to be more clear than that — elite opinion is the enemy. She knows perfectly well that this is a lie. But it’s politics as usual. I don’t want to dislike Hillary Clinton — she is smart and capable, and would be an enormously better President than John McCain. But treating experts as the enemy is a craven strategy to achieve short-term gains at the cost of substantial long-term harm. It’s sad to see her go down that road, and I hope she reverses course soon.

Today Steinn followed up a nice little post on the role of luck in science (is “lucky” an insult?) with a spot-on description of how being ahead of the curve can damn you in grant proposals:

selected referee comments on “A bold proposal to do something new and interesting”, years 1-3, with added bonus translation

1. very speculative, no track record in this area, would be helped by showing preliminary results proving methodology and showing that results will be forthcoming [trans: come on, first do the research then ask for funding, don’t you know anything?]

   trans: - huh, I never heard of this! Some new stuff. Speculative.
   Oy! He wants full postdoc for three years?
   Who does this guy think he is?

(Years 2 and 3 are equally good).

I think the reaction that Steinn describes can be summarized in Dalcanton’s Lemma of Proposal Writing: “It is nearly impossible to change a referee’s mind about something they think they already know“. If the reviewer comes to the problem with no preconceived notions (i.e. they’ve never read a single paper in your field), you can really make progress in educating them. Same deal if you’re moving forward on well-trodden ground (say, pushing SN Type Ia surveys to larger distances). However, if the reviewer knows something about your topic and thinks the problem is already solved, or uninteresting, or technically unfeasible, or crazy, 10 pages of perfectly formatted prose and elegant figures may still not be enough to change their minds, even if you are 100% completely and totally correct.

Shifting a referee’s frame requires that you first realize that most readers aren’t going to believe you if you’re talking about something that no one else is. Jumping into a bunch of details that seem sensible to you gets you nowhere, when the referee still can’t figure out why you’d bother even thinking about the question. You’ve got to knock down their frame before you stand a chance of getting anywhere. For example: “Although everyone assumes that stars form from gas, here’s a series of three plots demonstrating that that’s completely false when looked at in detail.” Or, “It may seem that the velocity requirements for measuring doppler shifts to detect extrasolar planets are beyond current technical capabilities, but here’s a series of plots where I show that current detection limits are indeed at a level where a monitoring campaign could detect shifts due to Jupiter-mass planets.” Or, “While the theoretical idea that the moon could indeed be made of cheese does not initially seem compelling, here are three analytical calculations suggesting that the properties of cheese could indeed be superior to rock in explaining the observed lunar properties, and thus that further work on the lunar cheese model (LCM) is warranted.” The frame breaking can’t be just a throwaway line, but must be direct acknowldegement of and attack on the paradigm that a likely reviewer would bring to the proposal.

Under the above Lemma, Steinn got shafted in Year 1 because the reviewer came with a frame that said “This can’t possibly work”, and, by not completing enough of the work before submitting the proposal, Steinn didn’t have enough ammo to break the frame. He’s also right in the “Who does this guy think he is?” comment, since the other way you can break a frame is to have enough of a rep that people know never to bet against you. The whole business is another example of Aspects of the Running of Science That Are True, Probably Unavoidable, But Not Necessarily Fair or Optimal.

The classic three pillars of an academic position are teaching, research, and service. While the University Administration sometimes seems to think of “service” as being synonymous with “sitting on committees”, many of us enjoy taking the broader view.

As part of my service activities, this weekend I had the pleasure to talk with a roomful of fantastic young scholars from the McNair program (officially known as the Ronald E. McNair Postbaccalaureate Achievement Program). The program was named after one of the astronauts who was killed in the Challenger disaster). He was also a physicist with a Ph.D. from MIT.

The McNair program identifies promising undergraduates who either are low-income, are first-generation college students, or are from an underrepresented minority group. It then provides extensive mentoring to encourage the students to continue on to graduate school. The mentoring takes the form of supporting the students in research projects in their own departments, guiding them through the steps involved in preparing a strong graduate application, providing an additional resource for academic and personal advising, and waiving application fees.

If you haven’t run across this program, keep an eye out for it. If you know a student who might be a candidate, encourage them to apply. Even more importantly, if you have a chance to work with a McNair scholar, jump at the chance. These kids are phenomenal. They’re interesting and driven, and a pleasure to know.

I’m usually not one to go all blog-happy about the latest press-release, but a recent one happened to be about a paper I had just read, so, I’ll dive on in.

