Dark Matters

Recently I've been reading about proposals to explain the "Dark Matter" phenomenon by modifying the law of gravity, as opposed to invoking some unseen form of matter. The original proposal along those lines was MOND: Modified Newtonian Dynamics, invented by Israeli physicist Mordehai Milgrom. Modified Newtonian Dynamics: A Review is an excellent summary of the observational evidence and theories as of late 2011. It mentioned some mind-blowing gravitational lensing phenomena some of which have resulted in spectacular images.

Einstein Cross

Einstein Ring

Cluster CL0024+17 

The blue streaks near the center of CL0024+17 are not part of the cluster itself, they are images of galaxies much further way which have been magnified and distorted by the gravitational lensing effects of this massive cluster.

Hong Kong Elementary School Admissions Test

How long did it take you to solve it? I'll tell you how I did in the comment section to avoid spoiling it for you.

Supernatural Horror in Literature by H. P. Lovecraft

Supernatural Horror in Literature (1927) by H. P. Lovecraft is a fantastic review, both for its breadth of coverage and the creepy way in which it is written. Here's the first paragraph:

The oldest and strongest emotion of mankind is fear, and the oldest and strongest kind of fear is fear of the unknown. These facts few psychologists will dispute, and their admitted truth must establish for all time the genuineness and dignity of the weirdly horrible tale as a literary form. Against it are discharged all the shafts of a materialistic sophistication which clings to frequently felt emotions and external events, and of a naively insipid idealism which deprecates the aesthetic motive and calls for a didactic literature to uplift the reader toward a suitable degree of smirking optimism. But in spite of all this opposition the weird tale has survived, developed, and attained remarkable heights of perfection; founded as it is on a profound and elementary principle whose appeal, if not always universal, must necessarily be poignant and permanent to minds of the requisite sensitiveness.

I've already acquired several of the classics he mentioned and will read them whenever I next feel the need to be weirded out. His only work of fiction that I recall reading was The Dunwhich Horror which was so creepy that I was never able to bring myself to read anything else by the author, despite my appreciation for the quality of his writing.

Lovecraft in 1934

Richard III

I just finished rereading Alison Weir's great book "The Wars of the Roses". Coincidentally, the article Perimortem trauma in King Richard III: a skeletal analysis recently appeared in the journal The Lancet. In 2012 a skeleton identified as Richard III's was discovered in Leicester, England and exhumed.  I also recommend a chilling 1995 film version of Shakespeare's play starring Ian McKellen set in an imaginary fascist 1930's Britain.

Digital photograph; arrow shows the penetrating injury to the maxilla

Richard III in Better Days

Movie Poster

OSA EARS

The Osa Peninsula is a remote, biodiverse region of Costa Rica, home to Corcovado National Park. It's the site of the OSA EARS listening station, an audio streaming project in the Costa Rican rainforest where you'll soon be able to listen to the sounds of the jungle in real-time. The project's web site is not quite ready, but there's an introductory video at Vimeo. The program director is the SETI Institute's first Artist in Residence and Guggenheim Fellow Charles Lindsay. You can email the project team at info@osa-ears.org. Very cool!

Beautiful Wind Map

There's a beautiful moving map of the wind for the United States at http://hint.fm/wind/. This is the moving wind map during Hurricane Sandy on October 30, 2012.

Turtles are more closely related to Crocodiles than Lizards!

CREDIT: G. GRULLÓN/SCIENCE
The orange line shows where turtles actually belong in this part of the tree of life, the dashed lines indicate previous suggestions.
New DNA techniques have recently been developed to more easily determine where species belong in the tree of life. See Large-Scale Gene Comparisons Boost Tree of Life Studies in Science. As you may have heard, birds and dinosaurs are closely related. Moving further up the tree, Archosaurs are a group that contain birds, dinosaurs and crocodiles as well as the extinct flying reptiles, the Pterosaurs. Thanks to this new research, turtles are now known to be the sister group to the archosaurs.
A red-eared slider.

Harriet Dark Art

Harriet Dark is an art student here in Boston. You can see more of her haunting work at Harriet Dark Art.

