Originally Posted by vseehua
In Einstein's frameworks, there is nothing that prevents anything from travelling faster from light. It just states that we cannot ever accelerate from 0 to the speed of light. However, it doesn't state that an particle cannot travel natively faster than light.
There are such hypothetical particles known as tachyons, but even if they were to exist information would still not be transmitted faster than the speed of light. General relativity reduces to special relativity in a local sense, but I've routinely read articles (usually re: big bang) which claims that the equations permit space to expand in such a way that two objects, located at a great distance apart, can have a recession velocity greater than the speed of light. Note that this refers to an expansion
of space, not motion through space - so Special Relativity is not violated.
(to see this space expansion thing - assume that the universe expands in such a way that its size is doubled every 1 year. So two planets A and B which were initially, say, 5 light years apart, would now be 10 light years apart. But this took place in the time span of only 1 year. So from the perspective of A, planet B would have receded much faster than the speed of light)
Most 'faster-than-light' phenomena involves 'cheating' in some sense - but information still is not transmitted faster than light. If that were to be the case, cause-and-effect would be literally turned upside down - one immediate consequence would be that the laws of physics would appear different to different observers. Terrible indeed, but so far we have no reason to conclude otherwise.
Originally Posted by vseehua
When you move, your time actually slows in relative to your surroundings, which makes it possible for light to stay at a constant speed however fast that you are moving.
This isn't quite accurate, actually. One of the fundamental postulates of Special Relativity is the universality of the speed of light - that whatever you do, whether you were to travel fast or slow or remain motionless, light will always travel at the same speed. It's taken as an AXIOM, a FUNDAMENTAL TRUTH - and so far that has been well corroborated by experimental evidence.
It's weird and mysterious, isn't it? A good way to understand this is to try comparing the speed of light (which is independent of both source and receiver), to the apparent speed of a ball (which depends on both the speed of the source and receiver), and the way in which sound travels (independent of the speed of the source, but dependent on the speed of the receiver relative to the medium).
re: Al-Bert - If you're serious about picking up Special Relativity, it's actually quite easy (only requires knowledge of Pythagoras' theorem and elementary algebra) - Halliday, Resnick and Walker has a chapter or two dedicated to a gentle introduction on the subject. Special Relativity by A.P. French. is more hardcore, but that happens to be my favourite text.