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Old 07-24-2019, 02:11 PM
 
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In the movie Interstellar, an astronaut traveled to another star at near light speed and later returned to earth to see his daughter older than he was. I understand space/time can bend/curve to accommodate light speed. However, I don't see how traveling near light speed can slow the aging process. Time can move fast or slow but a person's biological aging is an entirely separate thing. Once born, human beings march toward death/entropy at their own internal clock.

Since this aspect of time dilation has not been tested at all (we haven't sent humans in a spacecraft capable of near light speed travel), how do we know this is the way it works? Someone educate me please.

Last edited by davidt1; 07-24-2019 at 03:36 PM..
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Old 07-24-2019, 02:50 PM
 
Location: Seattle
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It didn't slow the aging process. Due to time dilation, the astronaut's frame of reference just had a different flow of time compared to the daughter's. This happens with real astronauts on board the ISS, although the age difference there is tiny. GPS needs to compensate for the effect of gravitational time dilation, for example.
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Old 07-24-2019, 03:22 PM
 
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Originally Posted by rjshae View Post
It didn't slow the aging process. Due to time dilation, the astronaut's frame of reference just had a different flow of time compared to the daughter's. This happens with real astronauts on board the ISS, although the age difference there is tiny. GPS needs to compensate for the effect of gravitational time dilation, for example.
Thanks but I not am getting what you are saying. The GPS thing I get. The age thing, no. If we wake up tomorrow to an earth that orbits sun ten times slower and rotates ten times slower, time would seem a lot slower but that would not let us live longer.

Last edited by davidt1; 07-24-2019 at 03:34 PM..
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Old 07-24-2019, 04:15 PM
 
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Quote:
Originally Posted by davidt1 View Post
Thanks but I not am getting what you are saying. The GPS thing I get. The age thing, no. If we wake up tomorrow to an earth that orbits sun ten times slower and rotates ten times slower, time would seem a lot slower but that would not let us live longer.
Time is affected by both speed and gravity. The faster an object moves, the slower time moves for that object. The stronger a gravitational field is the more slowly time moves.

Now for two people who are standing still, time moves at the same rate for both of them. But if one person starts walking and the other person continues to stand still, time moves more slowly for the person who is walking than for the person standing still. Because time is moving more slowly for the person in motion, he ages more slowly than the person who is standing still.

Similarly, a difference of one foot of altitude produces a measurable difference in the rate at which time passes. The higher you go the weaker gravity is and therefore the faster time moves. This is discussed in the article below.

https://www.livescience.com/8672-higher-faster-age.html

If there was no time you wouldn't age. Therefore, due to relativity, the person for who time is moving more slowly ages more slowly than the person for whom time is passing more quickly.
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Old 07-24-2019, 05:00 PM
 
Location: Seattle
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Originally Posted by davidt1 View Post
Thanks but I not am getting what you are saying. The GPS thing I get. The age thing, no. If we wake up tomorrow to an earth that orbits sun ten times slower and rotates ten times slower, time would seem a lot slower but that would not let us live longer.
If the person on Earth could watch the astronaut through a video feed, the astronaut would be moving very slowly. But from the astronaut's perspective, he is just moving about normally. It's like they are living in different universes with different time flows -- their own frames of reference. They each perceive they are aging normally, but see the other person as aging at a different rate.
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Old 07-24-2019, 05:02 PM
 
Location: Somewhere in northern Alabama
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Quote:
Originally Posted by davidt1 View Post
Thanks but I not am getting what you are saying. The GPS thing I get. The age thing, no. If we wake up tomorrow to an earth that orbits sun ten times slower and rotates ten times slower, time would seem a lot slower but that would not let us live longer.
Try thinking of it this way: We have experiential proof that clocks moving at increased physical speed while in orbit and then returned to Earth show as having run more slowly than identical clocks on Earth. Got that firmly in mind? Now think of those clocks being like old alarm clocks, ticking away the seconds. During the time in orbit the ticking is just a little slower. The same happens to the human heartbeat, as well as all the biological processes that make up aging.

The experience of time is a local phenomena, not a universal one. There is no standard universe clock that says it is now Blibbiddy billion years since the beginning of time at all points in the universe. "Now" is relative.

As for "Interstellar," that was a boring and not very good movie that lasted an eternity.
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Old 07-24-2019, 06:53 PM
 
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So if earth rotates or orbits the sun at near light speed, everyone would age very slowly?
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Old 07-24-2019, 07:12 PM
 
Location: Denver CO
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Originally Posted by davidt1 View Post
So if earth rotates or orbits the sun at near light speed, everyone would age very slowly?
They would age slowly relative to someone who was not on earth and was moving slower.
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Old 07-24-2019, 07:20 PM
 
Location: Upstate, NY
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Whenever I encounter a reference to this subject of think of a sci-fi novel by Joe Haldeman, The Forever War. I was a teenager when I read it but it really made an impression. In this text the main character travels throughout the universe as a soldier. When he returns to Earth everything has changed, years have passed. But he has only aged briefly.

https://en.m.wikipedia.org/wiki/The_Forever_War
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Old 07-24-2019, 11:27 PM
 
Location: Seattle
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Originally Posted by Joey2k View Post
They would age slowly relative to someone who was not on earth and was moving slower.
Okay, so part of the weirdness that is special relativity is that the people on this rapidly moving Earth would perceive the near motionless observer as also aging more slowly than they. What produces a net change in age is the differences in the acceleration history of the two observers. If the Earth were to decelerate and return to the near motionless observer before stopping, it has a different acceleration history than the motionless observer and would appear to have aged less. Gravitational acceleration has the same effect.

In a thought experiment it's called the "twin paradox".
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