Tzemach said:We should also remember that velocity is calculated V=d/t so that to agree on velocity we must also be using similar measures of distance and time. Small variations express themselves as variations in wavelength etc but it is sometimes interesting to think about large variations for instance if you were so near a black hole that time had slowed to the point that a second was equal to two seconds, how would you perceive incoming light? Try going the other way if a second was only equal to 0.5 of a normal second, how would the universe appear to you?
quantum123 said:The fact that light travels at c is because of how we define the metre.
You are talking about black holes which are described by general relativity. I urge you to look how "velocity" is defined in general relativity. You are making the mistake of using a classical physics definition within a general relativity framework. This will not work, as you will find out yourself.Tzemach said:We should also remember that velocity is calculated V=d/t so that to agree on velocity we must also be using similar measures of distance and time.
Sorry, I didn't use the correct way to express the concept in english: I was intended to mean nothing can "surpass" the speed of light, that is, something that starts from v<c and that cannot go beyond v = c.chroot said:No, it's not equivalent, and I have no idea why you think it is. Special relativity says absolutely nothing about c being the maximum possible speed, nor does it forbid tachyons. Special relativity quite happily admits particles that travel faster than light, with some consequences, such that their mass is imaginary, etc. Tachyons may be unphysical, and almost certainly don't really exist -- but the mathematics of special relativity does not forbid them.
Defined how?In its barest form, c doesn't even have anything to do with light. c is just a velocity, and it has the special status of being the only velocity that every observer will always agree upon. The fact that light travels at c is a consequence of its zero rest-mass. even if light did not exist, c would still be a meaningful velocity.
complexPHILOSOPHY said:In modern quantum mechanics, particles of matter called fermions possesses mass, however, particles of force called bosons do not possesses mass. Read up on Quantum Electrodynamics and Qunatum Chromodynamics for more information.
chroot said:In its barest form, c doesn't even have anything to do with light. c is just a velocity, and it has the special status of being the only velocity that every observer will always agree upon. The fact that light travels at c is a consequence of its zero rest-mass. even if light did not exist, c would still be a meaningful velocity.
marlon, it is also possible to make all of the same correct predictions using completely different assumptions about c. The standard formulation of special relativity has both a conventional and a non-conventional content. It is not possible to prove that the "c definition" is correct (e.g., the conventional content of the theory) without disproving the non-conventional content of the theory. Any claim that empirical evidence tends to show that the "c definition of special relativity is correct" actually amounts to a claim (inadvertently) that the non-conventional content of the theory is falsified.marlon said:The fact that special relativity allows us to make correct predictions within the appropriate physical regime, only shows us that the "c definition" is correct.
Aether said:marlon, it is also possible to make all of the same correct predictions using completely different assumptions about c.
I don't even know what that means but isn't the very basis of SR that c is an universal constant ? In SR c is the only velocity which will be the same for each and every observer. Now, in what "theory or version" of SR is this denied ?The standard formulation of special relativity has both a conventional and a non-conventional content.
It is not possible to prove that the "c definition" is correct (e.g., the conventional content of the theory) without disproving the non-conventional content of the theory.
Any claim that empirical evidence tends to show that the "c definition of special relativity is correct" actually amounts to a claim (inadvertently) that the non-conventional content of the theory is falsified.
marlon said:How ?
Please see these two papers:marlon said:How ?
No, this is only assumed in the standard formulation of SR. This assumption amounts to the selection of a convenient coordinate system.I don't even know what that means but isn't the very basis of SR that c is an universal constant ?
You can do a search of this forum for previous discussions of Lorentz ether theory (LET aka GGT). This "theory" is empirically equivalent to the standard formulation of special relativity, but maintains absolute simultaneity. It is presented only as a counter-example to the coordinate system used in the standard formulation of special relativity, and not as a competing "theory"'; these two coordinate systems actually make all of the same empirical predictions.In SR c is the only velocity which will be the same for each and every observer. Now, in what "theory or version" of SR is this denied ?
It doesn't make sense to say "my coordinate system works, so therefore it is correct", especially if you are implying by this that other coordinate systems must not be correct.I don't understand. SR works, so the c definition is "correct", what is the problem ?
Please see the bottom of page 1 of ref. 1 above:Again, i don't understand what you mean by this "non-conventional content of the theory "
J.A. Winnie said:According to the CS thesis [the conventionality of simultaneity], this situation reveals a structural feature of the Special Theory, and thereby of the universe it purports to characterize, which not only makes the one-way speed of light indeterminate, but reveals that its unique determination could only be at the expense of contradicting the nonconventional content of the Special Theory.
My apologies if I ever implied such a thing here. I do not try to argue this.pervect said:On the other hand, they then try to argue that changing a convention makes a theory a "different theory".
pervect said:The resulting theory with anisotropic clock synchronization isn't actually any different than SR, if appllied correctly (which seems to be somewhat rare).
Photons are not like tiny rockets speeding to catch up to c. They go as fast as the universe allows.marlon said:So but has c a different value in this theory ? I would find that hard to believe since light travels at c because of the zero restmass. If c had a different value, how does light still travel at c then ?
marlon
What we call "rest" is only observed as an average velocity through an appreciable time interval:DaveC426913 said:You know this leads me to the wild speculation that c is the natural state of the universe, and that only certain exotic particles in the universe - namely those with mass - behave oddly.
I wonder what the universe would look like if we turned it on its head - where c is the natural "rest velocity" and that what we call "rest" is the extreme, where rules break down...
P.A.M. Dirac said:...we can conclude that a measurement of a component of the velocity of a free electron is certain to lead to the result [tex]\pm c[/tex]...Since electrons are observed in practice to have velocities considerably less than that of light, it would seem that we have here a contradiction with expriment. The contradiction is not real, though, since the theoretical velocity in the above conclusion is the velocity at one instant of time while observed velocities are always average velocities through appreciable time intervals. We shall find upon further examination of the equations of motion that the velocity is not at all constant, but oscillates rapidly about a mean value which agrees with the observed value. --- P.A.M. Dirac, Quantum Mechanics - Fourth Edition, p.262, 1958.
DaveC426913 said:Photons are not like tiny rockets speeding to catch up to c. They go as fast as the universe allows.
I said photons travel at c because they have zero (rest)mass. There is nothing wrong with saying that. Point final. Also, i don't agree with what you say above. Because you seem to imply that two objects with equal mass would always travel with the same speed. Why ?So, look at it this way. Objects in the universe move at c - unless they have mass, which causes them to slow down (presumably via interaction with the Higgs field).
I may have underestimated your knowledge of the subject, and was attempting to address what I thought was a misunderstanding on your part. I confess I went a little too far into analogy.marlon said:Huh ? When did i say that photons needed to be accelerated ? Or when did i claim they were tiny rockets ?
This statement seemed to imply that if c changed, light would not, as if light had its own preferred speed, independent of c.If c had a different value, how does light still travel at c then ?
MajorComplex said:If nothing can travel faster than the speed of light, then how do black holes "exist" in our dimension? There's theories on the graviton right? Then shouldn't the graviton be traveling faster than the speed of light if it's strong enough to make light break it's own barrier?