I want to do a book report on Brian Greene's new publication in the worst way, but I'm not sure that I am capable of it. I used to read popular science books quite regularly, and I'd realized that it's been years since those days at about the same time that 'The Hidden Reality' caught my eye. As I was going through it I realized that reading, and keeping pace with, popular science texts is a skill which must be practiced, especially if one is not particularly well trained in physics.

That's not to say that he doesn't do a great job of explaining the concept behind 9 different types of multiple/parallel Universes quite engagingly; he does. It's more that, once I put the book down for a few minutes after every couple of pages to think about the implications of whatever mind-blowing concept he's introduced, the particulars begin to drain away because my poor little head is not lately used to holding on to the strange and complicated concepts behind Infinity, Relativity, Quantum physics, and String Theory.

However I'm going to try because I feel that my motive in writing about this book is more an effort to hang on as best as I am able to the understanding of a beautiful dream that fades quickly after waking than an attempt to convince anyone else to read it. Of course after completing that last sentence, I've sat and stared at the book cover for about ten minutes trying to figure out how to start. Sigh.

So here then; let's begin with the apology. Mr. Greene himself goes to great lengths in the book to make the reader understand that, at the moment, no versions of the multiverse which he posits are actually provable with hard data, and therefore may fall slightly outside the boundary of science. I say slightly, because though their detection may currently lie beyond our best detectors, they are in fact unavoidable outcomes of certain aspects of science which ARE scientifically sound, mathematically speaking.

As a comparison, when Einstein published his theory of General Relativity the technology available at the time was not capable of disproving his math. He came up with that theory using creative visualization, math and perspiration. And whatever other tools of genius he had at his disposal. But he himself did not go out and measure the Cosmic Background Radiation which ultimately helped to prove his theory correct. Now I'm not comparing Brian Greene or any other String Theorist to Einstein, (and neither was Greene in his book) merely the scientific process itself which is at work here. If you follow the math it leads to amazing places which, more often than you might think, describes the cosmos as it is in reality, even though it may also lead beyond all common sense. So this exploration of the side effects and the possibilities of infinity, string theory and math is extremely valid science, even if in the end it turns out that they've missed something and there are other things at work. You have to explore every avenue if you want to find out what's actually out there.

So why bother getting all excited over Parallel Universes if there's a chance it's inaccurate? *Because *it's exciting. And because, all things being equal, it's probably not inaccurate. It is currently science's best guess, much as Relativity and Evolution once were, and therefore worth a lengthy consideration.

So I'll start with the multiverse which I understand the most clearly, naturally. He calls it the Quilted Multiverse and here is how it works: There is some question in the cosmologist community whether the space that we inhabit is either very, very, very freaking large but ultimately finite, or whether it is in fact infinite. It all depends on the overall shape of the universe, which we don't yet know. (It's important to have a good grasp of the concept of infinity for this one, which I am lucky to have in some finite degree thanks to Rudy Rucker. His book 'White Light' is a rollicking exploration of infinity, and with extremely visual storytelling really helped me to glimpse what mathematicians actually *mean *when they use the term infinity. I highly recommend it.)

At any rate, If our Universe in fact turns out to be infinite (as the current trend of thought among cosmologists apparently believe is the likeliest scenario) then there is almost certainly another messiestobjects out there, writing up a book report about a publication by Brian *Browne*, (the last name of the author perhaps being the only difference between that Earth and this one) and positing some strange world where a version of himself is typing up a book report on a publication by a Brian *Greene*. In fact, there would be an infinite amount of Earths out there, that look just like ours. And there would be an infinite amount of other possible Earths as well. One, perhaps, that was solely inhabited by shrimp. Or one with *no *shrimp. Let your imagination go wild, like mine!

