Talk:Multiverse/Archive 3

Conscious Machines
"Most scientists entertain the possibility of creating artificial conscious machines[citation needed], and some artificial intelligence advocates even claim we are not far from producing conscious computers." Wait, isn't the same thing being said twice, but with a slightly different meaning? A computer usually is a machine (and a machine might be a computer). The "not far from" might mean one, ten or a hundred years, we must be more specific. And the "even" could be left out. I'll edit it some more unless you have some comments on this. Ran4 (talk) 12:22, 25 December 2007 (UTC)

The difference between observable fact, likely hypothesis, and speculation
This entire article is riddled with speculation presented as fact or likely hypothesis, and likely hypotheses presented as facts. If something has been observed in the real world, or if a finding has been made and replicated, that's a fact - but the interpretation of those facts is another matter. Speculation is a wonderful thing - humans would be mindless naked brutes wandering the savanna if they could not speculate. But it is critical to call speculation speculation, and fact fact, and not confuse the two.

When a theory is proposed that has no direct factual underpinnings, and is not verifiably predictive, it is speculation. This includes things like String Theory, right now - there is no laboratory or field evidence that String Theory is a valid model. And the same is true, at the moment, for all of the Multiverse variations - there just isn't any hard evidence for any of them, although lots of mathematical models seem to need them.

It's important to realize what is dependent on what, and what is a cause and what is an effect. Did we evolve hair because the invention of hair gel was inevitable? No. Is the universe dependant on our mathematical models? No. The universe is indifferent to what we say it is, and the beauty or simplicity of your math does not mean it matches the actual universe.

Please try to maintain some healthy skepticism as you write, and please do apply some reasonableness criteria.

For example, I have read claims that for each event which has more than one possible outcome, down to the subatomic level, a new universe is spawned for each outcome so that all outcomes happen somewhere. This is talked about in the press, is used as the basis of Science Fiction, and many people trot it out as part of their understanding of the world to excuse their bad behavior (since they are doing the good behavior in another universe). Of course, if true, this theory would necessitate creating untold trillions of trillions of new full-sized universes every picosecond. If you believe in this model, here are some basic questions which need to be answered:

1. What is the mechanism for taking a snapshot all of the information in the universe, down to the subatomic level, in such a tiny increment of time?

2. What happens when untold trillions of trillions of choice points happen simultaneously, as they always will?

3. What mechanism will analyse the many-to-many mapping of those trillions of choice points and decide which outcomes for each of them will be represented in each specific universe?

4. What is the mechanism for doing the actual creation of each entire mature universe?

5. And where does the energy come from for the creation of all these verses?

If you can't answer these questions without resorting to supernatural intervention, you might consider moving your belief from the "true" or "probably true" bucket in your mind to the "Way too many important parts of this are missing" bucket.

The same kind of hard questioning should be done for every multiverse theory presented in the article.

Let's attempt to use the scientific method here, it's a pretty good way to separate fact from wishful thinking.

EdgarCarpenter 04:41, 11 September 2007 (UTC)

Travelling To These Universes
If we were to take a space ship and travel to the ends of the observable universe, would we arrive in empty space between universes? And if we were to keep traveling will we eventually reach another universe? Or is traveling to another universes strictly limited to finding away through the 11th dimension? Anyone know what I'm talking about?Zachorious 09:15, 14 February 2006 (UTC)


 * 1) In most multiverse theories, we -- versions of us --already are in other universes! This can be turned into an argument against MV theories, since it seems to predict that our subjective exprience should be a lot more surreal and inconsistent than it is.
 * 2) In Quantum many-worlds theory, universes are not separated in space, they co-exist in the same space, but are kept separate, where they are separate, by decoherence.1Z 16:36, 14 January 2007 (UTC)


 * If there going to be called seperate universes than there would probably be something seperating them.--68.91.130.71 01:49, 27 November 2006 (UTC)

If I understand everything i've read, no one knows for sure. It makes more sence for the universe to be finite however the universe could be infinate. Also no one is even sure that there are multible universes there could just be one and thats it, this like most things in cosmology is just a thoery. The size of the observable universe is the very least the size of our total universe so if we were go to the end of our universe (if thats even possible) noone would even know what we would find because we can't see past the observable universe, so basicly my understanding is your asking questions that noone on this Earth can answer. --Riraito 22:48, 20 December 2006 (UTC)

Twin universe cosmology
adding research website on twin universe theory, can be studied a lot http://jp-petit.com/science/f200/a201.htm its links : http://jp-petit.com/science/f300/a301.htm

Arguments for multiverse theories
There appear to be listed here, arguments against multiverse theories. What about the arguments for multiverse theories? Shouldn't they be listed to? Well I've just listed one of them. 64.192.107.242 16:49, 20 February 2006 (UTC)
 * And I reverted it. The bulk of the first part of the article is the arguments for multiverse theories. --DV8 2XL 16:52, 20 February 2006 (UTC)

