Confused about time slowing down

[LBrandt]

Again, this is only true for someone at rest with respect to Earth and Planet X.

This will not be true as far as the Traveler is concerned. Remember, the speed of light is a constant relative to any inertial frame. Thus according for the traveler, the two signals travel at c relative to him (not Earth and Planet X). Thus Earth is fleeing away from its signal and Planet X is rushing towards its signal. Planet X gets its signal first, and its clock starts running from the Agreed upon starting value first. By the time that Earth has gotten its signal, quite a bit of time has already past on Planet X.

That doesn't make sense to me at all. Let's forget a traveler for the moment. I can visualize a clock on Earth and a clock on Planet X being set in sync simply by having simultaneous signals sent from a THIRD planet that is equidistant from both Earth and Planet X. Forgetting travelers, forgetting relativity, forgetting everything, I can do that! Surely, you will allow that scenario.

 

[nismaratwork]

That doesn't make sense to me at all. Let's forget a traveler for the moment. I can visualize a clock on Earth and a clock on Planet X being set in sync simply by having simultaneous signals sent from a THIRD planet that is equidistant from both Earth and Planet X. Forgetting travelers, forgetting relativity, forgetting everything, I can do that! Surely, you will allow that scenario.

If you forget relativity then your question is no longer meaningful! You can add an infinite array of intermediate planets, and your "difference" will become smaller and smaller at each step, but it's never eliminated. What you would require is that light not be the upper 'speed limit' at work, and have a means to send signals faster than light. That in essence, removes the entire need for and concept of, Relativity.

 

[granpa]

http://en.wikipedia.org/wiki/Relativity_of_simultaneity

this is what confuses all beginners. Rather than argue with the people here you would be better off taking the time to learn about this first.

 

[Janus]

That doesn't make sense to me at all. Let's forget a traveler for the moment. I can visualize a clock on Earth and a clock on Planet X being set in sync simply by having simultaneous signals sent from a THIRD planet that is equidistant from both Earth and Planet X. Forgetting travelers, forgetting relativity, forgetting everything, I can do that! Surely, you will allow that scenario.

I never said that you couldn't. The problem is that not everyone will agree that the Earth clock and Planet X clock are in sync.

Much of Relativity doesn't seem to make sense when compared to everyday experience.

We expect it to be the same time in Atlanta and New York regardless of whether we are standing along the road between them or driving along the road between them. Relativity says otherwise. It says that if you are driving from one to the other, it will not be the same time in the two cities. We just don't notice it because at the speed of a car the difference is too small to measure.

Relativity requires that we rethink how we consider time and space and toss out some of the notions about it that we got by observing the slow moving world around us.

 

[nismaratwork]

I really think the link I gave to The Elegant Universe's relativity section is a pretty simple and straightforward explanation. *shrug*