Scientism

Steven Pinker, a linguistics professor at Harvard and prolific author, has a provocative article at The New Republic web site, Science Is Not Your Enemy An impassioned plea to neglected novelists, embattled professors, and tenure-less historians (August 2013). Pinker says that science is now encroaching on matters traditionally in the realm of the humanities, for example human emotion and human values, and that has generated a backlash in various quarters: the humanities, religion and public policy. Scientism is a term - new to me - used by critics who believe that science is often misapplied when it address some of the traditional concerns of the humanities, religion and public policy. I have found many other things Pinker has written very interesting, especially when they are focused on his specialty, linguistics. However, this article seems to me yet another example of someone who knows a lot of science and feels like their scientific knowledge supports some of their other values and opinions, but their attempt to make their case unfortunately comes off very weak. I suspect that Pinker's article will often have the exact opposite effect of what he says he intends. Instead of reassuring people who think science overreaches, it will just seem like yet another attempt that misuses science to support someone's personal opinions. See The Scientism of Steven Pinker by Ross Douthat in the New York Times, for someone who didn't find Pinker at all convincing.

Faulty 'scientific' results have, of course, repeatedly been used to support personal biases, The Mismeasure of Man, by Steven Jay Gould is a collection of interesting historical examples. In some cases the errors and misinterpretations were really rather subtle, but invariably the errors somehow ended up supporting the preconceived notions of the investigators.

Bunker Hill

Bunker Hill: A City, a Siege, a Revolution is a 2013 book by Nathaniel Philbrick. It focuses heavily on Joseph Warren, a physician, politician and patriot general killed during the 1775 battle of Bunker Hill. The detailed accounts of the years leading up to and following the battle were quite interesting, especially since I've been a resident of the Boston area for most of my life. The Bunker Hill monument is easily visible from my windows. My favorite quotes from the book were from the loyalist pastor Mather Byles. When asked how he could be a "brainless Tory", Byles replied, "Tell me, which is better, to be ruled by one tyrant 3,000 miles away, or by 3,000 tyrants not a mile away?" He called the sentry stationed outside his house his "Observe-a-Tory". The Death of General Warren at the Battle of Bunker's Hill, June 17,1775 by John Trumbull

A Quantum Critique

Many reputable thinkers have had issues with quantum mechanics, notably Einstein, who said "God does not play dice with the universe", referring to the probabilistic outcomes predicted by standard quantum theory. The EPR Paradox (the 'E' stands for Einstein) and Bell's Theorem are two well-known examples of the somewhat peculiar predictions of quantum mechanics. John Bell is quoted saying about quantum mechanics

I did not dare to think that it was false, but I knew it was rotten!

The Fate of the Quantum by Nobel prize winner Gerard 't Hooft is a sophisticated critique of quantum mechanics which also touches upon philosophical issues such as Free Will. The standard interpretations of quantum theory often invoke the free will of experimenters to make independent decisions at the last second. 't Hooft complains that alternative interpretations are sometimes dismissed, on grounds more philosophical than scientific:

This explanation is usually also dismissed. It is called a ‘conspiracy theory’, and that is considered to be disgusting. But are ‘disgusting’, or ‘ridiculous’, valid arguments in a mathematical proof? We have reasons to doubt that.

More concretely the paper mentions the concept of Superdeterminism, which probably eliminates the possibility of free will and also evades the assumptions behind Bell's Theorem.
For what it's worth - probably not that much haha - I'm with 't Hooft on this one. Over the years I've bored my friends and even written an outline of a paper along these lines, but haven't polished my arguments into publishable form, so it's nice to see that someone as distinguished as 't Hooft has basically saved me the trouble. 't Hooft doesn't, at the moment, have a completely fleshed out proposal to compete with quantum mechanics and, alas I don't either. He finds Quantum cellular automata interesting in this context and so did I at one point, but he also mentions the same problem that caused me to give up on that - issues of compatibility with relativity.

The Invisible Gorilla Strikes Again!

This video is a test of selective attention, count how many times the players in white pass the basketball.

Casual observers may miss the gorilla, but what about expert observers? The following study tested radiologists looking for lung nodules in CT scans. A picture of a gorilla was inserted into some of the images. A majority of the radiologists did not notice! See The invisible gorilla strikes again: Sustained attentional blindness in expert observers by Trafton Drew, Melissa Võ, Jeremy Wolfe for a poster and here for a link to the full paper.

PSYCHOL. SCI.

Cosmography of the Local Universe

At Cosmography of the Local Universe there is a video showing the distribution and motion of the galaxies in our neighborhood. There is also an accompanying paper by Courtois, Pomar, Tully, Hoffman and Courtois. In the video "distances" are represented by velocities in km/s. It's difficult to figure out distances to galaxies directly, what we can actually measure is the "redshift" of spectral lines, which can be interpreted as a velocity, which is then assumed to also indicate distances, due to the fairly uniform expansion of our local universe. Another term appearing in the video is the 'Zone of Avoidance' or ZOA. Our own galaxy, the Milky Way, blocks our view of the galaxies, due to the the dust and stars of the Milky Way being concentrated around the plane of the Milky Way's disk. So we really don't have much information about the galaxies laying in those directions.

