- #1
Cerenkov
- 274
- 53
https://www.physicsforums.com/threads/is-the-universe-a-closed-system.620503/
Hello.
I was looking back at this thread from 2012 and, to be honest, I'm a bit confused.
Quoting Drakkith...
To our knowledge it is. At minimum you could count the observable universe as a closed system because anything outside it will not have had time to affect you locally due to the finite speed of light.
Ok, I understand what he's saying here, but my confusion concerns a process which I naively thought happened in the 'opposite' direction. I had thought that with the expansion of space carrying galaxies away at faster and faster velocities they would effectively 'leave' the observable universe. With this loss of matter and energy from the observable universe I had naively assumed that the observable universe could not be considered to be a closed system.
In a closed system I had thought that nothing could pass across the boundary. Since the observable universe is just a visual horizon and not a true boundary I'm currently confused as to why (and how) the observable universe can be considered a closed system.
Clearly I'm mistaken about something and I hope somebody can help me out here.
Thank you.
Cerenkov.
Hello.
I was looking back at this thread from 2012 and, to be honest, I'm a bit confused.
Quoting Drakkith...
To our knowledge it is. At minimum you could count the observable universe as a closed system because anything outside it will not have had time to affect you locally due to the finite speed of light.
Ok, I understand what he's saying here, but my confusion concerns a process which I naively thought happened in the 'opposite' direction. I had thought that with the expansion of space carrying galaxies away at faster and faster velocities they would effectively 'leave' the observable universe. With this loss of matter and energy from the observable universe I had naively assumed that the observable universe could not be considered to be a closed system.
In a closed system I had thought that nothing could pass across the boundary. Since the observable universe is just a visual horizon and not a true boundary I'm currently confused as to why (and how) the observable universe can be considered a closed system.
Clearly I'm mistaken about something and I hope somebody can help me out here.
Thank you.
Cerenkov.