Can someone point me at an explanation of how time differs depending on how fast you travel. Preferably in very simple terms if possible, without the equations etc. Or maybe someone here can help me? Maybe some of you will view this post as some 'smart alec' trying to be clever. Some of you will pity me. Some(most?) even think I'm babbling. But I really want to understand this. (I've been to bed once tonight and can't sleep from trying to work it out!) I've been trying to get my head round this for years.. I'll try and write how I understand it and maybe someone can help me. Note: Some or even all of what follows maybe complete drivel and half truths picked up from TV and radio. Using the clock thought experiment. If you travel away from the clock at the speed of light, the hands of the clock will appear stationary to you. Correct? Ok I understand that. If you travel towards a clock at the speed of light, the hands will seem to be moving twice as fast. Images arriving in your eyes at the speed of light, plus you are moving towards them at the speed of light equals twice the speed of light or time passing twice as quick. Is this good or nonsense? I have also heard that if you travel out into space at the speed of light for one year, many more years will have passed on the planet you came from. I don't get this? Surely, even if this is so, if you return to the starting point, time will 're-adjust' to be in sync again? It's all relative yes? Say we have planet A millions of miles to your left. And we have planet B millions of miles to your right. You are somewhere in the middle. There is a clock on each planet, and you can see both. You also have a clock with you. If you move towards planet B at the speed of light. Time on planet A RELATIVE to you and your motion has frozen? Time on planet B is passing twice as quick RELATIVE to your motion? Time for you remains is constant? Time itself does not change, just the way you perceive it? In different locations? Is this what is meant by relativity? It just depends on how fast you travel and in what direction in relation to the second object? But time really doesn't speed up or slow down in a given space? or do I miss understand? To babble further.. to experience time, you need to have motion. All things in the universe are in motion, so they experience time. If they ceased to move, they would no longer experience time so cease to exist? Also I read of an experiment with two atomic clocks. One was flown round the earth and was slightly out of sink with the other on returning. Can someone explain what this has to do with time? In my mind all it shows is that two counters go out of sink. They are, to me, representations of what we presume time is, and not actually time itself. So can someone explain how they came to the conclusion they did? I presume it has something to do with it being 'atomic' clocks and atomic is somehow linked to time? Sorry to be dense, but I just can't work it out myself. I'm not well educated, so simple examples and "Imagine it like this..." type of stuff please if you can. I'm going to sit here now and see if I get any replies. Might aswell I'm not going to get any sleep! Thanks. PS, where's the search option on these boards, I can't find it?