Open Multiverse
This section is wrong. I don't know exactly how to fix it, but point any physicist to the line "This assumption relies on the theory that at some stage in the past matter was distributed fairly evenly across space, and later condensed to form objects dense enough to become the source for a big bang." and I'm pretty sure they'll know it's wrong as well. Tlogmer 21:33, 1 March 2006 (UTC)
 * If I'm not mistaken it is from Alexander Vilenkin's ideas. Problem is it's hard to find any physicist that won't have issue with some of the ideas presented here; it was written as an overview of the many ideas that are circulating on this topic. --DV8 2XL 21:39, 1 March 2006 (UTC)
 * I'm almost positive it's a mis-statement of those ideas. The big bang theory presupposes space itself expanding, so the idea that there would be space "in between" big bangs is nonsensical.  (Could you point to one of Vilenkin's articles?) Tlogmer 21:45, 1 March 2006 (UTC)
 * I'll try and find one, give me a few days, I'm a little backlogged elsewhere. Please note that many of these ideas are not compliant with big-bang cosmology and keep in mind that this article is a discussion on current thought in this area - not a definitive work on the subject. I fact many of these concepts are diametrically opposed to each other. I'm mentioning this as there has been outbreaks of high POV editing attempted here as someone takes it on themselves to show us the 'One True Path' on this subject.--DV8 2XL 22:52, 1 March 2006 (UTC)
 * All the multiverses cited in the Scientific American article are compliant with big bang theory.  I'll look up the article and rephrase from there. Tlogmer 02:17, 13 March 2006 (UTC)

At a first shot try: Jaume Garriga and Alexander Vilenkin, “Recycling Universe,” Physical Review, D 57 (1998): 2230-44. but I'm not betting my life on it at this point. --23:26, 1 March 2006 (UTC)

"The size of the Hubble volume is directly related to the age of the universe; it grows at a rate of one light year per year, or exactly the speed of light." Shouldn't this be, "The radius of the Hubble volume is directly related..."? After all, a light year is a distance, and Hubble volume is a volume. James barton 16:38, 1 October 2006 (UTC)

We really need an expert to fix this because the universe is growing at a rate that is currently accelerating. There are many incorrect and inconsistant facts i see in this article.--Riraito 22:58, 20 December 2006 (UTC)

This didn't make much sense to me either. At first I thought 'If the observable universe is 46.5 billion light years in radius, wouldn't that make the universe 46.5 billion years old?' If someone could explain this to me, I would appreciate it. 09 January 2007


 * Relativity only forbids local travel at over the speed of light: there no reason why an extended (and therefore non-local) object can't increase it radius at a greater than light speed. For the expanding universe the recession velocity = H r where r= distance from us and H is the Hubble constant.  Make r large enough and you get v > c. --Michael C. Price talk 10:14, 9 January 2007 (UTC)

I was under the impression that the universe we live in is approximately 13 to 14 billion years old, so how can the "observable universe" be 46.5 billion? I think somebody misplaced a decimal. 4.65 billion, maybe? 70.145.75.61 22:03, 13 November 2007 (UTC)

Serious Problems

 * "The problem lies in the tension between classical notions of identity and quantum indeterminacy. In short, quantum reality does not allow classical - radically mechanical - 'identities' due to the Heisenberg Uncertainty Principle. However, in an infinite set of possible universes such a correspondence is presumed to exist. The question then becomes whether one can claim a distinction between entities that vary only in terms of some arbitrary dimensional metric in De Sitter space."

Can you honestly tell me that is readable?


 * "Recent pronouncements by Church authorities suggest the Catholic Church, now appears to reject all such hypotheses as well in what may be a reversal of a long standing hands-off policy regarding the physical sciences (see [3] [4] [5] and [6] for an alternate view)."

Not one of those links mention anything about "such hypotheses" (multiverse hypotheses). A good article could be written without much mention of intelligent design.


 * 1. The director of the Vatican Observatory (amongst many others) disagreed with Schönborn, an Austrian cardinal. It is incorrect to say that the Roman Catholic Church official stance is "the rejection of all such hypotheses". 2. The links mentioned don't say anything about multiverse hypotheses, only about ID.  3. Why is it necessary to put the Church under Anthropic principle?  4. These sentences don't add anything new.  Everything has been said in the sentence before (up until "Recent pronouncements by Church authorities...").  5. Dubious readabillity. ;  I believe these are reasons enough to delete this sentence and quote, or alter it to something as: "Some prolific members of the Catholic Church reject multiverse theories, and there is a conservative trend regarding these hypotheses." KevinGovaerts 13:34, 8 September 2006 (UTC)


 * Hugh Everett's many-worlds interpretation is NOT a mainstream interpretation. I know not one physicist that ascribes to MWI.  I challenge you to find one.  That's not to say that MWI is not without merit, but I wouldn't call it "mainstream" at all, considering the only time I heard of it was in a philosophy class (and never in any of the MANY grad/undergrad physics classes I've taken).


