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Science

One of Many 196

Posted by michael from the too-many-to-count dept.
sam_handelman writes "The nytimes has another astrophysics article up. Free subscription etc. It talks about how inflation predicts multiple universes, this week. Dennis Overbye wrote the article, which is nice if lightweight. More info on the theory of inflation. Inflation, which is harebrained on first examination, actually predicts stuff, giving it credibility. Want to be the Right Pinky of God? It may yet be possible."
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One of Many More

One of Many

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  • What about...? (Score:4, Funny)

    by cordsie ( 565171 ) on Wednesday October 30, 2002 @07:54AM (#4563182)
    Personally, I'm having trouble reconciling the theory of inflation with a few well established notions about the universe. Does this mean that there are many turtles supporting other planets almost identical to our own?

  • You can be the pinky.... (Score:4, Funny)

    by Sn4xx0r ( 613157 ) on Wednesday October 30, 2002 @08:01AM (#4563200) Homepage
    I'll be the brain :)

  • Inflation != Multiple Universes (Score:3, Interesting)

    by c_de_bugger ( 609837 ) on Wednesday October 30, 2002 @08:05AM (#4563208)
    From the article.
    In fact, Dr. Guth said, "Inflation pretty much forces the idea of multiple universes upon us."
    I read the article. Can anyone see where he justifies this statement with anything resembling logic?
    I accept inflation and the 'anthropic principle' as well argued theories. Inflation=multiple universes is not (or not here).
    • you missed it alright take two primordial lumps of matter before inflation. each one then gets inflated. one is our universe the other is another "universe" - it is too far away in time and space for us to ever be able to communicate with it so it is a separate universe - have anopthe rlook it is there

    • Re:Inflation != Multiple Universes (Score:5, Informative)

      by bradkittenbrink ( 608877 ) on Wednesday October 30, 2002 @08:36AM (#4563287) Homepage Journal

      I didn't see the explanation in the article, but from what I've heard the explanation is pretty simple. I think I read it in A Breif History of Time [google.com] or something like that. I probably don't remember it correctly but here goes nothing...

      The trick is that the collapse from an inflationary situation to normal spacetime can't happen instantaneously. By the time the collapse has happened and created a universe of normal spacetime, the inflation has already created more than enough (inflating) space/spacetime/cosmicstuff to replace it. So there will always be inflating stuff left over. Eventually this new inflating stuff will start collapsing into pockets of normal spacetime, creating new universes each time. The point is that the inflating stuff inflates too quickly to be consumed by the collapse process, so the process continues indefinitely.

    • From reading the article, the following is my understanding of why inflation predicts multiple universes:

      • Inflation is predicated upon certain conditions within the universe just a few planck times after the big bang (a planck time is on the order of 10^-32 or so seconds, I can't remember exactly off the top of my head).
      • If these conditions hold, inflation will occur. People pretty much believe that inflation did occur, for there is no other current way to accurately explain the rapid expansion of the universe in the first few planck times after the big bang.
      • Now, assuming inflation did occur, that means the conditions for inflation must have been met. Here is where "inflation=multiple universes" as you put, it comes into play. Those conditions necessary to create inflation exist in certain pockets of space-time (most notably at singularities, such as in the center of a black hole) in our universe.
      • Hence, if the conditions for inflation are met, surley something must be inflating. But we can't see results of such inflation in our universe, and therefore it probably means that the inflation is occuring in another universe. This is where the article is weak, and you are probably having your problem. They did not speak about the theories which allow for "new" universes to be created with different laws of physics, and how the preconditions for inflation meet these criteria. These theories have been around for quite some time, and are generally regarded as possible. That said, conditions which would cause these new universes are theoretical, and whether or not they exist are under debate. It just so happens that inflation theory forces some of these alternate universes to exist.
      • So if there are random points in our universe which cause inflation and the creation of new universes, then it is very possible that our universe is one such inflation due to circumstances within another universe. And so on, creating a "web" of inflated universes: the multiverse.
      I hope I've done some justice to the theories (sorry for the lack of links, I'll rumage through my books and try and post a followup later). If I'm wrong, or remembering things poorly, don't flame me, just reply and set things straight.
      • but this would mean that the laws of physics would no longer be laws.. If I lived on a proto-planet then I would be a creature that was much smaller than an electron and therefore must be made up of things that don't apply to the current physics..

        Granted everything we know in science is only a good guess and nothings is known as an absolute fact, but it's pretty demonstratable that particle physics is dealing with single particles, building blocks so to speak....

        Besides... I'd would be darn horrible to find out that we have been preforming planicide on entire civilizations and races every time a cyclotron or particle accelerator is fired up.
        • Yup. That's the theory.

          The laws of physics as we know them are the laws of physics for this universe and this universe alone. A different universe would have different laws of physics altogether.

          The theories and the article both state this very clearly. That's one of the fascinating things about our universe: that it's laws are so precise as to allow stars, and subsequently life, to form. Only a narrow range of laws allow such formations, and our universe is one of the few (although possibly infinite) number of universes with laws capable of creating and sustaining life.

          • The laws of physics as we know them are the laws of physics for this universe and this universe alone. A different universe would have different laws of physics altogether.

            I have been saying this to everybody that I have talked to for a few years now... but, I'm only 18 so it's not like anybody would take my thoughts seriously...

            Anyway, from this, I came up with a theory to explain why our explanations of our universe are so frekin complicated... and answer is somewhat simple...

            Quoting myself from my own personal website: "Our own existance deviates so much from the actual physical and chemical existance of the universe in whole that we have come up with theories and laws that only apply to us... and not to the universe."

            So all our theories and physical laws are only partly true. Sure, they work, but it's like trying to figure out a computer by talking about the plastic casing on the keyboard....

            This is why I stopped trying to ponder the existance of the universe, why I stopped trying to figure out how the hell we got here... because I realised that, from our standpoint in this universe, it is impossible...

            ...just my thoughts on the matter (...pun! get it?)
        • but this would mean that the laws of physics would no longer be laws ..