One of the characteristic features of the distribution of galaxies is the presence of voids: huge, roughly spherical regions in which galaxies are very sparse. I have a collection of interesting links to the literature about voids here.

“On the quantum theory of radiation” by Albert Einstein

In Einstein's 1917 paper “On the quantum theory of radiation” he introduced the concepts of stimulated and spontaneous emission of radiation, the effects that make possible lasers and many other fascinating devices. He accomplished this in masterful fashion by starting with the simplest of assumptions, all but one of which were traditional classical physics. Using just one basic quantum notion - Bohr's idea of quantized molecular energy levels - his amazing powers of deduction led him to hypothesize new observable physical phenomenon as well as rederiving Planck's radiation law in a very neat way. This was apparently also the first time that anyone realized that photons should carry momentum as well as energy. This English translation of the original paper is beautifully written. Here are two nice retrospectives: Einstein as armchair detective: The case of stimulated radiation by Vasant Natarajan; Rereading Einstein on Radiation by Daniel Kleppner.
A dim recollection of freshman physics is probably enough to follow much of Einstein's train of logic.
"A Theory Should be as Simple as Possible - but not Simpler"

I would have liked to have written a shorter title, but I did not have the time

I would have written a shorter letter, but I did not have the time. Blaise Pascal in Provincial Letters: Letter XVI; similar statements have been attributed to Mark Twain, T.S. Eliot, Cicero, and others besides. From Simplicity - Wikiquote.

Richard Holmes at the Radcliffe Institute

I attended a talk by biographer Richard Holmes at the Radcliffe Institute here in Cambridge yesterday (5/22/2013): The Scientist Within: Scientific Biography and The Creative Moment. I had read his book, The Age of Wonder: How the Romantic Generation Discovered the Beauty and Terror of Science which I found fascinating. I've found attending talks by authors of favorite books to be highly uneven, sometimes they are great and sometimes they are very disappointing. Sometimes the author is just how you pictured them, sometimes they are not all what you expected. In this case, happily, I was smiling appreciatively throughout his talk. In one gem from the talk, Holmes read a passage from Byron's Don Juan, Canto the tenth:

When Newton saw an apple fall, he found
In that slight startle from his contemplation --
'T is said (for I'll not answer above ground
For any sage's creed or calculation) --
A mode of proving that the earth turn'd round
In a most natural whirl, called "gravitation;"
And this is the sole mortal who could grapple,
Since Adam, with a fall or with an apple.

In contrast, William Blake found Newton's work deeply offensive. I had of course seen reproductions of the Blake monotype many times and had always thought of it as a rather heroic depiction, until Holmes pointed out Blake's actual opinion of Newton. He showed a slide of Blake's image along with a photo of the Eduardo Paolozzi bronze at the British museum.

Space Oddity cover by Chris Hadfield filmed aboard the ISS

"Solar Rain" video from NASA

Alternative History

I recently read A Palette of Particles, another fine book by the writer and physicist Jeremy Bernstein about the history of particle physics up to the Higgs boson. Bernstein mentions one chilling near miss in physics. In Rome in 1934 an Italian team led by Enrico Fermi actually observed nuclear fission. But they misinterpreted what they saw. Bernstein asks us to imagine how world history might have been different if fission was discovered in Fascist Italy in 1934 instead of four years later in Berlin 1938. Even though fission was discovered in Germany, by that time, the fascist powers were rapidly becoming very isolated from the rest of the scientific community. Lack of scientific knowledge might have been only part of the reason the Nazis weren't able to build a bomb, but it was probably a factor. After WWII several distinguished German scientists were held together by the Allies in England (Operation Epsilon) and their conversations were secretly recorded. Several of them, including Heisenberg, seemed surprised when they learned of the atomic bomb and may have mistakenly believed that an explosion would require tons of uranium, not kilograms.

The Variational Principles of Mechanics

I'm currently reading The Variational Principles of Mechanics by Cornelius Lanczos, the fourth edition published in 1970. From the preface to the first edition (1949):

The variational principles of mechanics are firmly rooted in the soil of that great century of Liberalism which starts with Descartes and ends with the French Revolution and which has witnessed the lives of Leibniz, Spinoza, Goethe, and Johann Sebastian Bach. It is the only period of cosmic thinking in the entire history of Europe since the time of the Greeks

The Action Principle may be the most profound principle in all of nature. The 18th century origins of the principle were colorful and controversial. Characters who were deeply involved included Émilie du Châtelet, an aristocratic lady; her lover, the writer Voltaire; and Fredrick the Great, King of Prussia! See The Berlin Academy and forgery.
Du Châtelet was a remarkable woman, her French translation of Isaac Newton's great work Principia Mathematica is still considered definitive. Café Gradot was the meeting place for intellectuals in Paris at the time, many of them her friends. When she tried to join her friends at their table, the management threw her out - women were not allowed in the cafés at the time. Undeterred, on later occasions she arrived attired as a man, and was able to participate in the discussions at the cafe without further incident.

