Sunday, May 29, 2011

New experiment on Casimir effect

From First Observation of the Dynamical Casimir Effect :
""One of the most surprising predictions of modern quantum theory is that the vacuum of space is not empty. In fact, quantum theory predicts that it teems with virtual particles flitting in and out of existence."

So begin Christopher Wilson from Chalmers University in Sweden and friends in their marvellously readable paper about a rather extraordinary piece of science.

This maelstrom of quantum activity is far from benign. Physicists have known since 1948 that if two flat mirrors are held close together and parallel with each other, they will be pushed together by these virtual particles.

The reason is straightforward. When the gap between the mirrors is smaller than the wavelength of the virtual particles, they are excluded from this space. The vacuum pressure inside the gap is then less than outside it and this forces the mirrors.

This is the static Casimir effect and it was first measured in 1998 by two teams in the US.

But there is another phenomenon called the dynamical Casimir effect that has never been seen.

It occurs when a mirror moves through space at relativistic speeds. Here's what happens. At slow speeds, the sea of virtual particles can easily adapt to the mirror's movement and continue to come into existence in pairs and then disappear as they annihilate each other.

But when the speed of the mirror begins to match the the speed of the photons, in other words at relativistic speeds, some photons become separated from their partners and so do not get annihilated. These virtual photons then become real and the mirror begins to produce light.

That's the theory. The problem in practice is that it's hard to get an ordinary mirror moving at anything like relativistic speeds."
(via Rajeev Ramachandran's google reader)

Saturday, May 14, 2011

Travelling for a while

Off to USA tomorrow to attend a conference in honour of a collaborator on the occasion of his 65th birthday; a person who reminds of K.L. Krishna who retired from Delhi School of Economics a few years ago. Will use this opportunity to visit a few friends and relatives on the east coast.

Some science links, May 14th

Razib Khan responds to Edge question 2011 WHAT SCIENTIFIC CONCEPT WOULD IMPROVE EVERYBODY'S COGNITIVE TOOLKIT? with a quote from John Ioannidis "There is increasing concern that most current published research findings are false....."

With that proviso here are some research reports that I found interesting.

Blind fish in dark caves shed light on the evolution of sleep (via 3quarksdaily)

Why sons inherit their mother’s curse.

Artificial Grammar Reveals Inborn Language Sense, Study Shows

Language Log in Let me count the ways has a quote of Cosma Shalizi which echoes Razib Khan's worries: "While perhaps not a truly epic fail, this is not a creditable performance. The paper probes a hugely complex tangle of issues relating individual minds, communication, social norms, artistic expression, social change and cultural transformation. There is no shame in not unraveling the whole snarl at once, but between the incompetent data analysis, the failure of logical imagination, and the deep misunderstanding of how works of art are made and used, it does nothing to advance our knowledge of anything."

Thursday, May 12, 2011

A science blog contributes to research

A memory for pain, stored in the spine:
"You slam your hand in a door, and the experience becomes etched into your brain. You carry a memory of the swinging panel, the sound as it crushes your flesh and the shooting pain as your skin gives way. Your body remembers it too. For days afterwards, the neurons in your spine carry pain signals more easily form your hand to your brain. As a result, your hand feels more sensitive, and even the lightest touch will trigger an unpleasant reaction. It’s as if your spine carries a memory for pain.

This is more than a metaphor. Two groups of scientists have found that one special molecule underlies both processes. It helps to store memories in our brains, and it sensitises neurons in our spines after a painful experience. It’s a protein called PKMzeta. It’s the engine of memory."

Wednesday, May 11, 2011

Brad DeLong's query

Why Is the Higher Education Market Failing?:
"None of this is clear to me.

I do observe that education and medical care are the two large sectors in which the private market did not have a strong presence a century ago and are also the two large sectors where market competition does not seem to produce lower prices. And I feel that there must be some connection."
Interesting comments. I would say ask David Labaree.

More good news about Binayak Sen

Binayak Sen on Plan panel committee .
See also Binayak Sen allowed to visit South Korea to receive award.


Several items of interest to Telugus in Maganti site Recent additions include several programs from All India Radio. For the recent additions check the site
జానుతెనుగు సొగసులు .

Gandhi in Abbottabad

From Gopalakrishna Gandhi's aricle Once in Abbottabad..., it seems to be an area where the Frontier Gandhi was popular at one time and Mahatma Gandhi visited thrice and on one occasion wrote to Hitler.
More from Amitabh Pal, and Ashish Vashi.