          It certainly, IMHO, means that the laws we know break. Very probably it means the laws we can conceivably test also do not apply.

          This does not mean there isn't any generalization of the basic theories which do apply. In fact physicists predict properties such a theory must have, which may lead to hypothesis of this kind.

          wether such hypothesis are true, or can even be tested, again, is a leap of faith IMHO.

          If I lived on a proto-planet then I would be a creature that was much smaller than an electron and therefore must be made up of things that don't apply to the current physics

          Here I think you may have a misconception of the notion of size. General Relativity tells us you cannot directly compare sizes over great distances. This means that the world we live in is a Riemann manifold ( a patchwork of local non congruent euclidian approximations )

          What all this means, is that comparing sizes inside a black hole (the above approximations break on the way) and outside is not only impossible, it is meaningless. It does NOT mean the laws of physics must be different in flat areas inside. (or that they aren't)

          Besides... I'd would be darn horrible to find out that we have been preforming planicide on entire civilizations and races every time a cyclotron or particle accelerator is fired up

          wrong. this may have conceivably been possible if current experiments would heve been close to the plank scale. However we're many many orders of magnitude away from achieving such cataclysmic energies.
          AFAIK we know pretty well the basics of what is happening in the sub-TeV scale.
        • Besides... I'd would be darn horrible to find out that we have been preforming planicide on entire civilizations and races every time a cyclotron or particle accelerator is fired up.

          Imagine all the legal ramafications if lawyers find out about even the possibility.

      • Re:Inflation != Multiple Universes (Score:2, Interesting)

        by Anonymous Coward
        (a planck time is on the order of 10^-32 or so seconds, I can't remember exactly off the top of my head).

        If you take the universal constants c (speed of light in m/s), G (gravitational constant in m^3/s^2kg), and h-bar (Planck's constant in kgm^2/s), and you arrange them so that the units cancel out except for one, you end up with the Planck units.

        So to get the Planck time, you multiply G by h-bar to cancel out the kilograms, getting a number in units of m^3/s^5. Now divide by c^5, and you're left with a number in units of s^2. Take the square root, and you're left with a number in units of seconds. That is the Planck time, sqrt(Ghbar/c^5).

        With G being 6.673x10^-11, h-bar being 1.054x10^-34, and c being 2.998x10^8, you end up with Planck time being 5.389x10^-44 seconds.

        The same can be done for Planck length (= c times Planck time = 1.616x10^-35 meters) and Planck mass (= h-bar over c over Planck length = 2.176x10^-8 kg).

        From that you can derive Planck density, which is something like Planck mass divided by the cube of the Planck length, which turns out to be something like 5.154x10^96 kg/m^3.

        A reasonable interpretation of these measures is that Planck length is the smallest possible length (i.e. indivisible), Planck time is the smallest possible time (i.e. indivisible) and Planck mass is the largest possible mass able to fit into one Planck space-time unit.

        This gives a sort of layman's explanation for the inviolability of the speed of light -- in order to travel FTL, you'd have to travel one Planck length in less than one Planck time, and since Planck time is indivisible, this is not possible. It also implies that at speeds lower than c, one either moves at c or not at all, since you can't travel a less than a Planck length in one Planck time. That is, speed is just an average between moving at c and moving at 0.

        You could also add into the mix the electric constant of free space to obtain a Planck charge. That's left as an exercise for the student :)

        --Rob

    • Re:Inflation != Multiple Universes (Score:2, Interesting)

      by Anonymous Coward
      Inflation theory means that the universe expands really fast, much faster than light. A recent calculation showed that the number of possible distinguishable quantum-state histories from the "start of time" to the present is (near-infinitely?) smaller than the number of histories arising from random fluctions in the inflated space - thus everything will happen somewhere, and probably not jsut once, but near-infinitely often.

      Individual histories won't communicate in most cases because they'll be very far apart (further than the light horizon) in space, due to inflation. There is a theoretical possibility of the histories "meeting". So an "earth where hitler won the war" might correspond to "go 10^10^10^10^10^10^10^10^10^10^10^10... light-years that way"

    • This may be true, but I don't really care.

      I have enough trouble worrying about economic inflation to give a rats ass about the inflation of multiple universes (universi?). For me, the existence of multiple universes(i, whatever) means one thing: somewhere, out there, another me is having sex with another Natalie Portman and another Janet Jackson AT THE SAME TIME.

  • Why harebrained? (Score:5, Informative)

    by Mr_Dyqik ( 156524 ) on Wednesday October 30, 2002 @08:07AM (#4563215)
    Why is inflation harebrained on first examination?

    It was originally proposed to address one of the big problems in the old big bang theory, namely that parts of the universe visible from Earth, that were so far apart that light couldn't have travelled between them since the big bang, looked pretty much the same. For this too happen, they must have been some sort of communication between them at some point in the past, but a fixed, unbreakable speed of light prevents this happening. This assumes that the universe has always been expanding, with the expansion being slowed by gravity only.

    Inflation just says that if the universe initially expanded much much faster than the current rate suggests it did, then those parts of the universe that are too far apart to communicate now, might have been able to communicate in the past. All of the complexity of the theory is in producing the physics that allows for, and causes the inflation.
    • Dyqik, that doesn't make any sense. There's no need for communication between two clusters after the big bang in the situation you describe: Given a limited set of circumstances that creates stellar bodies detectable at such great range, either those circumstances occur -- and we detect something -- or they don't, and we see nothing.

      With a limited set of circumstances, it's trivial to imagine a limited set of detectable outcomes, particularly if the laws of the universe are, well, universal. Stars too hot would have burned out billions of years ago; stars too cold we could not see. That leaves this very narrow region we're able to detect, and unsurprisingly everywhere we look we see the same thing. When there's something else, we're either too late or blind.

      Even this logic is unnecessary, though -- given that the visible regions were once part of the same singularity, all the "information" they'd ever need to remain related could have been exchanged at the point of the Big Bang itself. Absolutely identical output is theoretically justifiable, if there's a quantum level pseudorandom number generator at work. (Oddly enough, if there was, we'd never be able to tell, except through its occasional bugs...like entanglement, perhaps.)

