An interesting experiment Monday, Apr 2 2007 

(Via Madhur )

Physics Blogspeak : Part II Sunday, Jan 14 2007 

COSMOS Reveals the Cosmos (from Cosmic Variance by Sean)

The internet works so that we don’t have to! This week is the big annual meeting of the American Astronomical Society in Seattle, so expect to see a series of astro-news stories pop up all through the week. The first one concerns a new result from the Cosmological Evolution Survey (COSMOS) — they’ve used weak lensing to reconstruct a three-dimensional image of where the dark matter is.

AAS Report #3: Things that go boom! (From Bad Astronomy Blog)

It’s a fact of life that some stars explode. Actually, it’s a good thing: when stars explode they create and scatter the heavy elements that create us. The iron in your blood and the calcium in your bones were created in a supernova! So it’s important to study these objects, so we can better understand our origins.

But it’s also fun! Stars explode! Bang! Cool!

Today there were three press releases about supernovae. All three were surprising to me, and pretty interesting.

1) Kepler’s Supernova was a Type Ia

OK, so that title doesn’t thrill you. But that simple statement is actually the answer to a long-standing mystery. Ready for this? OK, sit back…

The AAS : a Nerd’s Eye View (from Galactic Interactions)

I’m in Seattle at the moment. I flew in yesterday; it’s cold, windy, and rainy. In fact, the rain was looking kinda slushy last night. While my wife from Minnesota might scoff at my calling this cold (it was just below freezing), in Nashville it’s been March-like temperatures.

I’m here for the 209th meeting of the American Astronomical Society. I’m going to try an experiment. I’ve never done the “live blogging” thing before, and indeed it’s entirely possible that I’m not using the term properly. It is my intention to post several posts this week inspired by things I see at the AAS. I can’t tell you what they will be yet, because they haven’t happened…. I’m hoping mostly to focus on interesting science and such, but anything that inspires me to blather is fair game as far as I’m concerned….

(Other posts in this series.)

Come On In, the Methane’s Fine (from Uncertain Principles by Chad Orzel)

The Times has an article announcing the discovery of methane lakes on Titan:

CDF’s New Results : W Boson Mass and Top quark Mass (From Quantum Diaries)

1)And the W mass is …
2) A summary Mw-Mt plot for Christmas 2006
3) More thoughts on the W mass
4) A new precise top mass measurement with jets
5) The new number

Physics Blogspeak : Part I Sunday, Jan 14 2007 

A collection of interesting posts from physics blogsphere :

Short Distances: Newton Still the Man (from Cosmic Variance by Sean)

Via Chad Orzel, I see that the latest constraints on short-distance modifications of Newton’s inverse-square law from the Eot-Wash group at the University of Washington have now appeared in PRL. And the answer is: extra dimensions must be smaller than 0.045 millimeters (in any not-too-contrived model)…

Undergraduate Theory Institute(from Cosmic Variance by Sean)

Sadly, I’m not here to announce that applications are now being accepted for students who would like to participate in this year’s Undergraduate Theory Institute. That’s because there is no such thing as the Undergraduate Theory Institute, at least as far as I know. (Google doesn’t know of one either.) But I think it would be a great idea — maybe if I post it here on the blog someone will start it.

It’s increasingly common for physics students to participate in some kind of research during their undergraduate years. The NSF has a very successful Research Experience for Undergraduates program, for example, that funds students to do summer research, typically at an institution other than their own. Getting involved in research as early as possible is a great idea for students, for a number of reasons. Most importantly, the flavor of doing real research, where the answers aren’t in the back of the book, is utterly different from almost any classroom experience or even self-study, where you are trying to learn material that someone else has already mastered. The move from following a course of study to striking out into the unknown is one of the hardest transitions to make during graduate school, and getting a head start is an enormous help. On a more prosaic level, it’s useful to work closely with an advisor who can end up writing letters of recommendation. And let’s not forget that it can be a lot of fun!..

Dancing Ball Lightnings in the Lab (from Backreaction Blog)

Ball lightnings are mysterious things: Small, bright balls of fire suddenly appear during a thunderstorm, swirl around, make sometimes funny noises, and leave behind a smell of ozone…

Since ball lightnings are not only spooky, but also very elusive, there has been a lot of speculation how to understand and explain them in a scientific way: People have suggested that it may be some ionised balls of plasma held together by their own magnetic fields, or even such exotic things as mini black holes leftover from the big bang…

A more “down to Earth” explanation was proposed in a 1999 Letter to Nature:..

From Griffiths to Peskin: a lit review for beginners (From “An American Physics Student in England” )

a.k.a. “How to get started learning QFT as an undergraduate.”

