XPost: sci.physics   
   From: pcdhSpamMeSenseless@electrooptical.net   
      
   john larkin  wrote:   
   > On 10 Feb 2026 21:58:30 GMT, ram@zedat.fu-berlin.de (Stefan Ram)   
   > wrote:   
   >   
   >> john larkin  wrote or quoted:   
   >>> Two gamma rays (zero mass total) can collide to produce a particle   
   >>> pair (which has mass.)   
   >>   
   >> Let's call the momenta of the two photons p0 and p1.   
   >>   
   >> We may assume p1 = -p0 as the two photons are moving towards   
   >> each other from opposite directions. Let's call the momentum   
   >> of the system of these two photons "p", then we have:   
   >>   
   >> p = p0 + p1 = p0 +( -p0 )= p0 - p0 = 0   
   >>   
   >> . Let's call the energy of this pair "E" and its mass "m". From   
   >>   
   >> E^2 = m^2 + p^2   
   >>   
   >> (in units with c=1) and   
   >>   
   >> p = 0   
   >>   
   >> , we get,   
   >>   
   >> E^2 = m^2   
   >>   
   >> for the pair. I.e., all its energy is mass. And this is the   
   >> mass the particle pair has after the collision.   
   >>   
   >> Newsgroups: sci.electronics.design,sci.physics   
   >> Followup-To: sci.physics   
   >> Subject changed.   
   >>   
   >   
   > The gamma rays had no gravitational effect on the rest of the mass in   
   > the universe, up until the instant that they collided to form a   
   > particle pair. Then a gravitational object magically appeared.   
      
   The gammas together had the same mass as the particle pair.   
      
   >   
   > Does't that create a spherical, symmetric, expanding bubble of   
   > gravity?   
   >   
   > I'm just an engineer, but I think this is real. People say it's not   
   > technically possible, or that the efffect is too small to worry about,   
   > or some other excuse for not saying that it could happen.   
   >   
   > There is an electrical equivalent. A metal sphere could suddenly   
   > become charged, and it would create a symmetric e-field pulse that   
   > expands at the speed of light, like a wave, but it isn't   
   > electromagnetic.   
      
   I know of no mechanism for that to occur either.  Charge is conserved, so   
   you’d have to transport it to or from the sphere.   
      
   Either way, it’s an electric current that’s measurable from the time it   
   starts out to the time it gets there.   
   >   
   > I guess that you can't make an antenna that radiates em waves   
   > symmetrically in all directions.   
      
   Depends on your definition. An antenna with one pair of wires couples to   
   one mode of the EM field in free space, and there are no monopole modes.  I   
   haven’t done the math, but I expect that three crossed dipoles driven 120   
   degrees apart would be isotropic.   
      
   The phase would be different in different directions. (Note that this   
   assumes very small dipoles—the usual half-wave wire things would talk to   
   each other, which might screw things up.)   
      
   Cheers   
      
   Phil Hobbs   
      
      
      
      
      
   --   
   Dr Philip C D Hobbs  Principal Consultant  ElectroOptical Innovations LLC /   
   Hobbs ElectroOptics  Optics, Electro-optics, Photonics, Analog Electronics   
      
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