relativity

[Zadoc]

Sorry if i sound ignorant, but i have had the theory of reletivity explained to me more than once in different contexts (like the one with the train) and i still dont understand it, could someone please try explain it in the simplest way posible, it ould be most appreciated thankyou

[Loosehead]

OK I'll have a bash.

Your sensations of movement speed etc are only relative to what you see around you. So you are travelling in a car at 30mph, you are only doing 30mph relative to the road. The road is on the surface of the Earth rotating at approx 1000 miles per hour, the Earth is orbiting the Sun at approx 60000 miles per hour, so your speed is only 30mph relative to the road. Let's consider the train, we've all had the sensation of moving when the train next to us is in fact moving, that is because all you can see is the other train, no other reference points so you only realise what is happening when the train has gone and you see the station and you realise that you are in fact stationary.
Does that help? what don't you get? What it is saying, among many other things is that what you see and feel is relative to your view point.

[bernardo]

You may be referring to the more tricky bits of the Theory of Relativity, for example the speed of light is constant, and is the same for every observer.  The mass of an object increases as its speed gets faster.  The length of an object gets shorter in the direction of travel.  In these sorts of tyhings, the mathematical equations are not too complicated.  Somebody once said that the problem with the Theory of Relativity is not with understanding it, but with believing it.

[slimfandango]

Before 'Relativity' they thought that the 'absolute' to which things could be related was absolute rest. Then they realized that this was wrong. At least that scottish inventor, Albert Einstein.

[Bert]

One of Einstein's thought experiments is quite easy to understand.  Suppose it WERE possible to travel at the speed of light.  Suppose you were going away from a clock at the speed of light, while you were looking towards it.  The time you see would stay the  same,  A watch on your wrist would tell you that time was passing, but what you see through the window of your spaceship would stay "frozen in time".