While theorists routinely work with the most fundamental degrees of freedom in their calculations, the world of an experimentalist, i.e., the real world, is quite different. Experimenters must cope with particles that decay too quickly to be observed; particles that don’t exist freely by themselves but only in bound, hadronized, and fragmented states that keep showering into even more particles; and particles that cannot be detected at all. And we theorists expect them to relate the pile of stuff they observe to our fundamental degrees of freedom, and to get it right, every time. Experimenters accomplish this feat with what looks like a huge pile of semi-organized chunks of metal, liquid, gas, wire, and cable, called a detector. It’s amazing, really. I am always in awe when I visit a detector! In order to interpret LHC (or Tevatron or B-Factory) data, a theorist must have at least a rudimentary knowledge of how a detector works.

Modern collider detectors are known as 4pi, or hermetic, detectors. (Burt Richter led the team which built the first 4pi detector in the 1970′s at SLAC.) A hermetic detector is simply one which completely surrounds the collision point, i.e., in more technical language, it covers all 4pi steradians of solid angle around the collision. The shape of a collider detector is essentially cylindrical and one can think of it as a can, with the interaction point being located at the center of the can. The can has a barrel piece, which has the beampipe as its axis, and two endcap pieces which fit in snugly to the barrel region. The snug fit is incredibly important, and the degree of snugness is called hermeticity. A detector whose components do not have a snug fit is not hermetic – it would allow particles to escape undetected. If this happens, not only do you lose the particles that you should see, but you have over counted the production rate of the ones you shouldn’t see. That’s obviously a bad situation. Unfortunately, no detector is ever perfectly hermetic — they all have cracks and experimenters learn how to fold that into their data analysis.

These cylindrical detectors are a series of subcomponents, each wrapped around each other, and each performing a specific job. A general all-purpose collider detector has the following components (looking at a slice view and starting at the interaction point and going out):

Vertex detector: This is a very tiny component which surrounds the interaction region as closely as possible. It is basically built of layers of silicon and if a particle has a lifetime of order a picosecond (10^-12 seconds) then its decay vertex (i.e., the track of the single particle splits into the 2-3 tracks of its decay products) can be observed. Bottom quarks, and sometimes charm quarks, can be identified in this manner. The vertex detector is the first component to get fried if something goes even slightly amiss with the beam.

Tracking Chamber: This component determines the trajectory of charged particles. The electromagnetic energy loss (via interactions with the medium in the tracking chamber) and momentum of a charged particle can be measured. It works by tracing the helix of the charged particle as it traverses the chamber in a magnetic field. The chamber is made of layers of finely segmented material, usually silicon.

Electromagnetic Calorimeter: High energy electrons and photons interact with the material in the ECAL and create showers of particles — this process occurs at an exponential rate allowing for the ECAL to absorb all their energy and they finally come to rest. The energy of electrons and photons is thus measured. Various materials are used (lead crystals are popular), but the calorimeter is usually transversely segmented.

Hadronic Calorimeter: Hadronic particles (jets of particles made from hadronized quarks and gluons), usually protons, neutrons, pions, and Kaons, interact with the material in the HCAL, creating showers, coming to a stop and thus depositing all their energy in the HCAL. This usually requires a fairly dense medium (steel scintillators are popular) and is also generally transversely segmented.

Muon Chambers: These are huge chunks of iron that surround the outside of the detector. Muons are heavy and relatively long-lived — thus they traverse the rest of the detector without stopping and track through to the outside chambers. Supposedly, muons are the only particle that can travel through the detector without showering and stopping in the calorimeters, but sometimes very energetic pions can make it through the hadronic calorimeter and punch through into the muon chambers. This is known as pion punch-through and gives a fake muon signal.

As you can tell from the above list, every detector also has a magnet, in order to track charged particles. The size and shape of the magnetic can vary quite dramatically, but it is usually quite large with state of the art magnetic field strength.

