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Understanding an example

Rusty
Posts: 2,109
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8/3/2010 8:07:31 PM
Posted: 6 years ago
Could someone please explain the bold words for me? I'm not trying to challenge anything, I genuinely don't understand the part.

"Einstein came up with an example to show the effects of time dilation that he called the "twin paradox." It's a lot like the Time Traveler game you just played. Let's try it out with a pair of pretend twins, Al and Bert, both of whom are 10 years old in their highly futuristic universe.

Al's parents decide to send him to summer camp in the Alpha-3 star system, which is 25 light-years away (a light-year is the distance light travels in a year). Bert doesn't want to go and stays home on Earth. So Al sets out on his own. Wanting him to get there as quickly as possible, his parents pay extra and send him at 99.99 percent the speed of light.

The trip to the star and back takes 50 years. What happens when Al returns? His twin brother is now 60 years old, but Al is only 10 and a half. How can this be? Al was away for 50 years but only aged by half a year. Has Al just discovered the fountain of youth?

Not at all. Al's trip into space lasted only a half year for him, but on Earth 50 years passed. Does this mean that Al can live forever? Nope. He may have aged by only half a year in the time it took 50 years to pass on Earth, but he also only lived half a year. And since time can slow down but never goes backwards, there's no way he could grow younger."


Okay, so here's what I don't understand. If the round trip measures fifty light-years in distance, and Al's traveling at almost the speed of light, shouldn't it feel like fifty years to him? I'm just not grasping the concept.

Thanks ahead of time.
mattrodstrom
Posts: 12,028
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8/3/2010 8:26:52 PM
Posted: 6 years ago
the time it takes for something to happen is Relative to the place from which you're observing it.

they put atomic clocks in jets or space-ships made em go REAL fast and found that the clocks in space slowed down relative to the clocks on Earth.

so... if they went EVEN FASTER (or further away) and came back then they'd go even slower (relative to the clocks on earth) though from the astronauts perspective time would pass normally.

It helps A LOT if you begin to think of space and time as being INTIMATELY related... essentially our interpretations of ONE thing The Space-Time Continuum!!!. Then you can see why the Space conditions would affect the Time conditions...
"He who does not know how to put his will into things at least puts a meaning into them: that is, he believes there is a will in them already."

Metaphysics:
"The science.. which deals with the fundamental errors of mankind - but as if they were the fundamental truths."
Korashk
Posts: 4,597
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8/3/2010 8:28:30 PM
Posted: 6 years ago
Simplest terms:

The faster you go the slower time goes, but only for those that are going fast.
When large numbers of otherwise-law abiding people break specific laws en masse, it's usually a fault that lies with the law. - Unknown
Floid
Posts: 751
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8/5/2010 12:46:18 PM
Posted: 6 years ago
Check out this link:

http://www.scribd.com...

This is a chapter out of Feynman's Lectures on Physics. It gets a little deep (I think the link is about 11 pages) and didn't read all the way through it to see if it left out important information that led up to this section, but he does an excellent job of illustrating exactly what happens in special relativity. For me it is one of those things you have to read a few times to real grasp, as I have read that section in my copy of the lectures numerous times (and on the rare occasion I start thinking about relativity for whatever reason I usually go back and read it again).
Rusty
Posts: 2,109
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8/5/2010 1:30:06 PM
Posted: 6 years ago
At 8/5/2010 12:46:18 PM, Floid wrote:
Check out this link:

http://www.scribd.com...

This is a chapter out of Feynman's Lectures on Physics. It gets a little deep (I think the link is about 11 pages) and didn't read all the way through it to see if it left out important information that led up to this section, but he does an excellent job of illustrating exactly what happens in special relativity. For me it is one of those things you have to read a few times to real grasp, as I have read that section in my copy of the lectures numerous times (and on the rare occasion I start thinking about relativity for whatever reason I usually go back and read it again).

Alright, thanks. Don't have time to read that right now, but I'm definitely going to check it out later. =)