What is the actual size of a photon?

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SUMMARY

The discussion centers on the size of a photon, concluding that photons are point particles in quantum mechanics (QM) with no spatial extension. Participants debate the relevance of the Schwarzschild radius and the classical electron radius in defining the limits of size for massless particles like photons. The natural size of a photon is suggested to be related to its wavelength, approximately λ, and the conversation highlights the complexities of measuring size in quantum contexts. Key concepts include the relationship between energy and mass, as well as the implications of black hole physics on particle size.

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  • Quantum Mechanics (QM) principles
  • Schwarzschild radius and its implications
  • Classical electron radius
  • Mass-energy equivalence (E=mc²)
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  • #31
ansgar said:
E = mc^2 is not valid for a photon...

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

or did you mean that m = m_0 x Gamma ?

then Gamma = infinity for photons...

sorry dmtr, there is something strange going on here :(

and what is a CS grad?

Computer science graduate. Read "complete failure in physics".

Yes. E^2 = (mc^2)^2 + (pc)^2. But m = 0. So E = pc.
Now I'm trying to calculate the equivalent increase of the mass of the black hole (assuming I throw that photon into it), AFAIK I can use the mass-energy equivalence principle - E = mc^2 for that.
 
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  • #32
The OP appeared to have not participated in this thread beyond the first post. As has been pointed out, this has been discussed already many times before, and a link to one of them has been provided.

How this thread has somehow meandered into a black hole is beyond me.

Zz.
 

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