I hate this image because idiots will see it, not understand what its showing, and make up some crazy shit based on it.
I hate this image because idiots will see it, not understand what its showing, and make up some crazy shit based on it.
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As I just explained, it's not really about observation, it's about causation. If two objects can never possibly interact, then are they really in the same universe?
Looking out in space is also looking back in time. Anything (roughly) that is further than we can observe in the microwave background would be further back in time than the beginning of time, and therefore doesn't exist at all in our universe. It's a bit brain bending.
So when you say never, do you mean not in the 'lifetime' of our sun, or?
Not till the heat death of the universe.
I guess I don't trust the human understanding of 'never'. It's more like 'we don't currently believe its possible', which has in the past been unreliable.
We'd need to break the speed of light, which isn't possible with our current understanding of physics, but who knows.
I would say yes they are part of the same universe because if you changed your position it would reveal things you didn't see before and mask thing you use to see. Not that that is possible yet, but there are no laws of physics preventing it, only our super short life spans.
That's just it. The laws of physics, at least as far as we understand them, absolutely preclude changing our position in any way that would reveal anything outside our observable universe. Lifespans don't come into it at all. If you lived forever traveling at the speed of light, you would never achieve that change of position.
The cosmic background is the leftover "noise" of the big bang, and we observe it roughly uniformly in every single direction. So where did the big bang occur? Everywhere. Everything that exists is precisely at the center of the universe, right where the big bang happened.
It's all about the concept of spacetime. Spacetime isn't space and time considered together, it's a singular thing that operates by rules that we are ill equiped to comprehend intuitively.
flat earth on a flat universe, MUFA make-the-universe-flat-again
The laws of physics, at least as far as we understand them, absolutely preclude changing our position in any way that would reveal anything outside our observable universe
I do not agree. I don't believe the laws of physics are the limiting factor.
The edge of the observable universe is moving away from us faster than the speed of light from our perspective. (Due to space stretching) So we'd need to go faster than the speed of light to catch up.
You could also use a wormhole to travel to different universes. It 'breaks' the speed of light, so all bets are off.