I apologize for taking so long to get back to your post. You are one of the few here who actually had some real substantive arguments to make and seemed to have a better grasp of what is actually involved in the issue. The number of posts I have been dealing with across multiple thread has made it difficult to keep up.
Unfortunately that is not true. He has to show that the current classical space-time could not have come from some previously (maybe eternally) existing physical state of any kind.
Craig already addressed that.
If there was a previous existing physical state prior to the big bang then that state would logically also have to have a beginning.
All you’ve done is moved the problem back one step.
And if there existed a reality prior to the spacetime universe, which itself had a beginning, then the format of Craig’s argument doesn’t even need to be changed. All you have to do is change what you identify the beginning point to be and the same argument still goes through to reach the same conclusion.
As Vilenkin said; everything we currently know points to a beginning of the universe. He is unequivocal in that. He might still be working at ways to figure out how the universe could be past eternal but he’s honest about what the current state of the evidence is.
“We have no viable models of an eternal universe. The BGV theorem gives reason to believe that such models simply cannot be constructed”.
“The Beginning of the Universe,” Inference: International Review of Science ¼ (Oct. 23, 2015)
-Alexander Vilkenin
“All the evidence we have says that the universe had a beginning”.
Cited in “Why physicists can’t avoid a creation event”, by Lisa Grossman, New Scientist (Janurary 11, 2012).
Guth didn’t even say the information we have doesn’t point to a beginning of the universe – he just says he doesn’t know. He does assert that he personally believes the universe is eternal and believes one day evidence for that will be found - but he doesn’t claim the current evidence even points to that being the case.
That is why Carroll’s video of Guth is misleading. He is trying to imply that Guth is refuting the conclusions of the BGV, but he isn’t. He’s stating his personal belief that he doesn’t know and suspects the universe is eternal - but Guth never claims he has evidence for this belief yet. You won’t find anything in his proposals where he claims the evidence is not currently pointing to a beginning.
Krauss even affirmed in his debate with Craig that he thinks the universe probably had a beginning, but that he also says he just doesn’t know for sure. So he’s going further by not just acknowledging that the evidence currently shows there was a beginning but is willing to say he thinks that is most likely what did happen. That’s no doubt why he has gone in the direction of trying to come up with “something from nothing” ideas.
Given that, if you want to dispute the idea that the universe had a beginning, the burden of proof is on you to produce some evidence or viable models for a potentially eternal universe to exist prior to the big bang.
You can’t do that.
Not only can you not do that, but there is no other viable working model currently that doesn’t have fatal problems or even the same problem as the big bang just moved one step back (I get more into explaining why that is further down in my posts).
Therefore, we are within reason to conclude based on all the evidence currently before us that the universe most likely had a beginning – therefore it had to have a cause.
As long as there are consistent mathematical theories that exist positing this that have not been evidentially refuted (and there are many) he cannot show this.
You can't point to any model of reality that works without running into one of the three problems:
1. It ultimately does have a beginning point of some sort.
2. It has no mechanism for explaining how an eternal quantum state could suddenly change to generate a non-eternal universe.
3. It is completely unverifiable and unknowable, and never could be known, and therefore is not a scientific theory (such as positing that there could be a higher reality that houses other universes completely disconnected from ours, and there is no way for us to ever detect or observe anything outside of our universe).
That’s why Craig was confident in saying Carroll couldn’t point to any model of a beginning universe that was successful at demonstrating it’s claim.
Carroll admits even his own model isn’t successful by saying it has problems. He doesn’t pretend he has an answer yet. He just believes he will eventually find the answer he’s looking for.
But what you want, hope, or expect to find doesn’t ultimately mean anything if all the evidence is telling us otherwise.
You don’t have any logical or scientific basis for being able to expect you will one day find evidence for the universe being without a beginning.
The reason you expect to find evidence of that one day is entirely philosophical in nature. You have a worldview of materialism which makes it impossible for there to be a beginning to the universe.
But you can’t prove your philosophy of materialism is true. Nor can you disprove all the alternative philosophies and show them to be logically impossible.
