Elegant Universe Question

[danny8522003]

I'm reading The Elegant Universe at the moment and it states that as people with clocks travel past each other at a significant constant velocity, they BOTH see each others clocks slow down.

 

This makes complete sense in that everything is relative etc, but i dont see how BOTH can be correct. Hopefully one of the experts can clear this up for me .

 

Cheers,

Dan

[RyanJ]

I'm reading The Elegant Universe at the moment and it states that as people with clocks travel past each other at a significant constant velocity' date=' they BOTH see each others clocks slow down.

 

This makes complete sense in that everything is relative etc, but i dont see how BOTH can be correct. Hopefully one of the experts can clear this up for me .

 

Cheers,

Dan[/quote']

 

Both are correct because they have different reference frames, the time in one reference frame is the combination of the space and the time of another and vice versa so both are actually correct

 

I;m actually bad at explaining these things in a meaning ful way so maybe the physics experts here had better give it a shot

 

Cheers,

 

Ryan Jones

[5614]

I look at you, see that you're moving quickly so also see that your clock is moving slowly.

 

You look at me, see that I'm moving quickly so also that my clock is moving slowly.

 

Just like I think it is you coming towards me and you think that it is me coming towards you... I think that your clock is slow and you think that my clock is slow.

 

=====

 

If it is still unclear then what exactly is your problem?

 

Does the analogy:

 

My clock says 10pm... your clock says 10:01pm so I think you're fast and you think I'm slow

 

help?

 

Or is your problem about how both clocks can both be slow?

[danny8522003]

Yea, i dont understand how BOTH clocks can be slow. I think i vaguely understand it, using an anology used in the book.

 

Don't think i was looking at it in a relativistic enough maner, thanks for the help!

 

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Although it seems as though both clocks would say 10pm and we'd both argue we were slower than each other, but i think i understand it now.

[guardian]

Another way to put it is - you're using 2 reference frames to come to the conclusion that both clocks are slow. You're mixing reference frames. If you pick one reference frame though you'll find that the clock (that's not with you) is slow and yours is just fine and vice versa (from the other reference frame). SO from 1 reference frame both clocks ARE NOT SLOW.

[Meti]

What the author is trying to communicate is the idea that the faster something moves in the three spatial dimensions, the slower time passes from the perspective of an outside party (to better understand this idea, read the thread entitled "New Idea" - I believe my post explains why this occurs). So, to *you*, your clock is moving perfectly - since it is moving at your speed. The *other* person, however, is moving quickly relative to you - so, the reason his (or her) clock would be slow has nothing to do with the way light travels, but time. They are moving fast, so their clock marks time slowly, as time passes slowly at high speeds.

 

So, while *your* clock actually says 10:01, and the *other* person's says (as *you* see it) 10:00.

But, at the same moment, to the *other* person, *your* clock says 10:00; and their clock (to them) says 10:01.

But from the point of view of a stationary third party, both clocks would read the exact same time: 10:00.

 

To each of the moving people, the other person's clock is moving slowly. Since both people are moving, both people's clocks show time slowly to the other person.

 

It can be said that each individual person's clock is moving correctly and slowly; it just depends on the point of view of the observer.

 

That should just about cover it. I hope I made it clear; it is a rather difficult thing to comprehend since most people's minds are developed with a rigid structure of rules and ideas; making it difficult to understand such abstract and bizarre concepts.

 

(btw, TEU is a wonderfully entertaining book, I hope you enjoy it)

 

~Meti