Posted on 06/25/2003 7:42:21 AM PDT by Junior
Is there a copy of you reading this article? A person who is not you but who lives on a planet called Earth, with misty mountains, fertile fields and sprawling cities, in a solar system with eight other planets? The life of this person has been identical to yours in every respect. But perhaps he or she now decides to put down this article without finishing it, while you read on. The idea of such an alter ego seems strange and implausible, but it looks as if we will just have to live with it, because it is supported by astronomical observations. The simplest and most popular cosmological model today predicts that you have a twin in a galaxy about 10 to the 1028 meters from here. This distance is so large that it is beyond astronomical, but that does not make your doppelgänger any less real. The estimate is derived from elementary probability and does not even assume speculative modern physics, merely that space is infinite (or at least sufficiently large) in size and almost uniformly filled with matter, as observations indicate. In infinite space, even the most unlikely events must take place somewhere. There are infinitely many other inhabited planets, including not just one but infinitely many that have people with the same appearance, name and memories as you, who play out every possible permutation of your life choices. |
(Excerpt) Read more at sciam.com ...
Which one of us are you asking?
That works out well because we're twins.
Wouldn't there be universes where you die and come back to life?
WMAP is the Wilkinson Microwave Anisotropy Probe, the device that produced the data upon which Prof. Tegmark bases many of his conclusions in the above article.
Actually, I think he's abusing the word infinite by assuming that it's all inclusive.
From his article, here is how he calculates the odds for someone's twin, not only existing in a parallel Hubble volume, but appearing in an infinite number of them.
One way to do the calculation is to ask how many protons could be packed into a Hubble volume at that temperature. The answer is 10^118 protons. Each of those particles may or may not, in fact, be present, which makes for 2 to the 10^118 possible arrangements of protons. A box containing that many Hubble volumes exhausts all the possibilities. If you round off the numbers, such a box is about 10 to the 10^118 meters across. Beyond that box, universes--including ours--must repeat. Roughly the same number could be derived by using thermodynamic or quantum-gravitational estimates of the total information content of the universe.This shortcut may work for the early universe, but I don't see how it could work for a time when humans have already evolved. It looks like he's incorrectly assuming that a human can appear anywhere in the Hubble volume, but instead it must appear on the surface of a habitable planet. Not only that, but it must be on a planet where the quantum states of my parents appeared, and their parents, and so on all the way back to the primordial ooze. And then he goes on to make the following conclusion:
Your nearest doppelgänger is most likely to be much closer than these numbers suggest, given the processes of planet formation and biological evolution that tip the odds in your favor.It seems to me that such required physical processes would greatly decrease the odds of my twin appearing in another Hubble volume.
The Hitchhikers Guide To The Galaxy: There is a theory which states that if ever anyone discover exactly what the Universe is for and why it is here, it will instantly disappear and be replaced by something even more bizarrely inexeplicable.
There is another theory which states that this has already happened.
(Some of you may object to the lack of electrons and neutrons. We can assume that for every proton, an electron is "along for the ride", and combine each proton with its electron to form a neutron, wherever the nuclear equation of state demands it. Alles klar, Herr Kommisar?)
As it turns out, however, not every IHV is physically allowed. In those 210^118 IHVs, almost all of them will be a uniformly dense mass of nuclear matter. In the reality, we can disregard them.
In the tiny subset of IHVs where the density is as low as we observe it to be in our Hubble volume, which we'll denote "Low-density Hubble Volumes" (LHVs), almost all of those will be a rarefied gas of protons. These we can disregard also, because in the real world gravity will collapse the gas into condensed objects.
In the tiny subset of LHVs where the matter is collapsed into dense objects, which we will call "Condensed Hubble Volumes" (CHVs), almost all of them will be unvariegated piles of homogeneous crap. In the real world, the condensed matter will be formed into galaxies, stars and planets, so we can disregard almost all CHVs. We'll call this subset "Proper Hubble Volumes" (PHVs).
To recap: the number of IHVs >>> # of LHVs >>> # of CHVs >>> # PHVs (where ">>>" means "gigantically greater than"). Tegmark's distance calculation reaches past all the IHVs, but that's a gigantic overestimate, because in reality you'll only find PHVs out there, and the PHVs happen to be the ones that contain the right conditions for making guys like you and planets like ours. Nature has already done almost all of the winnowing out of that ensemble of 210^118 possibilities. All of the absurd ones are gone, so you don't have to "reach past" them.
I don't think you can make that assumption. The rate at which parts of the universe are receding from us is proportional to distance. Extrapolating backwards, the time at which the Andromeda galaxy was right on top of us is exactly the time at which a galaxy a google of universes over was on top of us. Zero times "arbitrary" is zero.
Also, I don't think the radius of the hypersphere has anything to do with volume. If I understand things properly, the radius has to do with the curvature. For example, the universe could be all of one square meter in total volume, but the radius of curvature could still be infinite. So making that infinite radius more than just curvature, and saying that the infinite radius is both the radius of curvature and the radius of the volume of the universe, would also be an assumption (although it would be in some ways a satisfactory connection).
Let's see whether I can clear this up. Back it off a dimension, and consider the "hyperverse" to be like the surface of a balloon. Our Hubble volume ("universe") is like a tiny circle drawn on that balloon. The balloon has a radius, and the circle has a radius, and it seems like you might be confusing them. If I say "infinite volume", I'm referring to the area of the balloon, not the area of the circle.
Maybe this is just the second-best of all possible worlds, or somewhere else on down the line.
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