      --Dan

      • Re:Why harebrained? (Score:1, Informative)

        by Anonymous Coward
        We're not talking about star clusters. We're talking about why spacetime itself seems so flat. That can't be explained unless all the parts communicated with each other ... or unless they came from a very small part of the early universe, which inflated. That's Dyquik's point, and it very much does make sense.

      • Re:Why harebrained? (Score:4, Informative)

        by Mr_Dyqik ( 156524 ) on Wednesday October 30, 2002 @11:12AM (#4564322)
        If you take two opposite directions, and look at the CMB spectrum in those directions, the temperature is the same to within 0.00001K. Since the CMB radiation was emitted from those points at a redshift of about 1000, the emitting points that we can see today are about 2ct apart, where t is the age of the universe

        Due to the way in which the universe is currently expanding, extrapolating the motion of those two points back to the big bang shows that the two points were always further apart than ct, the maximum distance that light can have travelled since the big bang. The question then is: Why are two points in space, that can never have been in contact at the exact same temperature?

        Inflation answers the question by saying that when t->0 the expansion of the universe was so fast that the two points 2ct apart now were closer than ct.
        • I'm confused about your diction. Is "communicate" a term of special signigicance in astrophysics? Where I come from, it signifies the act of conveying a message from one entity to another. Why would two points that have the same tempurature necessitate "communication"? Couldn't it simply be a coincidence that the variables acting on those two points resulted in a similar outcome? Are we assuming that such coincidences are too far-fetched to occur, or have we ruled out the possibility of such a coincidence all together?
    • Actually, inflation was originally proposed when Hubble discovered redshift in all but the closest galaxies. Einsteins theory of general relativity also predicted that the universe would be expanding, but Einstein didn't want to believe that, so he introduced the cosmological constant into his equations to keep everything stable.

      • Re:Why harebrained? (Score:1, Informative)

        by Anonymous Coward
        Not the same thing --- what we mean by "inflation" here isn't the gentle, slow expansion of the Universe that's currently happening and is what you're talking about, but a period of massive immensely fast (much faster than light) expansion happening once right back at the beginning. Inflation in the sense meant here is a fairly recent theory.
    • How do the separate arms of a snowflake know to grow in roughly the same pattern? Arms 1 through 6 of Snowflake A [snowflakebentley.com] are alike. Arms 1 through 6 of Snowflake B [snowflakebentley.com] are alike. There are plenty of mutant-looking ones; however, you won't find any that have one arm off Snowflake A and others off B, C, D, etc. [snowflakebentley.com] Are the patterns determined by "information"? If so, how is it communicated over these distances? And how are they reading it? --It can't be information. So why should a similar situation, only bigger (the universe) require information?

  • Flat universe (Score:4, Insightful)

    by little1973 ( 467075 ) on Wednesday October 30, 2002 @08:10AM (#4563218)
    AFAIK, one of the advantages of this theory is that it explains why the universe seems to be "flat". And the answer is that we just percieve a tiny fraction of the universe, so it's not surprising we see the universe as if it was flat.

  • Google: no registration (Score:5, Informative)

    by mrBlond ( 141708 ) on Wednesday October 30, 2002 @08:14AM (#4563233)
    Please link to the Google version which doesn't require registration. [nytimes.com]

  • Multiple universes? (Score:3, Interesting)

    by mccalli ( 323026 ) on Wednesday October 30, 2002 @08:15AM (#4563238) Homepage
    it talks about how inflation predicts multiple universes

    This is one of my pet hates. By the very definition of the word [m-w.com], there can only be one universe. Or are the definitions now being changed?

    Cheers,
    Ian

    • Re:Multiple universes? (Score:5, Insightful)

      by Mr_Dyqik ( 156524 ) on Wednesday October 30, 2002 @08:28AM (#4563264)
      universe here means the area of the universe that we can (possibly) see, communicate with, and/or do physics experiments in. Since physics is limited to that region of the universe in which we can do physics experiments, then it is conceivable that there exist regions of spacetime that are inaccessible to us, by virtue of distance or some other parameter.

      Whether it is meaningful for physicists to talk amount these regions as _seperate_ universes comes down to what you think universe means, and what the values of the cosmological parameters are this week.

    • Re:Multiple universes? (Score:2, Insightful)

      by AGMW ( 594303 )
      I think that when the word Universe was coined, the eggheads hadn't come up with the idea of alternate realities et al, and so "Universe" was everything (see "universal").

      Unfortunately, the big-brained ones have now copped onto the Sci-Fi idea of these alternate universes (small 'U') and have seen that using a model such as this explains (and hence predicts) some of the observable behaviours, and, better than that, it seems to be a tighter fit that the previous ideas.

      Sorry Bud, but it looks like they just changes the (dictionary) meaning of Universe ...

      • Re: You've got it backwards. (Score:5, Interesting)

        by guybarr ( 447727 ) on Wednesday October 30, 2002 @09:11AM (#4563429)
        Unfortunately, the big-brained ones have now copped onto the Sci-Fi idea of these alternate universes

        I think you have a wrong picture: although the notion of different choices and their consequences is an ancient one, the notion of parallel universes came from science (everett interpretation, feynman-multiple-path approach to quantum mechanics) to SciFi and philosophy.

        As usual, the ideas flow from science to science-fiction. I asume this is because usually, nature is more bizare than what our imagination can predict. (and also because the best scientists are among the most creative people ...)

    • Re:Multiple universes? (Score:5, Funny)

      by SEWilco ( 27983 ) on Wednesday October 30, 2002 @08:52AM (#4563336) Journal
      Note to God: Remember to make English better in next universe.

    • Re:Multiple universes? (Score:5, Insightful)

      by amorsen ( 7485 ) <benny+slashdot@amorsen.dk> on Wednesday October 30, 2002 @08:56AM (#4563348)
      This is one of my pet hates. By the very definition of the word [m-w.com], there can only be one universe. Or are the definitions now being changed?

      By the very nature of the word, an atom cannot be divided.

      • By the very nature of the word, an atom cannot be divided.