The reason why this would be so is simply statistical. Matter is evenly distributed throughout the visible Universe on very large scales. What that means is, you can take a really big box, say about 100 million light years cubed and chunk it down here, then weigh all of the matter in it. Then pick it up and chunk it down over there, again weighing all of the matter. Do this in several locations throughout the Universe and you will find that each box-full of matter will weigh in at about equal amounts, and it will be so all throughout the Universe. The idea here is that while matter may be evenly spread throughout an infinite Universe, there is a finite amount of forms that matter can take.

So the implication of this is that matter, as much of it as there is, can only arrange itself in so many ways. It's like a deck of cards; there are 52 cards in a deck, and 52 cards can be arranged in 10^{67} unique ways. That number fully written out is 80,658,175,170,943, 878,571,660,636,856,403,766,975,289,505,440,883,277,824,000 which is obviously a really huge number. However, once you have arranged those 52 cards in that many unique ways, the cycle will repeat and you will start to get duplicate arrangements. Of course, some arrangements are more likely than others, so you will have odd random assortments of cards duplicate more often than you will see the deck fall out completely arranged from aces to Kings in all four suits, but as unlikely as that is, it *will *happen eventually.

The same is true for the arrangement of matter. In the entirety of our visible Universe, there are about 10^{10122} possible particle configurations. Which again, is a totally inconceivable number yet is definitely a *finite *number. Once you've reached every possible unique combination, the patterns will begin to repeat, and repeat infinitely. Thus, messyobjects is out there, messierobjects, and even an evenmoremessiestobjects, all trying to say hi to me right now. Since our brains and life experiences are nearly completely identical and in some cases *absolutely *identical, I can say hi to them and they've received the message! I know this because I've received their message, having sent one myself. We're totally braintext messaging across the infinite light years right now. They say hi back, and ask how's the wife and pets and I say oh, the same as yours, pretty much. *ad infinitum*. (Of course it's not a very *interesting *conversation, having identical thoughts and all, but there's always a downside.)

Whew. That was the first and easiest version of a multiverse in this book, and believe me they get far more difficult to grasp. The existence of the Quilted Multiverse depends only on discovering the shape of the Universe we currently reside in without calling any of the more unproven forms of science into the matter, but it is important here to note that Brian Greene and other String Theorists did not go out looking for multiverses. They did not read some ridiculous New Age drama and say "Oy, how can we finagle the math to come up with parallel dimensional portal-thingies in order to dazzle the public?" No, the attempt to understand actual *observed *phenomena through the framework of String Theory led them mathematically all on its own to many other different types of possible multiverses.

The Inflationary Multiverse, which better fits the definition of a multiverse in my extremely humble opinion, is one in which bits of our universe break off and inflate into bubble universes of their own, our Universe having broken off from another "larger" one at its own birth. There are also the Brane, Cyclic, Landscape, and Quantum types of multiverses. I like the Quantum Multiverse; it basically goes back to the Schrödinger's Cat thing, and Quantum uncertainty.

(jpeg of a print by Jie Qi) In case you are not familiar with Schrödinger's Cat, it is a Thought Experiment designed to help one visualize how Quantum Particles behave. The way it goes is, you put a cat in a box, close the lid, and have a radioactive atom timed to decay and open a flask of poison. In the quantum world, there is an equal possibility of the decay happening and causing the cat to be dead or alive when you open the lid. Until you open the lid, the cat is actually in an uncertain state, being both alive and dead at the same time which would be an unsettling thing to witness, I'm sure. The traditional outcome of this little game is that when you open the box, the probability wave collapses and the cat becomes one or the other. Thus the very act of observation determines the ultimate quantum state. (For a more accurate and less confused rundown of the thought experiment in mid-twentieth century science nerd jargon, visit the wikipedia page on the subject)

This is weird. But this type of behavior has been observed in quantum particle physics, hence the Quantum Uncertainty Principle and it does not apply to the world of things of our size, only to the realm of the very, *very *small. There is a gap between the quantum scale and ours where Quantum Theory breaks down and reality then becomes guided by Newtonian physics and Relativity. If you add String Theory math to this experiment, you can bridge the gap and in fact the cat is actually both alive **and **dead for *realsies*, *in two different universes!* Long, complex, nearly-incomprehensible-to-a-non-String-Theorist story short, the reason that Quantum particles behave so oddly is that we are seeing them play out every possible state of existence across a multiverse.

