# Hypothetical maximum energy of a single photon [duplicate]

I'm no physicist so it might be a stupid question but is there a maximum energy a single photon can have?

My idea was, that there might be restriction for the minimum wavelength and I thought about the Planck length: $$1.616 · 10^{−35}$$ m

So my hypothetical photons energy would be:

$$E=hf=\frac{hc}{\lambda}$$

So I put the values inside: $$E=\frac{6.62607015 \cdot 10^{−34}\cdot 299792458}{1.616 \cdot 10^{−35}} \frac{\text {J s m}}{\text{s m}}$$

which gives me the value: $$1.23*10^{10}$$ J

Is this the maximum amount of energy that a single photon can have, or is the concept of using the planck length as minimal possible wavelength not correct?

And are photons with that much energy even existing in the universe?

• – PM 2Ring Apr 1 '19 at 18:45
• The question linked to as a dupe has several answers, but the one that I think is the right answer is in the bottom, with only three votes: I don't see any reason there should be a maximum energy. Send me a photon of arbitrarily high energy, and I can increase its energy further in my reference frame (which is just as valid as any) by moving toward your source. – pela Apr 1 '19 at 21:24

We have no evidence for Planck-energy particles. The highest-energy cosmic-ray particle ever detected (which was probably a proton) carried 51 J, more than a billion times less. The highest-energy photons ever detected carry only nanojoules, another factor of a billion down the energy scale.

We don’t understand physics at the Planck scale, so we don’t know whether smaller lengths and higher energies are possible or not. But particles with Planck energies do not appear to be zipping around our universe, which is a good thing!

Using the Planck length as a cutoff makes sense because we are still not able to predict consistently what happens at higher energies.

This does not mean that you cannot have a "bigger" quantum of energy, e.g. a photon of higher energy. Sure if you have it, you would also have very non trivial quantum-gravitational effects.

To my knowledge there is no proof against the possibility of such photon. But maybe some approach to quantum gravity could offer an argument against it.