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Tue, 20 Aug 2013

Mapping the research literature

Paperscape visualizes all the arXiv papers. The arXiv is a pioneer in Open Data publishing from 1991 and started by Paul Ginsparg for high energy physicists (hep). It soon extended to most physicists.

According to it's importance (citation) each paper has a certain radius and the citations also link the papers to their position in the map. In addition there are helpful overall topics and one can click once zoomed in on each paper to know all the authors and the title. The colors correspond to each arXiv section.

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Sun, 21 Oct 2012

Quantum physics basics II

The words "quantum leap" lead to the second misconception that changes of said physical system are instantaneous, which is obviously wrong.

Unnamed ten year Debian dude, please take a physics 101: The photon of the LASER comes from a stimulated emission, which is a transition between different states.

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Sat, 20 Oct 2012

Basic understanding^Wmisconception of quantum physics

According to the release manager of Ubuntu the 10.12 release features the most minimal improvements: ''Doing is a quantum leap from imagining.``

Anyone having a minimal quantum physics exposure should be aware that a quantum leap is a very tiny leap. So according to the paraphrased intro this release should not even contain 'stable` updates?!

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Mon, 11 Jun 2012

1.5M CPU hours in 2012

1.5M CPU hours runs on the Vienna Scientific Cluster by my 3D+3V hard expanding loops code. It is simulating the Chromo-Weibel instability of a non-Abelian plasma in an 1d expanding background to account for the expansion of a Quark-Gluon plasma fireball in a heavy ion collision. The code is parallellised using Open MPI and one single run roughly needs 0.5TB memory to hold all the needed 5-dimensional matrices and ~ 72h to complete. The resulting heavy operation is of course matrix multiplication of those physical and auxilliary fields.

I tried to use git-annex on the resulting physical fields data output of ~ 150Gb and 300k files. Currently I do prefer git itself for it's speed and it only doubles the amounted space. I'm thrilled to see that git annex is still considering this "semi-extreme" usecase of lots of data files as it would help collaborators to have partial checkouts for laptop usage and quick checks. As the git-annex kickstarter is a rocket, i'd add my wish to see the current symlink mess go: desymlink git-annex.

Now it is the time to properly analyse all this data and get the full 3d paper follow up on Instabilities of an anisotropically expanding non-Abelian plasma: 1D+3V discretized hard-loop simulations (previous paper) out maybe soon. (;

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Tue, 20 Sep 2011

Recurring Maxima failures

Every once in a while I try out latest Debian/sid Maxima as it sees continuous development: Maxima git repo.

Todays failure is an integral given at the Bloc course "Aspects of QCD at Finite Density". It is an exercise to calculate following simple integral that should just give a Bessel function:

(%i3) integrate(exp(z*cos(t))*cos(a*t), t, 0, %pi);
                           %pi
                          /
                          [               cos(t) z
(%o3)                     I    cos(a t) %e         dt
                          ]
                          /
                           0

As usual the result it returns is the integral itself.. :/ So yes indeed Maxima is nice for simple undergrads calculation: Maximum Calculus with Maxima, but unfortunately don't expect much for more complex problems. The result is the partition function of the chiral perturbation theory in the simple setup of equal quark masses and one quark flavour family. Sadly Integrals returning Bessel functions seem to regularly fail.

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Wed, 21 Jul 2010

Solid bases in Theoretical Physics

Landau, L. D.; Lifshitz, E. M. (1976). Course of Theoretical Physics is still the most interesting and solid base that is to be considered as a reference and inspiration in Theoretical Physics.

The reference for "Classical Electrodynamics" is the book by J.D. Jackson. "Advanced Quantum Mechanics" by J.J. Sakurai is a popular student choice. Compendium of Relations contains various formulas and relations of the Standard Model. The Lecture Notes on General Relativity by S. Carroll are a solid introduction for an initiate relativist. "Quantum Field Theory in a Nutshell" by A. Zee is amazing. Quantum electrodynamics can be explored in the books by "The Quantum Theory of Fields" by S. Weinberg or "Quantum field theory" by L.H. Ryder or Quantum Chromodynamics in M.E. Peskin & D.V. Schroeder "An Introduction to Quantum Field Theory". The lecture notes on Quantum Chromodynamics (QCD) might be interesting for people diving into the particle physics standard model. "Finite-temperature field theory: Principles and Application" discusses systems in equilibrium but at finite temperatures and chemical potentials and thus connects to cosmology of the early universe.

The field of Statistical Field Theory has the classic "Quantum Many-Particle Systems" by J.W. Negele and H. Orland or the more recent "Quantum Field Theory of Many-Body Systems" by X-G. Wen or "Ultracold Quantum Fields" by H.T.C Stoof, D.B.M. Dickerscheid, K. Gubbels.

String Theory is so diverse that you'll find lots of different approaches, recommendations are Graduate Course in String Theory by A. Uranga, Applied Conformal Field Theory by P. Ginsparg, Lectures on String Theory by D. Tong or more introductory the book "A First Course in String Theory " by B. Zwiebach or the dense "Superstring Theory" by M. Green, J. Schwarz and E. Witten, "String Theory" by J. Polchinski. "Quantum Field Theory of Point Particles and Strings" by B. Hatfield assumes no previous stringy background and is known for excellent explanation of the path integral formalism. M. Nakahara wrote the wonderfull bridge to maths: "Geometry, Topology and Physics".

So please when looking for "references" in theoretical physics venture on solid grounds and don't get distracted by sketchy notes.

Update: Peter West pointed out that the The Feynman Lectures on Physics are missing as a timeless reference.

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