The Origin of the Universe: Scientific Theory or Hypothesis?

[revo74]

Layman here

Is the notion that our universe derived from a fluctuation which took place in a quantum vacuum scientific theory or just a hypothesis? I tend to believe the later, yet there are many scientists(particular motivated atheists) who talk about it as if it is scientific theory. Can some of you please expand upon this. Thanks!

 

[revo74]

55 views and no posts?

 

[Chronos]

The quantum fluctuation hypothesis has been around for a number of years. The confounding part is quantum fluctations are a property of empty space - which did not exist pre-bigbang.

 

[Chalnoth]

The quantum fluctuation hypothesis has been around for a number of years. The confounding part is quantum fluctations are a property of empty space - which did not exist pre-bigbang.

Well, it did if our universe stemmed from a fluctuation within a pre-existing universe.

 

[K^2]

Is the notion that our universe derived from a fluctuation which took place in a quantum vacuum scientific theory or just a hypothesis?

It's silliness. You need space for there to be vacuum and vacuum for there to be fluctuations. Having space would mean we are already talking about the universe after it started. Actually, talking about before/after implies it's after the universe started, since space and time are in it together.

Universe just is. We can talk to some degree about physics at the end point, but we cannot talk about "before" the big bang, since that's like asking what was before time. If there was no time, there was no "before".

 

[Chalnoth]

It's silliness. You need space for there to be vacuum and vacuum for there to be fluctuations. Having space would mean we are already talking about the universe after it started. Actually, talking about before/after implies it's after the universe started, since space and time are in it together.

Universe just is. We can talk to some degree about physics at the end point, but we cannot talk about "before" the big bang, since that's like asking what was before time. If there was no time, there was no "before".

This line of thinking presumes that the beginning of our region of space-time was the beginning of all space-time. We do not know this. In fact, I suspect that it is almost certainly not the case.

 

[Tanelorn]

Chalnoth me too. In fact I have a problem with inhomogeniety in the dimension of time in general.

 

[Lobar]

I had no problem with quantum fluctuations being the cause of the Big Bang. I always just thought that perhaps the quantum vacuum could have been the ordinary state of the pre-universe or outer universe. An infinite state with no beginning.

But I want to know, as with my thread that I started before, what the chances of us being Boltzmann Brains instead of being in the universe we observe? Would I have to look to another answer for the origins of the Big Bang? I always thought quantum fluctuations were a very good answer to that question until I read about Boltzmann Brains.

Anyone want to help me?

 

[K^2]

This line of thinking presumes that the beginning of our region of space-time was the beginning of all space-time. We do not know this. In fact, I suspect that it is almost certainly not the case.

That doesn't solve the problem. It just shifts it to some more global scope.

Or are you trying to imply something along the lines of an infinite universe around us, with matter and inflation being a local phenomenon? In that case, it sounds like an incredibly unlikely fluke to get all that matter out of a fluctuation in infinite space. Then again, with infinite space and time, it's bound to happen somewhere, and by virtue of requiring it to exist, we'd be here at the right moment in the right place.

But the universe just being it is a far simpler and more elegant solution. By principle of least assumption, I'd go with that.

Take a blank region of space-time with some arbitrary zero-fields, decompose these into a superposition of spherical expanding waves, and pick one of these to be your universe. Presto, big bang and all existence out of precisely nothing.

Not that there is any point in discussing this, since this is by very definition outside of realm of Physics.

 

[Chalnoth]

But the universe just being it is a far simpler and more elegant solution. By principle of least assumption, I'd go with that.

This is false, though. Think of it this way: it is much, much easier to completely define the set of all integers than it is to define a specific subset of the integers. It may seem a bit odd, but it is actually simpler, in mathematical terms, to have a prolific universe than to have just one universe (ours).

There's also no reason to make the leap from "much bigger than whatever came from our big bang event" to "infinite".

Take a blank region of space-time with some arbitrary zero-fields, decompose these into a superposition of spherical expanding waves, and pick one of these to be your universe. Presto, big bang and all existence out of precisely nothing.

That initial region of space-time isn't quite nothing, though.

 

[K^2]

This is false, though. Think of it this way: it is much, much easier to completely define the set of all integers than it is to define a specific subset of the integers. It may seem a bit odd, but it is actually simpler, in mathematical terms, to have a prolific universe than to have just one universe (ours).

I'm not saying the universe has to be unique, but since it's by definition the only one we have access to, it doesn't make a difference.

All I'm saying is that our world makes more sense as a global phenomenon in closed finite space than as a local phenomenon in infinitely large space. You may disagree, but it really doesn't make a difference. It's an aesthetic choice only at this time. There is no objective test of either.

That initial region of space-time isn't quite nothing, though.

Given. Our current understanding of GR requires some starting fabric, though. Quantum Gravity might resolve this, but I cannot consider implications of a theory that does not yet exist.