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Natural Science Forum / Physics / Relativity / December 2005speed of light versus c, again
it seams that the most selfestablished around here still consider c the speed of light in vacuum as the max speed in anywhere but they know they are wrong becus group velocity can reach infinity they argue sayong that group velocity carries no info, but who cares if it does, the issue is the max speed c existing group/phase velocity is a very existing velocity > it seams that the most selfestablished around here > still consider c the speed of light in vacuum as the max [quoted text clipped - 6 lines] > who cares if it does, the issue is the max speed c existing > group/phase velocity is a very existing velocity Who cares? Physicists care. They're very careful to explain what c is the maximal value of, and it does not include things like phase velocity or closing speed. http://scienceworld.wolfram.com/physics/Superluminal.html It is only the idiot who hears a snippet and misfires back triumphantly, "Physicists say c is the maximal velocity of *anything*, and that CAN'T be right, and therefore physicists don't know what they're talking about." PD > > it seams that the most selfestablished around here > > still consider c the speed of light in vacuum as the max [quoted text clipped - 8 lines] > > Who cares? Physicists care. are just saying that they are morons? in your analogy group/phase velocity is not existing? > They're very careful to explain what c is the maximal value of, and it > does not include things like phase velocity or closing speed. [quoted text clipped - 6 lines] > > PD > > > it seams that the most selfestablished around here > > > still consider c the speed of light in vacuum as the max [quoted text clipped - 12 lines] > > in your analogy group/phase velocity is not existing? There is no maximal speed that applies to everything existing. PD > > > > it seams that the most selfestablished around here > > > > still consider c the speed of light in vacuum as the max [quoted text clipped - 14 lines] > > There is no maximal speed that applies to everything existing. i supose you just said that there are no maximals on speeds therfore it can be infinity > PD > > > > > it seams that the most selfestablished around here > > > > > still consider c the speed of light in vacuum as the max [quoted text clipped - 18 lines] > > therfore it can be infinity There are some things that can have arbitrarily large speeds, yes. There are other things that cannot exceed c. Were you under the impression otherwise? PD > > > > > > it seams that the most selfestablished around here > > > > > > still consider c the speed of light in vacuum as the max [quoted text clipped - 20 lines] > > There are some things that can have arbitrarily large speeds, yes. threfore c takes the "arbitrarily large speeds" values ot the other "some things" > There are other things that cannot exceed c. > > Were you under the impression otherwise? here everywhere i just wanted to make clear about the _existing_ speeds which is verry nice that they exist > PD > > it seams that the most selfestablished around here > > still consider c the speed of light in vacuum as the max [quoted text clipped - 12 lines] > does not include things like phase velocity or closing speed. > http://scienceworld.wolfram.com/physics/Superluminal.html who cares what other morons you erronately call for "Physicists" (please remark the upercase) the question was simple, the max existing speed in univers, answer it > It is only the idiot who hears a snippet and misfires back > triumphantly, "Physicists say c is the maximal velocity of *anything*, > and that CAN'T be right, and therefore physicists don't know what > they're talking about." i never said that, dont be a fool better answer the damn simple question > PD > it seams that the most selfestablished around here > still consider c the speed of light in vacuum as the max > speed in anywhere Certainly not -- you got it wrong. But c is the _local_ limiting speed for any material, energy, or information transfer. And my "c" is not necessarily the speed of light, but rather is the invariant speed of the Lorentz group. > but they know they are wrong becus group velocity can > reach infinity Sure. So can phase velocity. So what? -- the front velocity of any EM wave never exceeds c, and both energy and information transfer travel at the front velocity. Tom Roberts tjroberts@lucent.com > > it seams that the most selfestablished around here > > still consider c the speed of light in vacuum as the max [quoted text clipped - 4 lines] > necessarily the speed of light, but rather is the invariant speed of the > Lorentz group. let away information transfer. We know that it can be double the speed of light. And it can be near infinite on short distances. > > but they know they are wrong becus group velocity can > > reach infinity > > Sure. So can phase velocity. So what? -- the front velocity of any EM > wave never exceeds c, and both energy and information transfer travel at > the front velocity. That statement is simply not true. A signal travels with group velocity. Inclusive front if it has the same frequency. Joe > Tom Roberts tjroberts@lucent.com >> > it seams that the most selfestablished around here >> > still consider c the speed of light in vacuum as the max [quoted text clipped - 7 lines] > let away information transfer. We know that it can be double the speed of > light. We do not know that at all. Learn about what the Nimitz experiment your are fond of misquoting actually implies before posting misconceptions > And it can be near infinite on short distances. Wrong. >> > but they know they are wrong becus group velocity can >> > reach infinity [quoted text clipped - 4 lines] > > That statement is simply not true. Yes it is. Your belief otherwise is a misconception. > A signal travels with group velocity. Inclusive front if it has the same > frequency. Information can only be sent at the front velocity - and obviously so at that. Bill > Joe > >> Tom Roberts tjroberts@lucent.com >>c is the _local_ limiting speed >>for any material, energy, or information transfer. > > let away information transfer. We know that it can be double the speed of > light. And it can be > near infinite on short distances. No, we _DON'T_ know that. In fact, no experiment has ever shown propagation of energy or information > c over any distance. Yes, group velocity can be > c, but no _information_ or _energy_ is transferred at that speed. In all cases where group velocity > c, to observe it requires the underlying waves be present beforehand, including all information and energy they carry. If the group approaches the waveFRONT from behind, the group DISAPPEARS as it reaches the FRONT. >>the front velocity of any EM >>wave never exceeds c, and both energy and information transfer travel at >>the front velocity. > > That statement is simply not true. You _REALLY_ need to learn about the topic before making such statements. What I said is true, and your claims are not. My saying so is not definitive; what matters is actually going and READING about the experiments and the theory. > A signal travels with group velocity. Not true -- when approaching the FRONT from behind, the group disappears as it overtakes the FRONT. There is no group if there is no wave, and the front of the wave travels with the FRONT velocity, which is always <= c. <shrug> Tom Roberts tjroberts@lucent.com seams -> seems argon and PD are too dumb to understand what is a /thing/ and what is not a /thing/. What is not a thing is many things or a thingkin. |
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