To give a little background, one game that astronomers like to play is “Find the oldest galaxy around at some time”. There are a number of reasons this game has so many eager practitioners. First, the oldest galaxies at any time are probably the locations of the some of the very first collapsed structures in the universe, which make them cool. Second, the most massive galaxies we see today seem to be those that that host the oldest stellar populations — turning this around, if you hunt for the oldest things at a given time, you’re hopefully finding the most massive things at that time. Finally, it’s very tough to figure out how the population of galaxies you see at one time is related to the one you see at the present day (i.e., just because a galaxy is blue and distorted 10 Gigayears (Gyr) ago, doesn’t mean it’s not red and symmetric today). However, if you stick to studying massive galaxies that already looked old 10 Gyr ago, it’s probably a reasonably good guess that they’re comparable to the predecessors of the most massive old galaxies today, giving you one of the few cases where you can match up the two populations with reasonable confidence.

Which brings us to the latest paper by Pieter van Dokkum and his collaborators, on the spectroscopic and HST/NICMOS follow-up of 9 massive red galaxies from the MUSYC NIR imaging survey. These galaxies are at redshifts of 2.5-ish, corresponding to about 2-3 Gyr after the Big Bang for WMAP cosmology. They are very red, and have spectra consistent with a dormant stellar population (i.e. one that stopped forming stars roughly a Gyr previously). An earlier paper by Kriek et al estimated masses for these galaxies (assuming reasonable models of the kinds of stars and dust that are in the galaxies), and found that not only are the galaxies dormant, they’re also extremely massive.

So, now you’ve got yourself a bunch of massive galaxies, that in spite of being no more than 2-3 Gyr old, already finished all their star formation a gigayear previously. Pretty nifty, and what you’d hope to find as the precursors of the old massive galaxies we see today. That’s all well and good, but the problem is that the galaxies are just too dang small. They’re tiny. The most massive galaxies today are typically much larger than the Milky Way, but the galaxies van Dokkum is reporting on are much much smaller. (On the plot at right, the solid scale bar shows a size of 10 kpc. On the plot below, the big solid dots are van Dokkum’s sample, and the little dots are the galaxies seen today in the Sloan Digital Sky Survey.)

Ok fine, you might say. A lot can happen in the intervening 10 Gyr. However, not that much can happen, since these galaxies are already pushing the mass limit of the most massive galaxies we see today. You therefore can’t grow the galaxies by padding them out with new stars from accreted satellite galaxies, without taking them over the limit (i.e. looking at the plot on the upper left, accreting new galaxies would take the galaxies up, but would also move them to the right). Even if you could pull this off, the centers would still be too dense. You also can’t magically puff the galaxies up over time. You could imagine perhaps driving a bunch of mass out of the center of the galaxy, maybe through stellar winds, but it would take an absurd amount of mass loss, even if you believed you could get all that mass out of such a dense honking galaxy. You could also imagine trying to disrupt the galaxies somehow by puffing them up kinematically, maybe through violent mergers. However, the problem here is that the galaxies are waaaaaay too dense. If the galaxies really are as dense as the plot above suggests, then they’re going to be almost impossible to disrupt. It would be like trying to disrupt an iron ball by dropping it into a bowl of pudding.

My take on this is that some of the assumptions that went into making the plot above are wrong, because it’s very hard to imagine hiding the descendants of incredibly massive, incredibly dense galaxies somewhere in the local universe. The authors understand this, and argue that it might be a combination of issues related to measuring the radius (loss of diffuse light at large radii, radial gradients in the conversion of light to stellar mass), and possibly the initial mass function (the great “here be dragons” of all extragalactic astronomy).

I actually think the errant step might wind up being the assumed conversion of light to mass. The standard lore is that when you observe galaxies in the NIR, the light is dominated by old red giant branch stars, giving you a reasonably robust conversion from light into stellar mass. However, at a redshift of 2.5, there’s no way that any star in the galaxy is older than 3 Gyr. In this case, most of the red light from the galaxy will be coming from asymptotic giant branch stars, which are notoriously difficult to model. Thus, the calibration of light to mass can easily be off. AGB stars can also give you a nice red spectrum like those observed, and can be potentially centrally concentrated in response to a central burst of star formation. I think the authors have done the best that they could with their analysis, but I suspect we may have run into some of the real limits of our current modeling.

While deeply held feelings about string theory (”Genius!” “Total Bunk!”) may sometimes drive us apart, all of us can certainly get behind the theory that chocolate is a net good. However, in spite of its appeal as a tasty eatable (with or without bacon), it’s actually a bit of a pain to work with. If you’ve ever tried to use chocolate in its melted form, you’ve probably discovered that chocolate has a number of peculiarities that frequently thwart your best culinary efforts. For example, if your melted chocolate becomes contaminated with an errant drop of water, the chocolate siezes up. If you try to reharden chocolate that’s been melted (say, in making chocolate covered strawberries), you’re frequently left with a matte finish and crumbly texture that in no way resembles the dark glossy chocolate you began with.

