Quantum Fluctuations: Meaning & Universe Creation

[mattthecat]

I want to get some opinions on quantum fluctuations what they mean, and how they could have created our universe. Thanks!

 

[edgepflow]

To try to make a long story short, a quantum fluctuation is when a zero energy vacuum makes some particles and antiparticles that quickly recombine preserving the zero energy.

Probably the first significant paper on creating the universe from a vacuum fluctuation was:

Tryon, Edward P. "Is the Universe a Vacuum Fluctuation," in Nature, 246(1973), pp. 396–397.

The idea was that the negative energy of the gravitational potential was balanced by the positive energy of matter thus preserving the zero energy.

Of course, the vacuum was preassumed to exist making this theory less significant today.

Some current models by Alex Vilenkin (amoung others) propose that a closed universe was on the verge of collapse but "quantum tunneled" into literally nothing making our universe. So the collapsing closed universe and physical laws already had to exist.

 

[mattthecat]

So it would seem that quantum fluctuations would only be relevant after the vacuum was already in place? We certainly need a broader understanding of non demensional existence prior to the big bang. Hypothetically speaking assuming the vacuum state would have always existed in a state independent of time, could quantum fluctuations inflate into bubble universes, time being created in ours? Is this what is meant by quantum tunnled into existence?

 

[Misericorde]

So it would seem that quantum fluctuations would only be relevant after the vacuum was already in place? We certainly need a broader understanding of non demensional existence prior to the big bang. Hypothetically speaking assuming the vacuum state would have always existed in a state independent of time, could quantum fluctuations inflate into bubble universes, time being created in ours? Is this what is meant by quantum tunnled into existence?

I'm not sure you have a viable model of anything without presupposing the vacuum. If you don't have it, then you're breaking QM statistics from the get-go.

 

[mattthecat]

So what would the model be of prior big bang vacuum? Obviously you need a vacuum for these fluctuations, however wouldn't the laws of physics not be defined yet?

 

[edgepflow]

So what would the model be of prior big bang vacuum? Obviously you need a vacuum for these fluctuations, however wouldn't the laws of physics not be defined yet?

Any sort of mathematical model humans create would of course be based on the laws of physics as we know them. That is, general relativity to the vacuum as a whole (probably an flat empty space solution) and quantum mechanics below the Planck length.

Could the laws of physics be different for the vacuum that sprouted our universe? I would guess the answer is most likely no. But to answer your original question, you need physics and spacetime to sprout universes from quantum fluctuations or tunneling events. I think most of the current mainstream models are of a closed universe in a separate space time that was about to collapse but instead the very unlikely event of quantum tunneling occurred and our universe big banged and inflated and so on...

 

[mattthecat]

Thanks for your response. A thought to add, I recently read a book by Lisa Randall a theoretical physicist who suggests the possibility of our universe existing as a brane in a higher dimensional spacetime.

 

[edgepflow]

Thanks for your response. A thought to add, I recently read a book by Lisa Randall a theoretical physicist who suggests the possibility of our universe existing as a brane in a higher dimensional spacetime.

Could be. There are many possibilities. Some like the collapsing closed tunneling idea I discussed; some still like the vacuum fluctuation; others like loop quantum gravity (a flat or open universe that is infinitely old that is approaching a singularity but bounces instead into our universe); some still like the more traditional idea of a general relativity model universe where space and time emerged at t = 0.

Myself, I am not a big multiverse, brane world, or eternal inflation person. I think a single universe with a beginning that perhaps hovered briefly in a quantum state, banged, and then inflated works for me.