        Yes and no - MW lists three meanings for atom, only the third of which describes the atom as a particle (which may be split). It's true that the other senses of the word preclude splitting any further, but they are other senses of the word.

        Cheers,
        Ian

        • Re:Multiple universes? (Score:3, Insightful)

          by bogado ( 25959 )
          This definition was created when we discovered that they in fact could be divided. Words mean whatever you understand of them. Dictionary can, and will be, changed. Language is a changing beast, and you can screem all you want that "hacker" is not an evil computer genius, that people will continue to use the word as they learned. This is culture. :-)

        • Before atoms were named atoms, MW would have listed only the two non-physics-compatible definitions. MW realized that the word is now being used to refer to something that isn't in the dictionary, and so they modified the dictionary to fit the usage.

          It is silly to say that it is wrong to use a word to mean something if it isn't in the dictionary. I'm sure terms like superconductor, Internet, and world-wide-web, were used years before they made it into a dictionary. A dictionary is nothing more than a documentation of how language is ALREADY used. The purpose of a dictionary is to make it easier for somebody who is new to a region or dialect or field of study to converse with those who are already within these groups.

          If the idea of multiple universes gains universal acceptance and the word universe is used in this manner in the general public, then after a few years you'll go to dictionary.com and find the definition has been modified. Why? Because people will only continue to buy from Merrian Webster as long as it is relevant - and documenting english as it existed in the 1800's isn't being relevant...
        • Yes and no - MW lists three meanings for atom, only the third of which describes the atom as a particle (which may be split). It's true that the other senses of the word preclude splitting any further, but they are other senses of the word.

          The best online explanation of the etymology of the word atom seems to be at a Geocities page [geocities.com]. I cannot believe I just made a link there. (If you see me recommending AOL and hotmail, please have me committed.)

      • Re:Multiple universes? (Score:1, Funny)

        by Anonymous Coward
        and since the very definition of the word is unchangeable, we must stop these heathenish studies before it changes the definition of the words!!!
    • By the very definition of the word [m-w.com], there can only be one universe.

      Take a closer look at the definition you linked to. Not a single one of the five different senses of the word gives even the suggestion that there can not be more than one. As I read it, all five imply that there can be more than one and/or that there is "suff" which is not part of it.

      Etymology: Latin universum, from neuter of universus entire, whole

      It is perfectly acceptable usage to use it to reffer to the entirety or whole of everything which is "connected". It is possible that there were multiple big bangs in parallel, possibly an infinity of them. If there is no contact between them, and never can be, then each is a seperate whole, another universe.

      -

      • Re:Multiple universes? (Score:3, Interesting)

        by mccalli ( 323026 )
        Not a single one of the five different senses of the word gives even the suggestion that there can not be more than one.

        1 : the whole body of things and phenomena observed or postulated

        ie. everything. Can't have more than one of those. If more 'things' are being postulated that match what previously we called the universe, then by definition they are subsumed into the current universe and we need a different word to describe what we used to have.

        Cheers,
        Ian

        • Re:Multiple universes? (Score:3, Interesting)

          by Alsee ( 515537 )
          1 : the whole body of things and phenomena observed or postulated

          And then of course there is everything that has NOT been observed or postulated. So that usage does clearly imply that "universe" is not "everything".

          Including everything "postulated" is not a requirement of all usages of the word. In most cases it is a pretty poor usage. You usualy don't want to consider non-existant things that have been postulated to be part of the universe.

          In this case we are talking about something that has been postulated but not observed. It is not part of our universe because it can never be observed. It is part of a seperate whole.

          Considering all of the "universes" to all be part of one universe is A valid usage, but it is not the only one.

          The different senses listed pretty much revolve a "whole body" of things that are in some way connected. If there is a second "whole body" of things that are connected with each other, and there is no connection between the two "whole bodies", then they can be reasonably be called two universes.

          -
    • it talks about how inflation predicts multiple universes

      This is one of my pet hates. By the very definition of the word [m-w.com], there can only be one universe. Or are the definitions now being changed?

      I would suggest getting over it. Merriem-Webster does not have the final word in what the term 'Universe' means, not in colloquial speech ("we the people" decide that through our use of language, and most people I know have become very comfortable with the notion of multiple universes a long time ago, even if said universes are merely relegated to the 'universe of what is real' vs. 'the universe(s) of what is fictional'), nor in scientific terminology, in which cosmologists like will have the final say.


      The term Universe, with the capital "U", is usually used for everything that we can ever have knowledge of, the entire span of space and time accessible to our instruments, now and in the future. This may seem like a fairly comprehensive definition, and in the past it has traditionally been regarded as synonymous with the entirety of everything that exists. But the development of ideas such as inflation suggests that there may be something else beyond the boundaries of the observable Universe -- regions of space and time that are unobservable in principle [...]

      This has led to some ambiguity in the use of the term "Universe". Some people restrict it to the observable Universe, while others argue that it should be used to refer to all of space and time. If we use "Universe" as the name for our own expanding bubble of spacetime, everything that is in principle visible to our telescopes, then maybe the term "Cosmos" can be used to refer to the entirety of space and time, within which (if the inflationary scenario is correct) there may be an indefinitely large number of other expanding bubbles of spacetime, other universes with which we can never communicate.


      Our knowledge of what is, and what may be, has far outstripped dated definitions of 'universe' ... either the meaning of the term will evolve accordingly, or new terminology will result.

      I'd give you less than 50% odds that your preferred definition is the one that ultimately prevails, but you never know. :-)
    • This is one of my pet hates. By the very definition of the word [m-w.com], there can only be one universe. Or are the definitions now being changed?

      As is discussed at length in the article, the definition of our Universe is controversial. The two alternatives are:

      1 Everything that is theoretically possible for us to ever observe

      2 Everything that exists

      This discrepancy was of little consequence up until twenty odd years ago, when researchers started to realize that these two might not be the same. I think many physicists prefer defintion 1, leading to terms such as 'multiverse' and 'multiple universes' to cover 2. It is also a good idea to say 'observable universe' to emphasize definition 1.