A nice graphic illustrating these various detector subcomponents and the particles they are designed to identify is:

The solid lines illustrate when a particle leaves a track in a detector component, and the showers depositing all their energy in the ECAL and HCAL are also shown. Neutrinos, by the way, sail smoothly through the detector unnoticed, and unbothered by all the material placed in their path.

This is a very basic and rudimentary description of collider detectors, but one that I give on the first day of class when I teach a Collider Physics course. A nice set of lectures, written for theorists, describing detectors and collider physics in more detail can be found in hep-ph/0508097 by my good friend Tao Han at the University of Wisconsin. I admit to stealing the above graphics from these lecture notes.

As you can see, detectors are very complicated and finely tuned instruments and my hat is off to the experimenters who make them work and give us the data!

Who says our commenters are anything less than perfectly awesome? In the course of reading Alejandro Satz’s review of Lee Smolin’s book, I came across a link to a comment on one of Clifford’s old posts. An elaborate review of a film that is completely imaginary, but demands to be made; it’s brilliant, and somehow I don’t think it got the attention it deserved when originally posted. It’s by “Steve,” but I don’t know anything more specific — if the real Steve would like to step forward, I’d be happy to give credit where it’s due!

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The “String Kings”, Scorsese’s latest, is a highly violent but satisfying gangster movie, certainly on a par with Goodfellas or the Godfather trilogy, and does give the viewer insights into the raw and violent world of fundamental string theory research. The film also boasts a first-rate Hollywood cast: Joe Pesci as Michael “Mo “Green; Burt Young as John Schwarz; Antonio Banderas as the hot-bloodied Juan Maldacena, who is as fast with a flicknife as he is with an ADS duality; Leonardo deCaprio as Lubos “The Kid” Motl; Robert de Niro as Tom Banks; Harvey Keitel as Joe “the (quantum) Mechanic” Polchinski, Michael Douglas as Michael Douglas; Amanda Peet as Amanda Peet, Terrence Stamp as Lenny Susskind, Jackie Chan as Michio Kaku, Samuel L Jackson as Clifford V. Johnson and Eugene Levy as “Boss of Bosses” Ed Witten. The film is characterised by some extreme and gratuitous violence and is not for the mathematically squeamish, but this is to be expected considering the subject matter.

In the film, Lubos Motl becomes involved with the string mafia at a young age. As he says in the film, “I always wanted to become a string theorist”. As an undergraduate he idolises the string theory gangsters in the US and eagerly studies every page of GSW, Vols. I and II. Upon graduating, the local Syracuse mob captain Tom Banks sees his potential and helps cultivate the boy’s developing criminal string career, offering him a postgraduate position. In graduate school Lubos is arrested by campus police for intimidating researchers in medicine, biology, engineering, arts and humanities into citing string preprints in their work. He admits nothing and is lauded by his superiors as a “stand-up guy”. Upon getting his Phd he moves to Harvard and gets to rub shoulders with some of the “made guys” within the east-coast string underworld. Ruthless and violent and described as “perturbatively unstable” he quickly establishes his reputation. From his Harvard base he helps the mob take over local bars, clubs, businesses, casinos, hotels, libraries, graduate schools and journal editorial boards. They run a sleazy escort agency called “Matrix Models”. The also conspire to channel, siphon and launder millions of dollars worth of grant money from the government. However, at this time the FBI also begin to keep a close watch…

Perhaps the most violent scenes in the film follow when “Boss of Bosses” Ed Witten, from a huge luxury mansion in Princeton NJ, calmly gives the order for a long list of people to be “taken out” (spoiler alert). In a chilling sequence, the film repeatedly cuts between the increasingly violent mob hits and Ed giving a seminar on the twistor space structure of 1-loop amplitudes in gauge theory. Lee Smolin is seen shot multiple times in the back as he writes LQG constraint equations on a blackboard. There is a scene showing work on an extension of the New Jersey turnpike, involving string henchmen (disguised with hard hats and overalls) a large cement truck and Peter Woit. Carlo Rovelli is kidnapped and strapped to a chair while the Kid goes through his quantum gravity monologue page by page with seething criticism before finally bashing his head in with the hardback edition. Another LQG theorist gets his dimensions compactified in a car crusher. These violent scenes generally stay with you long after the film is finished and have an unsettling effect.

