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Apart from just saying zero, is there a lowest frequency for a photon below which it is not possible to go?

Quote from: jeffreyHApart from just saying zero, is there a lowest frequency for a photon below which it is not possible to go?Why do you refer to it as "light" in the subject heading and here as "a photon"? They don't mean the same thing. If you're referring to photons then there is none. Suppose you had a photon traveling in the +x direction in the inertial frame S which you thought had the lowest possible frequency. Transform to a frame of reference that is moving in the -x-direction. In this frame the photon is red shifted meaning that the frequency is lower than it was in S. Therefore your assumption that there was a lowest frequency is wrong.

Typo Pete I meant photon.

I was thinking about light in particular before I posted this. I am thinking of locally emitted photons. So that the frequency can be detected in the local frame. Just like we can produce x-rays. Except I want the other end of the spectrum. I am assuming that zero frequency is out as that would have zero energy and I am also assuming that there must be a non-zero frequency below which it is not possible to produce a photon. Think in terms of a quantization of frequency. The Planck frequency you might say.

I can't think of a quantum transition below about 0.1 eV

is there a lowest frequency for a photon below which it is not possible to go?

Apart from just saying zero...

I guess the slowest you could turn on an electric or magnetic field on Earth would be about 5 billion years -

Quote from: alancalverdI can't think of a quantum transition below about 0.1 eVHow about the ...sorry, you cannot view external links. To see them, please REGISTER or LOGIN, with an energy around 5μeV?

What I was wondering is how the longest wavelength photon would interact with the shortest wavelength gravitational wave....sorry, you cannot view external links. To see them, please REGISTER or LOGINI have no idea how you could determine the wavelength relationship from the acceleration and mass of an object generating the gravitational waves. Actually detecting such long wavelength photons would also be a difficulty.

Quote from: jeffreyH on 15/08/2015 12:01:33What I was wondering is how the longest wavelength photon would interact with the shortest wavelength gravitational wave....sorry, you cannot view external links. To see them, please REGISTER or LOGINI have no idea how you could determine the wavelength relationship from the acceleration and mass of an object generating the gravitational waves. Actually detecting such long wavelength photons would also be a difficulty.In what way are you referring to gravitational waves interacting with light waves?

That's the bit I don't know. There should be an effect but what would it be?

Quote from: jeffreyHThat's the bit I don't know. There should be an effect but what would it be?The effect would be extremely difficult, if not a practical impossibility, to detect. A gravitational wave is basically a time varying metric, i.e. a "ripple" in spacetime curvature. As light passes through it will undergo changes in wavelength at a rate at which the gravitational wave oscillates. Therefore the light may or may not come through it with an altered frequency.