Ever since the idea of the Big Bang was conceived cosmologists who hated God looked for a way around creation. The universe couldn't have a beginning; it would ruin the perfect harmony of an eternal universe. No beginning, no need for an explanation, right? To celebrate Hawking's 70th birthday here is a third installment in the series on him, his cosmology, and his theology.
See Also Balking Hawking Part 1, Part 2, and Georg Cantor's Infinities Part 2.
"Many physicists have been fighting a rearguard action against [the Big Bang] for decades, largely because of its theological overtones. If you have an instant of creation, don't you need a creator?
Cosmologists thought they had a workaround. Over the years, they have tried on several different models of the universe that dodge the need for a beginning while still requiring a big bang. But recent research has shot them full of holes (see "Why physicists can't avoid a creation event"). It now seems certain that the universe did have a beginning."
Lawrence Krauss in his new book A Universe From Nothing tries to deal a knock-out blow to the deity by replacing one metaphysical system with another. God is given up for the multiverse, a cacophony of quantum randomness belching out universes like Our Idiot Brother.
It is in vogue now to redefine "nothing" to mean "the quantum vacuum that has always existed," but in an interview on Coast to Coast AM, Krauss does his fellow metaphysicists one better. He admitted that you don't even need a quantum vacuum or quantum laws, as NewScientist explains:
"However, the laws of physics can't be conjured from nothing. In the end, the best answer is that they arise from our existence within a multiverse, where all the universes have their own laws - ours being just so for no particular reason.
Krauss contends that the multiverse makes the question of what determined our laws of nature "less significant". Truthfully, it just puts the question beyond science - for now, at least. That (together with the frustratingly opaque origins of a multiverse) means Krauss can't quite knock out those who think there must ultimately be a prime mover. Not that this matters too much: the juvenile asides that litter the first third of the book (for example, "I am tempted to retort here that theologians are expert at nothing") mean that, by the time we get to the fascinating core of his argument, Krauss will be preaching only to the converted."
The multiverse: the great unknown and unknowable. A meta-space that is beyond our space-time and thus forever beyond our ability to test it. Being untestable the multiverse must surrender its claim to the title "science" and accept that it is now, and forever, metaphysics. To do away with the idea of a creation, an absolute beginning of the universe, Krauss throws science away and invents an untestable story. Even the Bible contains historical details that can be tested, the multiverse is just "bullshit metaphysics".
Metaphysicists have tried to propose systems where the universe (or multiverse) is eternal into the past, but Alexander Vilenkin of Tufts University has shot holes in all of them (even though he still believes in the multiverse, it had to have a beginning in the finite past).
Eternal inflation, the idea that the inflation that sped up the expansion of the early universe didnt' stop, it still continues in other regions of space beyond our cosmic horizon, spawning new bubble universes forever, was the first to go. Some thought inflation was eternal into the past too, but in 2003 Vilenkin and Alan Guth ran the calculations on Hubble's Constant and found that it doesn't work. Inflation may continue forever into the future, but it had to have a beginning in the past.
Next came the big bounce, the idea that after a long time, a trillion years or so, expansion slows and stops, eventually reversing until everything flys back into a single point called the Big Crunch. Then the shock of impact of everything on everything starts a new Big Bang, and the cycle continues forever. Unfortunately, disorder increases with time, so each new universe must be more disordered than the one that birthed it. If the cycle had been going on forever disorder would be infinite and the universe would be completely featureless. Since there's stuff in the universe the cycles couldn't have gone on forever. Some people then suggested that the universe just gets bigger with each bounce, so the disorder spreads out more so no one notices it (like in the M-Brane ekpyrotic model and possibly whatever the hell Penrose's new idea is - no one seems to understand his Aeons of time model, within the physics community or anywhere). But if the whole thing is getting bigger it had to start somewhere really really small, maximally small, and that means a finite beginning.
There's also an idea from the 1930s called the cosmic egg or primeval atom, where yes, there was a Big Bang 13.7 billion years ago, but the thing that banged was an uber-dense subatomic thing that existed forever until it got tired of existing as a tiny little particle and exploded. However, Vilenkin and a graduate student Audrey Mithani showed that quantum instability would have led to the egg's collapse after a finite time. The crack (the Big Bang) had to happen before the egg collapsed into oblivion so it couldn't have existed forever, even if it existed for a really, really long time before the Big Bang.
Vilenkin concludes[:] "All the evidence we have says that the universe had a beginning."
V.J. Torley of UD comments on the implications of a universe requiring a beginning. He reasons (muses, really), in line with William Lane Craig, that the cause of the universe, which cannot be within the universe itself, must be personal. Scientific and mathematic laws are just descriptions of observations. They are not Platonic furniture of reality, and they are causally inert. Only a person, an agent, can bring about the creation of the universe, acting for some reason. The evidence from fine tuning (not only of the universe, but if you read Georg Cantor's Infinities Part 2 and other links provided in the UD article, you'll see that the multiverse too must be fine tuned) is suggestive of a highly mathematical and aesthetic mind behind the constants of the universe.
There you have it, a birthday present, albeit a very bad one, from Alexander Vilenkin to Stephen Hawking: a universe with a definite beginning in the finite past.