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The Hidden Reality Draws Ire From Physicists 387

Posted by Soulskill
from the don't-anger-the-physics-nerds dept.
eldavojohn writes "Scientific American is running a piece by science journalist John Horgan attacking pop physicist Brian Greene's latest offering, titled The Hidden Reality. He's not entirely alone; Not Even Wrong backs him up and reminds us of a growing list of multiverse propaganda. The journal Nature ran a short piece (subscription required) trying to remind everyone that Greene's book is more theory than fact, but apart from those three responses, the popular press seems to be gobbling up this tantalizing concept of a multiverse. NPR offers an excerpt while SFGate and The Wall Street Journal entertain us with interviews of the controversial Greene. The New York Times and Salon seem to think it's worthwhile, with Salon even calling it 'the science behind' the multiverse theory. The New York Times thought it worthwhile to give Greene an op-ed column. For better or for worse, Greene has certainly brought this great debate to the public's attention — similar to his exhibition of String Theory."
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The Hidden Reality Draws Ire From Physicists

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  • by MrEricSir (398214) on Monday January 31, 2011 @03:41PM (#35060088) Homepage

    The press repeating pseudoscience as fact? Say it ain't so!

  • Colbert (Score:5, Informative)

    by just_another_sean (919159) on Monday January 31, 2011 @03:44PM (#35060108) Homepage Journal

    You can check out a fairly entertaining interview of Brian Greene by Stephen Colbert from last Thursday on Colbert's web site [colbertnation.com].

    I can't say this will educate you further one way or another and I am certainly not qulified to weigh in on either side of the debate but the guy was pretty candid with Stephen and, well, I found it entertaining...

    • by radtea (464814)

      You can check out a fairly entertaining interview of Brian Greene by Stephen Colbert from last Thursday on Colbert's web site [colbertnation.com].

      No I can't. Neither can anyone else outside the United States.

      • by NiteShaed (315799)

        No I can't. Neither can anyone else outside the United States.

        People in parallel universes are excluded as well. Stupid licensing, I wanted to find out who this "Colbert" person that does interviews is. The only famous Colbert here is Vice-President Stephen Colbert, who ran on the Stewart/Colbert ticket in 2000, beating O'Reilly/Hannity in a surprise upset. Enough about politics here in the Dominion of North America though, I'm sure it's probably not that different in your part of the multiverse.....

        • by arcsimm (1084173)
          So... what's the Dominion's policy towards inter-universal immigration?
          • by NiteShaed (315799)

            There's a good chance that you're actually already here, so you'd have to work that out with yourself....you don't have a goatee do you? The you that's already here may take that as a bad sign. Sorry, can't help referencing old episodes of "Stellar Voyage". I love that episode where Captain Curt and Mr. Stock go to the "evil" universe though.....

          • Depends. Are you willing to pick vegetables?
      • by stiller (451878)

        I can. In the Netherlands. No tricks required. We even get dutch commercials (joy)

      • You can check out a fairly entertaining interview of Brian Greene by Stephen Colbert from last Thursday on Colbert's web site [colbertnation.com].

        No I can't. Neither can anyone else outside the United States.

        I'm in France and can also watch it here (without a proxy). The trick with it and the Daily Show is to watch all the video clips and not the full episode in one go (i.e., that is, use this link [colbertnation.com] and not this [colbertnation.com]).

      • by Surt (22457)

        You could use a proxy.
        http://aliveproxy.com/us-proxy-list/ [aliveproxy.com]

      • Ah yes, Viacom, sorry, forgot how idiotic our entertainment companies can be here. Wasn't trying to tease anyone!

      • No I can't. Neither can anyone else outside the United States.

        The "full episode" is restricted, but various sections, including the Greene interview, seems to be available to a wider audience. I watched this from Norway.

        Here you go, direct link to the interview. [colbertnation.com]

    • Re:Colbert (Score:4, Informative)

      by chemicaldave (1776600) on Monday January 31, 2011 @04:46PM (#35060778)
      Users who can't watch the clip might be interested in this brief transcript I just typed up.

