Discussion in 'Physics & Math' started by SimonsCat, Jan 21, 2017.
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How does this differ from the well-known phenomenon of Cerenkov radiation?
Cerenkov radiation is the result of a charged particle exceeding c in a dielectric medium. The 'light boom' captured in OP YT vid is owing to scattered light from an already extant light pulse. The superposition of spherical wavefronts from 'fog' scattering particles generate a conical wavefront when entering the silicone layers - which mimics in appearance genuine Cerenkov radiation. There will be some complications owing to the usual angular dependent refraction T & R coefficients, but not that much to spoil the image of a 'light boom' badly named except for it's PR value. More research grants perhaps.
When you accelerate a charged particle, in a gravitational field, it will experience Larmor radiation, which is completely equivalent to Cherenkov radiation, which specifically applies to system capable of travelling in superluminal velocities (not in a vacuum state) but often in some special medium, like a superconducter. Electrons can briefly move faster than light in right kind of background environment, but they will loose all their energy and decay before they get too far!
So . . . if NOT Cherenkov-like, are we to presume that "something" (i.e., photon?, other) has actually (not virtually) exceeded the velocity of light, c?
Nothing but nothing will ever exceed 186,000kms/sec or 300,000mls/sec.
Light/photons are apparently "slowed" down in a medium.
..."186,000kms/sec or 300,000mls/sec"...
Nonsense. There is continued controversy among genuine experts over whether there is any radiation in the case of a charge in gravitational free-fall. Or when it is stationary in a gravitational field. In either case, any such 'radiation' would be entirely different in character to Cerenkov radiation.
Well, its a manifestation of the weak equivalence principle and we have measured Larmor radiation from accelerating electrons. If there is no dispute gravity field is an acceleration field, then yes, it seems very natural that a charged particle accelerating in a gravitational field is no different to one accelerating linearly in motion.
And I am completely correct in what I said anyway: the term that describes the same radiation in the Larmor phenomenon, to Cherenkov radiation is commonly called Bremsstrahlung radiation. It is a type of electromagnetic inertia that causes the deceleration of a system due to emission of energy in the form of radiation.
Wrong. Bremsstrahlung radiation is totally different in character to Cerenkov radiation - the latter doesn't involve acceleration at all as causative agent. And only weakly leads to gradual braking as effect not cause.
Cherenkov is a deceleration radiation!!!
here is what wiki has to say about it, noting one small difference between the two:
''Although the term, bremsstrahlung, is usually reserved for charged particles accelerating in matter, not vacuum, the formulas are similar. (In this respect, bremsstrahlung differs from Cherenkov radiation, another kind of braking radiation which occurs only in matter, and not in a vacuum.)''
So both are deceleration radiation phenomenon and in that respect, they are completely similar in nature. However, I have noted that it doesn't apply to a vacuum, I was very careful to draw that out. As I stated, we need new environments to explain superluminal velocities that are not described by vacuum solutions.
Thank you dmoe.....
I of course had that arse up, back to front Please Register or Log in to view the hidden image!
should be 300,000kms/sec or 186,000mls/sec Please Register or Log in to view the hidden image!
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You recall claiming (wrongly) a Wiki article cited in another thread being 'poorly worded'? This from para immediately below the formula shown in http://large.stanford.edu/courses/2011/ph241/keller2/:
"Second, it is interesting to note that Cerenkov radiation is readily differentiated from Bremsstrahlung radiation because the intensity does not depend on the mass of the charged particle, whereas Bremsstrahlung radiation does."
Which is just one distinction. The frequency spectrums and angular intensity patterns are also entirely different.
To reiterate from my #8: The cause of Bremsstrahlung radiation is linear deceleration of charge. The cause of Cerenkov (aka Cherenkov) radiation is motion of charge through a medium with phase velocity less than particle velocity. The effect in latter case being relatively weak deceleration in accordance with conservation of energy. Do not go on conflating cause and effect. Among other errors.
Well, yes, wiki does word things bad. You quoted it frequently in another thread the other day, if you have objections someone else using it as a refernce, I'd say, pot kettle black. My opinions on wiki haven't changed, but you seemed to have a raised the bar on what constitutes as an actual reference.
Anyway... these differences you mentioned seem so trivial next to how similar these phenomenon are. Subtle differences in more or less, similar phenomenon, in which one case uses deceleration radiation in a subluminal case, the other superluminal.
I do get the impression you are just trying to find any old claim to try and find fault in things that I say. If you find the statement '' Bremsstrahlung radiation is formally equivalent to Cherenkov radiation, then so be it. I have drawn similarities and cases in which they differ. Go on your mad quest though to find things I say wrong, in the end it has to be a good for a forum that wishes to discuss such things.
You are now at the level of making incoherent sentences. What point then to even try engaging with you. Do have a nice day.
Well I am sorry.
''If you find the statement '' Bremsstrahlung radiation is formally equivalent to Cherenkov radiation incorrect, then so be it.''
Are you just trying to make enemies with me, because you disagree with me?
No, you are simply spouting nonsense. Unfortunately it's been entirely up to me to correct you here, and I grow weary of doing it.
Are you really that delusional? You haven't corrected me at all, they are very equivalent the phenomena's in respect that accelerations in their environments leads to a deceleration radiation. I haven't really claimed any more than this, while drawing differences between the two, saying one holds for a vacuum, the other doesn't (and this was all before you even arrived to discuss this with me).
I don't know what else you want from me, a blue peter badge for your efforts maybe?
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