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
A simple way to think of it.
You’re always moving through time, t, and space, (x, y, z) at a speed of “10”. You can’t go any faster or slower than 10.
So if you’re completely stationary, you’re moving at a speed of “10”. Broken down it would look like this:
– Moving in the X direction at a speed of 0.
– Moving in the Y direction at a speed of 0.
– Moving in the Z direction at a speed of 0.
– Moving in the T direction at a speed of 10.
0+0+0+10 = 10
Lets say you start moving forward in the x direction.
– Moving in the X direction at a speed of 0.1
– Moving in the Y direction at a speed of 0
– Moving in the Z direction at a speed of 0
– Moving in the T direction at a speed of 9.9.
0.1+0+0+9.9 = 10
Still a constant speed of 10, but because you’ve started moving in the x direction, you’re speed in the T direction has decreased.
So now you can see, the fastest you move in space, the slower in time you move.
If you’re moving at a speed of 6 in the x direction, then you’re speed in the T direction must be 4 – much slower than someone who is stationary.
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