      Colbert: So there are other parallel universes out there.
      Greene: No. I'm not saying that.
      Colbert: Wait. That's all you've been saying.
      Greene: No no. The math suggests there's a possibility, but until we have experimental evidence for these things -
      Colbert: Math is not experimental evidence. Math is high falutin-doodilling.
      Greene: Math suggests things that you wouldn't be thinking about if you didn't have that mathematics as your guide. Then you need to do experiments.

      He seems pretty straightforward about this not being actual science.

      • by Nazlfrag (1035012)

        Of course this is actual science, experiments don't appear out of thin air, you first ask 'what if?' before you ask 'how?'. He theorises an experiment to test the existence of 'branes in that very interview (something about precise amounts of energy lost in particle accelerator experiments) . Science is more than confirming experiments though, it's coming up with them in the first place. Saying this isn't science is just flat out wrong, what it is not is proof.

  • by Anonymous Coward on Monday January 31, 2011 @03:45PM (#35060124)

    But the conservation of ire insures that an equal amount of economists will chill out.

  • by Stregano (1285764) on Monday January 31, 2011 @03:46PM (#35060136)
    This means that I can travel to the other universes, kill off the me from other ones and become stronger? I am pretty sure that the awesome Jet Li movie came out first (seriously, when he is going in regular motion and the sparks are in slow motion at the end, awesome). And yes, this is all 100% on topic since the movie discusses the multi-verse (it is not everyday that I can figure out a way to shove a Jet-Li reference into /.)
    • by slinches (1540051)

      This means that I can travel to the other universes, kill off the me from other ones and become stronger?

      No, this means that the book the article refers to is no more science than the terrible Jet-Li movie you're alluding to. Now, that's not necessarily a bad thing. It just can't be called science. Instead, I think it would more qualify as the philosophical extension of a few scientific theories. As long as Greene doesn't misrepresent untestable muti-verse theories as hard science, then I'd say that this book would at least be an entertaining read. I'd rather people read thought provoking psuedo-science

  • by grimJester (890090) on Monday January 31, 2011 @03:50PM (#35060174)
    Sounds like the submitter doesn't know the meaning of the word theory?
    • by jfengel (409917) on Monday January 31, 2011 @03:54PM (#35060220) Homepage Journal

      Even scientists, when they're not being absolutely rigorous, use "theory" in the "hypothesis" sense. It's common in culture, and scientists are still human, especially when off the clock.

      This is a scientific context and the summary really should be rewritten to use the more precise and accurate word "speculation", but "hur hur evolution is a theory not a fact" is so spectacularly and deliberately misinformed that no amount of rigor on the part of scientists is going to stamp it out. Those who grasp it will understand what was meant; those intent on misunderstanding will find a way to do so regardless.

      • by Tablizer (95088)

        Rather than get caught up in the distinction between "hypothesis", "theory", and "fact"; it may be more useful to view the evidence level on a continuum.

        People propose a "model" or an idea to potentially explain some initial observation. It starts out an embryo of an idea. The more evidence that favors it, the more "mature" it gets. There are no absolute "facts", only models that are heavily backed by empirical observation. Anything and everything we think is a "fact" may turn out to be wrong.

        We can only sa

        • by jfengel (409917)

          Absolutely. Talk to philosophers of science and you'll get all sorts of arguments about the line between fact, observation, theory, and so forth.

          But even most scientists are only dimly aware of that, much less the general public.

    • The word theory isn't limited to just a scientific context. For example: Game Theory, Chaos Theory, Probability Theory and yes, String Theory. It's okay to refer to mathematical frameworks as a theory.

  • Now tell me about a scientific fact, proposing that we talk about empirical science here.

    CC.
  • more theory than fact

    To scientists, these terms are not mutually exclusive.

  • What's so freakin' hard about getting that concept right? Oh, yeah, people can't spell (much less pronounce) "hypothesis".

  • Bad use of theory (Score:4, Insightful)

    by plopez (54068) on Monday January 31, 2011 @03:57PM (#35060246) Journal

    OK, it seems that even people who should know the difference can't distinguish between the word theory and hypothesis. What was meant in the write up when this was said "Greene's book is more theory than fact" is "Greene's book is more hypothesis or conjecture rather than theory". A theory has been tested and more than once. It is as close to fact as humans can get. This watering down of the word theory is bad, it causes people to be confused and discount theories. Which is why people doubt the theory of evolution or global climate change.

