XPost: sci.electronics.design   
   From: nospam@de-ster.demon.nl   
      
   DJ Delorie  wrote:   
      
   > So... a photon moving at speed of light has some   
   > energy-mass-whatever-equivalent, which is sufficient to warp spacetime.   
   > That change may cause other photons' paths to "bend" as if gravity were   
   > a force, regardless of time effects, because it's not a force, it's a   
   > shape.   
      
   'as if' is the word here.   
      
   > I think I got that part [*].   
   >   
   > I wonder, though, if there were some non-spacetime actual "force"   
   > between photons (I realize there isn't, but imagine one for a moment).   
   > If said force obeyed the usual F=ma, *now* would time dilation come into   
   > play wrt photons?  Two photons travelling next to each other, from their   
   > point of view (or any other), how would that force evolve itself over   
   > "time" ?   
      
   As already noted else-thread photons do interact electromagnetically.   
   (a purely QED effect)   
      
   > (yeah, stupid question maybe, but I still find the answers aka   
   > discussions interesting ;)   
      
   What is 'stupid' is your need to conceptualise this as a force   
   acting on a point particle.   
   The classical equivalent of it are extra, non-linear terms   
   in Maxwell's equations.   
   This might become observable in extremely strong fields   
   in laser focus experiments.   
      
   > [*] except if photons move at the speed of light, and "gravity" does   
   >     too, do photons create gravitational shock waves as they travel?  Or   
   >     does the distortion just travel happily along with the photon?  Or   
   >     just behind it?  How could we find out?   
      
   Not,   
      
   Jan   
      
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