In this thought experiment, my twin brother and I are both turning 20 at the airport.
At midnight on our birthday, we are both exactly age 20 years.
He stays put while I get on a 777 and fly around the world. The flight takes me 24 hours and so he waits 24 hours. I arrive and we are both age 20 years plus 24 hours.
If I instead get on an SR-71 and fly around the world at 3x speed of the 777, the flight takes me 8 hours so he waits 8 hours. I arrive and we are both age 20 years plus 8 hours. Clearly, we are both younger in this scenario than the first one.
If I got onto a super plane flying at 0.99x light speed and fly around the world, the flight takes me 1 second. Since I’m so fast, he should also only wait one second. Intuitively, I’m back and we’re both 20 years and 1 second old.
But my understanding of time dilation is that I’m 20 years and 1 second old when I’m back, but he would be much older since I was almost going at light speed.
Why is that? My flight and his wait time should both be much much shorter since I was flying much much faster.
In: Physics
>If I got onto a super plane flying at 0.99x light speed and fly around the world, the flight takes me 1 second. Since I’m so fast, he should also only wait one second. Intuitively, I’m back and we’re both 20 years and 1 second old.
General relativity says your example is wrong. For you, the flight takes 1 second as measured by your watch, but to your brother the trip takes lets say 10 minutes, by his watch. Or, if your brother sees the plane fly around the world in 1 sec, for you it’s even shorter. The frame of reference matters, this is why it’s called relativity, because time is not universal, it is relative to where you are when you measure it. It is just not possible to have a single device measure the same time in two places at different speeds. Plus you need to remember that your brother is not standing still, he is on a planet that has also moved hundreds or thousands of miles at the same time, relative to the sun, which is also moving at thousands of miles a second, relative to other suns and so on and so forth. Which is why we can’t have a universal clock or ruler…because time and distance are always measured against something else.
But it’s not just timekeeping devices that are effected, everything literally experiences time differently including the rate of your aging.
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