    Use the word right or don't use it.

    OK, I'll stop ranting.

    • by HiThere (15173)

      (N.B.: I'm *assuming* that this book is just asserting the Everett-Graham-Wheeler multi-world interpretation. If this is wrong, then please tell me so.

      But the thing is, here the proper word is neither theory nor hypothesis, but rather interpretation.

      Quantum theory has several different interpretations. These various interpretation agree on what the math says, and on what the known experiments say, and (usually) about what any experiment that has been designed would show. They all make the same predictio

  • by RevWaldo (1186281) on Monday January 31, 2011 @04:03PM (#35060300)
    ...where this book is up for a Pulitzer, so sticks and stones, ya haters!

    .
    • by Locke2005 (849178)
      Even more surprising, somewhere there exists a universe in which slashdot posters actually get laid!
  • Uhhh... whut? (Score:5, Insightful)

    by PCM2 (4486) on Monday January 31, 2011 @04:05PM (#35060318) Homepage

    Why all the negative spin in the summary? As far as I can tell, nobody is accusing Greene of "propaganda." Rather, this is /. propagandizing at its absolute worst.

    • Why call Greene a "pop physicist"? That seems to imply he's not qualified in his field, when one of the articles referenced calls him "a physicist at Columbia University" who is "is an immensely talented science explicator." It describes his other books as "smart, witty bestsellers."
    • TFA says Greene "draws ire from physicists," then goes on to explain that a journalist from Scientific American has written an editorial, and another blog agrees. Where are the physicists? I can't read the article from Nature, but just the abstract calls Greene's book "beguiling."
    • TFA goes on to accuse Greene of being "a cheerleader" for multiverse theory, a stance that puts him in the same camp, it says, as other notable physics propagandists.... such as Stephen Hawking. Whoah, hanging out in some bad company there.

    Here's the real summary: Brian Greene has written on string theory for a popular audience in the past, and he's also fascinated by some of the more fringe-y elements of physics, such as the multiverse theory. He has a new book out. He has not taken any public stance on the Tea Party, abortion, or the Iraq war -- and honestly, I think it's sad that it seems to have become a requirement of modern journalism to pretend that he has.

    • While John Horgan [johnhorgan.org] (author of the Sci Am blog piece) is not a crank, he does appear to be on thin ice, given his past works, of Rational Mysticism: Dispatches from the Border Between Science and Spirituality in 2003, and The End of Science: Facing the Limits of Science in the Twilight of the Scientific Age in 1996.

      Horgan does have a B.A. (as in Arts) from Columbia University (1982), and an M.S. from Columbia's School of Journalism (1983). I take it that is a Masters of Science, except how you can manage to g

      • I'm curious (Score:4, Interesting)

        by Xaedalus (1192463) <`moc.oohay' `ta' `syladeaX'> on Monday January 31, 2011 @04:55PM (#35060886)

        Did you ever read Rational Mysticism ? Because I did, and I found it to be very fascinating, written from a skeptic's viewpoint (as opposed to a cynical skeptic) and he came away with a lot of interpretations that I found intriguing.

      • Re:Uhhh... whut? (Score:4, Interesting)

        by ceoyoyo (59147) on Monday January 31, 2011 @05:03PM (#35060952)

        Mod parent up.

        Horan is also, as he points out himself, kind of cranky (in the bitter way, not the crazy way). I haven't read Greene's latest book, but his others cover established theory (relativity and QM) quite well, and then introduce string theory as something very much in development. I doubt very much his latest book departs significantly from that formula, as the label "pseudoscience" would require.

        Speculation is an important part of science, despite what Horgan thinks. The difference is that scientists don't claim their speculation is fact, but merely an interesting idea that perhaps should be studied further.

        The term poppernazi does seem to fit Horgan, and yes, if you allow a little bit of explanation, it is indeed a counter to his arguments.

      • I take it that is a Masters of Science, except how you can manage to get a graduate Masters degree in Science from a school of Journalism in a single year is an interesting concept in its own right.

