Many scientists have proposed that the universe emerged from a quantum field or spacetime, not nothing.
Right. But as I understand it, there are those that equate a possible zero energy level of the universe (positive energy and negative energy levels balancing each other out) with nothing and claim that it is actual nothingness, i.e., not anything. And that is how they propose the initial event of the universe began from “nothing.”
Because it is nothing. Or can be.
Watch this video if you have the time and interest:
@Jim and @Faizal_Ali, the “creation from nothing” in modern physics is often misunderstood. Perhaps you would be interested in reading this post I wrote: What physicists mean when we say creation from nothing.
As a caveat, I don’t think this is a good argument for the supernatural - I don’t think it bears any relevance.
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Your article does not apply to Vilenkin’s quantum tunneling model, if I understand correctly. He does not post a pre-existing field, but literally nothing other than the laws of physics.
It may be that it needs to be further clarified, but my op is not meant to be an argument for the supernatural. It’s directed at the statement that naturalists often make that there is “no evidence” for the supernatural. My contention is that what is meant by that statement is that there is, as defined in the op, no direct empirical evidence, which is evident since there’s no way to directly access the supernatural realm for direct scientific observation. And that to be correct the statement needs further clarification to distinguish the intended meaning from the term evidence in it’s broader application.
To say there is “no evidence,” I think clearly gives the general public the impression that there is no evidence at all. Since evidence can include other types of evidence besides direct empirical evidence, and as I’ve argued that those other types of evidence can be pointers to infer a supernatural realm in an abductive argument, I’m making the case that therefore without further qualification the statement in question is incorrect. Does that make sense?
As I mentioned in my post, the “Universe from Nothing” case is more complicated than the “Particle from Nothing” case, but the spirit is the same:
In the “Particle from Nothing” case, the closest thing to nothingness possible is the vacuum state, which has fluctuations due to the uncertainty principle. These fluctuations are the particles.
In the “Universe from Nothing” case, spacetime itself is taken to be quantum mechanical. The fluctuation of the quantum vacuum now generates spacetime in addition to particles. The same argument applies: due to the uncertainty principles, the vacuum state has fluctuations, which generate space and time.
As to the quantum tunneling model, this is how it works: Instead of a field an object called the wave function of the universe, which I will call O.
In the “Particle from Nothing” case, the field is defined over spacetime. For example, in my post the field is the length of spring as a function of where that particular ball-on-a-spring system is on the x-axis. In the tunneling model case, O is defined over the space of all possible geometry of space and configuration of matter/energy in the universe, called the superspace.
Then, one can use the Wheeler-DeWitt equation:
\hat{H}O= (\nabla^2-U) O = 0
which in short means that the energy of the universe is 0. Here, \hat{H}= (\nabla^2-U) is an operator that asks O the amount of energy it possesses. If this is unfamiliar, don’t worry about what the symbols mean, just note that the second equation looks a lot like
\frac{1}{2}mv^2 + U = E
the energy formula from high-school physics. As with the high-school formula, U is the potential. In quantum mechanics, one can tunnel through potential barriers, and the same is the case here. We can start at a point in the superspace in which there is no space or time, and tunnel through to another point in the superspace in which there is space or time.
Compare this to the “Particle from Nothing” case:
- Instead of starting with fields, we start with the wave function of the universe, O
- Instead of putting our field on spacetime, we put the wave function of the universe in the superspace
As is the case with the “Particle from Nothing” case, in which fields are not “nothing”, the wave function of the universe, O, is also not nothing. More abstractly, the superspace is also not nothing. Neither are the laws of physics we employed along the way. This is exacerbated by the fact that in this model we have to specify what \hat{H} is (i.e. what U is), which is putting even more things into the theory that is not nothing.
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So you seem to be saying that, so long as mathematical concepts and equations, and similar abstractions, exist, we cannot say “nothing” exists.
Is that correct?
If so, then this seems to be an even more intractable problem for the religious apologists. How can they demonstrate that math “began to exist”?
Correct, true nothingness does not even have a logic system to do math with. However, just to be clear, Vilenkin’s tunneling universe model is very far from this. It has the universal wave function, a superspace, a choice of \hat{H}, the laws of physics etc
That’s their problem not mine.
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But these are still all abstractions, right? We could say they do not “exist” in a material sense?