The film also cuts to the west-coast string operation where Stanford mobsters are experimenting with hard drugs. With on-location filming at the ITP (now the Kavli Institute) we see Polchinski (Keitel) and Johnson (Samuel Jackson) working on a lecture series, unfortunately with awful dumbed-down dialogue from Jackson:”This D-brane primers gonna kick serious ass mutha”. However, back east things go awry and the kid ends up in jail replete with orange jump suit taking the rap for his superiors, following an FBI sting (string?)operation. But he starts to run an operation from his cell smuggling in drugs and arxiv preprints for his fellow inmates.

However, the film badly degenerates into 70s and 80s actioner kitch near the end when the east-coast string bosses decide to take over Kaku’s NY pop science, popular book, tv and radio operation, thus stopping him making string theory understandable to “the stupid people”. It turns out though that Kaku who has 4 black belts can shatter a stack of D-branes with a single karate blow, and takes on the string mob, joined by fellow populariser Brian Greene played by Steven Seagal. However, some of the mob back west are not hapy including boss John Schwarz who says, “Kaku was writing string theory papers when some of you guys were struggling with high-school algebra”. What follows is an all-out turf war in NY’s China Town, with a badly dubbed Kaku (even though being Japanese), a sinewy, oiled lean, mean fighting machine…every muscle tensed ready to explode with lightening reflexes, taking out the string mob one by one in a scene shamelessly ripped off from the end of “Enter the Dragon.”

Overall, String Kings will appeal to fans fo the gangster genre and despite the ending will probably still become a Scorsese classic.

As most of you know, we pride ourselves here on being a top-down blog. We’re not one of those touchy-feely people-powered sites that are all “What would you like me to post about?” and “Whatever can we do to serve you?” Our attitude is, we know what’s best for you, and we’re taking time from our busy schedules to provide it, and you’ll like it or learn to. At Cosmic Variance, that’s just how we roll.

There is, however, an obvious exception to the rule: the comment sections. (Or should that be “are, however, obvious exceptions”? Grammar is not how we roll.) That’s where the people, our beloved readers, can let their voices be heard. A Habermasian zone of free communication, where all are welcome to participate in reasoned and passionate dialogue concerning the nature of the universe and our place within it. Okay, I’ll stop there.

So the question is: how can the comment sections be better? To decode this for our more innocent readers: how can we increase the signal-to-noise ratio? Increasing the signal is one obvious way, but that’s hard. The real question that I’ve been wondering about (haven’t consulted my co-bloggers on this) is: should we take more dramatic steps to decrease the noise? In particular, should we have a much heavier hand in discouraging, deleting, or even banning people who are rude, disruptive, off-topic, or just plain crackpotty? And in most specific particular: if we did so, are there folks out there who would judge the comment sections to be more useful, and might even be more likely to join in themselves?

Personally, I rarely read the comment sections on other blogs, even my absolute favorites. But I enjoy our comment threads here, and we certainly have some insightful and articulate commenters. Sadly, there are also the crackpots. To be absolutely clear, I am not referring to folks who are not experts in science or whatever else we happen to be talking about, but would sincerely like to join in the conversation, add an outsider’s perspective or ask a question or two. We like those comments, in fact those are our absolute favorites! Indeed, those are the ones that I most worry are being squeezed out by the noise. Likewise, we’re very happy to see comments that represent strong but principled disagreement with what we are saying. (We’ve been accused, unsurprisingly, of taking delight in stifing dissent, but the briefest glance at any of our controversial threads makes that a difficult position to support.)

