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Duros001 t1_j1i6tn4 wrote

You’re talking about time dilation

Almost an imperceptible time difference, but time is relative so a second will still “feel” like a second, you won’t feel different in the moment. If you start two stop watches and send one to the ISS for 1-2 years and bring it back to earth to compare to the “twin stopwatch”, we’re talking maybe a fraction of a second difference.

Send that stop watch to the very edge of a black holes event horizon and bring it back, we could be talking seconds, days or years, depends on a lot of factors.

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[deleted] OP t1_j1jp7df wrote

[removed]

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TwentyninthDigitOfPi t1_j1jsk7g wrote

The one nit I have is with the very end. It implies that the time dilation at the ISS isn't measurable, but we do have precise-enough clocks to measure it, and have done so.

But overall, it's really impressive!

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musiac t1_j1jwa0l wrote

It's not implying that with the measurable difference line, using measurable in that context is just taken to mean large or significant

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DirtFoot79 t1_j1jpkqq wrote

You are right about the time dialation effect. But you should be aware of how great those effects are. To think the time dialation effect would impact GPS calculations by 10 km a day.

I'm going to copy info from https://www.astronomy.ohio-state.edu/pogge.1/Ast162/Unit5/gps.html#:~:text=As%20such%2C%20when%20viewed%20from,by%2045%20microseconds%20per%20day.

"Further, the satellites are in orbits high above the Earth, where the curvature of spacetime due to the Earth's mass is less than it is at the Earth's surface. A prediction of General Relativity is that clocks closer to a massive object will seem to tick more slowly than those located further away (see the Black Holes lecture). As such, when viewed from the surface of the Earth, the clocks on the satellites appear to be ticking faster than identical clocks on the ground. A calculation using General Relativity predicts that the clocks in each GPS satellite should get ahead of ground-based clocks by 45 microseconds per day.

The combination of these two relativitic effects means that the clocks on-board each satellite should tick faster than identical clocks on the ground by about 38 microseconds per day (45-7=38)! This sounds small, but the high-precision required of the GPS system requires nanosecond accuracy, and 38 microseconds is 38,000 nanoseconds. If these effects were not properly taken into account, a navigational fix based on the GPS constellation would be false after only 2 minutes, and errors in global positions would continue to accumulate at a rate of about 10 kilometers each day!"

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jesselu123 t1_j1izhgq wrote

Black holes event horizon we would talk millions of years for keeping it there for few hours. Its really hard to think tho..

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