Consider two concepts: "simultaneous", and "stationary". They mean the same thing, but with the roles of time and space swapped. "Simultaneous" means "same time, different places". "Stationary" means "Same place at different times".
Ok.
Let's say you and I are out in space, drifting past each other at walking pace. From my POV, you are drifting south; from yours, I am drifting north.
Lets say I hold out a wrench and release it. From my POV, it is just hanging there in space. It is stationary. From your POV, it is not stationary at all, but drifting north at walking pace. In other words, I think you are wrong. You are saying "it's moving", when any fool can see that it isn't. But I can calculate how it looks to you.
(It's worth noting that we only disagree as far as motion along th north/south axis goes. We agree perfectly about whether somethings east/west motion is zero or not.)
Special relativity ca be viewed like this: not only does relative motion cause us to disagree about "stationary", it also causes us to disagree about "simultaneous". What form does that disagreement take? If I shine a beam of light southwards, it will travel at c. But you (who are moving south), will not see it as having velocity c-v, because you are wrong about how time is moving. Amazingly, your misconceptions about space and time will cancel out, and you too will see the beam travelling at c, albeit for the wrong reasons.
Of course, for you the situation is the converse - and there is no way to say that either of us is right..
Ok.
Let's say you and I are out in space, drifting past each other at walking pace. From my POV, you are drifting south; from yours, I am drifting north.
Lets say I hold out a wrench and release it. From my POV, it is just hanging there in space. It is stationary. From your POV, it is not stationary at all, but drifting north at walking pace. In other words, I think you are wrong. You are saying "it's moving", when any fool can see that it isn't. But I can calculate how it looks to you.
(It's worth noting that we only disagree as far as motion along th north/south axis goes. We agree perfectly about whether somethings east/west motion is zero or not.)
Special relativity ca be viewed like this: not only does relative motion cause us to disagree about "stationary", it also causes us to disagree about "simultaneous". What form does that disagreement take? If I shine a beam of light southwards, it will travel at c. But you (who are moving south), will not see it as having velocity c-v, because you are wrong about how time is moving. Amazingly, your misconceptions about space and time will cancel out, and you too will see the beam travelling at c, albeit for the wrong reasons.
Of course, for you the situation is the converse - and there is no way to say that either of us is right..
