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wolram
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Is it true that the speed of light is only dependent on the size of the universe, if the universe were much smaller would the speed of light be faster?
wolram said:Is it true that the speed of light is only dependent on the size of the universe
BiGyElLoWhAt said:
wolram said:Is it true that the speed of light is only dependent on the size of the universe, if the universe were much smaller would the speed of light be faster?
This particular theory was debunked by Bill Anders.Chronos said:Ranks right up there with the green cheese moon theory.
Has the wavefunction collapsed yet?rootone said:Surely the cheese could be both American and green without violating any known laws?
It will in about 10 minutes, my girl friend has advised me so. Goodnight.1oldman2 said:Has the wavefunction collapsed yet?
BiGyElLoWhAt said:If the value of c changed, but was the same throughout the universe over small ranges of time, meaning any experiment I could do would return 'c' as the speed of light, we would end up with the same lorentz transformation and same consequences, just with a different value for gamma.
BiGyElLoWhAt said:If c changes, then so will the numerical value of gamma, but time dilation between frames is still a thing.
BiGyElLoWhAt said:Interestingly, though, is that this implies a "god frame" so to speak. An "absolutely stationary" frame in which the size of the universe is measured in order to determine c.
BiGyElLoWhAt said:I linked to "variable speed of light theories" previously, and that is what this thread is about, no?
BiGyElLoWhAt said:I'm not advocating for the theories
BiGyElLoWhAt said:If c changes, then so will the numerical value of gamma, but time dilation between frames is still a thing.
You're right, I just assumed and since I wasn't ever corrected, assumed that to be the case.PeterDonis said:But we don't know if those are what the OP was asking about; he hasn't said.
I suppose it is a little bit out there. I'm assuming that the observational consequences of SR still need to be intact. In the ways that I know how to derive the Lorentz transformations via light clocks and the like, at any value of t in some frame, if an observer measures c in that frame and then in another, nearly-simultaneously for the observer in question, they will notice that time and length are both distorted. The postulates of SR, in fact, do assume that "c is constant". However, in practice, it doesn't seem to be utilized as strongly. "c is constant" means, to me, constant through both space and time. It seems to be used meaning constant through space. This may or may not be the case with GR. I'm not very far into GR as of right now.PeterDonis said:You're not even talking about them, as far as I can see. You're just waving your hands about what you think some imaginary theory in which ##c## varies might look like. What you should be doing, if you're really interested in the (speculative) theories along these lines already advanced, is to read the actual papers proposing them and see what they say, and then base your discussion on that (with references).
BiGyElLoWhAt said:I might be spouting off again.
In progress...PeterDonis said:Yes, you are. Please look at the actual papers.
...Joao Magueijo said:This remark was clearly made by Bekenstein [11], who pointed out that the “observation” of a varying dimensional constant is at best a tautology, since it relies on the definition of a system of units.
However, in his example, the meter was defined in terms of c. Of course c is constant if c is defined as a function of c!Joao Magueijo said:it is always possible to define units such that c remains a constant.
So this is explicitly about units. I don't think this is what OP was asking about. "Is the speed of light dependent on the size of the universe?" Changing units of length would be arbitrary, which leaves only time to vary, and that gets weird with SR when I think about it.We are now ready to define varying speed of light. VSL theories are theories in which you find yourself in a situation like the one in the last example, regarding the speed of light in vacuum. They are theories in which the dynamics is rendered more simple if units are chosen in which c is not constant.
BiGyElLoWhAt said:If we define the meter in terms of c, so ##1 \text{meter} = \frac{1}{299,***,***}\times c \times N_{\text{Cs}=1s} \times ( \text{duration of one excitation of cs}## )
What do you end up with? ##1=1## ?
BiGyElLoWhAt said:if you were to go old school, grab a meter stick, and define a meter to be that long, would you experience the same thing?
BiGyElLoWhAt said:So this is explicitly about units.
BiGyElLoWhAt said:I thought he was talking about, say Lagrangian or Newtonian mechanics as he was a shortly before that. As in the dynamics of motion.
BiGyElLoWhAt said:Give me a meter stick, an accurate clock, and the notion that electron mass is the same, and I can check to see if e is the same. If both of those are the same, but alpha varies, it must be in hbar.
BiGyElLoWhAt said:Why can't we use a meter stick and do trig on our fancy telescopes to determine a meter?