 * It would be nice to see ANY kind of citations of "arguments" against multiverse theories. It's not to say that there are no arguments, but each one listed could be someones soapbox rather than a bona fide argument against multiverse theories.   The stated "why this meta-law" hints of amaturish philosophy.  But I could be wrong, it would be nice to see a cite somewhere. --jabin1979


 * Where did you get the idea that it is not a mainstream interpretation? David Deutsch, for one. For physicists that bother about interpretations,  it's fairly popular as a matter of fact.--CSTAR


 * Look in any quantum mechanics book (Baym, C&T, Sakauri, Leboff). You will not find the mention of MWI in these books.  However you will find the Copenhagen in EVERY ONE (showing that physicists do indeed think about interpretation).  Two people do not make it main stream--even 10 wouldn't.  Copenhagen is the mainstream interpretation among physicists, for better or worse, there doesn't seem to be any other. But maybe you're talking about Philosphers.  Yeah David Deutsch is nice, I have his books too.  How many more can you name?  I can name several of his contemporaries that do not, or at least are silent on the issue  (Healey from UofA for one). Either way, I would argue that the hundreds of thousands of physicists that use QM on a regular basis don't ascribe to the MWI then it should count for something. Just a thought.--jabin1979


 * B. DeWitt, R. N. Graham, Everett's advisor Wheeler, Lev Vaidman, Max Tegmark  According to Michael CLive's FAQ
 * "Steven Hawking is well known as a many-worlds fan and says, in an article on quantum gravity [H], that measurement of the gravitational metric tells you which branch of the wavefunction you're in and references Everett."
 * See also
 * W. Schommers (Ed), Quantum Theory and Pictures of Reality, Springer Verlag 1989 (pp36-37)
 * --CSTAR 06:33, 10 March 2006 (UTC)


 * PS For whatever it's worth, I am agnostic on this matter.--CSTAR 06:33, 10 March 2006 (UTC)

I have added citations to the list detailing sources of the criticisms; I could have sworn the P.C.W. Davies one was in there from the beginning - if not it should have been. Mea culpa.

As for the wording, this is inherent in trying to balance an article so that it is accessible by a general readership and doesn't offend a more knowledgeable audience. I missed the mark in your case between the meta law entry and the trans world identity one. You can't please everyone.

Wikipedia is a work of record. It would be impossible and unfair to take a rigid line on any idea. WP:NPOV demands only that an editor write without undue bias for or against a concept - not that he/she toe some party line. I believe that this work meets those expectations. --DV8 2XL 14:40, 9 March 2006 (UTC)


 * By the way, DV8 I'm willing to chuck the Schonborn quote. I put it in and though it still seems relevant, I probably won't object to any editorial decision you make on this particular matter.--CSTAR 06:54, 10 March 2006 (UTC)

http://www.newscientist.com/channel/opinion/mg18524842.800

Viewing Overlapping
It seems section 1, 2 and 3 overlap and are redundant. This may be normal, if so than ignore me, but in my viewsettings, the edit buttons for sections 1 and 2 are actually behind the text of a section and section 1 seems to be a collection of data that is supplied by a number of other sections from 2 onwards. Can someone with a little more wiki knowledge have a look at it?

Infinite, uniform universe is uncontroversial?
I have an issue with a blurb in the "Open multiverse" section:
 * That the universe extends infinitely and rather uniformly in all directions is uncontroversial among physicists. (A finite universe is a minority view.)

Every physicist I've met either thinks the universe is finite, or refused to comment. The "uniform" part is also wrong, i think. (see ) --Snargle 05:59, 12 April 2006 (UTC)

The finate universe used to be the minority view, but it is now by far the majority, scientists now belive (as do I) that it makes more sence for the universe to be finate then infinate.--Riraito 23:00, 20 December 2006 (UTC)
 * No, the issue of the finiteness of the universe is far from settled. See past-eternal inflation which has many features of the steady state theory. --Michael C. Price talk 09:57, 9 January 2007 (UTC)

Trans-World Identity
What exactly is trans-world identity? --Aero77 05:59, 17 April 2006 (UTC)
 * A very short answer is that transworld identity just analogous to the problem of identity over the postulated ensemble of multiverses. A more complete answer awaits it's own article. --DV8 2XL 00:47, 18 April 2006 (UTC)

Question
I came here trying to learn about some awesome new multiverse theories but it turns out that I cannot understand more than a sentence of that article.
 * Go to the library. WP is not a replacement for books.--CSTAR 18:23, 18 April 2006 (UTC)
 * Perhaps that's true, but that's hardly a justification for an incomprehensible article.--Michael C. Price talk 09:54, 9 January 2007 (UTC)
 * Agreed. The article is catering for a niche group that can comprehend this sort of un-relenting jargon, but it has no place in a user defined encyclopedia. —The preceding unsigned comment was added by Syferus (talk • contribs) 01:10, 4 March 2007 (UTC).