The crackpots to whom I refer are those who know little or nothing about the subject but are convinced that they do, and are likewise convinced that the world needs to know about their theories, yet have absolutely no interest in listening to what others have to say. You know of whom I speak: the guy who has read the first chapter of The Elegant Universe and come away convinced that he knows more about how spacetime really works than these groupthinking string theorists, or the gal who constructed a model from ordinary household appliances that predicts the masses of all the particles in the Standard Model. (Neither of these examples refers to actual people, at least not to my knowledge; but I wouldn’t be surprised.)

So, do people prefer to let a thousand flowers bloom, even if some are indistinguishable from weeds, or should we play a more active role in deleting the nonsense? We’ve always been willing to delete/ban people who are repeatedly obnoxious, but it’s never fun to do so. We recognize that the free-speech zone that everyone is in favor of is not each individual blog, but rather the blogosphere as a whole. If anyone wants to push their own crazy theories about the birth of the universe, they should feel free to start a free blog and explain away to their heart’s content; we’re very happy to accept trackbacks to nearly any blog.

But individual blog comment sections aren’t public squares; they are more analogous to private living rooms. The preeminent statement of this philosophy was offered by Eugene Volokh, when he explains that comment threads are like cocktail parties to which the blog owners have invited you. It’s not supposed to be a free-for-all fracas in which rudeness and craziness must stoically be tolerated; it’s supposed to be an interesting mix of viewpoints from a wide variety of backgrounds, but one that comes together in mutual respect to create a stimulating dialogue.

And yet… and yet we almost always err on the side of letting people ramble on, at least until they become so impolite and/or disruptive that we have little choice. So what do you think? Would this blog be a better place if the Heavy Hand of the State slapped down some of the noisier contributors, or is the chaos part of the charm? (Responses from people who don’t usually comment are especially welcome.)

You know how George Bush is constantly admitting that he’s made grave mistakes, and apologizing, and hoping to do better in the future? Hmm, no, I guess you don’t. Meanwhile, Barack Obama is leading by example, as this excerpt from Wait Wait, Don’t Tell Me demonstrates. (Via Unfogged.)

The phone rings.

Lovelady: Lovelady. Newsroom.

Obama: Nicholas?

Lovelady: This is he.

Obama: Nicholas, this is Barack Obama.

Lovelady: Hey, how’s it going?

Obama: Man, I am calling to publicly apologize for messin’ up your game. I felt terrible. I didn’t know there were any ladies around. I just wanted to let you know that I’m deeply sorry. But if she was that superficial, then she wasn’t for you.

Lovelady: (chuckles) Well, I really appreciate it.

Obama: Well okay, man. Bye bye.

The call ends.

For context … read the whole thing. Audio here.

I would definitely vote for Obama if I hadn’t already pledged my support to The Editors.

How often do you get to vote for a dinosaur?

There was an interesting moment of irony on NPR this morning, in a segment discussing Harvard’s new proposed changes to the core curriculum. The changes are, broadly speaking, intended to make core courses more relevant, and to give students a background that is not guided by the traditional disciplines alone. For example, one might not have a history requirement, but might rather have a requirement to take a course from a category known as “The U.S.”, which would contain history courses, but also economics and other courses.

I have no interest in taking a side in this particular debate, not least because I haven’t fully studied Harvard’s plans. But what struck me about the NPR piece was what happened in the tiny part where science was discussed. One professor (not from the sciences) was defending the traditional approach (and again, I have no reason to agree or disagree with him personally) and, after all the talk about the humanities and obscure courses, he said something like (not a precise quote)

You would never ask a physicist, who is a world expert in, say, string theory, to teach a broad survey course to students and have to explain the difference between friction and impact [now in a softer voice] – if there is a difference between friction and impact.

This came from one of, as described by the presenter, the world’s most brilliant academics.

