# How does brain perceive time dilation due to gravity?

Einstein's General Relativity says gravity warps spacetime. Consider a hypothetical scenario:

1. A person travels into space from Earth.
2. He landed on a different planet in some far off galaxy where time runs slower than Earth. 1 hour on that planet is about 7 years on Earth. The person does not know anything about time dilation or relativity, so he's not aware that gravity slowed down the time.

I was wondering how that person's mind will perceive time. Does the brain think that lot of time has passed but in reality only 1 hour passed? Or is it like, the brain also slows down and adapts to time dilation?

• What dilation? I didn't notice any! Commented Jul 24, 2020 at 2:28
• See my answer to a related question at physics.stackexchange.com/a/491227/109928. Bottom line: it is misleading to think of time as "slowing down". Commented Jul 24, 2020 at 14:19

This is a common confusion thinking that there is such thing as a "real" amount of time. Time literally runs slower. The brain will think that an hour has passed, and an hour will have passed at that location. Saying "in reality 7 years passed" is incorrect. "7 years passed on Earth" would be correct.

All physical processes will slow down in that gravity well; all clocks will run slow. Since the brain contains physical processes (chemical reactions, electrical impulses, etc.) these will run slow too and for this reason, a person in that gravity well who looks at their wristwatch will not be able to detect the fact that it is running slow, because their brain is too.

• Isn't it more correct to say all processes will slow down relative to an observer not in the gravity well or in a different location within that well, but not in any absolute sense of slowing down? None of these three observers will notice any difference in the passage of their time. Commented Jul 23, 2020 at 20:28

Our brain is a bad device to measure time. Depending on several conditions we feel that time passes slowly or fast. And it happens in a gravity well or not.

That is why clocks were invented, and small differences as that caused by gravitational wells need very precise clocks to be detected.

• No, our brain is good for measuring time because we know about time dilation now. And it was first mentioned by a brain only (which was Einstein's brain). Commented May 20, 2023 at 6:23

I don't think that you would notice anything differently. Time dilation would also affect the speed at which your brain signals would comprehend your surroundings. You would notice physical differences in gravity being different from earth, which may make things gravitate faster or slower depending on the strength of gravitational pull, which should not be confused with the minds ability to experience time dilation.

• This answer was already given. Commented May 6, 2023 at 7:43