        Some schools have programs where you begin taking graduate-level coursework in your senior or even junior year of undergraduate study, and you begin whatever work is required for your thesis around the same time. The graduate-level courses generally fulfill elective requirements for your undergraduate degree as well as requirements for your graduate degree. The end result is that it only takes about one additional year to fulfill the requirements of a Master's degree.

    • by vlm (69642)

      I have no direct experience with his books. However, a good operational plan is whenever someone in the mass media describes anything as "smart" that is actually a codeword for "really freaking stupid" and/or its supposed to be an aspirational conspicuous consumption item for young college grads. This crappy overpriced car is "smart". Or voting for this professional liar is "smart". Or "smart" people eat this breakfast cereal. In other words assume the opposite when the mass media uses the word "smart". Doesn't by any means prove his books are worthless, but they're being promoted with a very tired almost anti-marketing message, so, its not looking good.

    • by jdgeorge (18767)

      Here's the real summary: Brian Greene has written on string theory for a popular audience in the past, and he's also fascinated by some of the more fringe-y elements of physics, such as the multiverse theory. He has a new book out. He has not taken any public stance on the Tea Party, abortion, or the Iraq war -- and honestly, I think it's sad that it seems to have become a requirement of modern journalism to pretend that he has.

      You had me for two sentences, then lost me with the lament about the state of journalism in a way that seems to apply neither to the actual topic at hand, nor to the discussion thereof here on Slashdot.

      • by PCM2 (4486)

        Did you read TFA?

        Multiverse theories don't turn me on anymore. Perhaps it's because of 9/11 and all its bloody consequences, especially the U.S. wars in Afghanistan and Iraq. Also, I have two teenage kids, and I'm worried about the enormous problems they're inheriting from my generation. Not only wars overseas but also global warming, species extinction, pollution, poverty, pandemics and so on.

        In other words, Greene's interest in string theory and the multiverse is (again, a quote) "immoral," because people are starving, we're fighting the war on terror, and blah blah blah. Therefore this journalist can manufacture false outrage, going so far as to describe aspects of multiverse theory as "loathesome," because .... again, I'm lost. Then the summary follows suit by describing Greene's book as "propaganda," as if he has some political position to push. He simply doesn't, and it's i

    • by snowgirl (978879)

      "pop physicist" doesn't mean that he's unqualified. Neal deGrasse Tyson is a pop astronomer/physicist but that doesn't make what he says wrong or bad.

      Some people are so adapted to the alternative and underground music scene that they fail to recognize real musical talent in the pop music market. Just because someone is a pop artist, doesn't mean that everything they churn out is shit.

    • Why all the negative spin in the summary?

      those who hold to the Copenhagen understanding are willing to say that a wave function involves the various probabilities that a given event will proceed to certain different outcomes. But when one or another of those more- or less-likely outcomes becomes manifest the other probabilities cease to have any function in the real world. So if an electron passes through a double slit apparatus there are various probabilities for where on the detection screen that individual electron will hit. But once it has hit

  • The guy is out on the most feeble of limbs with his multiverse idea, since 'string theory' itself is little more than conjecture... but to take the edge off the 'not science' rhetoric here, the guy is a very well regarded theoretical physicist. Is it any less scientific-wild-ass-guess than Hawkings' notions about black holes? No. He at least has enough clout to get data access to the CERN supercollider experiments, so its not like its -me- throwing this crap out there hoping it will stick.
  • by jbrodkin (1054964) on Monday January 31, 2011 @04:09PM (#35060362)
    I read Fabric of the Cosmos and thoroughly enjoyed it. I then read the Elegant Universe and grew more and more frustrated with each page as Greene delved into theories that can never be proven or disproven. At a certain point, this become little more than fantasy and has as much credibility as religion and mythology, both of which can also never be proven or disproven.
  • by Locke2005 (849178) on Monday January 31, 2011 @04:12PM (#35060376)
    In a parallel universe, Brian Greene is lauded as a genius and his interpretation of multiverse theory is universally accepted!
  • by jfengel (409917) on Monday January 31, 2011 @04:15PM (#35060406) Homepage Journal

    Science popularizers like Greene have to tread a careful line. They're not paid to talk about the most important work, which most people wouldn't understand. Real cutting-edge physics is comprehensible only to those extremely skilled in the art, which cuts out even the vast majority of scientists. But people like believing that they're getting dispatches from the front, especially in physics, because that's where people imagine lays the answer to Life, The Universe, and Everything.

