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View:  Topic list, Topic summary Topics 1 - 10 of 853  Older »
Description: Fundamental and philosophical physics. (Moderated)
 

Necessity of least action principle 
  I've developed the Feynman Path Integral from first principles, apart from physical requirements. And I'm trying to make contact with physics. It would help if there were a requirement that the variation of the action be zero. Then Euler-Lagrange equations of motion would procede from that. So does the evaluation of the path integral require... more »
By Mike  - Nov 5 - 2 new of 2 messages    

Looking for Feedback on an Exercise Calculating the QED Path Integral and Green's Functions in Curved Spacetime with Boundary Terms 
  In the file linked below, I have laid out an exercise upon which I would appreciate your feedback: [link] Basically, I am attempting in the three respective sections of this exercise to: 1) Integrate-by-parts, the classical electrodynamic action, in curved... more »
By Jay R. Yablon  - Oct 30 - 3 new of 3 messages    

What Happens to Fourier Transforms in Curved Spacetime? 
  In flat spacetime, one may take the forward Fourier transform, for example, of a vector J^u, according to: J^u(k) = $ d^4x J^u(x) exp[-i p_s x^s] (1) Does this change at all in curved spacetime? In particular, is it necessary to generalize the Fourier Kernel exp[-i p_s x^s], to something else, for example:... more »
By Jay R. Yablon  - Oct 22 - 24 new of 24 messages    

Does SR originate from basic medium behavior? 
  Given that in any medium the propagation speed is a physical characteristic of its foundational kinetic entities. It should therefore be obvious that this must result in something called the “law of equal paths”. This means that any propagating disturbance will travel an equal distance (path) in an equal amount of time.... more »
By Paul Stowe  - Oct 20 - 2 new of 2 messages    

A Macro-Mechanical Force From the Quantum Vacuum 
  Re: A Macro-Mechanical Force From the Quantum Vacuum Esteemed Colleagues! I am having great difficulty locating researchers who both believe that the ZPE is actually real and also have knowledge of solid state optics in the low nm range of the EUV Spectrum. This concerns my proposal for a device that... more »
By scott712  - Oct 19 - 2 new of 2 messages    

Is there an error in this contracted calculation involving the Riemann and Ricci tensors? 
  I have attempted to obtain a contracted version of the relationship: R^a_buv A_a = [&;_u, &;_v]A_b (2) which defines the Riemann tensor. The calculation is in the one-page file [link] The contracted result I end up with is:... more »
By Jay R. Yablon  - Oct 19 - 4 new of 4 messages    

What is the Gravitationally-Covariant derivative of the coordinates x^u? 
  I would like to discuss how one establishes the gravitationally-covariant derivative of the coordinates x^u. The context for the question I am raising here, arises from a comment made by Mark Hopkins in a separate thread on sci.physics.research (Integration by Parts of the Maxwell QED Action, Tuesday, October 06,... more »
By Jay R. Yablon  - Oct 18 - 4 new of 4 messages    

Deterministic physics 
  I've just finished paper in which I try to convince that quantum mechanics does not have to lead to indeterminism, but is just a natural consequence of four-dimensional nature of our world - that for example particles shouldn't be imagined as 'moving points' in space, but as their trajectories in the spacetime like in optimizing action... more »
By Jarek Duda  - Oct 16 - 5 new of 5 messages    

Simple? fundamental question about EM in cavity 
  If an atom emits EM radiation in an optic fiber (cavity) of lenght L and L isn't equal to n. lambda/2 will this atom radiate or not? A) If yes (radiates): There will not be a standing wave in the fiber as it is contrary stated in any textbook B) If no: The atom must learn the value of L at every instant of time... more »
By mercury  - Oct 13 - 11 new of 11 messages    

Another question on Dirac's GR book 
  I'm stuck again on a statement Dirac makes in chapter 26 of his GR book, on the gravitational action principle (p. 48). He has the integral I = {int} R sqrt(-g) d{sup 4}x, where R is the scalar curvature (the contraction of the Ricci tensor), g is the determinant of the metric, and d{sup 4}x = dx{sup 0} dx{sup 1} dx{sup 2} dx{sup 3},... more »
By Mike_Fontenot  - Oct 11 - 1 new of 1 message    

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