Are Many Worlds and the Multiverse the Same Idea?

By Sean Carroll | May 26, 2011 2:45 pm

When physicists are asked about “parallel worlds” or ideas along those lines, they have to be careful to distinguish among different interpretations of that idea. There is the “multiverse” of inflationary cosmology, the “many worlds” or “branches of the wave function” of quantum mechanics, and “parallel branes” of string theory. Increasingly, however, people are wondering whether the first two concepts might actually represent the same underlying idea. (I think the branes are still a truly distinct notion.)

At first blush it seems crazy — or at least that was my own initial reaction. When cosmologists talk about “the multiverse,” it’s a slightly poetic term. We really just mean different regions of spacetime, far away so that we can’t observe them, but nevertheless still part of what one might reasonably want to call “the universe.” In inflationary cosmology, however, these different regions can be relatively self-contained — “pocket universes,” as Alan Guth calls them. When you combine this with string theory, the emergent local laws of physics in the different pocket universes can be very different; they can have different particles, different forces, even different numbers of dimensions. So there is a good reason to think about them as separate universes, even if they’re all part of the same underlying spacetime.

The situation in quantum mechanics is superficially entirely different. Think of Schrödinger’s Cat. Quantum mechanics describes reality in terms of wave functions, which assign numbers (amplitudes) to all the various possibilities of what we can see when we make an observation. The cat is neither alive nor dead; it is in a superposition of alive + dead. At least, until we observe it. In the simplistic Copenhagen interpretation, at the moment of observation the wave function “collapses” onto one actual possibility. We see either an alive cat or a dead cat; the other possibility has simply ceased to exist. In the Many Worlds or Everett interpretation, both possibilities continue to exist, but “we” (the macroscopic observers) are split into two, one that observes a live cat and one that observes a dead one. There are now two of us, both equally real, never to come back into contact.

These two ideas sound utterly different. In the cosmological multiverse, the other universes are simply far away; in quantum mechanics, they’re right here, but in different possibility spaces (i.e. different parts of Hilbert space, if you want to get technical). But some physicists have been musing for a while that they might actually be the same, and now there are a couple of new papers by brave thinkers from the Bay Area that make this idea explicit.

Physical Theories, Eternal Inflation, and Quantum Universe, Yasunori Nomura

The Multiverse Interpretation of Quantum Mechanics, Raphael Bousso and Leonard Susskind

Related ideas have been discussed recently under the rubric of “how to do quantum mechanics in an infinitely big universe”; see papers by Don Page and another by Anthony Aguirre, David Layzer, and Max Tegmark. But these two new ones go explicitly for the “multiverse = many-worlds” theme.

After reading these papers I’ve gone from a confused skeptic to a tentative believer. This happened for a very common reason: I realized that these ideas fit very well with other ideas I’ve been thinking about myself! So I’m going to try to explain a bit about what is going on. However, for better or for worse, my interpretation of these papers is strongly colored by my own ideas. So I’m going to explain what I think has a chance of being true; I believe it’s pretty close to what is being proposed in these papers, but don’t hold the authors responsible for anything silly that I end up saying.

There are two ideas that fit together to make this crazy-sounding proposal into something sensible. The first is quantum vacuum decay.

When particle physicists say “vacuum,” they don’t mean “empty space,” they mean “a state of a theory that has the lowest energy of all similar-looking states.” So let’s say you have some scalar field filling the universe that can take on different values, and each different value has a different potential energy associated with it. In the course of normal evolution the field wants to settle down to a minimum of its potential energy — that’s a “vacuum.” But there can be the “true vacuum,” where the energy is really the lowest, and all sorts of “false vacua,” where you’re in a local minimum but not really a global minimum.

The fate of the false vacuum was worked out in a series of famous papers by Sidney Coleman and collaborators in the 1970’s. Short version of the story: fields are subject to quantum fluctuations. So the scalar field doesn’t just sit there in its vacuum state; if you observe it, you might find it straying away a little bit. Eventually it strays so far that it climbs right over the barrier in the direction of the true vacuum. That doesn’t happen everywhere in space all at once; it just happens in one tiny region — a “bubble.” But once it happens, the field really wants to be in the true vacuum rather than the false one — it’s energetically favorable. So the bubble grows. Other bubbles form elsewhere and also grow. Eventually all the bubbles crash into each other, and you successfully complete a transition from the false vacuum to the true one. (Unless the universe expands so fast that the bubbles never reach each other.) It’s really a lot like water turning to steam through the formation of bubbles.

This is how everyone talks about the fate of the false vacuum, but it’s not what really happens. Quantum fields don’t really “fluctuate”; that’s poetic language, employed to help us connect to our classical intuition. What fluctuates are our observations — we can look at the same field multiple times and measure different values.

Likewise, when we say “a bubble forms and grows,” that’s not exactly right. What really happens is that there is a quantum amplitude for a bubble to exist, and that amplitude grows with time. When we look at the field, we see a bubble or we don’t, just like when we open Schrödinger’s box we see either a live cat or a dead cat. But really there is a quantum wave function that describes all the possibilities at once.