      Tor
  • And there I was thinking that I was special and unique.

    Only to find out there may be more out there like me.

    Damm you Slashdot!!

    • Re:Drat, Multiple Universes.... (Score:1, Funny)

      by Anonymous Coward
      Yeah, but if you go to other universes and kill your counterparts you gain thier life force. Do it enough and you will be really good at kung-fu.
  • Moreover, cosmologists say, the laws of physics themselves, as experienced by creatures like ourselves, confined to four dimensions and the energy scales of ordinary life, could evolve differently in different bubble universes

    Or what if our bubble universe was just a small bubble trapped in another huge Whammo Bubble universe? Sure hope those giant kids are careful while they are waving their magic bubble wands around... ...boy wouldn't that just burst ourbubble!

  • Alan Greenspan (Score:4, Funny)

    by invid ( 163714 ) on Wednesday October 30, 2002 @08:48AM (#4563322)

    Don't tell Alan Greenspan about the inflationary universe. He'll try to control it with interest rates.

  • It talks about how inflation predicts multiple universes, this week.

    My, my... When I think that only last week it predicted a unique universe! ;@)

  • Now it is obvious why the world seems strange...we're in a "dud" universe.

  • Multiverse Schmultiverse (Score:5, Informative)

    by wiggys ( 621350 ) on Wednesday October 30, 2002 @08:54AM (#4563344)
    Dr Lee Smolin [edge.org] wrote an interesting (although difficult) book [york.ac.uk] about the multiple universe theory.

    He theorised that all of the universe's parameters (light, gravity, strong and weak nuclear etc) were self-tuned in much the same way that life is tuned for survival. Universes where the gravity was too strong, or the charge of a particle was too weak, didn't develop black holes. Our universe appears to have thousands of black holes, and we know for a fact our universe is tuned to support life, ergo, our universe will have "off-spring", with black holes being the mothers.

    He's basically doing what Creationists do - merging biological evolutionary theory with cosmological evolution, something which most scientists are quick to separate. I think he might be onto something...

    _______________

    • Our universe appears to have thousands of black holes, and we know for a fact our universe is tuned to support life, ergo, our universe will have "off-spring", with black holes being the mothers.

      Mothers of what, planets or new universes? I don't think black holes have much involvement in the formation of stars, etc. True, they hold galaxies together, but that is simply because they have mass. I suppose if it was unstable mass, then it would radiate away and scatter mass and galaxies would not stay together very well. But that is kind of an indirect issue.

      There is some speculation that the reason they can't find a simple fundimental model of physics is that the smallest particles are really similar to DNA. Look at those weird "string theory" diagrams, and tell me that does not look biological. A 10-dimensional DNA, kind of perhaps.

      However, selection for reproducing universes is not necessarily the same as selection for life-bearing universes. Either we are just a statistical fluke (anthropic principle, which does not require "unlikely"), or life forms in these kind of universes tend to find a way to trigger new universes with the same or similar parameters by setting off inflation in parallel dimensions. In that sense there indeed could be "creators" of sorts. However, "Universe triggeror" is probably a better term since they did not build the raw material. They probably don't give a sh*t about our prayers either, unless they really have too much time on their hands. Why is it that all the Earth gods allegedly give favors if you beg hard enough?

      Odd stuff. Darwin meets Q.
    • He's basically doing what Creationists do - merging biological evolutionary theory with cosmological evolution, something which most scientists are quick to separate. I think he might be onto something...

      He is not "merging" these theories, he is simply making an analogy... though I agree, it is a very appealing one. However, I don't see what this has to do with creationism, since creationists tend to reject biological evolutionary theory. I really don't see how claiming that God created the (singular) universe ~6,000 years ago is equivalent to, or even compatible with, the idea of "merging biological evolutionary theory with cosmological evolution."

  • Why oh Why!!! (Score:3, Funny)

    by phunhippy ( 86447 ) <zavoid.gmail@com> on Wednesday October 30, 2002 @08:57AM (#4563351) Journal
    Why oh Why must the [editors] post these type of articles early in the morning! My head is going to hurt all day now!

    thanks slashdot!

  • Einstein said - (Score:1, Funny)

    by mtec ( 572168 )
    God does not play dice with the universe.

    Looks like He just blows bubbles with it.
    Or maybe He's making a giraffe. In the end we may find out we exist inside of a cosmic balloon animal. God! I hope we're not a snake hat.

  • How dense can you get? (Score:3)

    by PigleT ( 28894 ) on Wednesday October 30, 2002 @09:31AM (#4563532) Homepage
    The second article, `inflation for beginners' says:
    the density was not infinite but "only" some 1094 grams per cubic centimetre. These are the absolute limits on size and density allowed by quantum physics.

    On that picture, the first puzzle is how anything that dense could ever expand -- it would have an enormously strong gravitational field, turning it into a black hole and snuffing it out of existence (back into the singularity) as soon as it was born.

    Erm, could someone explain to me just how dense 1094g/cm^3 really is? I'm trying to picture a bag of sugar and a small cube of steel here... and I'm thinking maybe there's a scaling problem somwhere...

    • Re:How dense can you get? (Score:1, Informative)

      by Anonymous Coward
      I'm thinking that was supposed to be 10^94 gm/cm^3 or something. Certainly 1Kg/cm^3 doesn't sound like much -- surely less dense than the core of the sun.

      There are a lot of messed up exponents in that article (missing minus signs especially), though it is very interesting overall.

  • Infinite universes?... (Score:3, Interesting)

    by Anonymous Coward on Wednesday October 30, 2002 @09:45AM (#4563597)
    If there were an infinite number of universes in which each and every chance outcome is played out, would there be a universe where someone invents a universe destroying machine and destroys all the other universes without being stopped by anyone?

  • an example we can all understand (Score:5, Funny)

    by el_gregorio ( 579986 ) on Wednesday October 30, 2002 @09:59AM (#4563698)
    to understand this theory, all you have to do is visit your favorite pr0n site using IE. you see the way your screen fills with an endless swarm of pop-up windows, each with their own content? think of those as little universes, each separate from the others, but united in their love of barely legal asian teens.
  • I've said it before, I'll say it again. There is no such thing as universeS. If there are multiple universes, then they're all part of the same Universe. This is the equivalent to thinking galaxies as different universes.

