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Isaac Asimov says that the photon energy of a gamma ray cannot exceed to the total mass-energy of the universe.
Is there a maximum frequency for a photon?
Perhaps the wavelength can't meaningfully be less than 1 Planck length.
There should be some sort of energy density in space associated with a photon. If you keep pushing up the frequency then you have enough energy density to create a micro black hole.
Quantum stuff instead of classical: Maybe photons always arise as a result of electrons changing orbitals around an atom or nucleons re-arranging themselves in a similar way inside the nucleus. Even the largest of jumps (from say n= ∞ to n=1) is still a finite energy change and there are only a handfull of different sub-atomic particles and only a finite number of ways of putting them together to make something with these energy states.
(I'm about 71% inclined that way)
then the follow up question has to be......What if you change reference frames?
Most assessments I’ve seen on this suggest that the amount of energy needed to probe something at the plank length is around that needed to create a black hole.
(About forming a black hole) That's not how it works any more than a black hole forming by raising the relativistic mass of some object above the energy density threshold, again, something that is done to Earth all the time.
The Planck length has no physical significance apart from being, theoretically, the shortest length of an object that can be measured with a photon. That doesn't imply the converse that you can't have a photon with a shorter wavelength.
That's like positing a maximum reference frame speed..... (along with more stuff about reference frames and Special relativity)
There are some ideas that space and time are actually quantised or discrete variables rather than being continuous.
Quote from: Colin2B on 21/02/2022 09:05:23Most assessments I’ve seen on this suggest that the amount of energy needed to probe something at the plank length is around that needed to create a black hole. Another good point.
if the energy of a photon is E = hf and f can go arbitrarily high then UNLESS the photon spreads out in spatial extent with increasing frequency, then surely you do have enough energy density to form a micro black hole. I don't know.
Anyway, a black hole has sufficient characteristics to describe a photon
I'm not certain if [ ... ] space is actually discrete and not continuous etc.
At the lower end, there is a limit to the energy of a photon we can observe at Earth's surface,
....we did all just step around the possibility that if you push the frequency of the gamma ray higher then we could get outside the range of energy that most of the current scientific theories work with.
But you seem to be conflating wavelength of a photon with its size.
No particle lacking in proper mass can form a black hole. A black hole is formed under conditions as defined by the stress energy tensor, and I don't think there can be a normalized tensor for a system consisting of a single massless particle.
A black hole has (among other properties) proper mass.
... If it eats any kind of mass, energy or mass parameter thing, then the mass parameter of the black hole will increase.
At the lower end, there is a limit to the energy of a photon... (because of pair prduction)....
Chinese astronomers claim to have observed gamma rays of 1 PeV
....but we've been generating bucketloads of 15 MeV photons for radiotherapy for as long as I have been in the business, and AFAIK work is proceeding on a high-brightness 6 GeV source in China....
...As this is informal, otherwise much would go into new theories...
As you’ve no doubt realised, the energy needed to create John Wheeler's kugleblitz put it out of being a credible possibility. However, it’s still a lot less than Asimov’s suggestion.
Black holes are completely characterised by only three parameters: mass, rotation (angular momentum) and charge.
Can mass equivalence be done with energy? Or an electromagnetic mass relation?
As much as the black hole loses a small amount of its energy
However, you are completely ignoring the theory that already exists for Kugelblitz, black holes that were formed entirely from radiation and not from any particles with some rest mass.
If that energy density exceeds a critical value then a black hole forms (according to conventional GR anyway).
Quote from: Halc on 21/02/2022 17:54:12A black hole has (among other properties) proper mass. I'm going to strongly disagree here. Maybe you're using the term "proper mass" is some special way, I'm not sure.
A Black hole has a parameter M, which we call the Mass parameter but it's just a parameter not the mass of a black hole, at best it's the equivalence of the mass required to generate the same gravitational field.
At a big distance (something outside the surface of the equivalent ordinary spherical mass, so that has to be outside the Schwarzschild radius) the gravitational field from a black hole is identical to that from an ordinary (not collapsed) spherical object of mass M placed an equivalent distance away from the observer).
If you (alancalverd) get a moment, is there a useful link to some information about how the latest high energy gamma rays are actually generated? X-rays are easy enough... just accelerate some electrons into a tungsten target inside an x-ray tube - but can you really push those frequencies up higher to the gamma range just by increasing the velocity of those electrons? Are your machines producing medical gamma rays directly from nuclear decay these days? Even if they are produced directly from nuclear decay, where are you (we) going to get even higher frequency gamma rays from after that?
Sorry I missed the question earlier!