    You can't even pretend to know much about string theory without some very advanced work in quantum mechanics AND general relativity, which means knowing an awful lot of very, very difficult calculus. For 99.9% even of readers of Scientific American, they're skipping straight past all of that.

    Which means, in essence, telling comforting lies. That's common in education, simplifying a subject to the point where it's essentially false. It's common in science (cf. genetics), but in other fields as well. History, as taught in schools, is so far from reality that college professors have to spend a full year (at least) undoing the damage.

    It's similar to the situation with space research: most of the actual science is done by the robots, but people like the human stories associated with manned flight. The real science is done practically with the rounding errors in the budget.

    In the case of string theory, that means that a bunch of people doing interesting but (bluntly) irrelevant speculation get far, far more attention than they deserve. It's not that they're right, wrong, or Not Even Wrong. People want to know what they're doing, because they've been told that we're Just Around The Corner from The Big Answers. It's a lie, and essentially everybody familiar enough with the work knows it. But they also know it's where the funding comes from.

    I mean seriously... a multi-billion-dollar supercollider? How on earth does that get funded? Because a bunch of people who can't tell a fermion from a boson imagine that they're part of a grand human experiment. And maybe, in the grand human scheme of things, it is worth the money, though I personally doubt it. Still, it's the dirty little secret of scientific work: popularizers write a lot of books about stuff that's really of very little earthy interest, in order to attract enough attention to the field of science to keep the actual work going on. The grad students counting bacterial colonies or coming up with new protein folding algorithms or other tedious stuff that slowly an un-telegentically advances understanding.

    I don't like the little turf war going on between the string theoriests, who get more attention than they deserve, and the anti-string-theorists, who are doing equally unproductive work. Both are intriguing speculations that might one day be of intense interest, but at the moment are of little value either practical or philosophical. They get attention only because they're right at the edge, but most of us are so far from the edge that they'd be invisible under any other circumstances. Both should be left to labor diligently in quiet, and let their little funding turf war be lumped in with the rest of the academic bickering rather than become a great philosophical debate.

    • "You can't even pretend to know much about string theory without some very advanced work in quantum mechanics AND general relativity, which means knowing an awful lot of very, very difficult calculus."

      I disagree. Certainly working in the field requires this, but understanding it at a basic level just as certainly doesn't.

    • by Locke2005 (849178)
      The supercollider probably never will prove the existence of the Higgs Boson or any other new particles, but look at the spin-off benefits to engineering: we now have an infrastructure in place to build really, really big helium cooled electromagnets! I mean, they must have learned something just by building all this exotic equipment!
    • Re: (Score:2, Interesting)

      by PCM2 (4486)

      People want to know what they're doing, because they've been told that we're Just Around The Corner from The Big Answers. It's a lie, and essentially everybody familiar enough with the work knows it.

      Jesus, paranoid much? The public is intellectually curious because they're being lied to. People like Stephen Hawking and Brian Greene have some ideas about how the universe might be organized but they're liars! They're lying to you! Don't listen! LA LA LA LA LA LA!

      Settle the fuck down. Brian Greene wrote a book in which he tries to explain some modern avenues of conjecture about physics in a way that you don't need to know "a lot of very, very difficult calculus" to understand. Period. Sorry if that cost y

      • Love your populist indignation, but unfortunately he's absolutely right. What physicists are doing at the "cutting edge" has almost zero resemblence to what we all read in Scinentific American or Discover. And however smart we like to think we are when we pontificate about this stuff at parties, if we don't know the "very, very difficult calculus" then we actually understand close to nothing. Physics IS mathematics. If you can't do (or follow) the math, then you don't know the physics. Period.

        That's not to

    • by snowgirl (978879)

      because that's where people imagine lays the answer to Life, The Universe, and Everything.