Silent Lights, photography by Sidney Regis

Sidney Regis has a photographic project called Silent Lights - it's beautiful!


photo by Sidney Regis

NEAR(ER) installation preview from Charles Lindsay

NEAR(ER) installation preview from Charles Lindsay on Vimeo.

Manta Rays at Socorro Island

video by Mike Murphy

La Paz, Baja California Sur

Sea Lions and Whale Sharks Oh My!

The Los Islotes sea lion colony, near La Paz, Baja California. Photos by Julian Bages.

I didn't even know he was there!

The sea lions were naturally curious about the whale shark, but the whale didn't appear interested in the sea lions or the divers.
However it did seem fascinated by the boats: it swam up to my boat and bit the propeller!

I'm on the left, blowing lots of bubbles haha.

For some reason I want to believe that I once saw a hexagonal whale shark spot pattern, but this one is a checkerboard pattern, as are all the other photos I can find.

A whale shark right on the La Paz Malecon! (my photo)

The Sun is Too Round

Back in the 19th century it was observed that the orbit of Mercury deviated from the predication of Newton's law of gravity - the precession of Mercury's perihelion. One simple explanation would have been that the sun was oblate: flattened at the poles and bulging at the equator. However the sun is much too round for that to work, instead Einstein explained most of the anomaly in Mercury's orbit with a modification of Newton's gravity - his theory of General Relativity. However there was still a small discrepancy between Einstein's theory and the actual orbit of Mercury which was expected to be explained by some flattening and bulging of the sun from perfect roundness. However, the actual shape of the sun has been mighty hard to measure to the required accuracy - until recently. Alas, it appears that the sun is still rounder than expected. How Oblate Is the Sun? by Douglas Gough in Science is a review of the history of this problem and The Precise Solar Shape and Its Variability by Kuhn et. al. in the same issue is a report on recent space-based measurements.

Fermat's Dilemma

Is Algebra Necessary? Andrew Hacker, a political scientist writing in the New York Times, believes that too many students in high school and college are subjected to the ordeal of learning algebra. He spends much of the article claiming that algebra is both useless and harmful to most of the students forced to take this horrible subject. He goes on to point out that taking an algebra class often doesn't even lead to an appreciation of the cultural significance of mathematics as a whole:

I WANT to end on a positive note. Mathematics, both pure and applied, is integral to our civilization, whether the realm is aesthetic or electronic. But for most adults, it is more feared or revered than understood. It’s clear that requiring algebra for everyone has not increased our appreciation of a calling someone once called “the poetry of the universe.” (How many college graduates remember what Fermat’s dilemma was all about?)

He's absolutely correct here, college graduates don't remember anything at all about Fermat's dilemma - that's because it was never mentioned! He probably meant to say Fermat's Last Theorem, a widely known mathematical curiosity. The end of algebra by Alexandra Petri in the Washington Post is a clever and funny response to Hacker's screed.

RdSeed: Intel announces a forthcoming randomness generator

Intel recently announced a new instruction for randomness generation - RdSeed - to be available in future generations of Intel processors.  RdSeed is intended to be compliant with forthcoming (summer 2012) NIST Standards SP800-90B and SP800-90C.  Intel's Ivy Bridge chips, already in production, have a randomness generator RdRand, but the forthcoming instruction may be easier to use for some cryptographic purposes.  There isn't much information about RdSeed yet, but I'm looking forward to learning more from Intel in due time - it looks exciting! Here's a link to a cryptography discussion group where David Johnston of Intel recommended that we can ask questions while awaiting for further disclosures from Intel.

The Big Higgs Questions

The Big Higgs Question by Nobel Prize winner Steven Weinberg in the New York Review of Books provides a history of the theory behind the Higgs Boson written by one of the key contributors.  The Higgs is important because previously known particles such as the W and Z, carriers of the weak nuclear force, are known to have a nonzero mass, but some mechanism needed to be added to the theory in order to give them a mass (particles can in fact be completely massless, for example the photon.)  There were other alternatives, but the Higgs mechanism was the leading candidate and the recent experiments at CERN pretty much confirmed the Higgs as the winner.  However, theorists are not finished being puzzled!  According to Weinberg, it would be much more "natural" if the Higgs mass were hundred thousand trillion times larger then what was just measured!  A slight discrepancy, for which there is currently no particularly good explanation.

