Not quite. The Standard Model is actually a Friedman-Lemitre model and it precedes the Hawking and Penrose theorems of the 70s.
I'm not familiar with a Friedman-Lemaitre model of the BBE. There is a Lorentz metric with those names attached to it -- I don't think we ever got into it very much in class, it was from the very early 1900's, maybe even 1910/1920 or so. Maybe I'll google it later -- perhaps they initially formed a model with the Lorentz metric I'm thinking of; but I'm pretty sure it's outdated as we barely touched on it at all other than in the name of historical science.
Call of the Wild said:Granted. As I said before, the argument doesnt depend upon a singularity point. As long as the model in some way suggest that the universe began to exist at some point in the finite past, then the argument is justified. But a singularity is not necessary. Speaking of Hawking, he said Almost everyone now believes that the universe, and time itself, had a beginning at the big bang (Hawking and Penrose, The Nature of Space and Time, pg. 20.) Even if modern BB models dont incorporate singularities, when you probe deep into them, they all suggests the universe is not past eternal but had a beginning at some point in the finite past. Once again, the standard bb model has the most empirical evidence supporting it, and it does suggest a singularity.
Touché on the Hawking quote; but this goes back to my original warning that in popular science the language is simplified for the non-mathematical/non-physicist community. To say the universe "...had a beginning at the big bang" can have several contexts: indeed, I've already openly declared that it's undeniable that the current state of the universe began with the BBE. The problem here is manyfold:
1) Popular science can get away with insinuating things that are "true enough" but ultimately untrue in the name of making it easier to understand for a layperson audience
2) The English language is not equipped to handle the notion of time on the Planck scale, in imaginary time, or potential multiple temporal dimensions*
3) Some physicists can be excellent at the physical sciences but otherwise utterly lacking in the metaphysics behind them (David Bohm comes to mind) -- it's entirely possible that some physicist here or there indeed holds a de facto misunderstanding of the ontological implications of the BBE
(* -- I once tried to solve a tricky problem by trying to "smooth it out" by using a gauge transform to even out the math. Much to my surprise, my choice of transform incidentally (and subtly) balanced my spatial dimensions with temporal dimensions: I ended up describing some crazy system with three spatial and three temporal dimensions. Whoops! That may not have been the best thing to do for my grade, but the salient point here is that nothing rules out multiple temporal dimensions outright; and English [or any other natural language] simply isn't equipped to deal with that!)
I explained lengthily and technically exactly where and why an assertion that time "began to exist" could arise from BB cosmology; but in the same post I explained exactly why that reasoning is erroneous. Finite geodesics don't necessarily imply a finite system, even temporally.
Call of the Wild said:The idea is coming from the implications of the model. As physicists John Barrow and Frank Tipler point out At this singularity, space, and time came into existence; literally nothing existed before the singularity, so if the universe originated at such a singuarlity, we would truly have a creation ex nihilo (Barrow and Tipler, The Anthropic Cosmological Principal, 1986, pg 442). Now as I said before, if you want to take a Hawking/Hartle model at which there is no singularity, that is fine also. But even on that model the universe still begin to exist. A singularity is not necessary and I only use the standard model because it has the most evidence supporting it. Any model that will suggest the beginning of the universe from a finite past can be used to support premise 2 of the KCA, that the universe began to exist.
Again, however, these models aren't suggesting an ontological beginning. A temporal or spatial dimension can prima facie begin a state without ontologically beginning at all. No one is denying here that the BBE marked a profound new thing that we refer to as time and spatial separation in the current state of the known/visible universe -- but nothing about that indicates that the universe itself, such as the energy and matter, had an ontological beginning.
Again, the reason some physicists are saying in popular science that there was a "beginning" is because most of them are using language that's easy to understand; and otherwise some few actually don't understand the metaphysics behind the notion: that was the point of the mathematical thread I made. The reason someone might make the assertion that there was an ontological beginning is solely because we have finite geodesics in our current models: the maths can go where the physical data can't, some might reason; and so they declare a beginning.
But by doing so, they're simply failing to understand the wider implications that I exposed in that post. Finite geodesics on some timeline don't indicate a finite existence.
Call of the Wild said:What the BB tells us is that the universe began to exist. In order for something to begin to exist, there must have been a time where it didnt exist. The word Ontological is a study of existence. If the universe began to exist, there was nothing ontological about it :0)
I don't feel as though you've really supported your argument, though. I've thoroughly supported my argument as to why BB models can be misinterpreted as an ontological beginning; and furthermore I justified fully why that interpretation is false and misguided.
I don't need to appeal to multiverse hypotheses for my points to be correct, but I think it might be prudent to use a multiverse scenario as a recognizable/cognitive example here just to make a point.
Suppose for a moment that there is a multiverse wherein new pockets of spacetime (such as our visible universe) bud off from other pockets of spacetime: each time in doing so there is a Big Bang-like event in the "new" pocket of spacetime.
Now suppose that cosmologists and theologians eventually develop in this new envelope of spacetime: the theologians will look at the cosmological data (which in principle doesn't go beyond their own pocket's formation) and say, "Aha! You see? The universe began ontologically." But the cosmologists will shrug and say, "Actually, we don't have enough to work off of prior to the Planck epoch, so you can't make that assertion." The cosmologists would be correct.
Again, I don't have to appeal to multiverses for my points to be correct -- but hopefully that analogy helps to demonstrate in at least one sense why apparently finite geodesics don't logically indicate an ontological beginning.
The real point here isn't that I'm arguing cosmology demonstrates there was no ontological beginning and that the universe has existed eternally: the point is that there is no data to support either assertion; and that we should therefore rationally be agnostic about the issue -- which includes abstaining from using a cosmological argument that assumes an ontological beginning of the universe. As has been my argument the whole time, that assumption would be entirely unfounded in reason.
Call of the Wild said:Point granted. The standard model needs to be modified. We need to use quantum physics at that point and no one is sure how this is to be done. But even when modified, the prediction that the universe had an absolute beginning is not negated. The Borde/Guth/Vilenkin theorem of 2003 showed that any universe that has been expanding throughout its history cannot be infinite in the past but must have a past space-time boundary. So, the second premise of the kalam is still confirmed by modern, not outdated, but modern cosmology.
Ah! Yes, you're probably referring to this paper. This is actually still a hot topic in cosmology. In fact, Vilenkin himself had this to say when asked whether or not their paper demonstrated that the universe had an ontological beginning:
Alexander Venkin said:If someone asks me whether or not the theorem I proved with Borde and Guth implies that the universe had a beginning, I would say that the short answer is "yes". If you are willing to get into subtleties, then the answer is "No, but..." So, there are ways to get around having a beginning, but then you are forced to have something nearly as special as a beginning.
(This was said in an e-mail exchange between Victor Stenger, Alexander Venkin, and Ken Voshee; posted on said blog with permission)