Friday, December 14, 2012

Sunday, November 11, 2012

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)

Saturday, September 29, 2012

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.

Tuesday, July 31, 2012

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.

Monday, July 23, 2012

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.

Monday, July 09, 2012

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 


Wednesday, July 04, 2012

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.

Fig. 1
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. 






Wednesday, June 27, 2012

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

Monday, May 14, 2012

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!

Tuesday, April 17, 2012

Sexy Graffiti near MIT


I heard that it's been there several years.

Thursday, March 29, 2012

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.

Monday, March 26, 2012

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!

Friday, March 23, 2012

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.

Tuesday, March 20, 2012

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.

Monday, March 12, 2012

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.

Thursday, March 08, 2012

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.

Friday, March 02, 2012

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

Wednesday, February 29, 2012

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

Sunday, February 26, 2012

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.