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From: ram@zedat.fu-berlin.de (Stefan Ram)
Newsgroups: sci.physics.relativity
Subject: Re: Positrons
Date: 8 Jul 2025 14:17:29 GMT
Organization: Stefan Ram
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Expires: 1 Jun 2026 11:59:58 GMT
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"Paul.B.Andersen" <relativity@paulba.no> wrote or quoted:
>Den 08.07.2025 00:02, skrev Stefan Ram:
>>"Paul.B.Andersen" <relativity@paulba.no> wrote or quoted:
>>>e⁺ + e⁻  →  γ + γ
>>>Energy and momentum are preserved.
>>>The energy equivalence of an electron and a positron is 0.511 MeV,
>>>so the energy of each of the gamma particles is 0.511 MeV. (0.024 Å)
>>>(Mass is converted to pure kinetic energy of photons)
>>Mass is /not/ changed in this process when the mass of the system
>>"γ + γ" is being compared with the mass of the system "e⁺ + e⁻".
>Why would you consider γ + γ as a closed system?

  Well, I was talking about a "system", not a "closed system".

  Many people go with 

E^2 = (mc^2)^2 + (pc)^2

  and emphasize that energy and momentum are conserved in a process
  "-->", while mass can be converted into "pure kinetic energy".

  Now, let's call the values before a process (left of the arrow "-->")
  "0" and those after the process (right of the arror "-->") "1".

  Then, what the people say would be:

E_1 = E_0     "Energy is conserved"
p_1 = p_0     "momentum is conserved"
m_1 < m_0     "mass is converted into energy"

  But these three assumptions are not compatible with

E_0^2 = (m_0c^2)^2 + (p_0c)^2 and
E_1^2 = (m_1c^2)^2 + (p_1c)^2

  !