The reasons for this should be familiar to any solid state physicist (or at least, they were to the one who made my wedding cake and first clued me in). Cocoa butter, one of the dominant ingredients in chocolate, contains several triglycerides that lock into a crystal form when cooled. However, there is not just one form that the triglycerides can lock into, but six of them (β(I) through β(VI)). Each successive form is more stable and has a higher melting point. Almost all commercial chocolate is in the β(V) form — from what I can tell, you only get to sample β(VI) in the afterlife, if you’ve been very, very good. When chocolate goes all wrong, it is usually a failure of the melted and cooled chocolate to recrystallize into the β(V) state. Similar problems can affect commercial chocolate suppliers as well, leading to chocolate that develops that unsightly chalky film we associate with old chocolate. Even previously stable β(V) chocolate can wind up with the same unsightly film after temperature fluctuations break down the crystal structure, or melt and reharden a thin layer on the surface. Given the commercial implications, there’s been some solid technical work on the structure of the magical β(V) form, which has been studied with x-ray diffraction using synchrotron radiation (more technical data here).

Given the above, when cooking with chocolate, one’s goal is to coax the cooled chocolate back into the β(V) form if one wants the end product to look glossy, be solid at room temperature, and have a nice crisp snap when bitten. The traditional mechanism for this is known as tempering (video here). Traditional tempering involves carefully controlling the temperature of the chocolate as it cools, so that the chocolate favors the preferred crystalline state. However, there is a vastly simpler mechanism, namely, seeding the crystal. If you take a lump of unmelted commercial chocolate, toss it into your bowl of melted chocolate, and stir for a bit, you’ll melt the new lump while cooling the melted chocolate. The cooling chocolate will then prefer the same crystal structure as the melting lump, such that when it hardens completely, you’ll find it in the luscious β(V) state.

PS. I can verify that the above works exactly as advertised. Last weekend I made the wedding cake above for the same solid state physicist who made mine a decade ago. (The cake was alternately described as looking like the Heatmiser’s hair, Mordor, and Garrett Lisi’s E₈ symmetry group, so you can imagine it was a pretty techie crowd). Making the thin chocolate sheets from which I cut the decorations, I got huge swaths of perfectly glossy chocolate. Occasionally, though, there’d be a small section with a matte surface, that was clearly a different crystalline form. Science. It works, bitches.

I’m going to take a vacation from blogging for a little while. Partly a mental-health break, partly a need to get other stuff done. But there are many things I would love to blog about! So here is a list of recent stuff I’ve saved — you can fill in for yourself all the illuminating and entertaining words that would undoubtedly accompany a full-blown discussion.

• Algae! The Editors chide me for carelessly conflating ethanol and biofuels. Fair enough. If algae are a clean and efficient way to capture and store energy from the Sun, I’d be all for it.
• Meanwhile, we continue to heavily subsidize corn for ethanol, and as a result people are dying.
• Don’t like your government? Take to sea and create your own!
• At some point I will say more about Ben Rosen’s great blog, and especially Harold Rosen’s great entry for the Google Lunar X-Prize, about which Deborah Castleman blogs here. Private ingenuity will be crucial to the future of human spaceflight, especially when NASA can’t remember how to replicate its heat shields from the 1960’s.
• I was going to score some non-partisanship points by criticizing Barack Obama for peddling nonsense about autism and vaccinations, just as John McCain does. (Hint: there is no connection!) Then I noticed that Hillary Clinton does the same thing, sadly. And, worse, Clinton has bought into John McCain’s panderiffic notion of declaring a summer holiday on gas taxes — at least Obama has come out squarely against that. (Encouragement to burn more fossil fuels is probably not sound policy.)
• You might also be interested in Michael Berube’s rundown of the candidates stances on disability issues. McCain’s, you’ll be unsurprised to hear, consists of exhortations along the lines of “Hey, disabled folks! Suck it up!”
• John McCain doesn’t want you to forget that Barack Obama is the preferred candidate of Hamas. He’s also the preferred candidate of nearly everyone outside the U.S., but whatever.
• At The Corner, Michael Novak continues Jonah Goldberg’s project of portraying Fascism as left-wing. His evidence is that a friend of Albert Camus’s joined the Nazi Party because everything in the world had lost its meaning. Novak seems to miss the fact that this anecdote proves the opposite of his point — Camus’s friend became a Nazi because the Nazis provided “a meaning in the destiny of our nation,” not because they denied the existence of objective meaning. But keep trying!
• Gerard ‘t Hooft proposes a locally finite model for gravity. A related discussion of whether the universe is continuous or discrete appears in an article from FQXi, which is annoyingly only available in pdf. I actually think the universe really is continuous, not discrete, for reasons that might become clear if I can just get this paper finished.
• Tomorrow, April 29, is Duke Ellington’s birthday. He was the master.

  And here is the orchestra, with Paul Gonsalves on tenor.

• Oops, almost forgot this one: Cosmo Girl! suggests you should design your own religion, just like you design your favorite Starbucks coffee beverage. (Simile theirs.)

Be excellent to each other.