eli5 What do we know about what’s outside the observable universe?
In: 0
We know nothing, but we can surmise it’s similar to the observable universe in density temperature and distribution (‘flatness’).
Absolutely nothing. The definition of “the observable universe” is everything we are capable of knowing about.
Unless we invent faster than light travel it is forbidden by the laws of physics to ever know anything about what is outside the observable universe.
The reason why we assume there is anything out there is because all of our theories of physics expect that we live in a small corner of a bigger universe. Additionally, the observable universe grows over time and we haven’t seen anything resembling an edge.
The reason why an “observable universe” exists at all is that it takes time for light to travel. The observable universe is simply everything where the light has had time to reach us.
We can’t know anything, that’s the entire point of it being outside the observable universe. Its impossible to observe. Now that limit might be moved back in the future, but at that point it won’t be unobservable anymore. We can’t know anything and we can never know anything, other than assumptions.
As far as we know, everything outside of the observable portion of the universe is exactly the same (on average) as everything we can observe.
There is nothing to indicate that our small observable portion is special, different, or unique; we just happen to be here and able to observe it.
We can’t observe anything first hand. But we know there is mass out there because it has an effect on things we can see at the edge of the observable universe. We also know that space is expanding outside the observable universe again for similar reasons.
It’s also theoretical possible due to the expansion of space that some objects which are now outside the observable universe left traces of their existence at the edge of the boundary before they moved outside. And those things might be possible to observe.
On a similar note, the things at the very edge of the observable universe now will at some point be outside the observable universe. And therefore anything we learn about them now would be considered known things from outside the observable universe.
Latest Answers