      Grammar Nazi alert: It's where the answer LIES. "To lay" is the act of putting something somewhere where it will then "lie".

      • by jfengel (409917)

        You're right! I can't believe I missed that. (Not a grammar nazi, but I am a professional writer, and I don't usually make mistakes of that kind.)

  • He's selling the idea of a multiverse, but if he can't tell us how to get to Tanelorn nobody should take him seriously.

  • "more theory than fact"

    That is a non-sequitur.

  • WTF is this shit? (Score:5, Insightful)

    by 0xdeadbeef (28836) on Monday January 31, 2011 @04:23PM (#35060498) Homepage Journal

    Someone who whines that the multiverse theory must necessarily be false because it leads him to uncomfortable conclusions regarding his personal belief in morality has no business criticizing any scientific theory, no matter how speculative it is.

    And seriously people, pseudoscience? You are claiming that Susskind and Hawking engage in pseudoscience, like Deepak Chopra?

    This criticism isn't based on scientific merit, this is envy of popular attention.

  • I'm not sure if "remind everyone that Greene's book is more theory than fact" was from Nature or the story submitter, but no wonder the general public is quite confused about science in general. The sentence implies that it's "just a theory" and that theories aren't highly thought of by scientists, yet the same types of people who object to Mr. Greene's work being though of as useful rant and rave when the theory of evolution is treated as anything other than fact.

    If his work is a theory and is supported
  • I've believed in a Multiverse since I was 12, before I dug my fingers into my Players' Handbook and DMG. If 20 million people play D&D, it must be true.

  • Hey -- yes, string theory makes few provable predictions, and if you understand the concepts in "the Elegant Universe" you'd know why, and also why Ed Witten is a hero. Yeah, it only predicts gravity, no big deal there. And it looks like handling the real issues with standard model, according to which, either quantum physics or relativity are dead wrong. That's gotta be the least talked about tiny flaw in current thinking -- and it's not a tiny flaw, it's an utter catastrophe in the existing theory, perio
  • by scorp1us (235526) on Monday January 31, 2011 @04:37PM (#35060704) Journal

    For they all are guilty of mental masturbation when it comes to physics. Oh, and include whomever postulated that the Higgs is so abhorrent to nature that it comes back through time to prevent its discovery. [timesonline.co.uk]

    It is a general "parallel universe" or "alternate reality" problem, and not any problem with your understanding. You (and everyone else) have failed to identify the matter/energy constraint. That is to say, if there is an alternative, it must be expressed in matter, and maintaining more than one reality requires additional matter (or base state of energy). I've conceptualized it with a familiar software developer concept: MVC: Model-View-Controller. Anytime when looking at gobs of data (including the state of reality) you need to look and interact with data in a uniform way. MVC allows for this. The model is the data model - the structure of, and data itself. List, tree, etc. The universe would probably express this as dimensional (3 or 10) planes of energy. Next is the view, with is the manifestation of the model. This would be an instantaneous snapshot of the universe, including velocities, etc. Finally the controller are the laws that work on the data. They do not work on the view, as the view is dependent of the model.

    Every time you propose an alternate time line, then you need to copy the model (you can share the viewer and controller (if you didn't things would be "noticeably different")) But to copy the model is to acquire the energy to express a whole other universe, and not once, but at every decision point on the time line.

    Physicists are just now starting to realize this and many are starting to argue that space-time is quantized on the order of Planck length (and time). While this is infinitesimally small, it vastly reduces the possible outcomes from infinite to a manageable number, possibly 1. Quantized space time locks down the source state and limits the possibilities of the next state, so it is feasible that the laws of the universe would only allow 1 possible next state. Heim was the first (that I know of) to argue for quantized space-time. I've since seen other people derive it on their own and get a similar (yet not identical) result
    (but all are some close value to Planck length)

       

  • From the TFA:
    "Multiverse theories aren't theories—they're science fictions, theologies, [...]"

    Theology is the keyword here. Postulating a multiverse with many similar universes to this one basically eliminates any objective significance this particular planet Earth with its history has. You can nuke everything and "know" that our culture will continue in other universes. So accepting a multiverse theory would destroy ethics: it would kill God.
  • Science has to start with data. We put data into models. These models make predictions, and we construct experiments to test those predictions. The best case scenario is when we see some novel authentic phenomena that is explained by the theory.