What I have to say here is not about Harvard, or about this particular professor, or about what a core curriculum should look like. However, I do think that this little exchange gets at the heart of what we often mean when we talk about the public perception of and proficiency in science. This person is clearly intelligent and well educated (in some agreed upon sense), and is defending the traditional approach as adequate, but in doing so betrays his clear ignorance of extremely basic science. Almost as importantly, in realizing that he didn’t quite understand what he had just said, he casually acknowledges that he doesn’t know the difference, like it is no big thing. Although this isn’t quite as egregious as not knowing the difference between Charles Dickens and John Grisham, it is in the ballpark, and I can imagine the look on my humanities friends’ faces if I expressed such a confusion.

I don’t know if Harvard should change its core curriculum, or what it will mean for the science part if they do. But one thing is clear, it is considered just fine, even among our most highly educated, to be scientifically illiterate. This is what we battle, in an age when an increasing proportion of important decisions depend on an appreciation of scientific issues. If there are academics who don’t have the tools to properly understand debates on global warming, the energy crisis, stem cells, evolution, genetic engineering, genetically-modified foods, nuclear power, and so on, what hope can we have that the correct decisions will be made by policy-makers, or that the public will understand enough to cast informed votes?

You may have read here and there about the genteel discussions concerning the status of string theory within contemporary theoretical physics. We’ve discussed it on CV here, here, and even way back here, and Clifford has hosted a multipart discussion at Asymptotia (I, II, III, IV, V, VI).

We are now very happy to host a guest post by the man who wrote the book, as it were, on string theory — Joe Polchinski of the Kavli Institute for Theoretical Physics at UC Santa Barbara. Joe was asked by American Scientist to review Peter Woit’s Not Even Wrong and Lee Smolin’s The Trouble With Physics. Here is a slightly-modified version of the review, enhanced by footnotes that expand on some more technical points.

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This is a review/response, written some time ago, that has just appeared in American Scientist. A few notes: 1) I did not choose the title, but at least insisted on the question mark so as to invoke Hinchliffe’s rule (if the title is a question, the answer is `no’). 2) Am. Sci. edited my review for style, I have reverted figures of speech that I did not care for. 3) I have added footnotes on some key points. I look forward to comments, unfortunately I will be incommunicado on Dec. 8 and 9.

All Strung Out?

Joe Polchinski

The Trouble with Physics: The Rise of String Theory, the Fall of a Science, and What Comes Next. Lee Smolin. xxiv + 392 pp. Houghton Mifflin, 2006. $26.

Not Even Wrong: The Failure of String Theory and the Search for Unity in Physical Law. xxi + 291 pp. Basic Books, 2006. $26.95.

The 1970′s were an exhilarating time in particle physics. After decades of effort, theoretical physicists had come to understand the weak and strong nuclear forces and had combined them with the electromagnetic force in the so-called Standard Model. Fresh from this success, they turned to the problem of finding a unified theory, a single principle that would account for all three of these forces and the properties of the various subatomic particles. Some investigators even sought to unify gravity with the other three forces and to resolve the problems that arise when gravity is combined with quantum theory.

The Standard Model is a quantum field theory, in which particles behave as mathematical points, but a small group of theorists explored the possibility that under enough magnification, particles would prove to be oscillating loops or strands of “string.” Although this seemingly odd idea attracted little attention at first, by 1984 it had become apparent that this approach was able to solve some key problems that otherwise seemed insurmountable. Rather suddenly, the attention of many of those working on unification shifted to string theory, and there it has stayed since.

Today, after more than 20 years of concentrated effort, what has been accomplished? What has string theory predicted? Lee Smolin, in The Trouble With Physics, and Peter Woit, in Not Even Wrong, argue that string theory has largely failed. What is worse, they contend, too many theorists continue to focus their efforts on this idea, monopolizing valuable scientific resources that should be shifted in more promising directions.