Ontological status of a fake universe?
would anyone seriously affirm that a virtual universe is of 'lesser' ontological status that our observable universe? If so, what would be the ontological criteria? What would also be assuring against a matrix-like scenario about observable universe? Also, the 'critique' goes on to the next question assuming that this is indisputable; I'd expect it being allmost universally disputed. There are no links to sources to this criticism stated in the article, could anyone source this particual 'critique'--Aryah 07:06, 11 May 2006 (UTC)
 * The idea is stated on page 12 of the P.C.W. Davies paper that is listed in the references section. --DV8 2XL 10:31, 11 May 2006 (UTC)

Right, thx, i'll RTFA :D btw I have not seen any wiki-wide custom about this, but some articles have the custom to provide links and footnote sources for every particular claim thats made; others, like this one, simply state refferences at the end. Whence the different approaches? Does wikipolicy have any prefferences about this?--Aryah 12:49, 11 May 2006 (UTC)

Measuring a Finite vs. Infinite Universe.

 * Tegmark notes that improved measurements of the microwave background radiation and of the large-scale distribution of matter may fortify or knock down two pillars of the multiverse, that of the infinitude of space and the theory of chaotic inflation. So some facets of the theory may be testable, at least.

I'm no expert, and I'll understand if people don't want to bother trying to catch me up. That said, this statement sounds fishy. How can we tell the difference between a finite universe and an infinite universe via background radiation? At most, we might be able to disprove the Big Bang (because, say, we notice really old radiation coming from an odd direction, and our technology has improved to pinpoint where the Big Bang "should" have been, and that matter from the BB couldn't possibly have reached the incredibly far place where we notice the super-old radiation from at the time). But how can we ever tell if we live in infinite space? If matter was evenly distributed, there might be some way of getting some e-like constant for "maximum amount of old stuff reaching us now," but if the universe was simply super-duper-huge, then the difference in measurement would be incredibly minute. That's assuming even matter distribution; if the universe is infinite but there really was only one Big Bang which sets a finite "length of the universe in light-years radius" from which matter emanates into the empty void, then I think it'd be impossible to tell the difference.

Forgive me if I show my ignorance with this. SnowFire 18:38, 26 May 2006 (UTC)


 * It really isn't whether or not the statement rings true, most of this topic is speculation at this stage of human understanding. What is important to the standards of Wikipedia is if can be established that Tegmark is being quoited correctly - which he is. See also WP:V --DV8 2XL 18:53, 26 May 2006 (UTC)


 * Oh, I understand that. I'm not saying it should be taken out of the article.  I'm just curious, and yes, I know that Wikipedia is not a message board.  Call it a request for even more explanation that might eventually make it into the article, if you will. SnowFire 19:20, 26 May 2006 (UTC)

Multiverse vs. Omniverse

 * A multiverse (or meta-universe) is the hypothetical set of multiple possible universes (including our universe) that together comprise all of physical reality

this very well may be ignorance but i thought multiverse is just a set of all possable universes and the omniverse was all universes and therefore all of physical reality or is it talking about reality to us then our universe would be all of reality correct me i'm probbaly wrong Phy1729 03:26, 2 June 2006 (UTC)

Max Tegmark
I started looking for a way to tidy the section on classification, but became a little confused regarding the actual reference. The text talks about a Scientific American article, yet the footnote in the next sentence links through to a yet to be published article. Clarity needs to be achieved here. I notice that on this talk page there has already been mention of using the citation method being employed on other pages. I personally think it is necessary for this article. -Fermion 05:20, 29 June 2006 (UTC)
 * It originally linked out to the SciAm article 207.164.4.52 18:29, 30 June 2006 (UTC)

If other universes are discovered, will our universe get a name?
Will we give our universe a name when other universes are discovered? Our galaxy got a name when other galaxies were discovered. Voortle 22:58, 29 August 2006 (UTC)


 * Depends on the nature of the other verses, whether any are worth naming (observable?), and whether you can theoretically go and visit them. FYI Pure speculation doesn't belong in an encyclopedia. --Snarius 08:24, 30 August 2006 (UTC)

