3 ms·

I'm familiar with the scattering of light by light, but I am not familiar with the scattering of light by a electric field, where can I learn more?

SiempreViernes 9y ago
https://en.wikipedia.org/wiki/Compton_scattering https://en.wikipedia.org/wiki/Compton_scattering and the famous low energy limit https://en.wikipedia.org/wiki/Thomson_scattering https://en.wikipedia.org/wiki/Thomson_scattering
- DoctorOetker 9y ago
  I'm familiar with Compton scattering (I did the experiment), but that is scattering from a charge(d particle). I would have expected Dyson to write "light scattering from an electric charge" or perhaps "from an electron" if he meant Compton scattering. I still read Dyson's sentence as light scattering from an electrostatic field (not clear if it would scatter from a homogenous field, or only gradients in electric field). Could others please chime in, and confirm SiempreViernes response, or enlighten us both? EDIT: Could this refer to pair production? The electric field of the highly positive nucleus affecting the virtual electron positron pair before it collapses and re-emits the scattered photon?
  - SiempreViernes 9y ago
    I don't think pair production makes more sense, it's probably Compton scattering because all QFT interactions using Feynman diagrams are expressed as particle interactions.
    - DoctorOetker 9y ago
      why would such interactions not be expressible to express as a particle interaction? first draw a Feynman diagram of an incoming photon the splits into electron and positron which recombine into an outgoing photon (an electron loop in the middle of the diagram) then on the bottom add an incoming proton which interact with a photon to either the electron or the positron of the electron loop...
      - SiempreViernes 9y ago
        I'm not saying pair production can't be expressed as a particle interaction; I'm saying all interactions with fields in QFT are expressed as particle interactions, so photon electron scattering is a perfectly valid interpretation of "light scattering from an electric charge" thinking of it more, I have a hard time seeing the conversion of a photon into two "electrons" fairly being termed "scattering".
        DoctorOetker 9y ago
        " so photon electron scattering is a perfectly valid interpretation of "light scattering from an electric charge" " But look up, you misquote Dyson: Dyson didn't write "light scattering from an electric charge" but wrote "light scattering by an electric field" . You also misread me: 1) a photon can not be converted into two "electrons" and I did not write this (but in the past positrons were called positive electrons). 2) the electron positron pair (from a single photon, internal to the feynman diagram) is only intermediate but as charges are influenced by a strong electric field (say a nucleus), before annihilating back into a single photon. 3) the incoming particles are a photon and a nucleus, and the outcoming particles are again a photon and a nucleus, this is obviously scattering This is different from Compton scattering (scattering of light from a practically free electron) or its low energy limit Thomson scattering, but in the case of scattering from atoms still high enough energy to eject an electron. This is different from Coherent Compton scattering, which is scattering of light from an atom, or rather from an electron that remains bound to the atom, such that instead of the compton wavelength of the electron, the compton wavelength of the atom is used: "Compton found that some X-rays experienced no wavelength shift despite being scattered through large angles; in each of these cases the photon failed to eject an electron.[5] Thus the magnitude of the shift is related not to the Compton wavelength of the electron, but to the Compton wavelength of the entire atom, which can be upwards of 10000 times smaller. This is known as "coherent" scattering off the entire atom since the atom remains intact, gaining no internal excitation." (From Wikipedia page on Compton scattering) I still interpret Dyson's "light scattering from an electric field" as probably referring to the Meitner-Hupfeld effect: https://en.wikipedia.org/wiki/Meitner%E2%80%93Hupfeld_effect https://en.wikipedia.org/wiki/Meitner%E2%80%93Hupfeld_effect Here's the Feynman diagram I have in my head: https://www.overleaf.com/read/dszzcbcqdqtk https://www.overleaf.com/read/dszzcbcqdqtk

SiempreViernes 9y ago

https://en.wikipedia.org/wiki/Compton_scattering https://en.wikipedia.org/wiki/Compton_scattering and the famous low energy limit https://en.wikipedia.org/wiki/Thomson_scattering https://en.wikipedia.org/wiki/Thomson_scattering

DoctorOetker 9y ago
I'm familiar with Compton scattering (I did the experiment), but that is scattering from a charge(d particle). I would have expected Dyson to write "light scattering from an electric charge" or perhaps "from an electron" if he meant Compton scattering. I still read Dyson's sentence as light scattering from an electrostatic field (not clear if it would scatter from a homogenous field, or only gradients in electric field). Could others please chime in, and confirm SiempreViernes response, or enlighten us both? EDIT: Could this refer to pair production? The electric field of the highly positive nucleus affecting the virtual electron positron pair before it collapses and re-emits the scattered photon?
- SiempreViernes 9y ago
  I don't think pair production makes more sense, it's probably Compton scattering because all QFT interactions using Feynman diagrams are expressed as particle interactions.
  - DoctorOetker 9y ago
    why would such interactions not be expressible to express as a particle interaction? first draw a Feynman diagram of an incoming photon the splits into electron and positron which recombine into an outgoing photon (an electron loop in the middle of the diagram) then on the bottom add an incoming proton which interact with a photon to either the electron or the positron of the electron loop...
    - SiempreViernes 9y ago
      I'm not saying pair production can't be expressed as a particle interaction; I'm saying all interactions with fields in QFT are expressed as particle interactions, so photon electron scattering is a perfectly valid interpretation of "light scattering from an electric charge" thinking of it more, I have a hard time seeing the conversion of a photon into two "electrons" fairly being termed "scattering".
      - DoctorOetker 9y ago
        " so photon electron scattering is a perfectly valid interpretation of "light scattering from an electric charge" " But look up, you misquote Dyson: Dyson didn't write "light scattering from an electric charge" but wrote "light scattering by an electric field" . You also misread me: 1) a photon can not be converted into two "electrons" and I did not write this (but in the past positrons were called positive electrons). 2) the electron positron pair (from a single photon, internal to the feynman diagram) is only intermediate but as charges are influenced by a strong electric field (say a nucleus), before annihilating back into a single photon. 3) the incoming particles are a photon and a nucleus, and the outcoming particles are again a photon and a nucleus, this is obviously scattering This is different from Compton scattering (scattering of light from a practically free electron) or its low energy limit Thomson scattering, but in the case of scattering from atoms still high enough energy to eject an electron. This is different from Coherent Compton scattering, which is scattering of light from an atom, or rather from an electron that remains bound to the atom, such that instead of the compton wavelength of the electron, the compton wavelength of the atom is used: "Compton found that some X-rays experienced no wavelength shift despite being scattered through large angles; in each of these cases the photon failed to eject an electron.[5] Thus the magnitude of the shift is related not to the Compton wavelength of the electron, but to the Compton wavelength of the entire atom, which can be upwards of 10000 times smaller. This is known as "coherent" scattering off the entire atom since the atom remains intact, gaining no internal excitation." (From Wikipedia page on Compton scattering) I still interpret Dyson's "light scattering from an electric field" as probably referring to the Meitner-Hupfeld effect: https://en.wikipedia.org/wiki/Meitner%E2%80%93Hupfeld_effect https://en.wikipedia.org/wiki/Meitner%E2%80%93Hupfeld_effect Here's the Feynman diagram I have in my head: https://www.overleaf.com/read/dszzcbcqdqtk https://www.overleaf.com/read/dszzcbcqdqtk