Smolin presents the rise and fall of string theory as a morality play. He accurately captures the excitement that theorists felt at the discovery of this unexpected and powerful new idea. But this story, however grippingly told, is more a work of drama than of history. Even the turning point, the first crack in the facade, is based on a myth: Smolin claims that string theorists had predicted that the energy of the vacuum — something often called dark energy — could not be positive and that the surprising 1998 discovery of the accelerating expansion of the universe (which implies the existence of positive dark energy) caused a hasty retreat. There was, in fact, no such prediction [1]. Although his book is for the most part thoroughly referenced, Smolin cites no source on this point. He quotes Edward Witten, but Witten made his comments in a very different context — and three years after the discovery of accelerating expansion. Indeed, the quotation is doubly taken out of context, because at the same meeting at which Witten spoke, his former student Eva Silverstein gave a solution to the problem about which he was so pessimistic. (Contrary to another myth, young string theorists are not so intimidated by their elders.)

As Smolin charts the fall of string theory, he presents further misconceptions. For example, he asserts that a certain key idea of string theory — something called Maldacena duality, the conjectured equivalence between a string theory defined on one space and a quantum field theory defined on the boundary of that space — makes no precise mathematical statements. It certainly does. These statements have been verified by a variety of methods, including computer simulations [2]. He also asserts that the evidence supports only a weak form of this conjecture, without quantum mechanics. In fact, Juan Maldacena’s theory is fully quantum mechanical [3].

A crucial principle, according to Smolin, is background independence — roughly speaking, consistency with Einstein’s insight that the shape of spacetime is dynamical — and Smolin repeatedly criticizes string theory for not having this property. Here he is mistaking an aspect of the mathematical language being used for one of the physics being described. New physical theories are often discovered using a mathematical language that is not the most suitable for them. This mismatch is not surprising, because one is trying to describe something that is different from anything in previous experience. For example, Einstein originally formulated special relativity in language that now seems clumsy, and it was mathematician Hermann Minkowski’s introduction of four-vectors and spacetime that made further progress possible.

(more…)

I don’t read many conservative blogs. I enjoy some quasi-conservative libertarian-types — Marginal Revolution, Daniel Drezner, Balloon Juice, The Volokh Conspiracy. (Even if libertarian policy principles are kind of crazy, they are often smart and provocative.) But the hard-core rightosphere, places like Little Green Footballs and Powerline and Michelle Malkin, I just find creepy. (But I must point out that I’m box office at The Free Republic: see here, here, here, and here. Freepers find me fascinating.)

It’s truly a different world, and worth an occasional glance, just to be reminded that the set of “important news stories” can be entirely distinct from what I might think. For example, I’d been completely ignorant of the menace of the flying imams, the subject of literally hundreds of breathless blog posts. Not being an aficionado of modern religions myself, at first I thought they had something to do with yogic flying, but it turns out that’s something else entirely.

The story is that six Muslim clerics were removed from a US Airways flight from Minnesota to Phoenix a couple of weeks ago, accused of acting suspiciously. They were led away in handcuffs before being questioned and released, while their flight left without them. US Airways refused to let them travel on a different flight the next day; they eventually flew home on other airlines.

As far as I can tell, the suspicious behavior consisted of the following:

• Praying.
• Speaking Arabic.
• Saying “Allah” out loud, several times.
• Remarking unfavorably about US policy in Iraq.
• Sitting in seats “reminiscent of a 9/11 hijackers seating configuration.” I think that means they weren’t all sitting together — some were even in first class!
• Requesting seat-belt extenders, even though they weren’t really all that overweight.
• Moving about the airplane, before takeoff, to talk with each other.

That’s about it.

To me, it sounds like the US Airways flight crew overreacted a bit. The seat-belt extender business is apparently suspicious because they could potentially be used as weapons. Picture in your mind’s eye, six imams (one of whom was blind) swinging their seat-belt extenders like nunchucks, overpowering a planeload of pasty Midwesterners. The “moving around” also has a relatively prosaic explanation — one of the imams who had upgraded to first-class decided to offer his seat to his blind colleague, who declined the offer. See, if they had been cold-hearted atheists who didn’t have religion to tell them to be nice to each other, all of this could have been avoided.

