Matter and Energy
Date: Around 1993
In nuclear physics, I have read that under some circumstances in a
particle accelerator matter will change to energy and then back to matter in a
matter of a few feet. Could you tell me how and why this happens?
Actually, modern physics theories have matter appearing and
disappearing all the time, and if it is fast enough they do not even have to
conserve energy (according to Heisenberg's uncertainty principle). Matter is
always created as particle- antiparticle pairs, however, due to other
conservation laws - for example electrons and positrons get created together.
In particle accelerators the idea is to bring protons or electrons to very
high energies. Then these high energy particles are smashed into one another
or into fixed targets, and all sorts of stuff can happen. The interesting
thing is when new particles are created - in particular if the energies are
right, the heavy quarks can be created (together with their anti quark pairs).
Since they are unstable, they decay within a very short time (and most likely,
having high energies themselves, after having traveled some distance, perhaps
measured in feet). And the decay releases more particles with high energy.
Actually I should probably clarify. "Energy" does not exist except as a
property of matter (if you include all particles, including the photons that
carry light, as matter). Since some particles are unstable, they can decay
and release energy, but that energy is then owned by the decay products.
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Update: June 2012