Guest hasato Posted April 29, 2004 Posted April 29, 2004 Hello to you reading my post. I am new on this forum and I hope someone can explain me something about "my quest" to unrafel the "mysteries" of Time Dilation in "somehow" plain english. I tried to read a lot about this subject on the internet, but one thing remains a mystery to me, and I hope you guys can give me a satisfying explanation Imagine, a atomic clock begin on a jet traveling on 99% lightspeed, and a atomic clock being complety stationary. After some while, when both clocks are together and completely stationary, why is the clock on the jetplane behind? Is it because there is simply no explanation possible, like huge masses "make" gravity...and travelling really "fast": 'just' makes time go slower; or is there a "real" explanation for this? Sorry for my bad english, it is not my first language. I hope someone can explain me this in plain english . Thanks!
swansont Posted April 29, 2004 Posted April 29, 2004 Imagine' date=' a atomic clock begin on a jet traveling on 99% lightspeed, and a atomic clock being complety stationary. After some while, when both clocks are together and completely stationary, why is the clock on the jetplane behind? Is it because there is simply no explanation possible, like huge masses "make" gravity...and travelling really "fast": 'just' makes time go slower; or is there a "real" explanation for this? Sorry for my bad english, it is not my first language. I hope someone can explain me this in plain english . Thanks! [/quote'] Because the speed of light is the same for all observers - this has some strange consequences. Time and distance measurements depend on the frame of reference of the observer; for inertial (non-accelerating) frames, moving clocks appear to run slow. And nobody has a "preferred" reference frame - you can't tell who is moving and who is at rest. In the experiment you describe, the reason one clock ends up slow at the comparison is that it must undergo an acceleration, and this changes its reference frame.
J'Dona Posted April 29, 2004 Posted April 29, 2004 I wonder... I'm not sure if this is related to the first question but it does to the last post. If one person was travelling at, say, 0.9c in one direction, and the other in 0.9c in the opposite direction, and they pass each other, then what would the two see of the other? (bearing in mind that light always appears to travel at c, and the rate at which the other would technically be approaching the other would be 1.8c) I could probably find an example of this in my version of "The Elegant Universe" and I know it can be explained somehow, but I'm at college now... EDIT: Heh, it's my birthday, I finished a 29300 word novella today, and I've got a Numerical Methods class in fifteen minutes, so overall I'm a little happy.
swansont Posted April 29, 2004 Posted April 29, 2004 I wonder... I'm not sure if this is related to the first question but it does to the last post. If one person was travelling at' date=' say, 0.9c in one direction, and the other in 0.9c in the opposite direction, and they pass each other, then what would the two see of the other? (bearing in mind that light always appears to travel at c, and the rate at which the other would technically be approaching the other would be 1.8c) I could probably find an example of this in my version of "The Elegant Universe" and I know it can be explained somehow, but I'm at college now...[/quote'] Here is a velocity addition calculator. For two people at 0.9c, you get a relative speed of 0.9945c
NavajoEverclear Posted April 30, 2004 Posted April 30, 2004 could you explain that reference frame change thing, maybe in different words? It sounded cool, but i dont understand what it means. But it didn't confuse--- because i simply didn't get it (like looking at a math problem that uses functions i haven't learned anything about). Maybe i'm just being stupid, but could you try saying it in another way. Just to be safe (so i don't have to ask again) pretend i'm a grammre school student.
swansont Posted April 30, 2004 Posted April 30, 2004 could you explain that reference frame change thing, maybe in different words? It sounded cool, but i dont understand what it means. But it didn't confuse--- because i simply didn't get it (like looking at a math problem that uses functions i haven't learned anything about). Maybe i'm just being stupid, but could you try saying it in another way. Just to be safe (so i don't have to ask again) pretend i'm a grammre school student. Basically, things don't transform the way we expect - speeds don't add linearly. We don't notice this at low speeds because the difference is so small. But the speed of light is the same for all inertial (non-accelerating) observers. This has some peculiar consequences, including the effect that speeds don't just add together, that time runs slower for someone who is moving, and distances are shortened in the direction of motion. It's not grammar-school material. Physics (and relativity or QM) isn't a simple subject. (BTW I don't think that people who don't "get" this stuff are stupid. But don't expect it to be easy)
Dave Posted April 30, 2004 Posted April 30, 2004 It's difficult to get your head around the concepts, but it comes with time. However the maths in GR looks pretty nasty, so I won't be taking that module next year methinks ;-) (took special relativity this year)
jordan Posted April 30, 2004 Posted April 30, 2004 However the maths in GR looks pretty nasty, so I won't be taking that module next year methinks I thought that Einstein wasn't very good at math and that his equations were pretty simple.
Dave Posted May 4, 2004 Posted May 4, 2004 I thought that Einstein wasn't very good at math and that his equations were pretty simple. It's a common belief that he wasn't good at math - however, he'd had quite a lot of schooling in the field, and believe me, if you look at some of the stuff, you'll understand that he knew what he was talking about.
jordan Posted May 4, 2004 Posted May 4, 2004 If only I could find some of his stuff to look at. It is all too complicated for me to understand, it will take a while for school to kick in enough for me to be able to learn and no one knows enough to teach me right now. I've read a few books on the subject, and all the equations I have seen are pretty simple. Mabey I've only seen the easy ones though.
Ms. DNA Posted May 5, 2004 Posted May 5, 2004 There was a special traveling exhibit on Einstein at the Field Museum in Chicago not too long ago. It featured some of his personal belongs and had demonstrations about certain parts of his theories -- including time dilation, if I recall correctly. Unfortunately, I don't know where that exhibit is right now.
Dov Posted May 7, 2004 Posted May 7, 2004 For a quick grasp and demonstration of speed effect on time dilation see : http://www.fourmilab.ch/cship/timedial.html And if you search "time dilation" by Google you'll have lots of presentations of various aspects...
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