But, ultimately, I don’t place too much blame on the flight crew for reacting as they did. A situation unfolding in real time is always unclear, and caution is warranted; better to inconvenience a few people than put an entire flight at risk. Although I don’t think the situation was handled well, it was an understandable overreaction, and should be something we can put behind us. Mistakes were made, sorry about that, can’t be too careful, etc.

The bloggers who jumped all over the original reports, though — they don’t think that way. They can’t think that way. It must have been a real threat, or their entire worldview is in jeopardy.

Debbie Schlussel is outraged that the imams haven’t been banned from flying on airplanes for all eternity. (For what, exactly?) Instapundit thinks that anti-Muslim sentiment is their fault. Michelle Malkin claims that one of the imams admitted supporting Osama Bin Laden! Okay, the alleged support was against the Russians in the early 1990′s, and was encouraged by the CIA at the time. But still! Pajamas Media thinks it must have been a “dry run.” Apparently, it eventually dawned on some people that praying loudly and shouting “Allah” would probably not be recommended doctrine if you actually did want to sneak onto an airplane and stage a surprise mid-air coup, so all that praying and talking in Arabic must have been part of a coordinated campaign to soften up security personnel before the next actual attack. Or something like that; I can’t keep all the theories straight.

The entire incident is reminiscent of the time in June 2004 when journalist Annie Jacobsen freaked out at the presence of a group of Middle Eastern men on a plane. Not only were the men completely harmless Syrian musicians, but it turns out that Jacobsen’s own behavior had potentially put the flight in danger, in the opinion of air marshals.

What would you do, if you were Annie Jacobsen? Realize that you had overreacted just a tad, and examine how deep-seated fears can lead to unwarranted conclusions? No, if you were Annie Jacobsen you would write a book about how we’re not nearly afraid enough of dark-skinned people on our airplanes.

We’re very proud, in this country, of our commitment to equality, liberty, and the rule of law. But a lot of Americans are living in fear right now, and are willing to sacrifice much of the freedom that makes this country what it is in order to combat that fear. How far are they willing to go? Newt Gingrich is campaigning against the First Amendment. Keith Ellison, the first Muslim elected to the U.S. Congress (and the guest of honor at the conference the flying imams were attending), is accused by Dennis Prager of undermining American civilization because he will take the oath of office on a Koran instead of a Bible. When radio host Jerry Klein suggested — as a spoof — that American Muslims should be forced to wear identifying tattoos or armbands, reminiscent of Nazi measures against Jews, he was disgusted to hear many audience members call in to express their full-throated support for the idea.

This fear is real, and politicians will take advantage of it, shamelessly and unapologetically. I’m not worried that the U.S. will descend into actual authoritarian rule, as these things are understood worldwide. But encroachments on liberty in the name of security can be pernicious and severe even if they come very gradually. That’s a much bigger threat to our society than terrorism will ever be.

Who gets more love, economists or physicists? Robin Hanson stamps his foot in frustration at the lack of respect economists receive, in a nicely self-undermining blurb (via Ezra Klein):

Consider how differently the public treats physics and economics. Physicists can say that this week they think the universe has eleven dimensions, three of which are purple, and two of which are twisted clockwise, and reporters will quote them unskeptically, saying “Isn’t that cool!” But if economists say, as they have for centuries, that a minimum wage raises unemployment, reporters treat them skeptically and feel they need to find a contrary quote to “balance” their story.

As Ezra and Kevin Drum point out, this is straightforwardly wrong on the merits: economists have a huge amount of influence over actual public policy, while admiration for physicists doesn’t get you too much beyond the “Isn’t that cool!” level, and occasional appearances on late-night radio. (It’s like conservatives complaining that most university professors are liberal, while they control the government, corporations, and the military.) Atrios and Echidne also point out that the single chosen example of economic wisdom, that the minimum wage raises unemployment, is wrong. And that physicists have quite the demonstrable track record of making statements about the universe that seem counterintuitive at first glance, but turn out to be right.

