Wow, this is really sparking some interesting discussion. I'm sure it will take some time to work through the Relativity and FTL FAQ.
There seems to be some disagreement about the question of homogeneity and anisotropy of the universe. As this relates to the existence of a universal center...
Thank you for pointing out that by a Lorentz transformation the total relative velocity is still less than 1c. I guess what's still confusing me is that if there is at least one point in the universe that is completely still, such as the center of the universe, then c is not just relative to two...
The situation could arise in a variety of ways, such as if the ship has no windows, or the instruments for measuring the positions and intensities of nearby stars were disabled. Practically, it wouldn't be that surprising if the situation did actually occur.
Thanks for all you replies!
It makes sense that velocity can only be measured between two objects. However, I am still confused about how the speed of light is an invariant constant. For instance, let's say you're traveling at the speed of light and you turn on a flashlight in the direction...
Let me preface this by saying I know very little about relativity. Last night a friend and I were discussing a particular scenario that will probably arise when humans begin to be capable of interstellar travel. Say you take off from Earth and accelerate to some velocity and then coast until you...