Supersymmetry on Lattice : An Introduction Wednesday, Jul 4 2007
Last week, I gave a presentation titled “Supersymmetry on Lattice- An Introduction”[PDF] as a part of a course on Lattice Field theory.
It was an attempt at outlining the broad issues that arise when one tries to put Supersymmetry in Lattice. I have uploaded the presentation in the link above – Readers comments and criticisms are welcome.
Feynman on the Relation between Physics and Mathematics Sunday, Jun 24 2007
An interesting experiment Monday, Apr 2 2007
Atmosphere of Exoplanets Sunday, Feb 25 2007
Astronomy and Astrophysics 7:00 am
NASA’s Spitzer Space Telescope has captured for the first time enough light from planets outside our solar system, known as exoplanets, to identify molecules in their atmospheres….
Spitzer, a space-based infrared telescope, obtained the detailed data, called spectra, for two different gas exoplanets. Called HD 209458b and HD 189733b, these so-called “hot Jupiters” are, like Jupiter, made of gas, but orbit much closer to their suns.
The data indicate the two planets are drier and cloudier than predicted. Theorists thought hot Jupiters would have lots of water in their atmospheres, but surprisingly none was found around HD 209458b and HD 189733b. According to astronomers, the water might be present but buried under a thick blanket of high, waterless clouds.
Those clouds might be filled with dust. One of the planets, HD 209458b, showed hints of tiny sand grains, called silicates, in its atmosphere. This could mean the planet’s skies are filled with high, dusty clouds unlike anything seen around planets in our own solar system…
The ‘More Info’ page on the press release links to two papers “A Spectrum of an Extrasolar Planet”
by L. Jeremy Richardson et.al. and A Spitzer Spectrum of the Exoplanet HD 189733b by C. J. Grillmair et.al. apart from some podcasts.
And via BA Blog, we are reminded that “Twenty years ago, astronomers witnessed one of the brightest stellar explosions in more than 400 years. The titanic supernova, called SN 1987A, blazed with the power of 100 million suns for several months following its discovery on 23 Feb., 1987.” Of course, the article doesn’t quite spell it out that the neutrino detectors were telling us something interesting three hours before the explosion was seen ! (See this link too – via Backreaction blog .)
‘Rings’ left by the Supernova Explosion
A Question in Geography Sunday, Feb 18 2007
Mathematical Physics 11:19 pm
A theorem in topology says:
For every continuous map there exists a pair of anitpodal points and in such that .
Specializing to the case , one might conclude that at any point of time there are two antipodal points on Earth’s surface (which is homeomorphic to ) having same, say, pressure and temperature (which together constitute of the theorem) .
Question: Isn’t it that the presence of polar caps (The Arctic and The Antarctica) where the day/night variation in temperature is quite low, may then be looked upon as a kind of `consequence’ of this theorem? (ofcourse the theorem doesn’t say where is located but at almost all other regions on Earth’s surface, the antipodal points are expected to have quite different temperatures due to day/night variation.)
ps1: One might worry about the validity of the assumption of continuity of and since there are wild local fluctuations; but I feel once you coarse-grain things out, this is a reasonable assumption.
ps2: For proof of the theorem, see http://www.mi.ras.ru/~scepin/elem-proof-reduct.pdf
Classical Mechanics and Differential Geometry Friday, Feb 9 2007
After learning basic concepts of classical mechanics, a wierd question arises about mathematical approach to this field. The general approach goes like this differential manifold structure is associated with lagrangian and symplectic structure comes with hamiltonian. We tried to learn this, so i am attaching project report(more like a formula sheet) with topic “differential geometric treatment to hamiltonian mechanics”. Please go through this and post some views on this mathematical approach.