time dilation trouble.

[cameron marical]

this time dilation stuff is just so hard to wrap my head around. i get what the twins paradox says it would do, but i dont understand why it happens. i just dont see how something can age different if its moving at a different speed. please, any help? thanks.

[iNow]

It's not intuitive, so you're not alone when you say that it's difficult to grasp. The simple answer is to remember that the rate at which time passes depends on the observer. Likewise, the length of a meter stick depends on the observer. Different observers see different things and experience the passage of time at different rates.

 

I know your brain really wants to reject it, but it's as simple as that.

 

 

 

I liked these animations when I first saw them. Perhaps they will help add to your understanding. Just be patient with yourself. If you learn a little bit about the process everyday, then eventually one day you will "get it" and be able to explain it to others who are in the same position you are in now.

 

Enjoy.

 

http://faraday.physics.utoronto.ca/PVB/Harrison/SpecRel/Flash/TimeDilation.html

 

http://faraday.physics.utoronto.ca/PVB/Harrison/SpecRel/Flash/LengthContract.html

 

http://faraday.physics.utoronto.ca/PVB/Harrison/SpecRel/Flash/TwinParadox.html

 

 

If you don't grasp what they are telling you the first time, then sleep on it, and try viewing them again tomorrow.

 

 

 

EDIT: Here's one more good one I almost forgot about:

http://math.ucr.edu/home/baez/physics/Relativity/SR/TwinParadox/twin_intro.html

Edited February 14, 2009 by iNow

[NowThatWeKnow]

this time dilation stuff is just so hard to wrap my head around...

 

You are not alone. As many times as I have read about the twins, it still confuses me. I was reading an article just yesterday about time differences between two inertial frames with no acceleration involved. I thought that acceleration is what broke the symmetry between the clocks but now I am not so sure. How else would you know who is traveling and who is at rest?

[swansont]

Time is not an absolute; it is relative. This is a consequence of c being a constant for all inertial observers.

 

No, it's not easy.

[Royston]

C is invariant, there's a brake in symmetry when the travelling twin changes direction...cameron marica, if you want a full description of what that means, I'm more than happy to describe it layman terms.

 

Just to add, it's not a paradox, it's only called as such, because it goes against common sense, i.e Galilean physics.

Edited February 14, 2009 by Snail

[NowThatWeKnow]

C is invariant, there's a brake in symmetry when the travelling twin changes direction...cameron marica, if you want a full description of what that means, I'm more than happy to describe it layman terms...

 

More then just cameron would benefit from you (or anyone else) putting it into layman terms. Two frames are doing the same thing relative to each other so what determines which twin stays younger? It seems that acceleration, deceleration and gravitational potential are the only differences to be considered. I recently read where the clock speed differences are consistent during a trip and do not happen at one point.

Edited February 14, 2009 by NowThatWeKnow

[Janus]

this time dilation stuff is just so hard to wrap my head around. i get what the twins paradox says it would do, but i dont understand why it happens. i just dont see how something can age different if its moving at a different speed. please, any help? thanks.

 

It comes down to how you view "time".

 

Let's try an analogy.

 

Start with two men standing at the same point on a featureless plane. They start walking in the same direction at the same speed. Now let's say that the direction they are walking is in the direction of "time". IOW, since they are walking in the same direction at the same speed, they are progressing through time at the same rate and aging at the same rate.

 

Now assume that Man B turns and starts walking in a slightly different direction than Man A, but still at the same speed. What happens to Man B's progress through time?

 

Well according to Man A, who judges progress through time as being in the direction that he is walking, Man B is falling behind and is progressing more slowly through time (aging slower).

 

But, according to Man B, he judges progress through time as being in the direction that he is walking, and it is Man A, that is falling behind and aging more slowly.

 

This is one of the standards of Relativity, there is no absolute time, but each frame judges time independently.

 

Now assume that Man B changes direction again so that his new path intersects that of Man A.

 

Again, according to Man A, Man B still progresses through time more slowly than he does and according to Man B, it is Man the progresses though time more slowly.

 

When Man B crosses the path of A, he turns and walks in the same direction as A, but is behind him( younger then him). But if according to him, A aged more slowly than he did while they were walking, then he should be ahead of A and older than him.

 

This is the Crux of the "Twin Paradox".

 

What this ignores is what happens to Man A according to Man B when he makes that second turn. When he turns, Man A's position in time shifts. According to Man B, A starts out behind him, but ends up ahead of him after the turn. (imagine you are standing with an object to your left and slightly behind you. Slowly turn to your left. The object, from your perspective, will move to being in front of you).

 

A then continues to progress more slowly through time until the paths intersect, but will have gained so much time during the turn, that when B reaches A's path, B will still be behind A.

 

Thus both A and B agree that during the total elapsed period, B ages less than A,

 

They will not however, agree on who was aging faster at any point in the trip, only that the combined effects led to the same result.

 

According to each man, nothing happened to alter his own progress through time and all alterations in time rate happened to the other guy.

[cameron marical]

ok, that makes sense, mostly. what about us on earth? what speed are we travelling and what declares that? is it the earths speed? does the earth have a speed? or is it every single different person varies judging by how their own bodys{referance frames} speed through space? i know this isnt really testable because no one here goes any where near the speed of light, but just curios. i guess this is kind of a crappily worded queston, but i cant think of any other way to ask it. and if earth does have a speed and thats what we are judged by{if that makes sense} then if whe lived on a faster traveling planet would we age slower?

[swansont]

ok, that makes sense, mostly. what about us on earth? what speed are we travelling and what declares that? is it the earths speed? does the earth have a speed? or is it every single different person varies judging by how their own bodys{referance frames} speed through space? i know this isnt really testable because no one here goes any where near the speed of light, but just curios. i guess this is kind of a crappily worded queston, but i cant think of any other way to ask it. and if earth does have a speed and thats what we are judged by{if that makes sense} then if whe lived on a faster traveling planet would we age slower?

 

Speed is always measured with respect to something. So when you ask the question, you have to specify that.

[cameron marical]

both the men would stay the same age, no matter how fast they go, or how fast they stop.

 

 

 

i know, this is the opposite of what relativity says, but the best way to learn things for me sometimes is when i lose to an argument, so im just saying this so someone goes and explains the reason why not.{it worked with the first post i put on here}

[swansont]

I suggest using the search function for other threads on the twin paradox, since it's been explained dozens of times.

[iNow]

There's also always the list of related/similar threads shown down at the bottom left of the page.

[cameron marical]

how did einstein possibly come up with this?

[iNow]

Lots and lots and lots of concentration, effort, creativity, and years of study. It also helped that he was around other great minds to challenge, correct, and guide him when needed.