"Now where did I leave that screwdriver?"
--- the other Big Higgs Question 

Religion and Analytic Thinking

I recently read Thinking, Fast and Slow by Nobel prize winning psychologist Daniel Kahneman.  He discusses evidence that we might have two quite different thinking mechanisms:  System 1 and System 2.  System 1, is fast, easy, intuitive - we are able to discover patterns and jump to certain conclusions nearly effortlessly.  However System 1 is somewhat error prone.  Consider the following puzzle:

The total cost of a bat and ball is $1.10; the bat costs a dollar more than the ball;  how much does the ball cost? 

 Most people answer this one quickly and alas, incorrectly.  Kahneman attributes this to using System 1.  The correct answer is at the bottom of this post.

System 2 is slower, more difficult, but much less error-prone - systematic, logical thinking as opposed to intuition.

His book provides numerous intriguing examples but is also a bit disheartening - even extremely well-trained people seem to have trouble solving many simple problems.

However, subjects that are prepared for an analytic task in various seemingly trivial ways - for example seeing certain words and pictures which prime them for reasoning systematically - go on to perform significantly better at certain simple but tricky tasks. 

There was a recent paper in Science Magazine, AnalyticThinking Promotes Religious Disbelief

by Will M. Gervais and Ara Norenzayan (April 2012), which applied the methodology discussed in Kahneman's book to see if that could be used to affect a subject's reported religions belief.  In particular, they found that subjects who were primed in ways that are known to promote System 2 thinking did subsequently report higher rates of religious disbelief.

Sample images of The Thinker (left) and Discobolus (right) used in study 2. The images shown here are similar to, but not the exact same ones used in the study. [Source: Wikimedia] 

In the study, subjects who were primed by seeing a picture of The Thinker were more likely to report religious disbelief than subjects that saw a picture of the discus thrower.  There were other experiments in the study which were also seemed to indicate that preparing subjects in ways that promoted System 2 type thinking also affected the rate at which the subjects then reported religious disbelief.

Religious belief is pervasive in human societies - which has always been quite mysterious to me.  Religion usually seems to involve 'faith' to a large degree (which I take to be the belief in something despite very little actual evidence.)  I, however, try to be cautious even when I have quite a lot of evidence.  I know from long and sad experience how easy it's been to fool myself!  It's always nice to have multiple ways to cross-check something, the more the better, and perhaps eventually the evidence gets to be so overwhelming, I might actually starting believing.  Religion doesn't seem to work that way, it's often reported to come upon people suddenly, they are "born-again", they have an ecstatic spiritual experience and a "conversion".

Even when I was very young, six or so,  religious belief didn't seem to make any obvious sense, yet it was very pervasive when I was growing up, so I was always quite curious as to what was actually going on.  The first thing I remember seriously reading on the subject was The Varieties of Religious Experience by William James.  It's been quite a while:  my impression was that while James was a very good writer, unfortunately I didn't really come away with much insight as to why religious belief was so common.

A few years ago there was a spate of books purporting to study religion "scientifically."  For example, Breaking the Spell: Religion as a Natural Phenomenon by the philosopher and cognitive scientist Daniel Dennett  and The God Delusion  by biologist Richard Dawkins.  I had found other books by the same authors quite fascinating, but not these two.  They seemed to be mainly hatchet jobs on religion by committed atheists with little to no real scientific content.  

So this recent paper in Science was a pleasant surprise, it seems to be a serious attempt to study some aspects of religious belief experimentally.  


By the way, if you're interested in the subtleties of interpreting these types of experiments see this blog post by Samantha Bernecker about the paper.  

The correct answer to the bat and ball puzzle is 5 cents - however, the most common answer given is 10 cents. 

A Labyrinth of Kingdoms

A Labyrinth of Kingdoms: 10,000 Miles through Islamic Africa by Steve Kemper is a biography of the African explorer Heinrich Barth (1821–1865) one of the first Europeans to visit the fabled city Timbuktu in Mali. Though not completely free of the prejudices typical of his time, he treated the African people he encountered in his travels as individuals, recorded their names, their languages and histories and was fascinated by their cultures and way of life.  He respected and appreciated the highly developed civilizations he found in Africa - we should too.  They had their problems of course, but also impressive achievements.  A great adventure story!

