Alexander Vilenkin and The Many Worlds Theory

I'm going to take a brief detour from Huxley during my trip to see my grandparents to talk about Alexander Vilenkin, professor of physics at Tufts University, and the leading authority on what is called The Multiverse.

Vilenkin wrote a book called Many Worlds in One: The Search for Other Universes. In it, he defends the idea of a Multiverse. Imagine that our universe is a grape. On Vilenkin's model, our universe is just one grape among many on a gravevine. In fact, there may be an infinite amount of grapes on this grapevine, or even an infinite amount of grapevines!

Basically, all the evidence for the Big Bang is from within one grape. As our grape expands - like a balloon - it looks as if ALL of space/time is expanding. But it's really just one universe on a grapevine, which spawns an infinite number of other grape-universes. The Big Bang just assumes that our grape is the only grape; space/time didn't have a beginning at the beginning of our grape, since there's an infinite amount of other grapes with their own space/times. Or, space/time is something like an umbrella over the gravevine as a whole. And since the grapevine is eternal, so is space/time.

We also have to remember that each grape is causally connected to every other grape, just as every grapevine is causally connected to every other grapevine: there's an infinite amount of grapes and an infinite amount of grape vines. Each grape and grapevine has a boundary and that boundary is what is called an event-horizon.

Vilenkin also believes that our grape is always inflating, like a balloon that's inflated with more and more air, so it expands more and more. This is strange though, because even though he thinks each grape is inflated eternally, the grapevines have a finite past. Maybe he means that each grape has a finite past and now that they have spawned they'll go on inflating forever.

According to the first inflationary theory, our universe is in a true-vacuum state. There is almost no density, like a desert with a little amount of trees. But earlier, the universe was in a false-vacuum state, having lots of density, like a jungle, thick with trees, foliage, and vines. This high density makes lots of gravity. But the gravity is overwhelmed by the energy from the density in the false-vacuum state. This energy causes a VERY powerful inflation, which makes the universe grow from the size of an atom to a size bigger than the universe as we see it today. But Vilenkin needs more than this inflationary theory.

Vilenkin, remember, wants to make the inflation of the grapes eternal. This is where scalar fields come in. These scalar fields determine how much density a false-vacuum state will have, like a gardener determines how many flowers to have in a garden. But these scalar fields have a special job to do: they have to get that false-vacuum state to expand so fast that when it starts to wither into true-vacuums (creating island universes: aka 'grapes'), the false-vacuum outruns (expands faster than) the island universes. This means the island universes are further disconnected from time. New island universes will pop up as the gap between the expanding false-vacuum and the other island universes gets bigger, like an ocean between two continents getting wider and wider leaves more and more room for more islands.

Very briefly: Vilenkin does say the Multiverse is finite. And he says the false-vacuum will go on inflating forever and ever. He does NOT explain how there is no violation of the second law of thermodynamics. More on that later.

As butter gets thinner and thinner the more it is spread, the center of the island universes get more and more hallow and dark the more it expands. At the rim of every island universe we have various Big Bangs, as the false-vacuum withers into true true-vacuum. In other words, every grape is growing, even though every grape is finite, since it had a beginning in the grapevine. Each grape (or island) had its own Big Bang. But here we have to make a distinction.

There is a Multiverse time and a time relative to particular island/grape universes. From the standpoint of the Multiverse's time, the islands/grapes pop up one after the other, successively. Vilenkin then does something very tricky. From the standpoint of each and every island/grape's time, each Big Bang happened at the same time (not successively)! So, from the Multiverse's standpoint, all those infinite amount of Big Bangs that WILL happen have, from the grape/island's perspective, ALREADY HAPPENED! That's why we can say here - in our grape/island - that there is already an infinite amount of grapes/islands. And this, ladies and gentlemen, is why we can say OUR island/grape is infinite. Excuse me? Am I the only one raising my eyebrows here?

Lets go further. Perched up in our island, we can only see so much: a frontier. The frontier keeps going, and if you kept traveling you'd reach the edge of the island itself. From Earth, though, we can only see so much. We'll call this our perch. Even though quantum mechanics says there's only a finite number of histories from the Big Bang to any perch (like there's only a finite number of pages that can be traced to the spine of a book), Vilenkin thinks there's an infinite number of perches IN our island! That means all the histories in our perch are echoed infinitely! What? Read that again.

Vilenkin doesn't prove that quantum mechanics can be a map of the physical world. To undercut this, we could point out the reality of free agents, people whose choices aren't random, which they'd have to be if quantum mechanics described them. I mean (per the above paragraph), think about it. Is my counterpart in another island/grape really typing this thread an infinite amount of times, in an infinite amount of ways (say, with a clown-suit on!)? Further, how does Vilenkin magically turn the infinite, TEMPORAL, FUTURE 'succession' of perches (let alone the islands/grapes) into the infinite, SPATIAL 'simultaneous' range of perches? How can you do this? I don't see it: at all.

On the one hand (from the multiverse's perspective), the islands are still popping up, as the ocean between the continents grows wider, as the false-vacuum (prodded on by these scalar fields) outruns the latest island. On the other hand (from the island's perspective), the islands are already there! Huh? I also see that Vilenkin espouses a B-theory of time, at least relative to the islands, which is strange. The only way for the infinite amount of islands to be already 'out there' is if their times are 'out there' too: hence, the B-theory. So, another way to undercut Vilenkin is to prop up an A-theory of time and give reasons why the B-theory isn't right. If it takes time for the 'wave of time' to reach a certain point in the future, the islands' times can't exist, and so neither can the islands.