If others are discovered, which may or may not happen because we don't even know if there are others, then they're are many possible outcomes to what would happen, all universes could exsist in a megaverse or they could be identical but where one person made a different choice or one atom decayed another way or a near infinate ammount of possibilities and there are lots of other options if they exsist in a megaverse I would imagine we'd call the megaverse the universe and create a new name, like I think we did for galaxcy, and they'd name what we call the current universe a new thing. I'm thinking of cells and how we then found new parts to cells then new parts to those and such and such and then we had the atom then we even broke that down and have parts to that. so maybe in the future we can break those parts of the atom down even more and more and more i can't fathom how far we can go until everything is string and ahhhhhhhh.... but anyway our universe could be a smaller part in a bigger universe or megaverse or whatever and that in a bigger universe or whatever and so on and on and on. I hope that makes sence to others and not just me I guess I answered the question with a we don't know and the fact we don't know is true for nearly everything about space the universe, things could surround our universe and then things around that and things around that just like with atoms and its just....we really don't know anything. Umm.. so i guess it will get a name if others are discovered. --Riraito 23:26, 20 December 2006 (UTC)

They have been named and the name correlates with the wave frequency/band of the particular universe. (Picture light through a prism).

We should just name our universe, because we probably aren't going to find another one. Our universe is ever-expanding, so why shouldn't the others be? First, how do we get to the end of an ever-expanding universe, second, can we, and third, once we get past our universe, will be able to get in to another one? —Preceding unsigned comment added by 71.233.61.64 (talk) 01:42, 4 January 2008 (UTC)


 * This is a talk page, not for general discussion or speculation on the subject. :)  J o s h  10:49, 21 July 2007 (UTC)

Colliding on a track
I am looking for an article about a recent (within last 5 years) theory that our universe and another are travelling a circuit and occasionally one catches up to the other and collides, triggering events within the universes. I don't know the name of the theory or who developed it. Conceptually, the last collision would have happened at the Big Bang. GBC 23:47, 5 December 2006 (UTC)

Thats an intresting thoery I would imagine you could go more ways with that thoery and i'd like to hear about this thoery and stuff like it to, somone send info to me or post it here or whatever please.--Riraito 23:32, 20 December 2006 (UTC)


 * See brane cosmology. Boud 15:38, 9 January 2007 (UTC)

Lewis and Modal Realism
Your discussion in the article of Lewis's modal realism is incorrect. You write:

"some philosophers such as David Lewis believe that all possible worlds actually exist (a position known as modal realism). This thesis is one of the central tenets of his book.[9]"

Lewis, nor any other modal realists believe that every possible world actually exists, they merely exist. The only possible world that actually exists is whatever world is considered actual. All others exist non-actually. Actual, on Lewis's view is an indexical term. I've edited the entry to fix this. —The preceding unsigned comment was added by 137.99.43.82 (talk) 17:21, 7 December 2006 (UTC).

Implications to religion
Are there any sources for the content of the section called "Implications to religion"? It looks a bit like original research to me. --Danogo 10:35, 26 December 2006 (UTC)

Can we get rid of the religious nonsense please? Just because a religious text happened to guess at a theory that later became scientifically contemplated doesn't mean anything. Thousands of religious texts have guessed at how the universe came about, including 'the earth was created in 7 days'. It was inevitable that one of those ludicrious texts would stumble upon a later scientific theory. There's no reason why the reader needs the reference. —Preceding unsigned comment added by 76.213.242.101 (talk) 06:15, 15 September 2007 (UTC)

Chapter 1: 'What if?'
The existance of alternate universes is ultimately determined by a 'What if?' statement. Alternate universes can even make fantasy and all fiction real with a simple 'What if?' statement. The ultimate determining 'What if?' statement needs previous 'What if?' statements to be true often. For example: The ultimate 'What if?' statement is known as A while all other 'What if?' statements are known as B-Z and 0-Infinite. This created the extremely long equation A=BCDEFGHIJKLMNOPQRSTUVWXYZ01234567891011121314151617181920...and so forth. Not all alternative universes have this, having less or even more needed requirments to exist. In exist/non-exist universes where the universe was created or not, the equation is simply known as A=A/B, A representing existing whilist B represents not existing. This equation would be referenced as the Alpha Equation, due to its explaining if a universe exists or not. The Omega Equation is the ending equation meaning the previously mentioned equation is applied unless the Alpha Equation is A=B. Nevertheless all of the characters is a 'What if?' statement, from the smallest detail to the turning-point in any story. --Eiyuu Kou 19:47, 30 December 2006 (UTC)

