In my undergrad physics course we were taught the basics of relativity. It was explained to us that something moving near the speed of light can somewhat time travel when compared to a stationary observer. So, how much younger would [Astronaut Koch](https://www.google.com/amp/s/amp.usatoday.com/amp/4676940002) be than us and how does this phenomena work?
In: Physics
The ISS experiences about 0.007 seconds less time for ever 6 months. Or about 14 milliseconds a year.
It all stems from the speed of light being the same in all reference frames. Normally if you run in the same direction as a bicyclist is cycling they will seem slower, and if you run in the opposite direction, they will seem faster.
This isn’t true with the hard cap on lights speed. If you run toward light or away from some massless particle at light speed, it doesn’t go faster or slower.
So while that car going 20mph is going 25 mph relative to you if you run at it 5mph, and it is only going 15mph relative to you if you try and Chase it, light will always be going light speed no matter how fast you Chase it or run from it
The only way this can happen is if time itself is happening differently for both you and that massless light
This has been confirmed as real and not math errors, as gps systems and the like need to account for it to work, otherwise they’re off.
I’m sorry I didn’t do a great job, I just don’t think there’s a truly eli5 way for this. You just have to accept some stuff because the human experience has no real reference for near lightspeed so it doesn’t make sense to our brains. It’s like trying to tell a turtle that’s only ever lived in a sheltered cave about how when you run really fast you have to take wind resistance into account, but it doesn’t really matter if you’re just plodding along. He will have no real experience with it.
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the basic premise is that when you move faster, in order for the speed of light to remain the same, time has to slow down. this is because space and time are related (space-time continuum). The actual amount of time dilation experienced at orbital speeds is very low, so low that you’d never tell the difference.
Well, there is a time dilation that can happen because of gravity, and one that happens because of speed. Though i cant tell you when a significant change will be, the ISS does not have a significant change, atleast not one that cant be properly adjusted for. In 6 months the ISS will lag 0,007 seconds behind earth, which would only mean shes 1/700th of a second younger after a year in space.
Space is not empty. What to us appears as nothing more than a dark, empty void; is actually a construct, a facade held fast by the goings-on at a quantum level – Where the seeds of our macro universal constants and laws of euclidian physics take root – the very threads of space, woven to those of time.
The two are inseparable by all but a few catalogued types of events.
And so; spacetime.
Space is elastic, it can be pulled and pushed and distorted to extremes. Near the center of a celestial object – star, planet, moon, etc – space is gathered tighter together; literally pulled together by the mass of an object.
The tighter space is squeezed, the faster time proceeds (to an outside observer, anyway). The further you get from an object’s center of mass – As space “loosens it’s slack” – Time moves slower.
Over the unimaginable distances of the cosmos, those heavy little “clouds” of contracted space exist at a slightly faster rate than the surrounding, dilated space; and that’s just fine.
It’s important to remember that time looks different to observers in differently dilated space. Even on the surface of the Earth, gravity (and thus, time) is not perfectly spherical. Earth’s gravity, for example, exists as peaks and troughs.
So, the local progression of time for you, might be infinitesimally faster or slower than time for an observer elsewhere. So small in fact, that you wouldn’t ever notice it with your natural senses.
The miniscule differences will never matter to current day astronauts, much beyond the fact that the temporal inconstancies are indeed numerically quantifiable.
This one took me a really long time to grasp but of everything I’ve seen [Minute Physics](https://www.youtube.com/watch?v=0iJZ_QGMLD0) had the best visual explanation of what is going on.
>So, how much younger would Astronaut Koch be than us and how does this phenomena work?
The faster you go, the slower your clock runs (according to others), and the higher you are up out of a gravity well, the slower your clock runs (again, according to others). However, these effects are more or less negligible at ISS orbital speeds and altitudes.
You are basically asking the same question as the Twin Paradox. If you send one away quickly in a rocket ship and after some time, the rocket turns around and comes back. The traveling twin would be younger.
[This Wikipedia article](https://en.m.wikipedia.org/wiki/Twin_paradox) does a pretty good job at explaining. Some of it is dense and not really ELI5, but it’s pretty good explanation.
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