Therefore, you have no scientific basis for assuming a priori that materialism is true. And if materialism cannot be assumed to be true then you cannot assume you will one day find evidence for an eternal universe.
Who said space-time is removed by these quantum theories. These quantum theories formulate a quantized version of space-time. Usually (like in loop quantum gravity) you recover a non-classical version of space-time from the theory.
You are mistaken. The models I am aware of which try to get away from a beginning for the universe all try to remove time itself from the equation prior to the big bang because removing time is the only way you avoid a logically impossible infinite regress into the past.
If you leave time in the equation, but simply tweak how it works, you don’t remove the infinite regress problem of the universe needing to have a beginning.
Hawking did try to assert there was no time before the big bang. He said saying time existed before the big bang is like saying there is something south of the south pole.
His model had space/time curve gradually away from a singularity point instead of it being a sharp expansion from a singularity point which is probably why he chose to use the analogy of how the earth’s surface gradually curves towards the polar point.
But once you reach the polar point there is nowhere beyond that point so you still have a singularity point that represents where space and time started to exist.
The BGV theorem does not apply to these quantized versions of space-time precisely because quantum theories ban singularities...there will always be a minimum dimension or minimum unit of time because of the granularity introduced by QM. So a quantized space-time exists but singularities do not. There simply cannot be a singularity in any theory of space time where quantum theories are incorporated.
You are misunderstanding Craig’s argument with regards to BGV.
The BGV theorem doesn't need to apply to the reality prior to the big bang in order for Craig's arguments to be valid.
It is sufficient for Craig’s argument to point out that the space-time universe as we know it had a beginning point.
The reason that is sufficient is because all the evidence we currently have says an eternal quantum universe prior to the big bang is not logically possible.
There is no mechanism you can model that would explain how you could go from an eternally existing quantum state to suddenly at some point in time creating the space-time universe in the big bang. Logically if the conditions for an eternal quantum state to create the space-time universe existed at some point along it’s timeline then there is no reason to think those conditions weren’t always present in which case why didn’t the eternal quantum state just create the space-time at the earliest possible point in it’s existence?
But if the eternal quantum state never began to exist then it existed infinitely into the past.
So if it existed infinitely in the past, then why would it only create our space-time universe a finite amount of time ago?
If it existed infinitely in the past, but created the space-time universe as early as it could, then that would make the space-time universe infinite in the past too.
But it is logically impossible for our universe to be infinite in the past according to the 2nd law of thermodynamics, the illogical impossible of there being an actual infinite number of past events regressing in space-time, and observations about the age of the universe which show it is not infinitely old.
That is why models that seek to deny the universe had a beginning have to try to remove time from the equation. Time forces you to conclude there had to be a beginning.
The idea of an eternal state prior to the big bang would necessitate some non-physics based answer for why this eternal state suddenly changed at some point along the timeline to generate the big bang. Because the same physics and conditions to generate the big bang would have had to be eternally present. And if those conditions are eternally present then why didn’t they happen earlier?
The only answer to that would be a mind that could make a choice to generate a change. Which is why, ironically, a single quantum eternal reality only lends more evidence to a theistic conclusion when you take it to it’s logical conclusion.
That’s why we get multiverse theories instead. Because you can’t justify there being only one eternal quantum reality that just suddenly changes. They need a universe generating engine that is always spitting out new universes to justify why ours would come in at some particular point.
But those models you will find have their own problems with singularity beginning points that need to be explained because they need to have a time factor in order to explain why our universe appeared at a given point in time.
Because if you don’t have a beginning point with time then you have an infinite past – but if you have an infinite past then that means the universe generating mechanism has had an infinite amount of time prior to the creation of the big bang in order to create it. But if it had an infinite amount of time to run through it’s machine that randomly spits out new universes constantly then there’s no reason to not conclude our universe should not have appeared earlier. But if it can appear any earlier than it did then it would have to appear infinitely earlier. Which would have to make the universe infinitely old. But we know that’s not the case.
That’s why any multiverse model has to have a beginning point out of necessity. They just try to obscure the fact that it does and they move the question of what caused the beginning back one or more steps from the big bang. But the problem is still there.