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Parallel Universes
Scientific American ^ | May 2003 | Max Tegmark

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.

Entire Article

Overview / Multiverses

(Excerpt) Read more at sciam.com ...


TOPICS: Miscellaneous
KEYWORDS: physics
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To: Junior
My luck one of them would be French.
101 posted on 06/25/2003 3:20:11 PM PDT by BulletBobCo
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To: Fitzcarraldo
In this scheme, when we die in one universe, do we die in all? Or does our awareness get transferred to one of the near copies?

Which one of us are you asking?

102 posted on 06/25/2003 3:24:51 PM PDT by TomB
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To: BulletBobCo
It should have been four to keep things balanced.

That works out well because we're twins.

103 posted on 06/25/2003 3:25:38 PM PDT by TomB
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To: Junior
You really have no connection to your other yous

Wouldn't there be universes where you die and come back to life?

104 posted on 06/25/2003 3:39:07 PM PDT by Fitzcarraldo
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To: Physicist
Star Trek:TNG had a great episode related to this subject, but instead what existed were quantum realities. Near the end of the episode, all the Enterprises started to appear. When "our" Enterprise tried to set everything straight, an alternate Riker in command of one of the ships said "We WONT go back! The Borg are everywhere!"

Kind of a chilling way to think of the alternate realities of Earth, perhaps one where Stalin ruled the planet?
105 posted on 06/25/2003 4:31:07 PM PDT by Skywalk
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To: Physicist
Interesting.

Glad I have a different construction on "reality."

What is the WMAP data?

Certainly God has declared that HE'S going to wrap the world and the Heavens up and start over with new ones . . . whatever that means.

But I've always experienced Him to be true to His Word. So, I expect to see it happen just as He declared it would.
106 posted on 06/25/2003 7:42:35 PM PDT by Quix (FAIR MINDED & INTERESTED--please watch UFO special Tues eve & share opinions)
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To: Quix
What is the WMAP data?

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.

107 posted on 06/25/2003 7:53:07 PM PDT by Physicist
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To: Physicist
Ah so.

Thanks.

I think I understand your point now.
108 posted on 06/25/2003 9:09:45 PM PDT by Quix (FAIR MINDED & INTERESTED--please watch UFO special Tues eve & share opinions)
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To: Physicist; Buggman
Buggman: Now go back and look at the original article: Does or does not the author abuse the use of the word "infinite" when he says the universe is infinite in size and mass?

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.
109 posted on 06/26/2003 5:19:48 AM PDT by Moonman62
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To: Junior
"The Universe - some information to help you live in it."

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.

110 posted on 06/26/2003 5:35:58 AM PDT by Mad Dawgg (French: old Europe word meaning surrender)
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To: Moonman62
Think harder, and look at the numbers again. The gigantic volume he's discussing is not merely sufficient to find a duplicate of you floating somewhere in intergalactic space. It is sufficient to find a Hubble volume exactly like ours in every particular, even under the absurd assumption that every mathematically expressible arrangement of protons is allowed. Let's call these "Imaginable Hubble Volumes" (IHVs).

(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.

111 posted on 06/26/2003 9:03:13 AM PDT by Physicist
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To: Physicist
Thanks for the clear expanation. In fact, it's disturbingly clear considering that there is nothing known in physics that would exclude such a possibility.
112 posted on 06/26/2003 2:09:07 PM PDT by Moonman62
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To: Physicist
You didn't directly address my main argument (that finite plus finite is still finite), but you did indirectly assure me that the guy who thought this stuff up isn't a crank. Therefore I deduce that the assumption I missed at first pass through the article is:

Assumption: The universe was infinite in extent at the big bang, just as it is infinite in extent now, but it was just a lot smaller back then.

I tend to like a tidy "little" finite universe better, but I can't think of any way one could tell the difference. So, OK, I guess I didn't read the article carefully enough.

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).
113 posted on 06/27/2003 9:36:00 AM PDT by thirdheavenward
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To: thirdheavenward
Assumption: The universe was infinite in extent at the big bang, just as it is infinite in extent now, but it was just a lot smaller back then.

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.

114 posted on 06/27/2003 2:27:16 PM PDT by Physicist
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To: Just another Joe
ROFL to Post 20! I keep an open mind, but my brains keep falling out. =]
115 posted on 06/30/2003 6:33:43 AM PDT by Arthur Wildfire! March (LIBERTY or DEATH!)
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To: Fitzcarraldo
"Wouldn't there be universes where you die and come back to life?"

Like Heavan and hell? Gee man, that's so politically incorrect... I love it!
116 posted on 06/30/2003 6:37:27 AM PDT by Arthur Wildfire! March (LIBERTY or DEATH!)
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To: Ancesthntr
If there is, why is HE the one that sold all of his Internet stocks and used the proceeds to buy out-of-the-money QQQ puts in late March of 2000? Huh, why? And can he loan me some money?

Maybe this is just the second-best of all possible worlds, or somewhere else on down the line.

117 posted on 06/30/2003 6:38:08 AM PDT by Puddleglum
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To: Physicist
"...infinite radius..." someone said? Isn't that an oxymoron? How can infinity have a radius? People keep thinking inside the box.
118 posted on 06/30/2003 6:40:04 AM PDT by Arthur Wildfire! March (LIBERTY or DEATH!)
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To: Junior; mhking
I think I figured out how Hellery! did so well with cattle futures and why MacAwful, head of the DNC did so well in Global Crossing-- they're time travellers!
119 posted on 06/30/2003 6:47:49 AM PDT by Arthur Wildfire! March (LIBERTY or DEATH!)
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To: Moonman62
I'm glad things are cleared up for you. Nothing to clear things up like discussions on 'infinite radius', which is a giant vacuum of thought. Deep, man. Impossibly deep, which is the heart of it-- an infinite radius is an impossibility. As Phil V would say, we need to toss away the shackles of linear thinking and think three dimensionally, which is why I'll go and make a sandwich.
120 posted on 06/30/2003 6:56:09 AM PDT by Arthur Wildfire! March (LIBERTY or DEATH!)
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