Quantum Field Theory (QFT) plays a key role in all branches of theoretical physics. For students interested in high energy theory, exposure to QFT at any early stage is slowly becoming the standard for top American graduate schools. This is already the case for the Mathematics Tripos at Cambridge…

An inspired student with adequate background should be able to take quantum mechanics in his/her second or third year and then progress directly to a ‘real’ QFT course with a bit preparation, without going through the rigmarole of a year-long graduate quantum mechanics course.

Instead, I present a rough guide to pedagogical QFT literature so that a motivated student can prepare for a graduate-level QFT course or a get started with a self-study during the summer after his/her undergraduate quantum mechanics course. As a someone who was in this position in the not-too-distant-past, I hope some personal experience with the pros and pitfalls of the listed texts will be helpful for other other students interested in doing the same….

2006 – Year of Maxwell ? Sunday, Dec 17 2006 

I just realised(via a physicsweb article ) that this year is supposed to be the 175th anniversary of the birth of James Clerk Maxwell. Quite in the year to realise it I suppose 😉

So what impression of Maxwell would you have gained if you had met him in his prime, as a young Scottish undergraduate Donald MacAlister did in Cambridge in 1877? You would surely have been charmed, but perhaps also surprised to meet – as MacAlister put it – “a thorough old Scotch laird in ways and speech”. As the proprietor of an 1800 acre Scottish estate, Maxwell had all the qualities of the better kind of Victorian country gentleman: cultivated, considerate of his tenants, active in local affairs, and an expert swimmer and horseman too.

Few would have guessed that this “Scotch laird”, so disarmingly old-fashioned even in 1877, was a scientist whose writings remain astonishingly vibrant in 2006 and the greatest mathematical physicist since Newton. In addition to his work on electromagnetism, Maxwell also contributed to eight other scientific spheres: geometrical optics, kinetic theory, thermodynamics, viscoelasticity, bridge structures, control theory, dimensional analysis and the theory of Saturn’s rings. He also worked on colour vision, producing the first ever colour photograph…

Even if his achievements are somewhat overshadowed in the public’s eye by those of Einstein, whose successes were marked by a great series of events last year, it is a measure of Maxwell’s standing that 2006 – the 175th anniversary of this birth – has been dubbed Maxwell Year.

Anyway, this gives me an excuse to return back to writing about Maxwell about whom Feynman famously remarked

From a long view of the history of mankind — seen from, say, ten thousand years from now, there can be little doubt that the most significant event of the 19th century will be judged as Maxwell’s discovery of the laws of electrodynamics. The American Civil War will pale into provincial insignificance in comparison with this important scientific event of the same decade.

I guess I should add that the revolt of 1857 would also pale into provincial insignificance….

Since I have already linked once to peoms by Maxwell , I will now link to one of the oldest biographies of Maxwell – the one written by Lewis Campbell and William Garnett (Link to PDF file).

The 1997 Digital Preservation of “The Life of James Clerk Maxwell”

..There are very few biographies of Maxwell. The most comprehensive biography was written by a life-long friend, Lewis Campbell with help from William Garnett. It is considered a primary historical reference on Maxwell. Published in 1882, shortly after Maxwell’s death, it is today found only in the rare book rooms of large libraries. However, now the entire text of the book with figures included is available here…

It is a long and interesting book filled with a lot of anecdotes written at a time when mechanical theories of ether were still in vogue. This of course, does not undermine its significance in History of physics . …

To quote what Weinberg wrote three years ago in his “Four Golden Lessons” addressed to a Scientist

Finally, learn something about the history of science, or at a minimum the history of your own branch of science. The least important reason for this is that the history may actually be of some use to you in your own scientific work. For instance, now and then scientists are hampered by believing one of the over-simplified models of science that have been proposed by philosophers from Francis Bacon to Thomas Kuhn and Karl Popper. The best antidote to the philosophy of science is a knowledge of the history of science.

More importantly, the history of science can make your work seem more worthwhile to you. As a scientist, you’re probably not going to get rich. Your friends and relatives probably won’t understand what you’re doing. And if you work in a field like elementary particle physics, you won’t even have the satisfaction of doing something that is immediately useful. But you can get great satisfaction by recognizing that your work in science is a part of history.

Salam Tuesday, Nov 21 2006 


Ten years ago, on 21st of Novomber, 1996, Abdus Salam, who was among the co-founders of the Standard Model died at his home at Oxford.

