4 upvotes, 2 direct replies (showing 2)
View submission: Ask Anything Wednesday - Physics, Astronomy, Earth and Planetary Science
What is time? I understand what we as humans say it is and how we experience/label/measure it. But objectively, outside of experiencing it, what is it?
Comment by 8npemb at 26/04/2023 at 17:36 UTC*
11 upvotes, 3 direct replies
According to Einstein’s theories of relativity, time is just another dimension, like up/down left/right forward/backward. This additional dimension gives us a four-dimensional space called spacetime.
Everything moves through spacetime at the speed of light. We aren’t quite sure why, but we understand this to be true with Einstein’s theories. The faster (and we’re talking really much faster) an object moves through space, the slower it must move through time, so that it maintains the same speed through spacetime.
It helped me to think about a car that can only move at a constant speed, say 60 mph. The car is on an infinite 2d plane. The car can move North, East, or some combination of North and East, but still can only move at 60 mph. If the car is moving at 60mph North, it is not moving East at all, and vice versa.
Now switch North with “Time”, and East with “Space”. The car can only move at the speed of light (something like 300,000 km/s). So, it can move completely in the “Time” direction (like a photon would do in a vacuum) or completely in the “Space” direction (or likely a combination of both). The more it moves through space, the less it moves through time.
That’s Special Relativity (without explanations of observers and how it all depends on how you’re actually viewing said car too).
But yeah, time as we understand today is just another axis that we move through. Only difference is that we can’t move backwards through time.
Comment by Fit-Personality-6549 at 18/06/2023 at 00:15 UTC
1 upvotes, 0 direct replies
Damn interesting....
So, idk how to explain properly but time is a dimension.. Just like there are space dimensions there are time dimensions, i mean we live in a world with three space dimensions (x y z axis) and one time dimension... So basically we can only experience time in one direction but if there is an universe with two space dimensions creatures living in it can probably experience time in two directions... I mean they can probably go into past and it would be really normal for them.
(Please ignore it if it doesn't make any sense i haven't slept for so long and my brain ain't working)