Boulder School Lecture Notes Thursday, Jan 18 2007 

I found a School website containing lecture notes on various topics in condensed matter, so thought of posting here:

Boulder School

Most of it look quite well organized for independent reading.

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….

Happy Perihelion ! Wednesday, Jan 3 2007 

Via Bad Astronomy Blog, we are informed that

Today, January 3, on or about 20:00 Universal Time (2:00 p.m. Pacific time), the Earth will reach perihelion, its closest approach to the Sun. The distance from the Sun to the Earth will be roughly 147,093,600 kilometers (I have found several different distances on different sites, and this is an eyeball average).

with a statutory warning that

Remember, our distance from the Sun doesn’t affect our seasons (much).

So, Happy Perihelion ! 🙂

Don’t miss the The Top Ten Astronomy Images of 2006.

Now, last but not the least, via the same blog, I came across a treasure-trove for those who are interested in astronomy – What’s Up 2007 – 365 Days of Skywatching , a superb online book !

If somebody knows the present Astro-club co-ordinators, do pass on.

Ising model and Epsilon Expansion Monday, Jan 1 2007 

As one might know that topology plays an important role in the classical O(2) model in d=2 (i.e. x-y model in two dimension) becuase one can have non-trivial excitations, namely, vortices. These excitations, while having a huge energy, can contribute to the partition function at high temperatures becuase the entropy associated with them is also proportionately large. One can easily verify that perturbative epsilon-expansion (i.e. an expansion in no. of dimensions) fails here. The reason which is often cited is that such an expansion destroys all information related to topology since atleast till now there is no homotopy theory for fractional dimensions.

Considering an even simpler case, the ising transition in d=2 could be looked upon as condensation of domain walls which are again topological objects. My question is: why does an epsilon-expansion in this case works out quite nicely? (note: here one does an expansion near the lower critical dimension which is one). Is it that notion of domain walls can be extended to even fractional dimension in some way?

Btw, one might like to visit the website  which contains a collection of open problems in mathematical physics. Coming to a problem related to this post (though somewhat remotely), one might be surprised to find through this link that the perturbative result of O(N > 2) model in d=2 being always in a single disordered phase at all temperatures has actually not been rigourosly proved. Infact, it is even disputed by some numerical results (though I don’t claim any understanding of these). See for example,

Journal archives of Royal Society Tuesday, Sep 19 2006 

The Royal Society home page has an interesting announcement.

Nearly three and a half centuries of scientific study and achievement is now available online in the Royal Society Journals Digital Archive following its official launch this week. This is the longest-running and arguably most influential journal archive in Science, including all the back articles of both Philosophical Transactions and Proceedings.

For the first time the Archive provides online access to all journal content, from Volume One, Issue One in March 1665 until the latest modern research published today ahead of print. And until December the archive is freely available to anyone on the internet to explore.(emphasis mine)

Spanning nearly 350 years of continuous publishing, the archive of nearly 60,000 articles includes ground-breaking research and discovery from many renowned scientists including: Bohr, Boyle, Bragg, Cajal, Cavendish, Chandrasekhar, Crick, Dalton, Darwin, Davy, Dirac, Faraday, Fermi, Fleming, Florey, Fox Talbot, Franklin , Halley, Hawking, Heisenberg, Herschel, Hodgkin, Hooke, Huxley, Joule, Kelvin, Krebs, Liebnitz, Linnaeus, Lister, Mantell, Marconi, Maxwell, Newton, Pauling, Pavlov, Pepys, Priestley, Raman, Rutherford, Schrodinger, Turing, van Leeuwenhoek, Volta, Watt, Wren, and many, many more influential science thinkers up to the present day. ..

Seems like something worth checking out.

Eprintweb Monday, Jun 26 2006 

Holla this is jeet. Thought i'd share this with you all.Came across this in Quantum Pontiff. Nice site to organize what you want/are going to read. Basically a front end to arxiv