ajs@hpfcla.UUCP (ajs) (05/27/85)
We hear about (and deal with) electromagnetic waves from radio to micro,
to infra-red, to visible, to X-ray, to gamma. But what about beyond?
Silly question: Is there any limit to the energy a single photon can
carry, i.e. to its frequency, or the shortness of its wavelength?
My silly guess: Yes, at least in practice, because of quantum mechanics
and uncertainty. When the wavelength is short enough, the interaction
with a charged particle (electron) causes vibrations of such small
amplitude (or short duration?) that they aren't really there at all.
Or maybe, conversely, the photon has so much energy that it wants the
charged particle to oscillate so fast with such a large amplitude that
it would exceed the speed of light. End of silly guess.
If there is no limit, whaddya call the waves more energetic than gamma
waves? "High energy gamma waves?"
OK, now let's see some amusing discussion, hopefully more informal than
technical. A thousand pardons if this has been discussed before and I
missed it. A thousand curses to anyone who copies this whole posting
into the front of their response, instead of just the second paragraph!
Alan Silverstein, Hewlett-Packard Fort Collins Systems Division, Colorado
{ihnp4 | hplabs}!hpfcla!ajs, 303-226-3800 x3053, N 40 31'31" W 105 00'43"grl@charm.UUCP (George Lake) (06/03/85)
The shortest frequency that light can have is roughly 10^43 Hz. This is one oscillation per Planck time. A photon has an energy, E = h*nu. h is Planck's constant and nu is the frequency. It's wavelength is nu * c, the spee of light. It's equivalent mass, M = E/c/c. It's Schwarzschild radius in G*M/c/c, where G is Newton's constant. Get out your handy list of constants and solve for a photon whose wavelength lies inside its Schwarzschild radius. Gravity swallowed it !
gwyn@brl-tgr.ARPA (Doug Gwyn <gwyn>) (06/06/85)
A photon swallowed by its self-gravity?? What have you been smoking?
friesen@psivax.UUCP (Stanley Friesen) (06/07/85)
In article <11228@brl-tgr.ARPA> gwyn@brl-tgr.ARPA (Doug Gwyn <gwyn>) writes: >A photon swallowed by its self-gravity?? What have you been smoking? Actually, he is probably *right*, common sense is totally useless in quantum physics, at that level the truth is often very wierd from a human point of view. In fact the gravitational interactions of light, as predicted by quantum theory, have been well validated in the form of light being bent by massive obercts(such as the Sun, or a galaxy). The extension of this to the limiting case could well produce the effect specified. Remember, mass and "energy" are *equivalent*, thus the energy content of a photon is *also* a sort of mass. -- Sarima (Stanley Friesen) {trwrb|allegra|cbosgd|hplabs|ihnp4|aero!uscvax!akgua}!sdcrdcf!psivax!friesen or {ttdica|quad1|bellcore|scgvaxd}!psivax!friesen
mcgeer%ucbkim%Berkeley@sri-unix.ARPA (06/08/85)
From: Rick McGeer (on an aaa-60-s) <mcgeer%ucbkim@Berkeley> Surely the wavelength is c/nu, not nu * c. In this case, we have: c/nu < MG/(c^2), where M = E/(c^2) = (h nu)/c^2. This implies: c/nu < (h nu)G/c^4, or: nu^2 > c^5/hG now, c = 2.998E8 m/s, h = 6.626E-34 Js (= N-m-s), and G = 6.673E-11 N-m^2/kg^2 solving, we have: nu^2 > 0.0678E85, or nu^2 > 6.78E83, or nu > 8.23E41 Hz. The wavelength (= radius of black hole) is 3.64E-34 m. Question. (1) Such a black hole would give off Hawking radiation like nobody's business. Anyone have the Hawking curve handy? What would be the temperature of such a photon? Rick.
brooks@lll-crg.ARPA (Eugene D. Brooks III) (06/08/85)
> A photon swallowed by its self-gravity?? What have you been smoking?
Some have how big it is confused with how big a hole it can go through.gwyn@brl-tgr.ARPA (Doug Gwyn <gwyn>) (06/09/85)
> In article <11228@brl-tgr.ARPA> gwyn@brl-tgr.ARPA (Doug Gwyn <gwyn>) writes: > >A photon swallowed by its self-gravity?? What have you been smoking? > > Actually, he is probably *right*, common sense is totally > useless in quantum physics, at that level the truth is often very > wierd from a human point of view. I wasn't questioning anything based on common sense, I was questioning the meaning of the whole scenario on theoretical grounds. > In fact the gravitational interactions of light, as predicted > by quantum theory, have been well validated in the form of light being > bent by massive obercts(such as the Sun, or a galaxy). The extension > of this to the limiting case could well produce the effect specified. > Remember, mass and "energy" are *equivalent*, thus the energy content > of a photon is *also* a sort of mass. ? Where can I read about this quantum theory of gravity? I've been wanting one of those for a long time. Be careful trying to explain physics to me; I was a theoretical physicist in an previous existence. I may think your careless sloshing together of half-understood concepts a bit naive. :-)
nrh@lzwi.UUCP (N.R.HASLOCK) (06/11/85)
> From: Rick McGeer (on an aaa-60-s) <mcgeer%ucbkim@Berkeley> > > The wavelength (= radius of black hole) is 3.64E-34 m. > > Question. (1) Such a black hole would give off Hawking radiation > like nobody's business. Anyone have the Hawking curve handy? > What would be the temperature of such a photon? > > Rick. Come now. We are talking of a black hole containing a single photon. How is it going to radiate more than a single photon? How much energy does it take to maintain the black hole? Does this question mean anything? -- -- ihnp4! vax135! lznv!nrh Nigel allegra! The Mad Englishman or The Madly Maundering Mumbler in the Wildernesses Everything you have read here is a figment of your imagination. Noone else in the universe currently subscribes to these opinions. "Its the rope. You can't get it, you know."
mikes@AMES-NAS.ARPA (06/11/85)
From: mikes@AMES-NAS.ARPA (Peter Mikes) That Schwarcschild limt determines the highest frequency of course assumes that wavelength can be used as proper radius of sphere which contains the photon's mass. Does a (any) present theory supports such an assumption?
grl@charm.UUCP (George Lake) (06/12/85)
Guess I'd better jump back into the frey. Special relativity does allow Lorentz boosts to arbitrarily change the frequency of light. General relativity must be brought in when the energies approach the Planck energy or mass-- that of the photon that has been discussed. The Hawking radiation time of a Planck mass hole is the Planck time. That is the same as 1/frequency of the same photon. It will not radiate a single photon. A black hole of Planck mass has much more entropy than a single photon.