# Energy in special relativity

vidmar
As far as I know in classical mechanics of Newton energy is merely an attribute of matter (more a defined concept rather than a starting point). With Einstein this changes (or at least so the formula E=mc^2 would imply). Energy is now equivalent to matter (no longer is it merely one of its properties). My question is then, in addition to the energy of the electromnagnetic waves (light), what other forms of energy (if any) could exist should e.g. all the matter in the universe transform itself to energy (as far as the modern theories predict). Any thoughts on this subject would be greatly appreciated.

pmb_phy
vidmar said:
As far as I know in classical mechanics of Newton energy is merely an attribute of matter (more a defined concept rather than a starting point). With Einstein this changes (or at least so the formula E=mc^2 would imply). Energy is now equivalent to matter (no longer is it merely one of its properties). My question is then, in addition to the energy of the electromnagnetic waves (light), what other forms of energy (if any) could exist should e.g. all the matter in the universe transform itself to energy (as far as the modern theories predict). Any thoughts on this subject would be greatly appreciated.
People seem to confuse this point a lot of the time. Einstein never proved that matter has energy. That was a basic starting assumption, e.g. a body emits radiation and radiation has energy -> this can be used to prove that the change in energy is proportional to the change in mass.

Pete

mitchellmckain
Your question is confusing because first you acknowlege that we now know that matter is a form of energy and then you ask what kinds of energy it can turn into. If by matter you mean all forms of energy with rest mass then the only other forms of energy would be massless particles. This would include photons which represent electromagnetic waves, but also includes the graviton (the particle responsible for gravity), the neutrino perhaps? gluons? ... The question is very suppositional. The only process we know by which matter is converted completely to energy is the annihilation with antimatter in which case it is electromagnetic radiation which is produced. There is also the theory that all the matter in the universe was created from a symmetry breaking decay of a high energy vacuum, so it is concievable that a reverse process could convert matter back into this high energy vacuum. ???