    When I was reading cosmology many years ago, it struck me as philosophy. It still does. But philosophy is not bad, and not necessarily not science. Remember that science began as natural philosophy that threw out the all the previous assumptions of how the un

  • So maybe I'm a horrible 'literalist' (not sure there's a word for that, so I guess I'm ... not?) but there's only one Universe.

    One.

    Any other kind of 'verses' are all a part of this same Universe, that realm which encompasses all of existence. To include further things within the Universe is possible, but it is not possible to have more than one Universe. Even a "Multi" verse is yet still a "Uni" verse when one considers the whole as a single whole... as one without any logical doubt can do.

    Theref
  • Greene's NYT op ed piece perpetuates the silly notion that photons will somehow stop in their tracks and start going backwards due to the accelerating expansion. No they won't, they will just be red shifted further and there will certainly continue to be some asymptotic limit to how far away the furthest galaxies were that we are seeing, but everything we can see now is in a sense in front of the CMB and the CMB will keep coming, no matter how cold it gets.

    While it must remain outside the realm of direct ob

  • by da cog (531643) on Monday January 31, 2011 @05:20PM (#35061120)

    As a physicist, I believe that the many-world interpretation of quantum physics is the best because it is more practical than its competitors.

    The first major competitor is the theory that the world is deterministic and its just our lack of knowledge that causes us to perceive a non-deterministic world. The problem with this is that we have no evidence in favor of this proposition and to the extent we have any evidence it is *against* this proposition.

    The other major competitor is the theory that the wave function of the whole universe collapses every time we make a measurement. This agrees very well with experiment as long as the person asking the question is the one doing the measurement, but it has a major problem: since wave functions don't collapse unless measured, what counts as a measurement? For example, does collapse only happen when *I* make a measurement? If so, why should I be uniquely privileged? Alternatively, does collapse happen whenever some human being makes a measurement --- that is, if I perform the Schroedinger's cat experiment but with a person instead of a cat inside the box, then has the wave function collapsed even if I never open the box (assuming it is perfectly insulated)?

    The advantage of the many-worlds interpretation is that it solves the problem of measurement by *not* treating measurement as being an special-case exception to the rules; it postulates that the wave function of the universe never actually collapses. Given this, how do we make sense of the fact we human beings *do* observe such a collapse? The answer actually appears right in the math: when we demand that a particle in a mix of states tell us which state it is in, it causes us to become entangled with the particle so that a *portion* of the universe splits into two states: one with the particle in the first state and us seeing it in the first state, one with the particle in the second state and us seeing it in the second state, and so on. So from the perspective of each of the observers the wave function has collapsed even though it never did. What happens then if you put an observer in a box and have him or her make a measurement? The answer also appears in the math: although the universe splits inside the box, it does not split outside the box.

    This might seem fanciful, but it is something that we can actually test. Although we cannot put human beings in a box for ethical reasons, we can put increasingly large systems in the box that act as "observers" of some particle (by engineering an interaction between the observer and the particle) and then perform interference experiments to determine whether the wave function in the box has collapsed or not. Every such experiment we have performed has shown that the wave function does in fact *not* collapse inside the box but rather splits.

    So what is the mathematical difference between being inside the portion of the universe that splits and being outside it? It is simple: if you are outside the portion that splits, then the wave function of the universe can be expressed as a tensor product between you and splitting portion. If you are inside the portion that splits, then this can never be the case.

    Thus it turns out that measurement *already falls out of quantum mechanics* in a mathematically rigorous and observer-independent fashion, as long as we are willing to accept that a consequence of this is that from the view of someone external to the universe there is a (mathematically rigorous) sense in which there are multiple copies of you and I within the universe. Sure, if we don't like this consequence we can add a rule that gets rid of it by specifying that the wave-function collapses, but then you have to introduce some arbitrary rule that specified that some macroscopic bodies have the power to cause a collapse but not others. Now in fairness, there do turn out to be mathematically rigorous ways to do this and some of them even provide testable predictions so one of them might be proven correct one day, but there is

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