For those who don’t know him, he was one of the recipient of the Nobel Prize in Physics(1979) “for their contributions to the theory of the unified weak and electromagnetic interaction between elementary particles, including, inter alia, the prediction of the weak neutral current” in short, for what physicists call the Glashow-Salam-Weinberg Model (which along with Quantum Chromodynamics and Classical General Relativity form the foundations on which all physics stands).

Was just reminded of him as I was doing some calculation with the Salam-Strathdee Superfield Formalism in (Supersymmetric extension of) Glashow-Salam-Weinberg Model. It is amusing how pursuit of science brings back names from far away…

As Salam himself mused before beginning his Nobel Lecture

Scientific thought and its creation is the common and shared heritage of mankind. In this respect, the history of science, like the history of all civilization, has gone through cycles. Perhaps I can illustrate this with an actual example.

Seven hundred and sixty years ago,a young Scotsman left his native glens to travel south to Toledo in Spain. His name was Michael, his goal to live and work at the Arab Universities of Toledo and Cordova, where the greatest of Jewish scholars, Moses bin Maimoun, had taught a generation before.

Michael reached Toledo in 1217 AD. Once in Toledo, Michael formed the ambitious project of introducing Aristotle to Latin Europe, translating not from the original Greek, which he did not know, but from the Arabic translation then taught in Spain. From Toledo, Michael travelled to Sicily, to the Court of Emperor Frederick II.

Visiting the medical school at Salerno, chartered by Frederick in 1231, Michael met the Danish physician, Henrik Harpestraeng – later to be-come Court Physician of King Erik Plovpenning. Henrik had come to Salerno to compose his treatise on blood-letting and surgery. Henrik’s
sources were the medical canons of the great clinicians of Islam, Al-Razi and Avicenna, which only Michael the Scot could translate for him.

Toledo’s and Salerno’s schools, representing as they did the finest synthesis of Arabic, Greek, Latin and Hebrew scholarship, were some of the most memorable of international assays in scientific collaboration. To Toledo and Salerno came scholars not only from the rich countries of the East and the South, like Syria, Egypt, Iran and Afghanistan, but also from
developing lands of the West and the North like Scotland and Scandinavia. Then, as now, there were obstacles to this international scientific concourse, with an economic and intellectual disparity between different parts of the world. Men like Michael the Scot or Henrik Harpestraeng were singularities. They did not represent any flourishing schools of research in
their own countries. With all the best will in the world their teachers at
Toledo and Salerno doubted the wisdom and value of training them for
advanced scientific research. At least one of his masters counselled young
Michael the Scot to go back to clipping sheep and to the weaving of
woollen cloth.

In respect of this cycle of scientific disparity, perhaps I can be more quantitative. George Sarton, in his monumental five-volume History of Science chose to divide his story of achievement in sciences into ages, each age lasting half a century. With each half century he associated one central figure. Thus 450 BC – 400 BC Sarton calls the Age of Plato; this is followed by half centuries of Aristotle, of Euclid, of Archimedes and so on. From 600 AD to 650 AD is the Chinese half century of Hsiian Tsang, from 650 to 700 AD that of I-Ching, and then from 750 AD to 1100 AD – 350 years continuously – it is the unbroken succession of the Ages of Jabir,Khwarizmi, Razi, Masudi, Wafa, Biruni and Avicenna, and then Omar Khayam – Arabs, Turks, Afghans and Persians – men belonging to the culture of Islam. After 1100 appear the first Western names; Gerard of Cremona, Roger Bacon – but the honours are still shared with the names of Ibn-Rushd (Averroes), Moses Bin Maimoun, Tusi and Ibn-Nafi-the man who anticipated Harvey’s theory of circulation of blood. No Sarton has yet chronicled the history of scientific creativity among the pre-Spanish Mayas and Aztecs, with their invention of the zero, of the calendars of the ‘moon and Venus and of their diverse pharmacological discoveries, includ-
ing quinine, but the outline of the story is the same – one of undoubted superiority to the Western contemporary correlates.

After 1350, however, the developing world loses out except for the occasional flash of scientific work, like that of Ulugh Beg – the grandson of Timurlane, in Samarkand in 1400 AD; or of Maharaja Jai Singh of Jaipur in 1720 – who corrected the serious errors of the then Western tables of eclipses of the sun and the moon by as much as six minutes of arc. As it was, Jai Singh’s techniques were surpassed soon after with the development of the telescope in Europe. As a contemporary Indian chronicler wrote: “With him on the funeral pyre, expired also all science in the East.” And this brings us to this century when the cycle begun by Michael the Scot turns full circle, and it is we in the developing world who turn to the
Westwards for science. As Al-Kindi wrote 1100 years ago: “It is fitting then for us not to be ashamed to acknowledge and to assimilate it from whatever source it comes to us. For him who scales the truth there is nothing of higher value than truth itself; it never cheapens nor abases him.”