Tuesday, May 10, 2011

Dan Quillen RIP

A great mathemacian passes away unnoticed and Steve Landsburg is outraged The Architect.
A description of some of his work here with the following comment of Hyman Bass:
"Mathematical talent tends to express itself either in problem solving or in theory building. It is with rare cases like Quillen that one has the satisfaction of seeing hard, concrete problems solved with general ideas of great force and scope and by the unification of methods from diverse fields of mathematics. Quillen has had a deep impact on the perceptions and the very thinking habits of a whole generation of young algebraists and topologists. One studies his work not only to be informed, but to be edified."
Algebraic Topology mailing list carries a message from his widow.
From Mathoverflow Which of Quillen’s Papers Should I read?

Sunday, May 08, 2011

A review of 4 books about Pakistan

by Ahmed Rashid Cry, the Beloved Country
The endlessly deepening crisis that is Pakistan
(via 3quarksdaily)
P.S. Reading recommendations from Nilanjana Roy Speaking Volumes: The Bin Laden bookshelf. The list includes a book by Ahmed Rashid

Thursday, May 05, 2011

Hot Hands and Reasoning

Jonah Lehrer writes in The Reason We Reason:
"Why, then, do we believe in the hot hand? Confirmation bias is to blame. Once a player makes two shots in a row – an utterly unremarkable event – we start thinking about the possibility of a streak. Maybe he’s hot? Why isn’t he getting the ball? It’s at this point that our faulty reasoning mechanisms kick in, as we start ignoring the misses and focusing on the makes. In other words, we seek out evidence that confirms our suspicions of streakiness. The end result is that a mental fiction dominates our perception of the game.

Here’s where things get meta: Even though I know all about Tversky and Gilovich’s research – and fully believe the data – I still perceive the hot hand. I can’t help but watch the NBA playoffs and marvel at the streakiness of shooters, from Kobe to Rose. (Personally, I’d love to see an analysis of Ray Allen. If that man doesn’t show the hot hand, then it really doesn’t exist.) And I’m not alone in my stubborn skepticism. Red Auerbach, the legendary coach of the Celtics, reportedly responded to Tversky’s statistical analysis with a blunt dismissal. “So he makes a study,” Auerbach said. “I couldn’t care less.”

The larger question, of course, is why confirmation bias exists. This is the sort of mental mistake that seems ripe for fixing by natural selection, since it always leads to erroneous beliefs and faulty causal theories. We’d be a hell of a lot smarter if we weren’t only drawn to evidence that confirms what we already believe.

And this leads me to a fascinating and provocative new theory of reasoning put forth by Hugo Mercier and Dan Sperber. In essence, they argue that human reason has nothing to do with finding the truth, or locating the best alternative. Instead, it’s all about being able to argue with others"

One of the authors of the new study Hugo Mercier comments "The production of arguments is biased--as you describe. But argument evaluation ought to be fairly objective: after all, in many cases you're better off being convinced rather than clinging to false beliefs. One of the commenters suggests "Hopefully at some point winning an argument will become more correlated with having the truth on your side." In fact, this is already the case. When people are in groups and argue about logical, mathematical or factual problems, they robustly converge on the best solution.
If the production of argument was unable to influence other people, it would be pointless. But if listeners were not mostly influenced for their better good, they would not be listening. The evolutionary logic suggests that reasoning can lead us towards the truth, if only we reason with people who disagree with us to start with."

But I still believe in 'hot hand', partly because I have not studied the work of Amos Tversky and Thomas Gilovich and do not know the assumptions involved. It would be also interesting to study these biases in complex cases like the recent death of Osama and what happenned. About Pakistan's knowledge or lack of Osama's whereabouts, two secular people of Pakistani origin seem to have different opinions The curious case of Osama Bin Laden..(Omar). The case may not matter to some but is of importance to many in various decision making processes. The information is incomplete or distorted for security or other reasons. One can expect a whole spectrum of opnions and beliefs on various aspects of the case and I wonder what lessons can be drawn from them about cognitive biases.
P.S. Slate's complete coverage of the fall of al-Qaida's leader.

