The Universe expanded from a singular mathematical nothing-point, literally called a singularity.
• …(General Relativity) GR’s Singularity Big-Bang model is true.
• …(BGV Theorem) Spacetimes that expand on average all begin.
• …(2nd Law) Total entropic decay has not arrived yet.
• …(Generalized 2nd Law) Total generalized entropy has not maxed out yet.
General relativity is true or adequate, describing with sufficient accuracy the full birth and growth of space from a singularity.
• …General relativity makes accurate prediction elsewhere.
• …Space in fact did expand from a hot-dense state.
• …Spacetime came into being from from some singularity. [See above]
“If we push backwards far enough, we find that the universe reaches a state of compression where the density and gravitational force are infinite. This unique singularity constitutes the beginning of the universe—of matter, energy, space, time, and all physical laws. It is not that the universe arose out of some prior state, for there was no prior state. Since time too comes to be, one cannot ask what happened before the initial event. Neither should one think that the universe expanded from some state of infinite density into space; space too came to be in that event. Since the Big Bang initiates the very laws of physics, one cannot expect any scientific or physical explanation of this singularity.” [Bruce Reichenbach, “Cosmological Arguments,” in The Stanford Encyclopedia of Philosophy (2017)]
But so what? Plausibly…
•…The singularity is preceded by other spacetime regions and/or universes.
Any Universe eternally inflating/expanding on average requires infinitely-fast travel (Experts1)(Elaboration2)(Justification3).
But so what? Plausibly… … [All forthcoming]
•…Space has an infinite contraction phase (i.e. contracts on average).
•…Space has cycled infinitely (i.e. is static on average).
•…Space underwent time-reversal from an infinite past (i.e. non-average expansion).
The BGV theorem is widely accepted.
• Alexander Vilenkin: “It is said that an argument is what convinces reasonable men and a proof is what it takes to convince even an unreasonable man. With the proof now in place, cosmologists can no longer hide behind the possibility of a past-eternal universe. There is no escape: they have to face the problem of a cosmic beginning.” [Many Worlds in One (Hill and Wang, 2006), 176.]
• William Lane Craig & James Sinclair: “The Borde–Vilenkin–Guth (BVG) singularity theorem is now widely accepted within the physics community. As of this writing, it has gone largely unchallenged.” [The Blackwell Companion to Natural Theology (Blackwell, 2004), 142.]
• Gott-Li: “The question of first-cause has been a troubling one for cosmology. Often, this has been solved by postulating a universe that has existed forever in the past. Big Bang models supposed that the first-cause was a singularity… with a proper theory-of-everything, one could perhaps push through to earlier times. Inflation has solved some of these problems, but Borde and Vilenkin have shown that if the initial inflationary state is metastable, then it must have had a finite beginning also. Ultimately, the problem seems to be how to create something out of nothing.” [J. Richard Gott and Li-Xin Li, “Can the Universe Create Itself?” (1997), p.41]
• Audrey Mithani, Alexander Vilenkin: “Did the universe have a beginning? At this point, it seems that the answer to this question is probably yes. Here we have addressed three scenarios which seemed to offer a way to avoid a beginning, and have found that none of them can actually be eternal in the past. Both eternal inflation and cyclic universe scenarios have Hav > 0, which means that they must be past-geodesically incomplete. We have also examined a simple emergent universe model, and concluded that it cannot escape quantum collapse. Even considering more general emergent universe models, there do not seem to be any matter sources that admit solutions that are immune to collapse." [Did the universe have a beginning?, http://arxiv.org/pdf/1204.4658.pdf]
We know this because any eternally inflating space would require infinitely fast travel. This is relevant because an object traveling infinitely fast in space is impossible, producing absurdities and violating the laws of relativity.
>• James Sinclair: "Vilenkin affirms that any universe (including universes modeled by higher dimensional cosmology, pre–Big Bang cosmology, and so forth,) which, on average, expands has to connect, in a finite time, to a past boundary (pers. comm. with Sinclair, March 4, 2004).
• Alexander Vilenkin: "Our argument shows that null and time-like geodesics are, in general, past-incomplete in inflationary models, whether or not energy conditions hold, provided only that the averaged expansion condition Hav > 0 holds along these past-directed geodesics. (Borde, Guth, & Vilenkin 2003, p. 3)39 A remarkable thing about this theorem is its sweeping generality. We made no assumptions about the material content of the universe. We did not even assume that gravity is described by Einstein’s equations. So, if Einstein’s gravity requires some modification, our conclusion will still hold. The only assumption that we made was that the expansion rate of the universe never gets below some nonzero value, no matter how small. This assumption should certainly be satisfied in the inflating false vacuum. The conclusion is that past-eternal inflation without a beginning is impossible. [Many Worlds in One (2006), 175)
Although the 2nd law of thermodynamics says the total entropy of an isolated system can never decrease over time, the Universe's entropy in fact is far from its maximal amount; its useable energy is still winding down.
• Stars are still burning.
The 2nd Law of thermodynamics applies to black holes and similar types of horizons (hence the “Generalized 2nd Law”), suggesting that even in a quantum-gravity context (like the Planck era), the conclusion of the Penrose singularity theorm applies.1 This is relevant because...
>• Aron Wall (Studies quantum gravity and black hole thermodynamics as a Lecturer at the University of Cambridge): “…it strongly suggests that either the universe had a finite beginning in time, or else it is spatially finite and the arrow of time was reversed previous to the Big Bang [i.e. tornadoes put houses back together, and eggs unscrambled themselves]. In the latter case, it could still be said that the universe had a beginning in a thermodynamic sense, because both branches of the cosmology would be to the thermodynamic future of the Big Bang” [Classical and Quantum Gravity Vol 30 No 16 (2013), p.27 on arXive.]
Using pure a priori reasoning, we can discern that the the number of previous events up until now needs to be finite in number, meaning there was inevtiably a first event.
• …An infinite number of things can't exist in the world
• …An actual infinite can't be formed by adding
A cosmic model is true wheren the contiguous whole of space and time lacks a beginning.
•…The Aguirre-Gratton Time reversal model
•…The Baum-Frampton Cyclic model
•…The Carroll-Chen Reversed arrow of time model
•…The Gott-Li model
•…The Hawking-Hartle “no boundary” proposal
•…The Linde-type “Eternal Inflation” model
•…The Penrose Conformal Cyclic cosmology
•…The Steinhardt/Turok Cyclic model
•…The Vilenkin “Tunneling from nothing” model
•…The String Landscape inflationary model
This is relevant because, “If we were able to construct a complete and compelling naturalistic account, the necessity of appealing to God would be diminished.” [Sean Carroll, The Blackwell Companion to Science and Christianity]