Nor mine. But I do like to cause them problems. 
This goes into what “existing” means and that is a philosophical rabbit hole that I’d rather not go into right now. What I can say is that: to me fields on a spacetime (of the “Particle from Nothingness” case) stand at the same level of “existing” as the wave function of the universe on a superspace. If you think fields on spacetimes “exists” in reality, then so does O on a superspace.
Technically I am a religious apologist, just not that kind.
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Yes, but to see why you have to think about what the evidence actually is, and what a “beginning” actually means.
Redshift, expansion, CMBR is all evidence that the universe used to be much smaller than it is today. The CMBR is specifically a prediction of the claim that the universe was once upon a time so small and dense that it was opaque to electromagnetic radiation because charged particles had not assembled into stable atoms. As the universe expanded, it also cooled enough to allow stable atoms to form, and when this happened electromagnetic radiation could traverse space relatively unhindered. An imprint of this time in the microwave range, also called the surface of last scattering, is now today detectable in the CMBR. It is important to understand that the universe need not have been infinitely small, or to have literally sprang into existence out of nothing, for the CMBR to have formed. All that is required for this is that the universe was very small and dense and expanded from this state of higher density, that’s it. Redshift and expansion are also just evidence that the universe was smaller. You can put the rate of expansion into a coordinate system and draw a line going back to an imaginary T=0 to derive a prediction that the universe was once infinitely hot and dense, but that is an extrapolation beyond the data we actually have. We technically don’t know if time began, or if there was a first moment in the form of a singularity.
Even if we did, that doesn’t help you, because if time literally goes back to a very first moment when the universe was a singularity, then it doesn’t go further. Which means there was never a time at which there was nothing. Rather there was a state of infinitely high density and curvature, but that isn’t nothing. So because the universe has existed for all of time, and since we can’t go back further than time itself, there is no “coming from nothing” that needs to be “caused”. It was never the case that there was nothingness instead of the universe. Rather, the universe has an earliest moment when it was infinitely hot, dense, and curved, and it is incoherent to talk about a before this because there can’t be a before time itself.
Here’s a very simple argument that could be filled out more, but more or less does what’s necessary.
If the initial event responsible for the existence of space, time, matter, and energy has a cause
See this is a problem right out of the gate, because you are treating this problem as if there was some event, a “coming into existence out of nothingness” that needs to be explained. But there is no evidence that there was ever such a beginning. In fact it is logically incoherent to talk about this being the case, as it would imply time itself existed, when there was “nothingness” as the state of the world.
I think you would need to justify those assumptions philosophically. As far as I can tell there had to be an initial event according to BGV, and the cause and effect of that initial event could have happened spontaneously.
What assumptions? What I say follows straightforwardly from the meanings of the words I used. There can’t be a “before” time itself, in the same way there can’t be a further north of the northernmost point.
As far as I can tell there had to be an initial event according to BGV, and the cause and effect of that initial event could have happened spontaneously.
I don’t see how this relates to what I wrote. The BGV theorem does not imply a transition from a state of absolute philosophical non-being to a state of the universe existing. Rather it merely implies there was a first moment of time in the sense that the length of the dimension of time into the past is finite, it has an “end” in the past. The theorem doesn’t say that there was “nothingness” somehow even further before this first moment of time.
Obviously, but again,
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Sure, did not mean to imply otherwise.
I understand 
I just wanted to make explicit that while I am religious, I do not have any problem with these issues.
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Think of it this way. Somebody puts a curve in a coordinate system based on some data you have, and you now have to extrapolate back before the first data points. Different models, different equations, entail differently shaped curves, and therefore different physical events.
My understanding is that, besides the standard model, there are far too many problems with other models that they don’t attain as viable models. Is that not true? That seems to be the opinion of at least many scientists, including Vilenkin.
What do you mean by reasonable? Considering QM is theoretical and the different interpretations vary quite significantly with no consensus reached after more than 80 years, I would say using areas of it that are not well understood to make possibility assessments of reality is a lot less reasonable than looking at the reality of what’s already been empirically verified.
Basing such type of judgments on empirical grounds seems to me a much more reasonable approach to take. And correct me if I’m wrong, but everything physical that can be directly accessed and observed has been shown to began to exist and have a cause.