And by the way, do read the whole thing – if not for anything else atleast for the Pauli Stories 🙂

…The hut also contained Professor Villars of MIT, who was visiting Pauli the same day in Zurich. I gave him my paper. He returned the next day with a message from the Oracle;
“Give my regards to my friend Salam and tell him to think of something better”. This was discouraging, but I was compensated by Pauli’s excessive kindness a few months later, when Mrs. Wu’s, Lederman’s and Telegdi’s experiments were announced showing that left-right symmetry was indeed violated and ideas similar to mine about chiral symmetry were expressed independently by Landau and Lee and Yang. I received Pauli’s first somewhat apologetic letter on 24 January 1957.

Thinking that Pauli’s spirit should by now be suitably crushed, I sent him two short notes I had written in the meantime. These contained suggestions to extend chiral symmetry to electrons and muons, assuming that their masses were a consequence of what has come to be known as dynamical spontaneous symmetry breaking. With chiral symmetry for electrons, muons and neutrinos, the only mesons that could mediate weak decays of the muons would have to carry spin one.

Reviving thus the notion of charged intermediate spin-one bosons, one could then postulate for these a type of gauge invariance which I called the “neutrino gauge”. Pauli’s reaction was swift and terrible. He wrote on 30th January 1957, then on 18 February and later on 11, 12 and 13 March: “I am reading (along the shores of Lake Zurich) in bright sunshine quietly your paper…”
“I am very much startled on the title of your paper ‘Universal Fermi interaction’ …For quite a while I have for myself the rule if a theoretician says universal it just means pure nonsense. This holds particularly in connection with the Fermi interaction, but otherwise too, and now you too, Brutus, my son, come with this word. …”….

Although he signed himself “With friendly regards”, Pauli had forgotten his
earlier penitence. He was clearly and rightly on the warpath.

… I must admit I was taken aback by Pauli’s fierce prejudice against
universalism – against what we would today call unification of basic forces –
but I did not take this too seriously. I felt this was a legacy of the exasperation
which Pauli had always felt at Einstein’s somewhat formalistic attempts at
unifying gravity with electromagnetism – forces which in Pauli’s phrase “cannot
be joined – for God hath rent them asunder”….

There is something more to Salam’s Legacy than Electroweak Unification. And of course, I’m thinking of the Abdus Salam International Centre for Theoretical Physics (ICTP) at Italy. And in a more subtle way, He also stands for a struggle – a struggle to provide the students from the third world(and in particular Pakistan) the joys of science…

To Quote Hoodboy

In interacting with Salam, I could see that two strong passions governed his life. Physics research occupied him intensely; his mind would lock onto a problem making him oblivious to all else. He would engage only the most challenging and difficult problems of the field, problems that only the greatest can dare try. The elegance of his solutions were startling, as for example in his brilliant creation of what are called superfields. Without this powerful mathematical concept, physicists would have a very hard time to progress beyond a certain point in grappling with the basic laws of nature.

Salam’s other passion was Pakistan. I have never been able to understand why he was so dedicated to the country of his birth given that he was virtually ostracised there, being an Ahmadi. I can remember that when the members of the physics department at Quaid-i-Azam University sought to invite him for a lecture after he received the Nobel Prize, the idea was vetoed when the student arm of a vociferous religio-political party threatened to use violence if he came to the campus. In spite of this and much more, Salam was never embittered and he never gave up trying to do whatever he could for his country.

So on this day, let us wish that hundreds of years hence, let nobody speak of him the way Salam spoke of Jai Singh – let nobody say “With him .. expired also all science in ” Pakistan .

“Life of a Star” – KITP Blackboard Lunch Monday, Nov 20 2006 

Am just listening/seeing one of the “Blackboard Lunches” from (Kavli Institute of Theoretical Physics) .

I’ve already linked to an absolutely great series of talks online at the KITP site. But, I suspect that that one post hasn’t done justice to KITP …

But, this week I came across another set of “Blackboard Lunches” which are great too.

Now, I am seeing this one – The Life of a Star.

The Life of a Star
Dr. Lars Bildsten, KITP

Using only chalk and one figure, I will derive the luminosity, lifetime, and major properties of all stars and explain why their ultimate fate (white dwarf, neutron star or black hole) depends on their mass. After this event, you should be able to explain it to your family and friends.

It’s a great talk (from the first two minutes I gather that even “geologists and string theorists” can understand it 😉 ).