I just had a look on the chapter "gravitation and relativity" of the motion mountain on line downloadable book (Author: C. Schiller). The "derivation" of GR from a statement...

According to the principles of Fourier transformation, the spectrum of a sinusoidal wave train with a finite length (switched on at time t=0 and switched off at time t=T) is...

To spin my last post a bit further: It appears that one could say then that the temporal coherence of a given frequency spectrum can not be less than the coherence...

Recently I saw an announcement that the axion had been discovered. See "http://www.eurekalert.org/pub_releases/2006-12/uab-ltf120606.php". What do you all think about this?

I have a question concerning mathematics, but with implications for mathematical physics. From a purely geometrical point of view, can one say that there is a rigorous...

Consider an expanding sphere of shrapnel which propagates at speed v from the source of an explosion. If the trajectories of shrapnel particles a and b are separated by...

After a long delay, I've finally got some quantitative results for what happens when you unreel a hyperelastic string above a horizon with a constant rate of unreeling of...

In 1916 Schwarzschild communicated to Einstein the following derivation of his Schwarzschild metric. "On the gravitational field of a mass point according to...

Hi experts: Does anybody know why most planet orbits in solar system all lay down close to the equatorial plane of Sun's rotation axis, with planets translating in the same...

I have put the new, twentieth edition of my freely downloadable physics textbook in pdf form on http://www.motionmountain.eu Over 1380 pages lead through the whole of...

Happy holidays to all. I have just finished a formal course based on Peskin and Schroeder's book on Quantum Field theory. So far the Feynman diagrams have had no...

A theoretical physics FAQ http://www.mat.univie.ac.at/~neum/physics-faq.txt This site contains answers to some more or less frequently asked questions from...

It seems that electromagnetic disturbances in a dispersive medium cannot satisfy a standard wave equation since there would be no dispersion. So what "wave-like" equation is...

There is a standard argument that demostrats how an accelerating charge sets up a disturance in the electric field lines that propagates at the speed of light. There is an...

The Yang-Mills gauge theory is invariant under gauge transformations. But there are certain non-Yang-Mills gauge theories which are invariant ON-SHELL under gauge...

Einsteins principle of equivalence, as usually explained, seems strange (to me) from the point of view of (pseudo) Riemannian geometry. As explained in some relativity...

In discussions about consciousness there is sometimes mentioned a concept originated by Roger Penrose: "objective reduction". As I understand it, it is the idea that a...

Hello, I introduced a quantum model of super-relativistic particle as a composite of a harmonic oscillator and a free particle with the Hamiltonian H = 1/2 P2 + 2c2/hbar2...

Hi: What is the shortest wavelength at which light is completely non-ionizing to any and all parts of the human body regardless of duration of exposure or intensity of the...

Hi; Can anybody explain me whatis the relation between electron movement in a conductor and power factor. i.e. how can we relate change in power factor with change in...