Error in the "Open Multiverse" section
"Thus, there are an infinite number of regions of space the same size as our observable universe -- an infinite number of observable universes, that is. This infinite set (which must contain, among other things, an infinite number of identical copies of you,[4] the nearest of which is about 10^{10^{29}} meters away, and an equally infinite number of not-quite-identical copies) comprises the level-I multiverse."
 * See Cardinality of the continuum, Countable set, and Aleph number to see what is wrong with this statement. While it is true that in an unbounded space there would be an infinite number of observable universes, this would be countable infinity (Aleph null) The number of possibiltities one of which is an "exact" copy of you is uncountable. (in fact the set of real numbers- your body mass, your lifespan, etc is uncountable.) Even in an open multiverse, there is zero probabiltiy that there is an exact copy of you. In fact, there is zero probability that any two objects even have the same mass. The original statement is mathematically wrong. The last part of the paragraph- "an infinite number of not-quite identical copies is still valid however. JeffStickney 16:02, 28 January 2007 (UTC)
 * The deleted text was not in error and it was sourced. Your rebuttal  assumes ("in fact the set of real numbers- your body mass, your lifespan, etc is uncountable.") that are an infinite number of configurations of matter and energy possible within the observable universe.  This is false, the entropy of any region is limited by the Bekenstein bound.--Michael C. Price talk 16:28, 28 January 2007 (UTC)
 * I stand corrected, and have reverted my previous edit. I'm not necessarily convinced by the discrete spacetime theories, but now that I see what the statement was based on and realize it was not simply bad math, I put it back in.JeffStickney 17:18, 28 January 2007 (UTC)
 * Thanks, I've added a line about the Bekenstein bound to make it slightly clearer. Also linked in the Hubble volume and removed an erroneous statement about how quickly it grows.--Michael C. Price talk 21:21, 28 January 2007 (UTC)

Multiverse - Origin of Term
I just watched a documentary called, " What We Still Don't Know", by Sir Martin Rees who makes the claim openly that he coined the term "Multiverse". In this Wikipedia article, the writer claims that the specific term "multiverse", was originally coined by William James. It is an openly stated claim that Sir Martin Rees makes(he is the Astronomer Royal for England) during this documentary. The narrator in the documentary makes the assertion that, and I quote, "Martin Rees coined a new word to describe the idea" (mulitverse)and Sir Martin Rees goes on to state, "I have chosen the word multiverse". --Cosmica 21:05, 5 February 2007 (UTC)

Other universes
Who knows, there could be new universes, what if there are? If so, what will be there, let alone if we ge there, of course thats a few billion years away so I would say there is more than 1 universe (even though I can't understand quantam physics) —The preceding unsigned comment was added by 206.58.38.88 (talk) 03:48, 15 April 2007 (UTC).

Question
I read some parts of this article, but I have a question. If there are really multiverses, where are they? I mean, if we're here in this space on this earth, where are these universes located? —Preceding unsigned comment added by Verjolas (talk • contribs)
 * Space,(at least the part we are in)is expanding, and it is expanding rapidly enough to produce an event horizon- information from outside the horizon cannot get in because it would have to travel faster than light to counter the rate of expansion. This event horizon hides all but a finite bounded region from us, and yet people speak of the "size of the universe", the "age of the universe" and the moment "when time began" as if the piece we are capable of seeing (which we already know to be limited by the expansion) is all that exists. In the "open multiverse" scenario, that piece that we can see-the piece that eminated from the big bang and is refered to as "THE" universe is a small part of a much larger (and perhaps infinite) picture.JeffStickney 23:01, 12 June 2007 (UTC)

Tone/De-abstraction
This article is written in a very informal tone. There's a lot of "that is", "you", and informal section headers ("It's bad science", "It's not science" etc). Aaron Bowen 10:56, 14 June 2007 (UTC)
 * I've renamed the section headers under criticism, hopefully bringing them to a better style. I think whoever started those sections may have been slightly biased.  J o s h  10:38, 21 July 2007 (UTC)
 * I love you guys and I am pleased that so much can be said about the topic (gives me hope personally), but is there a "Parallel Universes for Dummies"? Much of this is written in jargon not for the common man. Chris 22:52, 13 August 2007 (UTC)

Phonetic injunction and redefinition of terms
The "term" "Uni'verse" contains self descriptors. This is to say that it's meaning can be determined using phonetics. The most ancient definition of the root "Uni" that I have discovered is meant to signify "One", or oneness, Unity. The term "Verse" also is distant in origin. One associated term is "version". Consider the terms "Di'Versity" or "Uni'Versity as examples.

The primary point of this dissertion is to direct attention to the notion that their "Can be only one" Uni'Verse. It is not possible, according to our laws of grammar as a species, for the Uni'Verse to exist in plurality. It is possible, however, to have contained within "The" Uni'Verse, Sub-sets and Epi-sets of "Verses", or versions. Language is said to be our base programming. This is why this error in description is of profound importance.

