Tuesday, December 13, 2011

Cosmology and the Multiple You: Part Two

The quantum mantra revolves around the theory that in physics, anything not forbidden is compulsory - given enough time and/or space. While there is nothing forbidden about an identical twin(s) of yourself existing elsewhere in the cosmos, how compulsory that is depends on what sort of cosmological model you adopt.

You are unique, aren't you? There never has been a person exactly like you before, there isn't now, and there never will be. Maybe! Depending on what's really real in all things cosmological, the odds that there are identical copies of you out there can range from plausible if improbable, to plausible and probable, to in fact near certainty, even certainty. The key issue revolves around the concept of infinity, or near infinity. If one has an infinite number of universes to play around with, and/or infinite time, then every possible history is, sooner or later, somewhere, compulsory.

Continued from yesterday’s blog…

Thirdly, could there be another you or multiple copies of you in the Multiverse? That's not only plausible, but much more likely than if only our one Universe exists.

Discussion: We live in a Universe that is very friendly to life-as-we-know-it (life-not-as-we-know-it is another can of worms that need not concern us here). That is, it seems that the various physical laws and physical constants are fine tuned to allow our kind of life. If any of those values were slightly greater or slightly lesser, the biophysics and biochemistry that allow organic life forms to exist wouldn't be possible. For example, if gravity were ever so slightly weaker, atoms/molecules wouldn't coalesce into macro-bodies like galaxies and stars and planets. If gravity were ever so slightly stronger, stars would be far more massive on average, and the more massive a star, the shorter it's lifespan, to the point where there wouldn't be enough time for life in a young solar system to develop before the parent star went poof! So, that fine tuning leads to a trio of possibilities.

The first is that we (meaning the Universe's life forms) are just incredibly lucky that our one and only Universe just happened to meet all the Goldilocks criteria that allow us to exist. The second is that there is indeed, an intelligent designer responsible for those conditions. For want of a better word, let's call this intelligent designer "God". (There's an interesting variation on this theme and that is this Universe was created by an extraterrestrial intelligence in another Universe, a feat which might be relativity simple to a highly advanced technology able to manipulate the basic forces of physics.)

The third possibility is that there is a Multiverse. We can all agree that our Universe is a Goldilocks universe. We can also all agree that we can imagine other universes, while superficially akin to ours (it would at least have space and time), have differing values for some of all of the physical properties we associate with ours - differing values for the physical constants, the types and numbers of physical forces and particles, the physical laws that are part and parcel of physics, etc. It's akin to humans - we're all superficially similar, yet each one of us (past, present and future) is unique (even identical twins differ and the same applies to clones as well as nurture affects us as well as nature). So, like we have a multiverse of humans, we could have a multiverse of universes (the Multiverse), some of which, like ours, will be Goldilocks universes, although most won't be because some critical constant(s) or force(s) or particle(s) or law(s) will be different enough not to allow the complexity we associate with life-as-we-know-it.

In other words, there exist dozens, hundreds, thousands, hundreds of thousands, maybe multi-millions or billions (or more) of universes where the physical laws and constants may well be different. That being the case, most universes will be barren of life because their physics, hence chemistry, aren't compatible with life-as-we-know-it. But a few, by chance, will be Goldilocks Universes. It wouldn't surprise anyone that because we exist, our Universe must be a Goldilocks Universe.

How exactly a Multiverse would come about is neither here or there. But there is at least one theory. To help explain various observational cosmological anomalies that would follow a traditional Big Bang, several decades ago the idea was floated that immediately following the Big Bang came a period of ultra-rapid inflation, before the expansion settled down to a far slower rate. Today, inflation is widely accepted as part and parcel of the Big Bang model. However, inflation need not have ceased at the exact same nanosecond everywhere. That is, if inflation continued on at one point, another Universe would quickly form, and if inflation didn't shut down exactly at the same moment, another bubble or pocket or baby universe would bud off, and so on and so on, resulting in a sort of bubble/foam collective of universes - the Multiverse.

The upshot is that lots of universes (a Multiverse), could mean a lot of you! However, distances separating the various copies of you are now even vaster, so again, getting together for dinner and drinks isn't possible.

Fourthly, could there be another you or multiple copies of you in Parallel Universe(s)? It's plausible, but perhaps not all that probable.

Discussion: We've all seen various sci-fi shows where our heroes get propelled into some sort of parallel or mirror universe. The characters they meet are close to, but not identical to themselves. The history they encounter is similar to, but not identical to the history they know. Of course that's for the sake of the plot. A parallel universe could easily contain a parallel you. Unfortunately, sci-fi aside, while there's theoretical reasons to postulate parallel universes, there's no known way of getting to them (and therefore no way of meeting yourself - assuming another yourself exists). But like in the Multiverse concept, if there are multi-billions of parallel universes, that increases the odds of a duplicate you.

To be continued...

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