User talk:Iolaum

Energy and mass
It is energy and mass which are conserved separately in relativity, not energy and "matter." (Matter is poorly defined, but it certainly is not conserved if photons can be made out of matter particles). Mass, on the other hand, must be conserved if energy is, since mass and energy always differ from each other by a simple factor of c^2 (of course, for that to be true the type of "mass" is determined by the type of energy, as relativistic/total E gives rise to relativistic M, and invariant/rest E gives rise to invariant/rest M). See mass-energy equivalence for more. Total E can be connected to invariant M as well, but the equation is the extended energy-momentum relation. But M is still conserved. S B Harris 16:35, 23 February 2010 (UTC)

Neither mass can be said to be conserved separately than energy in SR.

A particle of mass M emitting a photon will lose mass. Energy will be conserved but the mass of the two new particles will be less than M. Iolaum (talk) 16:58, 23 February 2010 (UTC)