Barth approaching Timbuktu

Bring Up the Bodies by Hilary Mantel

Writing a satisfying sequel can't be easy. However George R. R. Martin managed to do it for me three times - the first three sequels to Game of Thrones were all excellent. But alas, the most recent installment in his A Song of Ice and Fire series, A Dance with Dragons, fell completely flat. Martin did have very plausible extenuating circumstances - he was involved with the production of the HBO series of Game of Thrones, which was very well received.
Wolf Hall was the prize winning historical novel by Hilary Mantel, a story set in the time of Henry VIII, which featured his very able functionary/henchman Thomas Cromwell. Wolf Hall brought us through the events of Henry's marriage to Anne Boleyn, ending portentously just prior to Henry's arrival at Wolf Hall, the home of the Seymour family and Jane, the next "winner" in Henry's ongoing wedding lottery.

Her next book Bring Up the Bodies covers the rest of Henry's calamitous marriage to Anne and his growing infatuation with Jane Seymour. Despite the high drama of the actual historical events, fodder for innumerable retellings historical and dramatic (I remember enjoying the film Anne of a Thousand Days long, long ago - it was panned by the critics, but I was young then and probably easier pleased than I would be today) Bring Up the Bodies was surprisingly unengaging. Perhaps it was because the focal character - Thomas Cromwell - was himself in a reasonably secure position during that period, so it lacked the propulsive forces of vulnerability and peril that, though I probably should be ashamed to admit it, usually work well enough for me. To be fair, Mantel is a very witty writer and flashes of that do appear in this book, though not as often as in the first one. Mantel is projecting a trilogy, and if we cheat and look ahead in the history books, Thomas Cromwell's further career ends up parlous indeed - so I will definitely give the author another chance when it comes out!

Sexy Graffiti near MIT

I heard that it's been there several years.

Younger Dryas Impact?

The Younger Dryas was a cold period about 12,000 years ago that lasted about a thousand years. The previous ice age had seemingly ended, but then the Younger Dryas was a return to cold conditions. Many large animals became extinct around that time, possibly because of the rapidly changing climate.
There is a controversial hypothesis that the Younger Dryas was caused by an extraterrestrial impact. See Evidence for an extraterrestrial impact 12,900 years ago that contributed to the megafaunal extinctions and the Younger Dryas cooling for the original article in PNAS (2007). The controversy peaked with this highly skeptical article Mammoth-Killer Impact Flunks Out in Science (2010).

After a new study failed to find nanodiamonds, impact experts are flatly rejecting outsiders' claims that an impact 12,900 years ago devastated the megafauna.

However the proponents of the impact hypothesis have not surrendered! Evidence from central Mexico supporting the Younger Dryas extraterrestrial impact hypothesis in PNAS (2012) details new evidence from lake sediments in Mexico.

Fiona Apple

Fiona Apple is promoting a new album and her recent performance received a good review at the New York Times: Fiona Apple Returns to the Faithful.
She also has the most charming collection of music videos. Here are my favorites.

That Obscure Object of Confusion

I just watched Luis Buñuel's last film, That Obscure Object of Desire (1977). Even I couldn't help noticing that the character Conchita (the obscure object of desire) was played by two different actresses Carole Bouquet and Ángela Molina. The first time I noticed this, one actress leaves, another one returns, but all the other characters don't seem to notice the difference. What the hell was going on? Strangely enough, I quit noticing the difference too! I can recall the first scene in which I noticed the switch but after that, I didn't notice the further switching at all! In the script, there really was only one character. As an experiment, the filmmakers just chose to use two different actresses for the same part and exchanged them seemingly at random.
Even more weirdly, the two actresses don't really look much alike!

Walter Lewin at ESG

I had the pleasure of lunch today at MIT's Experimental Study Group (ESG). The special guest was Walter Lewin a retired MIT astrophysicist known for his popular online physics courses.
Professor Lewin is 76 but he still has a very sharp wit, however the MIT undergraduates were no slouches either.
He was asked, "What do you tell a student who doesn't like physics?"
"Well, I can tell you that they had a lousy teacher. That's the only possible reason. I can make anyone like physics. I can make a dog like physics."
Laughter from the students.
After being peppered with questions from the students for a half or hour or more, he was asked, "Do you have a favorite area of physics?"
"No."
"A least favorite area of physics?"
"Thermodynamics, I hate it"
"Did you have a lousy teacher?"
Everyone laughed including Professor Lewin.

Professor Lewin has a new book out For the Love of Physics.

Did Herman Weyl really prefer Beauty to Truth?

There's a famous quotation attributed to the mathematician and physicist Hermann Weyl:

My work always tried to unite the true with the beautiful; but when I had to choose one or the other, I usually chose the beautiful.

