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Photon with Planck Energy 
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#1
Aug1213, 11:24 AM

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What are the properties of a photon with Planck energy? Is it even possible to interact with it, or does it just travel trough all matter?



#2
Aug1213, 12:11 PM

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The Planck energy is an approximate energy, not an exact one. It is believed to be the energy range at which the quantum effects of gravity become important.
They talk a lot about the Planck energy on TV. However our best current theory, the Standard Model, is not expected to remain valid at such a high energy, and what actually does happen at the Planck energy, to the photon or to any other particle, is at this stage pure speculation. 


#3
Aug1213, 12:48 PM

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To reach the Planck scale, you have to collide two particles with an energy of the order of the Planck scale.
A photon with the Planck energy (in our lab), colliding with something on earth would be certainly a very interesting collision, but it would not go beyond the limit of our current theories (there could be new physics, but there does not have to be). The energy of a photon is framedependent. For every photon, there is a frame where its energy reaches (or even exceeds) the Planck scale. 


#4
Aug1213, 12:58 PM

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Photon with Planck Energy



#5
Aug1213, 02:18 PM

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Let's collide the photon with a proton:
(E_P,E_P,0,0) + (m_p,0,0,0) leads to a center of mass energy of ##\sqrt{(E_P+m_p)^2E_P^2} \approx 5 EeV = 5 \cdot 10^6 TeV##. More than we can produce in collider experiments, but way below the Planck scale of 10^{16} TeV where gravity becomes significant. 


#6
Sep2613, 11:54 AM

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But before that happened, I would wonder if it would constitute a tiny black hole that would instantly evaporate  releasing a shower of other particles. 


#7
Sep2613, 01:41 PM

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#8
Sep2613, 02:17 PM

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(But we should still be somewhat skeptical about any extrapolation of current theory to such a remarkably energetic photon). 


#9
Sep2613, 02:41 PM

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Edit: I should add that the amplitude for the lowestorder process for lightbylight scattering, at high enough energies, is about 10000 times smaller than the amplitude for photonelectron scattering. 


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