XPost: sci.physics.relativity, alt.atheism, sci.skeptic   
   From: PointedEars@web.de   
      
   Dawn Flood wrote:   
   > On 12/13/2025 4:23 PM, Thomas 'PointedEars' Lahn wrote:   
   >> JTEM wrote:   
   >>> For example, and I've already pointed this out a   
   >>> number of times so you doubtlessly missed it but,   
   >>> there's is no "Distance" or "Space" to a photon.   
   >>   
   >> We simply do not know that.   
   >>   
   >> While it is correct to say that zero proper time elapses along lightlike   
   >> geodesics (ds^2 = +- c^2 (d tau)^2 = 0 ==> (d tau) = 0 ==> Delta tau = 0),   
   >> we also know that *a photon has no inertial rest frame* as that would   
   >> contradict the postulate of the constancy of c, one of two postulates which   
   >> make up the special principle of relativity which special relativity is   
   >> based on, *and* the Planck--Einstein relation E = p c = h f.   
   >>   
   >> Curiously, special relativity fails to describe *completely* a motion at the   
   >> speed c that it is based on.   
   >   
   > Thank you so very much for your post!!  It's always great to have a   
   > physicist among us!!!   
      
   Thank you.  I am not a physicist (yet), but I do have studied Physics for   
   many years (at a university), including special relativity and quantum   
   theories (currently I am studying quantum field theories in an MSc course).   
      
   There was a time not so long ago when I also subscribed to this naive   
   pop-sci interpretation until it was pointed out to me by someone else (I   
   think it was on Quora, and it may have been a physicist, too) that the   
   existence of a such a rest frame is a contradiction (to the special   
   principle of relativity, to begin with).   
      
   It would be great if it could be resolved, but I have no particular idea   
   how.  One possibility would be that the mass of a photon is not actually   
   exactly zero; then it(s rest frame) would not be moving at c, but slightly   
   less than that, and it could exist.   
      
   On the other hand, in quantum electrodynamics a photon cannot be understood   
   as a point particle with a position (not even an uncertain one) in the first   
   place, but must be understood as a non-local excitation state of the   
   quantum-electromagnetic field.  It therefore exists everywhere (and at all   
   times) from the outset.  The semi-classical photon is merely where the peak   
   of that state, so to speak, is largest, where and when it has a high   
   probability to be found.  In Feynman's (path integral) interpretation, it   
   takes all paths between two points simultaneously.  Both correspond nicely   
   to the naive interpretation that a photon is everywhere at the same time as   
   for it the rest of the universe is infinitely length-contracted, and the   
   purely mathematical result that zero proper time elapses along its   
   worldline.  But I do not understand what that could mean.   
      
   F'up2 sci.physics   
      
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   PointedEars   
      
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