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Old 09-26-2010, 03:38 PM
 
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I was reading an article based on Einsteins relativity that stated that your head is a few nanoseconds younger than your feet because it is at a higher altitude. A test was done where they placed clocks at different altitudes and found that the higher they were the slower the time went. Manly because they were further away from the central gravity of Earth.

Another note was that if you could travel at 90% the speed of light then 10 years for you would be 1000 years for the rest of us. There is even a video on it that put people on a train that traveled at 90% and when the train finally stopped 10 years later, 1000 years would of went by on Earth. So does that mean if it takes around 5 LY to get to the nearest star at light speed then if you traveled at 90% would you get there sooner or would you somehow slow down to everyone else since for every year 100 years goes by for those not going 90% the speed of light?

Its very confusing for me since the video makes it out that you are traveling through time and if we went that route on a spacecraft then by the time we get to the star 50+ generations on Earth would of went by
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Old 09-27-2010, 12:34 AM
 
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Correct. Einstein really changed the way we think of time. The idea of relativity here is that the velocity of time travel is directly related to the velocity at which an object experiences displacement. If you take two clocks and sync them together. Leave one on the ground while putting the other on in a plane and flying it around the world. And then compare the times, the one that flew around the world will have experienced less passing of time. On this scale you would need very accurate atomic clocks and the variation in time would be incredibly small.

On the other hand, what we call a time line is actually not a straight line. It's a line that in progression forms little loops back onto itself creating the possibility that matter can theoretically revisit a moment in time that has already occurred. This is another theory which is supported by Einstein's own work. This one has not been proved. Further, in order for this theory to be true, the "grandfather paradox" would need be resolved.

This is covered in the most basic physics classes.... or in a conceptual level in a basic HS science class. Interesting stuff really. If this catches your interest, I absolutely recommend taking a physics course for fun. It really is fun when you aren't taking it for a grade.
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Old 09-27-2010, 03:51 AM
 
Location: Ohio
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Wow, that stuff was way beyond me.
Guess I'll just go stand on the roof.
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Old 09-27-2010, 01:47 PM
 
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Here's an article that helps clarify the subject a little better.

Cosmic Log - Relativity affects your age ... just a bit
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Old 09-27-2010, 02:02 PM
 
Location: 10110001010110100
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This aging thing has also got to do with gravity if I am not mistaken. Lack of gravity and high altitude were the main reasons why astronauts who returned Earth from prolonged space voyages looked hardly aged.

Really is interesting stuff. The topic of 'Time' itself is mind-blowing if you really think deep...and since I got a relatively small brain, I refrain from dwelling on the subject.
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Old 09-27-2010, 02:02 PM
 
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Quote:
Originally Posted by NJBest View Post
On the other hand, what we call a time line is actually not a straight line. It's a line that in progression forms little loops back onto itself creating the possibility that matter can theoretically revisit a moment in time that has already occurred. This is another theory which is supported by Einstein's own work. This one has not been proved. Further, in order for this theory to be true, the "grandfather paradox" would need be resolved.
There are views that can bypass the "Grandfather Paradox", assuming parallel universes happen to exist. In such a scenario, you could go back in time and kill your grandfather. However, since you would be in a different parallel universe, the grandfather in that universe could be killed by you because he's not actually your grandfather, but rather a duplicate version of your grandfather. Meantime back in your own universe, your grandfather would still be just fine.
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Old 09-27-2010, 02:30 PM
 
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Originally Posted by TurcoLoco View Post
This aging thing has also got to do with gravity if I am not mistaken. Lack of gravity and high altitude were the main reasons why astronauts who returned Earth from prolonged space voyages looked hardly aged.

Really is interesting stuff. The topic of 'Time' itself is mind-blowing if you really think deep...and since I got a relatively small brain, I refrain from dwelling on the subject.
Gravity seems to have a hand in time differences because objects with mass have gravity wells that warp spacetime. The aging thing also has to do with the relative position of the observers from each other. From the viewpoint of each observer, time seems normal. So the astronaut doesn't feel any difference, nor do the observers on the Earth. But as you accelerate and travel faster toward the speed of light, spacetime becomes stretched. If you look out the window of a spacecraft, or even an automobile on the freeway, things close to you look like a blur, but things distant from you seem to pass by your view more slowly. Meanwhile, inside your spacecraft (or car), time doesn't seem to pass by for you any faster or slower than if you were standing outside. However, that's clearly not the case since your position is in motion. The faster you accelerate, the shorter the amount of time it takes to get between Point A and Point B. This involves Special Relativity, where as stationary objects of different altitudes involves General Relativity. Admittedly, I'm expressing it with extremely simplistic examples.
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Old 09-27-2010, 02:45 PM
 
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Its like back to the future where changing one thing in the past puts you on a completely different time line or universe for that matter.

Also I go to college so taking a physics class for fun seems a bit scary since its at an even higher level than what I took in HS. I could put the class down as a 'fun' class so that my grade in it won't be recorded on my transcript and won't hurt my GPA.

This is a very interesting Though it still makes me wonder.... If you went to a star at 90% would the people on Earth expect you to arrive on the due date or will they receive a reply 100+ years into the future?

What I am saying is will the people on the craft get there before the due date while those on Earth receive the message of arrival on the due date? meaning the the clocks on the craft are saying its a few years to early to of arrived while in reality they did get there sooner...
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Old 09-27-2010, 05:53 PM
 
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Originally Posted by rgomez912 View Post
Its like back to the future where changing one thing in the past puts you on a completely different time line or universe for that matter.

Also I go to college so taking a physics class for fun seems a bit scary since its at an even higher level than what I took in HS. I could put the class down as a 'fun' class so that my grade in it won't be recorded on my transcript and won't hurt my GPA.

This is a very interesting Though it still makes me wonder.... If you went to a star at 90% would the people on Earth expect you to arrive on the due date or will they receive a reply 100+ years into the future?

What I am saying is will the people on the craft get there before the due date while those on Earth receive the message of arrival on the due date? meaning the the clocks on the craft are saying its a few years to early to of arrived while in reality they did get there sooner...
Let's assume the craft can travel at the speed of light. Since the clocks on the craft would be traveling at the same speed at the traveler, the onboard clocks would be relative to the view of the traveler. Presumably those on Earth should be able to reasonably calculate the passage of time and time differences for both the craft and the Earth. From the perspective of those on Earth, after 100 years it would be presumed the craft has made it to it's destination. If the craft sent a message from its destination, it would take another 100 years before the message would be received on Earth, meaning 200 years would've passed by on Earth before the message was received.

In the link I provided above, there's a link to a clever shockwave program that shows relativity. Look for "This old-schoool calculator". You can select a star destination, adjust the speed of the craft (up to 99.99%), and adjust the ages of twins (one is the traveler, the other is back on Earth). The result will show the passage of time for both the traveler as well as those on Earth.
(Requires Shockwave plugin)
NOVA | Einstein's Big Idea | Time Traveler | PBS
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Old 10-07-2010, 12:24 AM
 
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As I get older time seems to go by faster and faster.. Now if I had just any old Starship capable of Warp 1 I'd be happy
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