Contemporary physicists (in particular String Theorists) have been known to go on about how "beautiful" they find some theory (typically their own haha) especially when hard evidence to support that theory is nowhere in sight. There's usually a kind of tacit implication that the expositor is better in touch with the mysteries of the cosmos than the great unwashed who don't appreciate the "beauty" of their revolutionary new theory. After all the great Weyl valued Beauty over Truth didn't he? Peter Woit points out in a recent blog post Dyson on Fringe Physics, String Cosmology and Hermann Weyl that the context of that quote is quite significant and it's more than a little misleading to take it out of that context. It was published in a paper by Freeman Dyson in Nature on the occasion of Weyl's passing:

Characteristic of Weyl was an aesthetic sense which dominated his thinking on all subjects. He once said to me, half joking, ‘My work always tried to unite the true with the beautiful; but when I had to choose one or the other, I usually chose the beautiful’. This remark sums up his personality perfectly. It shows his profound faith in an ultimate harmony of Nature, in which the laws should inevitably express themselves in a mathematically beautiful form. It shows also his recognition of human frailty, and his humor, which always stopped him short of being pompous.

A particular example of this was Weyl's gauge theory of gravity, which turned out to be fatally flawed, but which he was reluctant to abandon because of its beauty. As it turns out, some of the principles that he used in this unworkable theory of gravity found use later on in other areas of physics. However, just because Weyl liked one of his theories that didn't work out at first, but some of the ideas later proved to be useful, doesn't mean the odds are particularly good at all for contemporary theorists with pet theories they claim to be beautiful. The libraries have aisles and aisles full of journals and dissertations which haven't turned out to be significant and it's extremely likely that the vast majority of them will never turn out to significant, not least because they often contradict each other!
The rest of Woit's blog post is worth reading too, as usual.

Randomness on Your Next Chip?

Generating truly random numbers is actually quite tricky. Intel has announced that its next generation of computer chips, Ivy Bridge will have a new instruction RDRAND which will quickly generate a random number for you right on the processor chip - nice huh. But how random will it be? That may depend on how you want to use the random numbers. One very demanding application is cryptography. Most cryptographic protocols require a very high quality source of random numbers. Is the output generated by Intel's new RDRAND instruction good enough for cryptography purposes? The devil is in the details and the most detailed source of information I could find is this Intel document: Bull Mountain Software Implementation Guide. According to that document the random number is generated in three stages:
1. A Hardware Entropy Source
2. A Conditioner which distills the entropy into high-quality nondeterministic random numbers
3. A deterministic random bit generator which is seeded from the conditioner

The entropy source uses thermal noise within the chip's silicon to output a random stream of 0's and 1's.
The conditioner takes pairs of 256-bit samples from the entropy source and algorithmically combines them into a single 256-bit number which is supposed to be even "more random" than the bits generated by the hardware.
The deterministic random bit generator or DRBG "spreads" that 256-bit conditioned number into as many as 511 128-bit samples.

The DRBG they used is called CTR_DRBG, which defined in section 10.2.1 of the following pdf document from NIST: Recommendation for Random Number Generation Using Deterministic Random Bit Generators. Intel uses the AES block cipher option.

Intel has filed a US patent application, number 20100332574, here's a link to the USPTO page for the application and a link to another patent web site, faq.org which I found a bit easier to use.

The Intel Bull Mountain document has a section titled "Guaranteeing DBRG Reseeding"

Some may furthermore feel it necessary, for standards compliance, to demand an absolute guarantee that values returned by RdRand reflect independent entropy samples within the DRNG

which goes on to list a couple of techniques

to guarantee that the random value returned is based on an entropy sample independent from the prior function invocation, and independent from the subsequent function invocation

which may enable one to circumvent the DRBG.

Here's another skeptical discussion of using RdRand in cryptography: RDRAND and Is it possible to protect against malicious hw accelerators?

Too bad, it might have been nice if the raw hardware entropy source was directly available, so that applications could test and manipulate it directly.

The Schneier on Security blog from September 2011 has extensive comments on the new Intel random number generator.

Intel’s Digital Random Number Generator (DRNG) from some members of the Intel team contains some nice slides explaining the architecture.

Conceptual Foundations of the Ivy Bridge Random Number Generator by Jesse Walker of Intel Labs provides slides discussing some of the theory.

I'm working on a web site dedicated to the Intel RdRand facility, currently there's a glossary and bibliography, I'm also working on an article about using RdRand in cryptography which I will post there.