    If there is evidence of there being multiple universes and they interact with eachother, than they simply make up one Universe and we have our terminology wrong. And if there are multiple universes that do not interact with eachother, than there's no scientific foundation for it to begin with which makes it a load of bs. You can apply this to any other article that discusses "universes" or even "parallel dimensions".

    • Re:Load of bs... (Score:2, Informative)

      by djembe2k ( 604598 )
      OK, the article does a lousy job with this point, but it actually goes to what is different about this theory. We can think of the Universe as
      1. Everything (basically the definition in the parent post)
      2. OR
      3. All the stuff created in the big bang, from here to the edge of what we can see, up to the background radiation "echoing" from the big bang, where a single set of rules of physics apply to everything.
      We use these two definitions interchangeably, because the common understanding of the big bang says we can. This theory says we can't, and it says that there are multiple "universes" in the second sense of the word.

      The Times article does say that these universes are "theoretically" reachable from one another, in the sense that there's no wall between them, no freaky "separate dimension" problem or anything like that. But inflation basically causes so much space to come into being between them so quickly that they are further apart than light (or any force or interaction) could have travelled in the time since their creation.

      What this implies is that they are not physically separated from one another, but their physics are separated from one another. They are so far apart, and so completely incapable of any interaction bridging the sheer gap of inflation between them, that they could have radically different rules of physics, different speeds of light, and so on.

      That isn't equivalent to saying that different galaxies are different universes (as the parent post says). It is saying that two radically different portions of the one big massive *everything* are different "universes" in some sense, and maybe that is a silly and stupid thing to say given the pure meaning of the word. But the point is that, given a common colloquial understanding of what a/the "universe" is, this theory says there are more than one.

      • Big Massive Everything = Universe. There is no such thing as universes. The only way for us to legitimately theorize that there is matter formed independent of our big bang, outside our known cosmos is if there were some kind of interaction between the two. Obviously, there is none, therefore its a bogus theory with no evidence supporting it. Even if there were evidence, this would by no means suggest that there are multiple universes, but rather that our Universe is different from what we suggested.

        In summary, if we can't see it, and we can't interact with it and we cannot detect any effects of it, then there can be no legitimate scientific theory for it to exist. And on the other hand if we CAN detect it then it DOES interact with our Universe which means that we SHARE the same Universe. There simply is no such thing as universes. Anyone who uses the term is either not following the scientific method or simply does not understand the term.

        • Re:Load of bs... (Score:2, Insightful)

          by djembe2k ( 604598 )
          Lots of people in this thread are getting caught up in semantics, which really isn't interesting, and which really isn't physics. If the only thing you don't like about this theory is the choice of words, then you really aren't objecting to a serious part of the science.

          But kevlar's point above is a much more important one, namely, at what point does science become philosophy or religion or whatever, but no longer science.

          The standard philosophy of science answer is that a theory is scientific not when there is evidence supporting it, but (and the difference is slight, but not inconsequential) when it is falsifiable. Basically this means when you can describe an experiment that would create evidence that could (depending on the results of the experiment) contradict and invalidate the theory. (Philosopher Karl Popper came up with this defition of a scientific theory, and it is still widely used.)

          In other words, if something can't ever possibly be proven wrong, it isn't science. If it could be, it is, even if you haven't yet done the experiment, or even lack the technology (as opposed to pure science) to do it. (Yes, this does create a grey area, since some experiments may not ever be realistic, or not in the next several centuries . . . .)

          Many theories in physics and astrophysics have been put forward without empirical evidence to back them up at the time of their creation, and then later, improved technology has made it possible to do the experiments that either falsify them or else support them. Particle accelerators are the prototypical example. Others are observations of the effects of gravity on light (by viewing stars during an eclipse), or careful examination of small variations in planetary orbits, both of which were understood as providing potential falsifying evidence of general relativity well before they were able to carried out. (Of course, both have since been conducted, and neither did provide falsifying evidence.)

          Note that this understanding of science means that nothing is ever really definitively proven true. More and more empirical evidence can support a theory, but you never know when some other observation will provide falsification. Here, the obvious example is Newtonian physics, which sure looked good for an awful long time, but now we can observe exceptions at extreme speeds and energies that demonstrate the need for relativity.

          So (to get back on topic), does this mean that this theory is absolutely unscientific? Well, let's do something radical, and look at the article.

          For Dr. Rees, the Astronomer Royal, it is not necessary to observe other universes to gain some confidence that they may exist. One thing that will help, he explained, is a more precise theory of how the cosmological constant may vary and how it will affect life in the universe. We should live in a statistically typical example of the range of universes compatible with life, he explained. For example, if the cosmological constant was, say, 10 percent of the maximum value consistent with life, that would be acceptable, he said.

          "If it was a millionth, that would raise eyebrows."

          Another confidence builder would be more support for the theory of inflation, either in the form of evidence from particle physics theory or measurements of the cosmic Big Bang radiation that gave a more detailed model of what theoretically happened during that first trillionth of a trillionth of a second.

          Here are a couple of specific examples which the author calls confidence builders, but which are in fact potential falsifiers. So, at least in principle, it is scientific.

          The problem is that there are other theories which work with the same sets of observable scientific results which are, potentially, much simpler and less messy. So now you get into an Ockham's razor issue, which let's you argue that this is a lousy scientific theory, but not that it is unscientific.

    • You contradict yourself. First of all, if this is an issue of terminology then why object to what people call a universe or multiverse. As long as you know how the bird walks, swims and flies, then what does it matter if people choose to call it a duck or a bird. So we have a universe within a multiverse and that's how they spawned off one another ... The understanding is in these relationships, and not the word choice.
    • I've said it before and I'll say it again. The map is not the terrain... nor is it the universe.

      The cosmos cares not a wit for our terminology.

