Louisville Process Theology Network

Endless Possiblities

" The newest mind-bending descriptions of reality dreamed up by the world’s smartest physicists, and explained by superstar superstring theorist Brian Greene in his latest book The Hidden Reality, include untold numbers of extra universes.

A million universes isn’t cool. You know what’s cool? Ten to the 500th power universes.

In this book, Greene describes hidden worlds, alternate realities, holographic projections, and multiverse simulations. He obviously likes to drop you into the middle of the action first and then explain the backstory but he has an elegant knack for anticipating questions and immediately dealing with any confusion or objections.

Greene was already an important string theorist when his enormously successful first book— The Elegant Universe—catapulted him into the firmament of popular physics with the other stars of the genre, Carl Sagan and Stephen Hawking. With that book and in his PBS miniseries based on the bestseller, Greene introduced quantum mechanics and Einstein’s theories of special and general relativity before heading off into the multi-dimensional realms of Calabi-Yau manifolds and super-symmetric string theory.

This time Greene describes nine different theories which imply that we are living in a vast multiverse. He’s pretty confident that some of them are true, but less sanguine about others. For example, he thinks chances are small that we’re living in a vast simulation with other universes running as parallel processes on some higher-order cosmic computer.

The simplest type of parallel world Greene describes is called the quilted multiverse. Simply put, our cosmic horizon is about 14 billion light-years away. Even the Hubble Space Telescope can’t see beyond that, because light from further away hasn’t yet had time to reach us yet.

But just because that’s the horizon of our vision, it doesn’t mean that’s the edge of the whole universe: ships don’t fall off earth when they sail out of view.

 In fact, Greene argues, there are very good reasons to think that the big bang created an infinite universe. If matter is more or less evenly distributed through the whole thing, then there must be other pieces that look just like ours, other islands in the cosmic sea, each with a radius of 14 billion light years that are simply beyond our limited horizon. These islands make up the patchwork of a quilted multiverse.

There are something like 10 to the 500th power different possible aspects of string theory, each of which would result in a different set of observed particles and physical constants.

Sort of like how monkeys typing for an infinite amount of time would eventually produce Shakespeare, an infinite universe would mean by statistical laws that there must exist other patches that look exactly like our own.

That means somewhere there is an island universe containing another earth filled with doppelgangers of you and me—in fact, infinitely many of them, though they’re far too distant for us to reach.

That may seem utterly strange, but it’s just math following from basic assumptions.

Greene posits that what we call our universe is simply a part of an even vaster entity which is still undergoing incredible expansion. The part that we call our universe condensed out of that expanding chaos like a water droplet forming out of a cloud of steam. That droplet, furthermore, looks infinite from the outside, and therefore contains within it the whole quilted multiverse talked about before. But floating out of reach are infinitely many other droplet universes as well.

If multiverses within multiverses are making your head hurt, buckle down because Greene has six other possibilities for parallel worlds.

He also has one big philosophical point, though, that could change the way we view the very goals of science.

We will never see these other universes, but we might find evidence that they do exist. Though Greene is optimistic about the possibility of confirming some of the predictions of string theory and multiverse physics in the near future, certain questions don’t seem immediately resolvable. Is there a particular reason why an electron weighs as much as it does, or that gravity is as strong as it is?

Maybe not, Greene suggests, except that these values are one of the enormous number of possibilities given by string theory and that if these values were even slightly different, life as we know it would be impossible.

We see what we see not because there is some mathematical imperative that things must be this way, but rather because of the very fact that we are here and able to marvel at our universe in the first place.

Excerpts from a book review at Amazon.com