Self-quoting
In the Multiverse section we have The Wikipedia article on "Mormon Cosmology" notes. I'm pretty sure this is bad practice, but I don't know enough about this subject to be prepared to correct this. Can someone else hope? LukeSurlt c 21:03, 13 August 2007 (UTC)


 * You're right. Way too much detail here: put in a pointer to the main article.--Michael C. Price talk 22:44, 13 August 2007 (UTC)


 * The link between Mormon cosmology and this article is tenous at best. Can we just get rid of this? It's filler. Unnecessary filler. —Preceding unsigned comment added by 76.213.242.101 (talk) 06:20, 15 September 2007 (UTC)

Coinage
Is there a reference for the claim that William James coined the word multiverse? This video states Martin Reese coined the word. ~ UBeR 01:51, 29 August 2007 (UTC)

Spencer Danby
How notable is this guy? His objections seem rather crude. Form quantum many world theories, all the branching and copying that he finds so difficult is already in the structure of the WF, minus collapse. 1Z 15:36, 11 September 2007 (UTC)

Universe Intersection
Is it not logical to assume that if our universe is expanding, any alternate universes are also expanding in like manner (all though at varying speeds depending on variables)? If so further deduction would tend to say that these universes would eventually intersect, right?

Is this touched on in any theory (I must say I don't understand much of the jargon either) or am I just being stupid? (a likely prospect) 70.104.110.41 21:48, 13 September 2007 (UTC)

Spencer Danby
In support of someone else's concerns, I would suggest that the 'Spencer Danby' stuff be taken out. Not only do his criticisms of Lewis, as presented, fail to properly understand modal realism but, as noted elsewhere, he does not appear to be a recognised authority on such matters. His book does not appear to be available (or I can't find it in any of the major bookstores) and his arguments, as presented, seem fallacious. Although there may be similarities between Lewis' theory and multiverse theory, the connection is superficial at best, as it is presented in this article. Until a more developed commentry on the connection between the two is included, it is misleading to characature such a complex philosophical theory in this manner. —Preceding unsigned comment added by 198.96.38.193 (talk) 17:12, 21 September 2007 (UTC)

M-theory
I believe the section on M-theory is innacurate. It discusses colliding "branes", is actually referring to braneworld theory. I don't believe Witten's M-theory in any way discusses the formation of the universe as occurring from collisions of branes and instead that's an interpretation of some physicists. Intead, I believe M-theory only shows how all different string-theories are equal by mathematically exposing dualities between the different competing theories by inversion of R and other dualities. However, since I'm just a casual observer of string theory, I'll leave it up to someone more knowledgeable than I to validate that statement. -- Netdragon 21:47, 23 September 2007 (UTC)

Doest the multiverse hypothesis entail the existence of the Biblical God?
I think it does, at least functionally. Here is why: According to Tegmark (who in the article is responding to all the criticisms of the multiverse) “all structures that exist mathematically exist also physically” (see Max Tegmark). But there exists a mathematical structure that describes a universe where a SAS (self-aware substructure – which for short we shall identify by “Yahweh”) creates a toy universe and plays with it making inscribed stone tablets to magically appear, burning bushes, parting the Red Sea, and so on. One can certainly mathematically describe such a universe. So according to Tegmark such a universe actually exists, and ours may be the toy part of it. Great – I can see the headlines “An MIT prof claims that Yahweh exactly as described in the Bible exists somewhere out there”.

My point of course is that any naturalistic hypothesis that entails the physical existence of Yahweh is just nonsense. The idea that anything that is mathematically describable is also physically actual is not strictly speaking logically impossible, but can fairly be called “the mother of all speculations”. After all what it really says is that anything not impossible is real. I mean take your pick: perpetuum mobile? It exists in many universes. A universe where planets are made of Swiss cheese? Of course. All of us living eternally and doing nothing but discussing Tegmark’s ideas? Sure, why not, actually this happens in more than 10^100 universes. A universe that consists of three kittens plus a copy of multiverse? Bertrand Russell must be starting to spin in his grave, but according to Tegmark that universe exists too.

Of course it’s easy to make fun of Tegmark’s idea, but to be fair the so-called Many-worlds interpretation of quantum mechanics, which is arguably the most popular ontological understanding of quantum mechanics among physicists today, implies similar nonsense as there are few phenomena that quantum mechanics actually prohibits – but at least quantum mechanics itself is constant in all baby universes there. On the other hand of course Tegmark’s multiverse entails the truth of the many worlds-interpretation in many universes that are just like ours. The mind spins. Dianelos 09:23, 28 September 2007 (UTC)

If indeed the mutliverse is an infinite ergodic field, then any quantum state with non zero probability almost surely exists. That includes all universes described above. The path of causality is immaterial because all paths are represented, even the most improbable. —Preceding unsigned comment added by 97.80.140.10 (talk) 02:16, 8 November 2007 (UTC)

Issues with "Trans-world identity issues"
I have removed the following paragraphs:

'The problem

'The problem lies in the tension between classical notions of identity and quantum indeterminacy. In short, quantum reality does not allow classical – radically mechanical – 'identities' due to the Heisenberg Uncertainty Principle. However, in an infinite set of possible universes such a correspondence is presumed to exist. The question then becomes whether one can claim a distinction between entities that vary only in terms of some arbitrary dimensional metric in De Sitter space.