  • It seems to me that since the cosmologists have been working hard since the Big Bang theory was first proposed to work out the manner in which this universe (lets start by not assuming its the only, or one of many, but just...here) came into being. This has worked out well with many other fields since both ends of the spectrum, quantum and astronomical, have been feeding back more solid information (be they constants or otherwise) to "keep the cosmologists on track". But it seems in just the last 5 or so years, the facts about what we *don't* know about the universe are begining to make the theories of cosmology a bit out of touch.

    For example back in 1998 when studies of distant supernova gave thorough evidence of an increase in the speed [indiana.edu] of the universes expansion. Now, this one still seems to be giving headaches to most all the theorists, and it seems to me that working around, or flat out ignoring that fact when building the "big theory" leaves a bit to be desired. Now enter Dark Matter [queensu.ca]. The lack of a comprehensive understanding of either A) the particle composition of the universe in the order of about 88% or B) an understanding of gravity to a power of 10 gives us yet another piece of the puzzle we're basically clueless about. Now, I understand that the purpose of these kinds of theories is just that, to test out hypotheses against what we do have in terms of fact and go from there, but it seems like maybe we should shelve the Big Theory Of Everything and work a little harder on the Theory of Very Specific Things That We Know We Don't Know.

    That being said, IANA(astromomer/cosmologist/physicist) so please, jump down my throat and tell me what *I* don't know because I for one am willing to admit that I don't have it all figured out quite yet.

    • "But it seems in just the last 5 or so years, the facts about what we *don't* know about the universe are begining to make the theories of cosmology a bit out of touch." Well, a good analogy would be to liken the process of developing theories of the universe to reverse engineering a very large software project. The underlying code language the software developers would be writing in would be represented by Quantum Mechanics and Relativity. Objects, functions and such would be analogous to the Big Bang Theory, Newtonian Mechanics, Electromagnetism etc etc. Astronomers and their equipment are likewise similar to software users/testers. As their tools get better and the number of testers becomes larger the more likely they are to notice features, bugs and quirks in the software application as a whole. As the software developers (theorists) get better they are able to tweak the functions and sometimes discover new parts of the programming language in an attempt to make their emulation a better representation of the original. Progress always goes in ebbs and flows. There are somedays when you think you have hit a break wall, but there are others when you can write some wonderous code and feel like you know it all. Its the same for a Theoretical Physicist. "For example back in 1998 when studies of distant supernova gave thorough evidence of an increase in the speed [indiana.edu] of the universes expansion. Now, this one still seems to be giving headaches to most all the theorists, and it seems to me that working around, or flat out ignoring that fact when building the "big theory" leaves a bit to be desired." Well the link you provided suggested evidence for the existance of Einstein's cosmological constant. Something that has recently been proposed as a mechanism for aberrations in the velocity of some of NASA's deep space probes. It didn't suggest the expansion waas increasing in speed though. "Now enter Dark Matter [queensu.ca]. The lack of a comprehensive understanding of either A) the particle composition of the universe in the order of about 88% or B) an understanding of gravity to a power of 10 gives us yet another piece of the puzzle we're basically clueless about." Dark matter is a theory to plug the holes produced by astronomers own conflicting observations. It is entirely consistant with previous theories, and explains nicely why galaxies rotate at the speed they do, but do not appear to have enough *luminous* matter around them to produce the gravitational forces needed. It is becoming more and more obvious that the missing matter is in fact super massive black holes at the centres of these galaxies. "but it seems like maybe we should shelve the Big Theory Of Everything and work a little harder on the Theory of Very Specific Things That We Know We Don't Know." Well, the Big Bang theory per se has been shelved! Just like the original software, it is still in developement, producing new and strange things like the article above. Personally as an ex-physicist, In would consider the origin of the universe as something very SPECIFIC that we know we don't know much about ;o) "That being said, IANA(astromomer/cosmologist/physicist) so please, jump down my throat and tell me what *I* don't know because I for one am willing to admit that I don't have it all figured out quite yet." Ask any of the big names in Physics today and they will all agree with you, they haven't figured it all out either. You are not alone.

  • Multiverses?

    You mean this might mean that somewhere in the multiverse there might be a universe comprised entirely of "people" that look exactly like Lance and Britney?

    Excuse me while I (and the rest of the "me's" in the multiverse) go out and hang ourselves....

  • Humanity's egocentrism (Score:5, Insightful)

    by Danny Rathjens ( 8471 ) <slashdot2.rathjens@org> on Wednesday October 30, 2002 @12:16PM (#4564883)
    How long will it take for humanity to learn that we aren't as special as we've always assumed?
    • Some groups of people used to think they were the center of the world(e.g. Zhong Guo==Middle Kingdom)
    • Bigger groups used to think that earth was the center of reality and everything literally revolved around humans.(A belief vigorously defended)
    • Leewonhoek's microscope revealed a smaller scale of reality than we knew, and it was quite some time before people accepted it.
    • Newton's theories seemed to describe how all reality worked until we realized different things were going on at very small and very large scales.
    • Now we have a much greater understanding of things at the quantum scale and the universal scale, but it seems obvious that that is not the end of it.
    Why do we seem to assume that the scale of reality is finite and coincidentally matches the same scale at which we exist? I think that based upon all of our prior fumblings we would be more likely to conclude that reality extends to a much smaller scale than the quantum and a much greater scale than that of the observible universe; even that it is infinite in both directions.
    • "Why do we seem to assume that the scale of reality is finite and coincidentally matches the same scale at which we exist? I think that based upon all of our prior fumblings we would be more likely to conclude that reality extends to a much smaller scale than the quantum and a much greater scale than that of the observible universe; even that it is infinite in both directions."

      Why do you think scientists make this assumption? The quantum scale I think you're referring to is approximately 30 orders of magnitude (10^30) below the scale we are familiar with in every day life. The size of the observable universe is 30 orders above our scale. And no one is saying that's the end - you can easily construct models, which are consistent with observation, in which the final volume of the universe is infinite. As for the smallest scale, there is a natural length scale in nature. It's the only length you can make by combining the fundamental constants in nature (Planck's constant, the speed of light, and the gravitational constant), and it's the very short quantum scale I referred to above. We *do* think something special happens there, but it may or may not preclude shorter lengths from being a meaningful concept.