Vilenkin also thinks that by putting out into the galactic ocean an infinite amount of islands, the design that our island has won't be improbable at all! If there's an infinite amount of islands, then of course an island like ours is bound to pop up sooner or later, he'd reason. All the scalar fields have to do is weather a quantum fluctuation, which will make a certain vacuum shrivel off from the false-vacuum (like a petal from a flower). Each vacuum has certain values, and these values are the constants that you hear about: the ones that are 'fine-tuned', like an instrument. But if there's an infinite amount of islands, each with there own values/constants, it's no wonder we see the fine-tuning in our own perch! We see what we want to see in Nature, since we're humans. We see intelligence because intelligence is doing the seeing.

Psychologically, it's almost as if Vilenkin is motivated by the desire to dethrone Man. Okay, perhaps the motivation for the Big Bang is to enthrone him again. Who knows? But at least, the Big Bang is consistent with the evidence we see from our perch. We don't even see any of the other perches, let alone the other islands/grapes, let alone other grapevines! So, at the very worst, you have a motive and no evidence on the one hand, and a motive and lots of evidence on the other. That's why I'll always take the Big Bang right now. It's that simple.

But let's put that aside. Remember, if the A-theory of time is true, Vilenkin's grapes/islands don't even exist yet: that means there ISN'T an infinite number of them. This down plays the probability point from the many-worlds theory. There's only as many islands as have popped up since the beginning of the first withering of the first false-vacuum: which would be the multiverse itself, the granddaddy grapevine. Is it at all probable that our universe (island/grape) with all its fine-tuning values/constants would have sprouted so soon? I mean, cosmically, 15 billion years isn't that long.

Lets go back to the eternal inflation point. Recall, Vilenkin thinks the multiverse will inflate forever. Okay, how? Well, Vilenkin thinks the scalar fields have properties that are in the driver's seat of the inflation going on forever. But guess what Vilenkin says on page 61?: "Another important question is whether or not such scalar fields really exist in nature. Unfortunately, we don't know. There is no direct evidence for their existence" Uh oh. So, we have no good reason to think the multiverse eternally inflates. That's a bit of a problem, no?

Another problem: why hasn't the multiverse died out yet? I mean, it's been around for an infinitely long time. I feel like this concept of infinity is tossed around and only certain philosophers know what it really entails. Shouldn't the multiverse have died a heat-death by now? Shouldn't there be thermodynamic equilibrium by now? If not, why not? Is our universe just an island of disequilibrium? If so, why is our island so big? I mean, it's pretty large. Shouldn't it look much smaller, shouldn't it be more probable that it be smaller if the whole grapevine was in equilibrium? Roger Penrose thinks that the odds are VERY VERY small that our island would be as big as it is. It should be about the size of our solar system, let alone our galaxy, let alone our perch, let along our grape/island!

And why don't I see strange things like a giraffe appear out of nowhere in my living room and then disappear again? The odds against that happening are a flea compared to the elephant of there being an island that has the constants/values for life, if - of course - there WAS a multiverse.

And if there WAS, did IT have a beginning? Ironically, Vilenkin - along with Arvind Borde and Alan Guth - in 2003, said that if a universe is expanding, it's got to have a beginning: it's got to have a space/time frontier. This principle pretty much applies to any model. Here it is, straight from the horses' mouth, 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" (p. 176). Thus, the mutiverse had a beginning. So, it popped into being out of nothing. Or, quantum tunneling? If so, why can't God bring it about that way too? At least, with God we have an efficient cause. This brings us to Vilenkin's model: quantum creation!

Imagine that the first state of our universe is a basketball filled with a false-vacuum, with teeny tiny bits of matter in it. If our basketball has a small enough radius, Newton says it'll collapse; but quantum physics says it'll tunnel, which will make our basketball inflate. So, there's two states. First, there's the state before the quantum tunneling; second, there's the state after the tunneling. But Vilenkin thinks that the state BEFORE the tunneling is NOTHING. Yet that's not what Vilenkin's diagram shows in his book. It shows that every step of the tunneling is SOMETHING into SOMETHING else. Vilenkin seems to think that if you DO have a radius whose measure is zero, that's the same thing as having NO radius. But it's NOT the same thing. In one case, you have SOMETHING; in the other, you have NOTHING.

Vilenkin admits it's not UTTERLY nothing. He wants this apparition 'nothing' to be subject to quantum laws. So, Vilenkin is comfortable with saying that there was a time when there was the laws of physics and yet no universe! Hmmmm. But that's not true when we realize that by 'no universe', Vilenkin means 'the state prior to the tunneling', when the radius measured 'zero'. But guess what? That state had some properties. Nothingness is the absence of properties! Not the same thing. So, Vilenkin misunderstands 'nothingness'.

Interestingly, Vilenkin has put on his 'philosopher hat' when he starts to wonder just what these laws of physics are. Are they abstract objects? Vilenkin says, YES! They are concepts that actually exist in a Mind. Excuse me? It's on page 205. Check it out!

So, there doesn't seem to be good reason to believe in a multiverse. Vilenkin's model is flawed big time. It presupposes a B-theory of time, which I think is flawed. The Big Bang model is still the best model. The many-worlds hypothesis doesn't have an infinite amount of worlds to work with; and it's pretty unlikely that an island would pop up that would permit life so early! 15 billion years isn't a long time, cosmically. Quantum mechanics doesn't describe everything in the natural universe. There's no reason to think the scalar fields can make the multiverse expand forever. Even if the multiverse is true, we should be seeing a MUCH smaller island than we do, in fact, see from our perch. And still, the odds against the fine-tuning of our island is still HUGELY improbable. On top of all this, the multiverse had a beginning, as Vilenkin points out. But it doesn't come from nothing, since Vilenkin misunderstand 'nothingness'. It comes from the false-vacuum state prior to its quantum tunneling! Well, guess what Vilenkin: that has properties - so, it's not nothing.