Re: Energy?

Stefan Ram <ram@zedat.fu-berlin.de> wrote:

  In a chapter of a book, the author gives this relation for a
  system with mass m = 0:
 
E^2/c^2 = p^"3-vector" * p^"3-vector"
 
  . Then he writes, "This implies that either there is no particle
  at all, E = 0, or we have a particle, E <> 0, and therefore
  p^'3-vector' <> 0.".
 
  So, his intention is to kind of prove that a particle without mass
  must have momentum.
 
  But I wonder: Does "E = 0" really mean, "there is no particle."?

It is nonsense, from a practical point of view.
Maybe you need a better textbook?

E = 0 merely means an energy which is too low to be detectable.
We know that there must be infinitely many of those photons.
See under 'infra-red catastrophe', in which infinitely many IR photons
still have a finite energy,

Jan