      So certainly no practicing scientist who thinks about these issues would make the assumption that there's anything special about human scales - in fact, precisely the opposite. One of the powerful principles of modern cosmology is the idea that we do *not* live in a special time or place, and therefore that we have to explain why the conditions we inhabit are generic.
    • Argument from History is a fallibility. Btw.

  • semantical contradiction (Score:1, Interesting)

    by Anonymous Coward
    The word "universe" means "all things taken as one."

    This theory, according to the summary, suggests that there are other realms of things.

    Logically, those other realms would still be subsets of the universe.

    As such, it is a semantic contradiction to say there are "other universes."

    $0.02
  • "Once you've discovered it's easy to make a universe out of an ounce of vacuum, why not make a bunch of them?" asked Dr. Craig Hogan, a cosmologist at the University of Washington.

    Show me "an ounce of vacuum", and I might start taking you seriously.
  • One things I often think about is that if a exactly like ours universe were to exist, then there would be beings within it that have consciousness and understanding of the universe they are within, and would philosophise about it. Because of this, it may be that we don't exist, we are just the product of what would happen if we were to exist. Likewise, there are many other universes that you can think of that would have other conscious people within them who think they exist, but really don't.

  • More ambitious multiverses (Score:3, Interesting)

    by SiliconEntity ( 448450 ) on Wednesday October 30, 2002 @02:59PM (#4566453)
    Max "Mad Max" Tegmark [upenn.edu] has a more ambitious multiverse theory [upenn.edu]. It goes way beyond inflation, black holes, and even the Many Worlds Interpretation of quantum mechanics.

    His idea is that all possible mathematical structures exist, and that we live in one of them! At some level, physics can be considered a branch of mathematics. Hence our universe can be considered as an enormously complicated mathematical structure. The question is, why this structure instead of some other?

    His answer is that all mathematical structures exist, but that most of them are unsuitable for life. The paper linked above analyzes many different possibilities in terms of numbers of dimensions, numbers of time dimensions (yes, you could conceive of a universe with two-dimensional time), various other parameters, and he shows that structures that we would think of as living would have a hard time existing in universes much different from our own.

    The Tegmark model can be thought of as the simplest possible physical theory. If physics is reducible to mathematics, then saying that all mathematical structures exist can be put more simply: Everything exists.

    A similar model based on computation is proposed by Juergen Schmidhuber [idsia.ch]. Rather than Tegmark's mathematical structures, Schmidhuber proposes that all computations exist. Given that any mathematical model of a universe can be simulated by a computer program, these two formulations are roughly equivalent.

    But Schmidhuber's approach has the advantage that it provides a natural way to say that some universes are more probable than others: namely, universes with short programs have more "measure" than universes with long programs. It follows that our universe probably has a relatively short program, which therefore explains why we observe that physical laws are mathematically simple.

    It's pretty heavy stuff, but certainly exciting to see that researchers are (somewhat reluctantly) beginning to entertain multiverse models. The more ambitious "everything exists" theories are still too extreme for the mainstream, but I suspect that they, too, will get increasing attention over the next few decades.

  • I just finished reading a book by Eric J. Lerner called "The Big Bang Never Happened" (yes, I was skeptical at first as well)

    It actually turns out to make some very good points about the rise of Big Bang cosmology. In a nutshell:

    - The earliest incarnation of the Big Bang theory was posited by a Belgian priest, Georges-Henri Lemaitre, in his "primeval atom" theory, based on Einstein's equations and supported only in observation by the Hubble redshift (expansion). This theory very conveniently supported the Christian dogma of creation "ex nihilo" (out of nothing).

    - The revision(s) of this original theory had only tenuously been supported by observed phenomenon. Contemporary cosmology relies quite heavily on mathematical deduction; trying to make the universe fit the theory (faith) as opposed to the other way around (scientific method); a conflict which is apparent through the history of science and which Lerner pounds soundly into your head.

    - The Big Bang is only one of many solutions to Einstein's equations and has been persued mostly out of a desire to seek the most beautiful and sleek solutions (and remember - beauty is in the eye of the beholder, or beer-holder, but I digress)

    - The current paradigm supports the assertion that the universe must be closed with a cosmological constant (a self-confessed afterthought by Einstein) near or equal to one. This assertion demands that there must be much more matter in the universe than we have observed, ultimately sending particle physicists on the hunt for so-called "Dark Matter" (which has yet to be confirmed or observed). In the meantime, other theories exist that have no need to inflate the mass of the universe artificially and can explain formation of structures at the observed mass density (a density that adjusts the cosmological constant to about .02-.2)

    - Alternate theories that are based on observation have been summarily dismissed by the 'status quo'. These theories have arisen from the assertion that the laws of physica in the universe behave the same way as they do here on earth (and where we can observe) and that self-similarity is a tool that can be used to model structures in the laboratory (or in-silico) to explain structures and processes on the universal to the sub-microscopic level.

    - Big Bang theory posits a great many bizarre phenomena that can only be mathematically verfied and have not been observed or duplicated. Cosmology has moved far away from the realm of scientific method, instead relying on the exotic world of mathematics (nothing wrong with math, unless you are trying to explain the universe without confirming by observation)

    And on and on... he does a far better job of explaining it all (full disclosure: I'm not a cosmologist) -- read the book (or don't).

    -t_kiehne
    • Yah, I read this book, I've also read rather scathing critiques about it (mostly about selective presentation of evidence, a scholarly no-no on the order of murder for the rest of us).

      What the author fails to mention is that EVERY solution so far explored, other than the currently adopted one, fails at observation time. Every one.

      Heck, Godel himself came up with a rotating solution for the Universe, but the while the laws of physics would've remained the same, the APPEARANCE of those laws would've been dramatically different (think constantly moving frame of reference magnified).

      Sorry, but don't feel too bad, I thought it was a good book too, until I did the research on it.

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