
cartrite
john Van Vliet wrote:my understanding was there was an honest "oops "
dealing with the relativistic change in speed in the GPS timing satellites there was a aprox. 80 to 100 ms difference that was not taken into account
MiR wrote:...
What I actually meant, however, is, that there must be still a possibility at all in our - virtually unexplored - universe. Just maybe a mathematical solution what an option opened to be faster than light.
...
Michael
Wiki wrote:In modern physics, the notion of causality had to be clarified. The insights of the theory of special relativity confirmed the assumption of causality, but they made the meaning of the word "simultaneous" observer-dependent.[6] Consequently, the relativistic principle of causality says that the cause must precede its effect according to all inertial observers. This is equivalent to the statement that the cause and its effect are separated by a timelike interval, and the effect belongs to the future of its cause. If a timelike interval separates the two events, this means that a signal could be sent between them at less than the speed of light. On the other hand, if signals could move faster than the speed of light, this would violate causality because it would allow a signal to be sent across spacelike intervals, which means that at least to some inertial observers the signal would travel backward in time. For this reason, special relativity does not allow communication faster than the speed of light.
But here's the short description...
Imagine: not far from our planet (in my example 24 light years away) ignites a new star. The light needs 24 years until we can see it on earth. Well situated - across from the earth - an exoplanet, also 24 light years away from the new star. Also on this exoplanet light takes 24 years.
Accordingly, the speed BETWEEN the first light waves (photons) which reaches Earth and exoplanet exactly after 24 years must have twice the normal speed of light. (This is the mathematical option I was talking about...)
I think what Michael may be suggesting is that the photons would pass each other at a realatibe speed of twice the speed of light (like 2 cars traveling at 60mph in opposite directions have a relative speed of 120mph), however this does not break any physical laws.Fenerit wrote:Accordingly, the speed BETWEEN the first light waves (photons) which reaches Earth and exoplanet exactly after 24 years must have twice the normal speed of light. (This is the mathematical option I was talking about...)
If the Earth is in the middle, the exoplanet is at 48 ly (2 x 24 ly) from the sun; while if the sun is in the middle, then both are at 24 ly and the statement above doesn't make sense; since it seem confusing a numeric variable with a measure.