Manta Trust

Giant Mantas are my favorite creatures of the sea, here's a photo one of my favorite encounters from 2010:
photo by Sten Johansson
I just learned about the web site Manta Trust from Daniel Fernando, who I met in Sri Lanka last year. Daniel is a marine biologist and is very knowledgeable and dedicated to manta conservation. He is based in Sri Lanka - a beautiful country which has abundant and varied marine life but limited resources at this point in its development and history.


The Manta Trust web site is an excellent source of information about manta rays and conservation.
Here's one of my previous blog posts on mantas.

An Opinion about Standing Armies

According to Issacson's biography of Franklin, Old Ben wasn't the only wit at the 1787 Constitutional Convention:

A standing army is like a standing member. It's an excellent assurance of domestic tranquility, but a dangerous temptation to foreign adventure.

--- Elbridge Gerry

Ben Franklin Biography

I just finished Walter Issacson's highly entertaining biography of Benjamin Franklin.

One month before his death at age 85, Franklin - who had suffered poor health for several years and knew he did not have long to live - wrote about his religious beliefs with his usual good humor:

As to Jesus of Nazareth, my Opinion of whom you particularly desire, I think the System of Morals and his Religion as he left them to us, the best the World ever saw, or is likely to see; but I apprehend it has received various corrupting Changes, and I have with most of the present Dissenters in England, some Doubts as to his Divinity: tho' it is a Question I do not dogmatise upon, having never studied it, and think it needless to busy myself with it now, when I expect soon an Opportunity of knowing the Truth with less Trouble

Supercontinent formation and True Polar Wander

There have been several periods in the history of this planet when all the continents have united in a single supercontinent. The most recent occasion was the supercontinent Pangaea, which began to break up 175 million years ago with the formation of the proto-Atlantic Ocean.
Map of Pangaea

Not only do the continents move around relative to one another, the entire solid earth may shift with respect to the earth's axis of rotation: True Polar Wander (TPW). The article Absolute plate motions and true polar wander in the absence of hotspot tracks in Nature (2008) discusses the evidence for TPW at the time of the formation of Pangaea, 300 million years ago.

Supercontinent cycles and the calculation of absolute palaeolongitude in deep time, also in Nature(2012), outlines a far-reaching theory that tries to explain where and how a new supercontinent forms in relation to the previous supercontinent in the cycle. The next supercontinent is conjectured to be Amasia which may form due to the closing of the Arctic and Caribbean seas.

She chills me out - thanks to my oxytocin receptor gene

Can your girlfriend help chill you out before some stressful activity? It probably depends on whether you have the G allele of the rs53576 single nucleotide polymorphism of the oxytocin receptor gene, according to this study in PNAS: Common oxytocin receptor gene (OXTR) polymorphism and social support interact to reduce stress in humans . See a previous blog post You're Nice, He's a Jerk - is it because of your Oxycotin receptor genes? for more fascinating research about the behavioral differences attributed to different variants of this gene.

Step up to the bar - the Milky Way bar

Apparently there's a bar/box shaped concentration of stars in the center of our Milky Way galaxy.

This central bar is oriented about 20 degrees from our line of sight to the center of the galaxy - so the diagram above doesn't look quite right to me. The bar seems to rotate like a cylinder - rigidly. This type of structure is typical of many galaxies, not just ours. There's evidence that our bar is a fairly uniform population, there's no real evidence of recent mergers. That's inconsistent with a model of galaxy formation by merger, which seemed to work well for elliptical galaxies. Our Milky Way is a barred spiral - different from ellipticals - but it was thought for a while that the central bulge of spirals might have formed a similar manner. Now that no longer appears to be true.
For some scientific details see The Bulge Radial Velocity Assay (BRAVA): II. Complete Sample and Data Release and OUR MILKY WAY AS A PURE-DISK GALAXY—A CHALLENGE FOR GALAXY FORMATION.

Magma

Magma is melted rock, when it reaches the surface it's called lava. Magma comes from deep underground where it's much hotter, so the rock down there is melted, isn't it? Well not really. Beneath the earth's crust is the mantle and it's by and large solid too. The difference between the crust and the mantle is mainly chemical, they are both solid.
So then, where does magma come from, how does all that rock melt and create such appalling displays at volcanic eruptions?

As it turns out, magma forms by decompression melting. Not only is the temperature higher deep underground in the mantle, the pressure is also terrifically greater. We usually think of solids melting when the temperature rises, but they can also melt when the pressure decreases. Peridotite the mantle rock, is solid at the high pressures and temperatures found down in the mantle, but it will melt when the pressure is released by an opening to the surface - a volcano.