In fact, I think these three sentences point to a definite failure on the part of physicists to successfully get their message across. We physicists talk about crazy things all the time — extra dimensions, black holes, quark confinement, wavefunction collapse, conservation of momentum, the Earth moving around the Sun. Things that, on their face, seem to be incompatible with our everyday experience. But we don’t just throw these ideas out there randomly; they are hypotheses that we’re driven to by the constraints put upon us by the data. Some of these ideas may turn out to be wrong, and some may be right, and we have certain well-tested procedures for sorting them out. (In the wake of Milton Friedmann’s death, folks have been re-arguing his contention that successful predictions from an economic model are more important than correct assumptions underlying it. I would hope that both are important.) Unfortunately — and to a signficant extent this is our own fault — it’s not always clear to the person on the street which ideas are speculative and which have come to be accepted, nor is it clear that we have good reasons even for the wildest speculations.

But the idea that three dimensions are purple and two are twisted clockwise — that’s intriguing. I’ll have to look into it.

Update: Robin Hanson expands on what he meant about the minimum wage.

NASA has officially announced its plans to put a permanent base on the Moon. This is all part of the Moon, Mars and Beyond program that has sucked the life out of astrophysics research at the agency. But going to the Moon would be incredibly exciting in its own right, if it didn’t cost any money. (Nobody knows how much it actually will cost.)

The plan is to first finish building the International Space Station using the Space Shuttle. The Shuttle is scheduled to be retired once and for all in 2010 — so I gather that we won’t actually be doing much with the ISS once we finish building it. Meanwhile, NASA will be developing a new set of spacecraft, featuring the Orion Crew Exploration Vehicle that will be launched on Ares rockets. The goal is for the new system to be functional by 2014, if not earlier.

And then on to the Moon — reaching there by 2020, hopefully with a continually-manned station by 2024. Not much is known about what such a base would look like, although there is some idea of putting it somewhere that the astronauts could replenish some resources through mining. The South Lunar Pole is apparently an interesting destination, perhaps near Shackleton crater.

It’s frustrating to be so lukewarm about the Great Human Adventure in Space, about which I’d much prefer to be enthusiastic. But nothing about the operation inspires confidence, much less wonder. NASA Deputy Administrator Shana Dale described the program in this tired bit of management-speak:

“This strategy will enable interested nations to leverage their capabilities and financial and technical contributions, making optimum use of globally available knowledge and resources to help energize a coordinated effort that will propel us into this new age of discovery and exploration.”

Do people really talk like that? It sounds straight out of Dilbert. Complete with numbingly bullet-pointed Powerpoint presentation!

Maybe the concerns are misplaced, and NASA will be able to aggressively pursue human exploration of space without sacrificing their unique contributions to cutting-edge astrophysics. But I’d be just as happy to let NASA concentrate on the science at which they excel, and leave the space-cowboy stuff to the X-prize folks.

The Times Online is reporting that

The Ancient Egyptians built their great Pyramids by pouring concrete into blocks high on the site rather than hauling up giant stones …

If true, this would be quite amazing to me, and there appears to be some science (at least the words) backing it up.

… according to Professor Gilles Hug, of the French National Aerospace Research Agency (Onera), and Professor Michel Barsoum, of Drexel University in Philadelphia, the covering of the great Pyramids at Giza consists of two types of stone: one from the quarries and one man-made.

“There’s no way around it. The chemistry is well and truly different,” Professor Hug told Science et Vie magazine. Their study is being published this month in the Journal of the American Ceramic Society.

The pair used X-rays, a plasma torch and electron microscopes to compare small fragments from pyramids with stone from the Toura and Maadi quarries.

They found “traces of a rapid chemical reaction which did not allow natural crystalisation . . . The reaction would be inexplicable if the stones were quarried, but perfectly comprehensible if one accepts that they were cast like concrete.”

If this holds up then I’m definitely going to start pushing my theory that The Lighthouse of Alexandria consisted of a huge LED.