As an interesting aside, that particular multiverse explanation is where the idea comes from that every time one makes a choice, universes diverge and a separate reality for each choice carries on it's course. It may sound a bit hippie or New Age-ish, but if String Theory turns out to be correct, this in fact may actually be happening, right now, right next to you.

Another multiverse is the Holographic Multiverse, which is conceptually easy, but also very hard to explain the whys and wherefores of. This one is due to the nature of information and how it is stored in the universe, and when looked at closely begins to look a bit as though all matter as we see it is actually a projection of another type of matter on a distant quantum dimensional surface. In this multiverse all of our actions, in fact all interaction between all forms of matter everywhere is a shadow play. We're hand puppets. Don't ask me to explain the science though. It has something to do with Black Holes, very tall drinking straws, and math. Beyond that, I haven't retained a thing. Damn it.

The final multiverse of the book is the so-called Ultimate Multiverse, a distinction earned due to a new twist on the Anthropic Principle, which is the idea that asking the question *"How is it possible that our planet, our very universe have the conditions necessary to bring forth life?"* is meaningless because life evolves in the place to which it is suited. In other words, we are here both to ask the question and be the answer. I like this one for purely philosophical reasons, as it's an (yet another) answer of sorts in the debate between religion and science, at least for a certain set of debate points. The religious often like to point out that the Universe, Life, and Everything are far too complex to have "just happened" which is about as far as their understanding of the sciences of Cosmology and Evolution usually go. A very sad, limited viewpoint indeed.

At any rate, the Ultimate Multiverse answers the question of why the Physical Laws of our particular Universe are just right in order for galaxy, star, planet, and life formation to "just happen". Because in an infinite multiverse, where every possible Universe that *can* exist *does *exist, one with our physical laws and conditions for life merely becomes an inevitability, not a miracle. Therefore there is no "why" of existence, merely the statistical likelihood of it. You'll note that the Ultimate Multiverse differs from the Quilted Multiverse in the sense that, with the latter, there may be an infinite set of volumes with repeating particle configurations, allowing for infinite versions of themselves, however they are all still set in the same Universe as we are and subject to the same physical laws, merely separated by distances too large for any technology to ever cross. The Quilted version answers the question of why there is life on *Earth*, but does not answer the why of the overall conditions in our Goldilocks Universe and its particular laws of physics being *just right* in order to allow life to come about in the first place. The Ultimate Multiverse does, however. It states that while there are Universes like ours with just the right amount of density for galaxies, stars, and planets to form, there are also an infinite amount of stillborn ones. Our Universe is the Royal Flush that comes along once in a blue moon... or rather once in a Blue Iteration.

There are solid mathematical underpinnings to the Ultimate Multiverse, as well as for all of the others, but I'm not going there. If you want to try to understand them, or any of the other concepts, I suggest that you pick up a few popular science books and get cracking. 'The Hidden Reality' is wonderful, but unless you've already attempted to come to grips with the ideas behind Relativity, Infinity, or Quantum Physics, you might want to get a more basic picture of the Universe first. 'Cosmos' by Carl Sagan is an excellent place to start for basic Cosmology, that Rucker book I already pimped for Infinity, and Brian Greene's earlier work 'The Elegant Universe' is a great introduction to String Theory. So get busy with the head scratching, braniac!

Another great way to contemplate infinity, by the way, is to obsessively-compulsively watch fractal zoom videos. I've posted about fractals before, here and here. I don't know how, but I'm sure that fractal math figures in to multiverses somehow. This one magnifies the Mandelbrot set 10^{275} times, and ends up at a copy of itself. Apropos.

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