'Suggested resolutions include the possibilities that:


 * Synchronous unitemporal parallel universe ontologies are invalid.
 * Synchronous unitemporal parallel universes belong to a part-whole relationship.
 * Quantum fluctuations average out within the Heisenberg limit between duplicates.
 * Alternative criteria are needed to hermeneutically assess the concept of 'identity'.
 * Objects may not be completely identical. Nonquantifiable attributes of objects may vary over an infinite range.   '

The issue of trans-world identity is a well-known one, at least in possible-worlds theory, and deserves to be mentioned. However, this subsection appears to confound it with a different issue, namely, the meaning of 'identity' in the context of quantum indeterminacy. The author seems to be talking about the school of thought which claims that the states of quantum objects are objectively uncertain, and then talking about trans-world identity in the context of a multiverse theory which adopts objective indeterminacy. This is at best a highly specialized subtopic, and these would also appear to be original reflections. Also, the author (DV8 2XL) has abandoned Wikipedia, and we can't ask what was intended; and at least one technical term is being misused, de Sitter space. DV8 2XL originally (in August 2005) wrote "Hilbert space" here, and then "corrected" that to de Sitter space a few months later. Since quantum states are elements of a Hilbert space, the original version might make more sense; the subsitution may have come from the references to a "de Sitter multiverse" in string theory. In any case, there are too many issues to resolve here and no way to resolve them without contacting the original author. Mporter (talk) 17:19, 6 January 2008 (UTC)

Does anyone even know what they are talking about?
There are so many problems with this articles it is not funny.

Firstly

"If the Many worlds interpretation is true there are so many copies of our universe that the existence of at least one planet like Earth is not surprising." has absolutely no relationship to the rare Earth Hypothesis it refers to. This needs to be referenced at the very least.

None of what is mentioned of string theory is referenced either, likely just to be opinions (including M-Theory).

"According to Max Tegmark,[2] the existence of other universes is a direct implication of cosmological observations." does not belong in classification.

There is an obsession with alternate versions of yourself that has spread throughout the article, put it in a single section or do away with it. Remember that there is nothing special about a person, no soul, just matter so how would one define another version of themselves?

In Level 4 "M-theory might be placed here". Seriously, wtf?

Some physicists believe that the universe is spatially unbounded... about 46.5 billion light years in radius.

Thus, there are an infinite number of regions of space the same size as our observable universe – an infinite number of observable universes, that is. This infinite set (which may contain, among other things, an infinite number of identical copies of you,[7] the nearest of which is about 10^{10^{29}} m away, and an equally infinite number of not-quite-identical copies) comprises the level-I multiverse. By the Bekenstein bound there are only a finite number of configurations possible within any region, hence exact duplication is inevitable."

This is not science, logic or even a kind of human though sequence that i know of. The fact that our universe has a radius determined by the speed of light in no way leads to the conclusion of infinite space beyond that nor does it lead to the conclusion that other, let alone infinite number of universes exist beyond our own. This section needs either total rewriting or deletion. The quote included in this section is also without a source.

Bubble universe is not referenced

Big Bounce is completely separate to the multiverse, who wrote this thing?

"; and therefore more mathematically theoretical and metaphysical than scientific in nature." not needed and not clearly written

Second paragraph in non-scientific claims needs to be referenced

Bad science needs to be rewritten, ill do it, and the second paragraph either sourced or deleted

Final sentence in Occam's razor needs to be referenced, its really not that hard people

"The above fails to state why the observed universe is unique", is unfounded

"Einstein raised this possibility when he wondered whether the universe could have been otherwise, or non-existent altogether" reference needed

Creating more problems, makes some good points in the first paragraph, i will look to see if i can clean it up.

"Another objection to the existing multiverse theories is a challenge to the criteria for defining universes. In most multiverse theories, universes are labeled by laws of physics and initial conditions. It might be argued that these terms are narrow and chauvinistic; there may be criteria for categorization that lie completely beyond the scope of human comprehension." If you need to be told this you do not understand Multiverse theory.

Anthropic principle, i wont touch this even though i disagree with it. someone who wrote the main article would be more certain.

"Incidentally, this of course assumes that our observed universe is 'real' and not virtual; at least one philosopher, Nick Bostrom, has proposed that this may not be the case." Incidentally as we are bound by the laws of our universe this can never be tested and does not deserve mentioning.

Is the virtual universe section needed at all, its relation to the rest is disputable.

Sikh Beliefs, This could have easily been taken out of context and is not referenced. Deletion.

I will make changes that i have outlined above. Learn to reference, learn to not put in personal opinions and learn that because it is so complexly written that it is nearly incomprehensible does not make it science.

Sedecrem (talk) 13:31, 7 January 2008 (UTC)