Wednesday, May 04, 2011

From Timbuktu Chronicles

I came across this post in the Seed Magazine Opening up Science . It has a video:
"The video below looks at scientific knowledge building using wikis and other web 2.0 tools to pass along agriculture methods at the local level, but it also hints at how one could pass along science at the local level if there was the language to talk about it."

Tuesday, May 03, 2011

Some reactions to Osama's demise

Kristen Breitweiser in Huffington Post Today Is Not a Day of Celebration for Me :
"When my husband was killed on the morning of 9/11, television stations around the world ran split-screen video. They showed the buildings still burning juxtaposed against young Arabs celebrating in the streets. That disturbing vision left me incredulous; it was forever emblazoned on my psyche.

Ten years later, now fully awake in the bright sunlight of the day, when I contemplate the definition of victory for our country when it comes to the death of Osama bin Laden, I can only think about the damage that has been done.

I think about the thousands of lives lost -- American, Afghani, Iraqi. I know firsthand the sorrow those families have felt. I ponder how the billions -- maybe trillions -- of dollars could have been better spent. I remain alarmed about the continued expansion of absolute Executive power in the name of fighting this seemingly ongoing and never-ending "war on terror." I worry about the further erosion of our constitutional rights. I wonder when our troops will ever be called home. I know all too well, that thousands of young American men and women soldiers will never have the opportunity to return home. And of course, I fear reprisal.

But more than anything, I cannot seem to remove the optics of the giddy, gleeful throngs of Americans who took to the streets celebrating in the early morning hours."

Amanda Marcotte in Slate Bin Laden's Dead, Let's Party (via 3quarksdaily):
"I understand the urge to silence and shame people for being ecstatic that we finally got Bin Laden. The fear that jubilation could turn into nationalism and then to bloodlust has real world evidence to back it up. But I would argue that liberals do ourselves no favors by shushing and shaming people's joy. There's another option that is both more humanistic and more productive in the long run: grappling with this celebratory mood and channeling it toward policy goals such as shutting down Gitmo and getting out of Afghanistan.
One reason the war on terror has dragged on and on with no end in sight is that Americans have been deprived of a victory, and politicians both Republican and Democrat are afraid of being seen as losers who backed out of a fight without obtaining that victory. Well, now we have it. And if you doubt that, we have the crowds of celebrants in the street to back it up. That is, after all, what victory looks like in the American imagination. We think of the end of WWII and we don't think about the bomb or Hitler in a bunker. We immediately think of a sailor kissing a strange woman on the street. We think of joy. Joy provides emotional closure, which we never got after 9/11 and the distraction in Iraq. Maybe this joy at Osama Bin Laden's death can provide that for us. And maybe then we can finally have politicians say that we won, and so we can finally shut down the illegal prisons, the ongoing war, and maybe even the ridiculous security theater at airports. But if we scold and silence the joy away, we'll never get a chance to find out."
More at The Econmist Killing bin Laden: Let's call it a day (via Rajeev Ramachandran's google reader)

Second article of the series by Suresh Kolichala

పలుకుబడి: వ్యుత్పత్తి, నిరుక్తము

Sunday, May 01, 2011

Two reviews by William Easterly

Measuring How and Why Aid Works—or Doesn't , a review of More Than Good Intentions By Dean Karlan & Jacob Appel and Poor Economics By Abhijit V. Banerjee & Esther Duflo (via Chris Blattman):
"Unfortunately, the books also indulge another sort of irrationality: the demand for big, general statements even if you're discussing limited, context-specific matters. The authors criticize over-promising and generalizing in the aid business, but they too often do their own exaggerating when it comes to what their methods can deliver. Both books end with overselling, "five key lessons" (Banerjee and Duflo) or "seven ideas that work" (Karlan and Appel), ignoring their own previous cautions about sensitivity to context and the limits to each intervention. Other economists criticize overselling as a common fault of those who do these small experiments.

But let's extend the same consideration to these authors that they show for the people they study. They have fought to establish a beachhead of honesty and rigor about evidence, evaluation and complexity in an aid world that would prefer to stick to glossy brochures and celebrity photo-ops. For this they deserve to be congratulated—and to be read."

The Happiness Wars , a review of International Differences in Well-Being, edited by Ed Diner, Daniel Kahneman, and John Helliwell
via the post Money buys happiness after all

Ravi Kannan wins the Knuth prize

A description of some of his work by a colloborator with the recent royal wedding thrown in here