Thread: Time travel
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Old 25-10-2009, 08:48 PM
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sjastro
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Quote:
Originally Posted by Nesti View Post
Doesn't the pion decay occur instantaneously. In that the tunneling of the alpha particle, from within the strong force's expressed radius to outside the strong force's expressed radius, takes no time at all...the alpha particle then decays within the radius of its wavelength, radiating out as the weak force (radiation)?

Cheers
Mark
Decay of the alpha particle does not involve the weak force hence time reversal doesn't occur. Beta decay does.

In particle physics, particle interactions occur if symmetry is invariant before and after the interaction.
Experimentally it has been found that parity (P) and charge conjugation symmetries (C) are not conserved in beta decay. Neither are the 2 symmetries together (CP). By introducing a time symmetry T, the combined symmetry CPT is invariant and the interaction proceeds.

A more technical description of this can be found at:

http://en.wikipedia.org/wiki/CPT_symmetry

Regards

Steven
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