All of these however do not contend with the sweeping BGV theorem in the long run. Assuming an "always positive" expansion rate is simply violated by "bouncing scenarios including LQC" according to Ashtekar. Oscillating Also called the Big Crunch. Under an oscillating model of the universe the current expansion we currently observe is just one part of a cycle, and one cycle of infinite cycles.
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I posted about the " My Good Friend meme " — so named by thoughtful reader Ryan — employed in origins debates by materialist advocates. That means, guys like Dr. Carroll and Prothero, Krauss, Ward, etc. Yesterday, Coyne posted videos of Craig-Carroll as well as Craig-Krauss , neither of which, he says, he has actually watched. Now Ryan writes in with a good correction to what I said earlier. In the encounter with Dr. Craig, Sean Carroll invoked his buddy physicist Alan Guth, a co-author of the Borde-Guth-Vilenkin theorem which seems to point the universe as having a beginning, an inference friendly to theism, to say the least.
See here for the clip. Carroll wrote in post-debate comments that Craig "used the celebrated by theologians Borde-Guth-Vilenkin theorem , which says that a universe with an average expansion rate greater than zero must be geodesically incomplete in the past.
Which may even be true! Craig thinks we do have a strong reason, the Borde-Guth-Vilenkin theorem. So I explained what every physicist who has thought about the issue understands: that the real world is governed by quantum mechanics, and the BGV theorem assumes a classical spacetime, so it says nothing definitive about what actually happens in the universe; it is only a guideline to when our classical description breaks down. In the debate, Carroll cutely projected photos on a screen behind him showing Dr.
Carroll is trying to get mileage out of the fact that Guth was willing to pose for pictures and use them to give the audience the impression that Craig has misunderstood or misrepresented his source when he had done no such thing. Nobody knows. In the interim, there is always some fanciful, inscrutable — and usually untestable — materialistic hypothesis ready to be wheeled on to the stage, to be propped up by hook or by crook, even if that means ignoring the very knowledge that we praise the sciences for helping us to attain, allowing that, in the final analysis, it might all just be more ignorance in disguise, which, evidently, is a conclusion far more desirable than the existence of God.
#336 “Honesty, Transparency, Full Disclosure” and the Borde-Guth-Vilenkin Theorem
Concerning the BGV theorem Craig is correct in saying that the result holds for any geodesic observer with a non-comoving congruence of time-like geodesic test particles which is on average over the past expanding in a generalized sense, within general relativity , in the sense that such an observer geodesic is necessarily past-incomplete. That is not what he says, of course, but to my ears his statement of this is as good as one can expect. That does not imply a creation event. What it does mean is that if e. I am fairly certain that this is not an in any way controversial result. Ultimately, both the BGV theorem and the quoted paper on the generalized second law may be interpreted as supporting the idea of some sort of "creation event," in the sense that they do not conradict it and serves to narrow down other possibilities. However, in the same way they could then be interpreted as supporting any theory they do not contradict.
When someone produces a private, unpublished statement from a person contradicting what that person has consistently said in his published work, you can bet something is fishy. That was what I immediately suspected here. Krauss regarding this email. Here is the email as Krauss reproduced it taken from his Sydney powerpoint slide : Hi Lawrence, Any theorem is only as good as its assumptions. The BGV theorem says that if the universe is on average expanding along a given worldline, this worldline cannot be infinite to the past.