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celebrei
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I was wondering from a physics point of view if it is plausible for the universe to have caused itself to be...
BlackHole213 said:A closed universe is when the universe keeps expanding but will eventually get back to its starting position.
BlackHole213 said:...A closed universe is when the universe keeps expanding but will eventually get back to its starting position. ...
celebrei said:I was wondering from a physics point of view if it is plausible for the universe to have caused itself to be...
Chronos said:... The theory goes that the universe arose from a quantum fluctuation in whatever state existed a prior to that. It is as good as any a priori theory of how the universe arose. ...
Chronos said:In a temporally finite universe, the issue of a beginning is inescapable.
Nope. Self-causality is certainly strange, but it is not illogical. That is to say, there doesn't appear to be any logical contradiction posed by the possibility of self-causation. It is definitely strange, however. In quantum mechanics, one could see loop contributions to Feynman diagrams as being self-caused.DevilsAvocado said:Catch-22
I can’t tell about the physics, but logical it must be – No.
Chalnoth said:Nope. Self-causality is certainly strange, but it is not illogical. ...
Dmitry67 said:No, I can provide an example. "Big bounce" scenarios, for example.
Dmitry67 said:I really don't like the interpretation that Universe "contracted", because it requires some magic event when entropy suddenly decreased.
Dmitry67 said:I think it is much more easier to interpret the contraction as expansion, so entropy decreased all the way down to the BB. It means, that for all observers in such Universe time time flowed FROM the BB, like in ours. So it is a symmetrical double-sided BB.
Why not ask that question for a nuclear decay? How does, for instance, a Uranium 238 nucleus 'choose' one moment to decay as opposed to another?DevilsAvocado said:Okay (warning I just finished a full course at the http://www.youtube.com/watch?v=kQFKtI6gn9Y" ), so how does one explain this 'little' dilemma:
If BB is a single event, and time and space were 'created' at t0 – How is it possible for QM/Feynman diagrams to 'choose' a moment, 13.8 billion years ago, to cause its own 'creation'? If there is No time – there are obviously No moments to 'choose' for a start... right??
Chalnoth said:Why not ask that question for a nuclear decay? How does, for instance, a Uranium 238 nucleus 'choose' one moment to decay as opposed to another?
I merely pointed out that in quantum mechanics, there are a large number of events that are "uncaused" in a sense: they have a certain probability per unit time of occurring, but they don't occur at a certain time because of a certain event.DevilsAvocado said:I think you misunderstood me, and/or vice versa.
Chalnoth said:I merely pointed out ...
Chalnoth said:I merely pointed out that in quantum mechanics, there are a large number of events that are "uncaused" in a sense: they have a certain probability per unit time of occurring, but they don't occur at a certain time because of a certain event.
It's not difficult to imagine that this process might well extend to space-times in quantum gravity.
I don't understand at all what you were getting at.DevilsAvocado said:It’s cool, I misunderstood you. So, any thoughts on the "Feynman-Einstein dialog", right or wrong?
Well, there is a cause in the sense that there are laws of physics which provide the potential for certain interactions to occur, and so they do with some frequency. It isn't difficult to imagine that the same sort of thing might occur for space-times. This isn't the same cause-and-effect relationship, though, as it's not a matter of some event occurring which causes some other event. Instead it's just that X happens because the laws of physics are a certain way. So self-caused is perhaps a somewhat better description than uncaused (e.g. in the instance of a virtual particle, virtual particles appear because they have certain interactions with other bits of matter).celebrei said:Correct me if I'm wrong but quantum mechanics doesn't allow for an event without a cause and even virtual particles occur because the potential for their occurrence is contained in the relevant lagrangian, what QM does allow is a cause w/o necessarily an effect eg: throwing a particle at a barrier may or may not cause it to reflect back
Chalnoth said:I don't understand at all what you were getting at.
Chalnoth said:... This means that we have to find a way of describing the quantum behavior of the system without using either space or time.
If we can discover a way to overcome that particular conceptual hurdle, then maybe it will make perfect sense how a universe could randomly appear out of nothing.
Dmitry67 said:This is why I like MUH - it answers all such questions (by making all them meaningless :) )
Hehe.DevilsAvocado said:Thanks a lot Chalnoth! This kind of extremely interesting information makes me serious wonder if I did chose the wrong occupation...!?
You must keep this forum up to date, in case 'something' happens!
BIG THANKS!
Edit: And it for sure feels reassuring that this was not only a personal 'mad idea'...
Chalnoth said:... Unfortunately, though, I strongly suspect that it will be quite a while before we have a solid quantum gravity theory.
Chalnoth said:... then maybe it will make perfect sense how a universe could randomly appear out of nothing.
celebrei said:I was wondering from a physics point of view if it is plausible for the universe to have caused itself to be...