beginning of the universe could have been a chance matter, a very unusual quantum event.
myra
That sounds very queer. Could you amplify it, please?
geoffrey
Not as a real cosmologist could, but I’ll do my best, and hope I get it more or less right. It is well established that what is called a “vacuum” in quantum physics is not an empty nothingness. What are known as “virtual particles” are constantly appearing and disappearing within it. They are like the basic particles that make up you and me, but they last only for a tiny fraction of a second. They come into being and pass away at random, without any determining cause: for at the quantum level determinism does not hold. Now the smaller the energy required to produce such a particle, the longer the time it can last. But the universe could very well have zero energy.
leslie
I beg your pardon?
geoffrey
It’s true. The mass, and therefore the energy, of the universe is of course enormous. But its gravitational energy is also enormous, and apparently this counts as negative where the other is positive. Don’t ask me why, but I am assured that this really is so.
leslie
Is that correct? The last time I heard, they were saying that there was an enormous amount of “dark energy” pushing the galaxies apart, counteracting the pull of gravity; and this would presumably outbalance the “negative energy” you speak of.
myra
None of us knows whether this is in fact correct. I think we’d best assume Geoffrey’s position for the moment, just for the sake of argument.
geoffrey
Thank you. Theories may of course change. But the point about the mass and gravitational energy is that the two may very well cancel out, or nearly so. So that if the universe emerged from the “vacuum” as the result of a chance fluctuation, it could continue to exist for a long time, perhaps indefinitely, without relapsing back into nothingness. Hence you could have a simple beginning to the universe which was not caused by anything, any more than the randomly occurring virtual particles are caused by anything.
leslie
It sounds a fascinating—dare I say, an amusing—speculation. But I can’t see that it makes any real difference, even if the energies did balance out. Is the universe that emerges in this way simple? The universe is not just a balance between mass-energy and gravitation-energy! It has far more to it than that: it has laws, and conditions for those laws to operate, and an indescribable web of intricate detail arising from these. Why did this very specific universe leap into being from the vacuum? And, what is more, is the background simple? You still have to explain the origins of the “vacuum” itself.
geoffrey
At least some physicists have suggested that you don’t even need that vacuum. The universe might tunnel its way into existence out of nothing.
leslie
I am glad you don’t seem to endorse their views! For of course no conclusion can follow when there are no premises. There may be laws of nature which say “Given X and Y, there is such-and-such a chance that a virtual particle will appear,” or even “Given X and Y, there is such-and-such a chance that a universe will appear,” though I confess I find the latter hard to believe. But certainly there can be no law that says “With nothing given at all, a universe will appear”; from nothing you can infer nothing.
geoffrey
Frankly, I rather incline to agree with you. I only mentioned this position because it has been held. The other one, which does allow for a basic vacuum, is much more serious.
myra
I wonder if there’s a catch in that position too. It arouses memories, in me anyway, of an old argument one used to hear occasionally before modern advances in cosmology. Theists were apt to cite the Second Law of Thermodynamics. Heat can only pass from one body to a colder body. This means there is a steady tendency for heat to even itself out across the universe; “entropy” tends to increase.
leslie
Meaning?
myra
Oh, dear. Entropy has been described as a measure of how close a system is to equilibrium or uniformity. For instance, if half a system is hot and half cold, there will be a tendency for it all to even out; and in that case the “entropy” of the system is said to increase. I hope that makes sense to you. And the fact that entropy tends to increase was taken to show that the universe was “running down,” heading for complete uniformity, and had been running down all its life. It must therefore have been “wound up” at its beginning.
Now to this it was sometimes answered that the universe, given sufficient time, might have “wound itself up” by sheer chance, out of chaos. This was very unlikely to happen, but in infinite time even the very unlikely will happen. God was not needed to “wind the universe up” and set it going.
The classic objection to that was that it was more likely to have wound itself up to its present state than to any previous one, because any earlier state would have had lower entropy, and would therefore have been more highly organized than now. It was actually more likely that we and the world around us sprang from chaos complete with our memories and apparent history than that the primeval universe did. And the question I wanted to raise was, would not the same objection apply to your “emergence from a vacuum,” Geoffrey?
geoffrey
No, I don’t think it would. Entropy is irrelevant to the possible emergence of the universe from a quantum vacuum. The old argument you quoted was trying to show that a world with a low entropy could have emerged by sheer chance out of one with a high—a wound-up one out of a run-down one. And I agree that this won’t do. But we aren’t now talking about a world with high entropy as the background from which the world emerges; we’re talking about a quantum vacuum, a state of affairs where particles, and perhaps more than particles, are constantly coming into being and vanishing again
leslie
But if the only consideration that affects what emerged from the vacuum is its total energy, then any system with zero energy is equally likely to emerge. And of course if the world had zero energy thirteen billion years ago, it has zero energy now. Although the universe as it is now is not more likely to have emerged than the primeval one was (which was the catch in the “old argument” Myra was describing), it is surely just as likely to have done so. And this would make nonsense of the whole scientific enterprise—not to mention common sense.
(There is a pause in which all three try frantically to think of something to add)
myra
I begin to wonder whether we haven’t come to something of an impasse. To Geoffrey this vacuum suddenly exploding into the beginnings of our universe, with no reason for its existence, seems simpler and more probable than belief in God; to Leslie it seems the reverse. I must say, I tend to agree with Leslie. This is no doubt largely because I do in fact believe in God already; but I think I might agree even apart from that belief. A vacuum with the potentiality for this universe, right down to teacups, ladybirds and the ink on this page, strikes me as far from simple, or easy to accept as “brute fact.”
