Akita T
Caldari Navy Volunteer Task Force
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Posted - 2008.09.01 13:59:00 -
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Edited by: Akita T on 01/09/2008 14:03:01
I can only  at most of you.
Ok, slowly, basic "what we think we know today about photons", semi-classic interpretation (bit of photon bla bla, mostly newtonian stuff).
Photons have no REST mass (or, at least they are assumed to have none, because they don't exist at speeds lower than c).
In their own reference frame, photons might have some mass, or they might not... but they have zero speed (in its own reference frame, everything has zero speed for itself, duuh).
For all intents and purposes, for a human observer (aided by whatever devices you want), they are pure (kinetic) energy that behaves similar to what a particle would behave when interacting with other particles.
The "theoretical" mass of the photon (for impulse/energy calculations when it interacts with other particle and BEHAVES like a particle, to some degree) can be calculated with E=m*c^2, where E=h*c/wavelength, so m*c*c=h*c/wavelength, therefore m = h/(c*wavelength) = h*frequency/c (here h is Planck's constant).
If manage to leech enough energy out of the photon (decrease frequency / increase wavelength) so that the photon would have to "dip" below the speed of light, the photon ceases to exist. You can only leech energy in discreete quantities (quanta), so there is such a thing as "the weakest possible photon", and there's a limited number of photon energies between two given frequencies.
So... how does all this black hole mumbo jumbo come into this ?
Simple as pie, actually.
Due to how photons interact with regular particles, for each individual photon, you have a certain (theoretical/interaction) mass, derived from their (kinetic) energy, which depends on frequency... the higher the frequency, the larger the "fake mass".
In order to "escape" a gravity well, any particle has to SHED kinetic energy (into potential energy) depending on how much mass it has.
A black hole is simply a gravity well so powerful, that the photons would have to shed MORE kinetic energy than they already have in order to escape it... and their frequency doesn't really come into this, because their "fake mass" is larger the more kinetic energy they carry, so all frequencies are affected equally bad.
So, there you go, the definition of a black hole (how massive a black hole has to be to be considered a black hole) and the explanation why photons are "trapped".
I say "trapped", because they don't just vanish... they keep "spinning" around the black hole, (almost//theoretically) never leaving its gravity well... so, to an outside observer, it's as if they were "sucked" into it.
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