Keep that in mind, and now let’s introduce the second key ingredient: horizon complementarity.

The idea of horizon complementarity is a generalization of the idea of black hole complementarity, which in turn is a play on the idea of quantum complementarity. (Confused yet?) Complementarity was introduced by Niels Bohr, as a way of basically saying “you can think of an electron as a particle, or as a wave, but not as both at the same time.” That is, there are different but equally valid ways of describing something, but ways that you can’t invoke simultaneously.

For black holes, complementarity was taken to roughly mean “you can talk about what’s going on inside the black hole, or outside, but not both at the same time.” It is a way of escaping the paradox of information loss as black holes evaporate. You throw a book into a black hole, and if information is not lost you should (in principle!) be able to reconstruct what was in the book by collection all of the Hawking radiation into which the black hole evaporates. That sounds plausible even if you don’t know exactly the mechanism by which happens. The problem is, you can draw a “slice” through spacetime that contains both the infalling book and the outgoing radiation! So where is the information really? (It’s not in both places at once — that’s forbidden by the no-cloning theorem.)

Susskind and Gerard ‘t Hooft suggested complementarity as the solution: you can either talk about the book falling into the singularity inside the black hole, or you can talk about the Hawking radiation outside, but you can’t talk about both at once. It seems like a bit of wishful thinking to save physics from the unpalatable prospect of information being lost as black holes evaporate, but as theorists thought more and more about how black holes work, evidence accumulated that something like complementarity is really true. (See for example.)

According to black hole complementarity, someone outside the black hole shouldn’t think about what’s inside; more specifically, everything that is happening inside can be “encoded” as information on the event horizon itself. This idea works very well with holography, and the fact that the entropy of the black hole is proportional to the area of the horizon rather than the volume of what’s inside. Basically you are replacing “inside the black hole” with “information living on the horizon.” (Or really the “stretched horizon,” just outside the real horizon. This connects with the membrane paradigm for black hole physics, but this blog post is already way too long as it is.)

Event horizons aren’t the only kind of horizons in general relativity; there are also horizons in cosmology. The difference is that we can stand outside the black hole, while we are inside the universe. So the cosmological horizon is a sphere that surrounds us; it’s the point past which things are so far away that light signals from them don’t have time to reach us.

So then we have horizon complementarity: you can talk about what’s inside your cosmological horizon, but not what’s outside. Rather, everything that you think might be going on outside can be encoded in the form of information on the horizon itself, just like for black holes! This becomes a fairly sharp and believable statement in empty space with a cosmological constant (de Sitter space), where there is even an exact analogue of Hawking radiation. But horizon complementarity says that it’s true more generally.

So, all those pocket universes that cosmologists talk about? Nonsense, say the complementarians. Or at least, you shouldn’t take them literally; all you should ever talk about at once is what happens inside (and on) your own horizon. That’s a finite amount of stuff, not an infinitely big multiverse. As you might imagine, this perspective has very deep consequences for cosmological predictions, and the debate about how to make it all fit together is raging within the community. (I’m helping to organize a big meeting about it this summer at Perimeter.)

Okay, now let’s put the two ideas together: horizon complementarity (“only think about what’s inside your observable universe”) and quantum vacuum decay (“at any point in space you are in a quantum superposition of different vacuum states”).

The result is: multiverse-in-a-box. Or at least, multiverse-in-an-horizon. On the one hand, complementarity says that we shouldn’t think about what’s outside our observable universe; every question that it is sensible to ask can be answered in terms of what’s happening inside a single horizon. On the other, quantum mechanics says that a complete description of what’s actually inside our observable universe includes an amplitude for being in various possible states. So we’ve replaced the cosmological multiverse, where different states are located in widely separated regions of spacetime, with a localized multiverse, where the different states are all right here, just in different branches of the wave function.

That’s a lot to swallow, but hopefully the basics are clear. So: is it true? And if so, what can we do with it?

Obviously we don’t yet know the answer to either question, but it’s exciting to think about. I’m kind of inclined to think that it has a good chance of actually being true. And if so, of course what I’d like to do is to ask what the consequences are for cosmological initial conditions and the arrow of time. I certainly don’t think this perspective provides an easy answer to those questions, but it might offer a relatively stable platform from which definite answers could be developed. It’s a very big universe, we should expect that understanding it will be a grand challenge.

  • math

    Well obviously each observer is at the center of their universe.

  • Alan

    Fascinating and thanks for the article. But does this make things more complicated or less!

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  • Dean Robinson

    The problem I have with these concepts is, where does the energy, or mass, come from to create a duplicate universe when “we” (the macroscopic observers) are split into two”.

  • Matthew Saunders

    Beautiful riff, Sean :) Are you still gobsmacked at all the stuff you write, which was once considered fringe and crazy, is now so different? :)

    The first time I ever considered the multiverse concept was from Michael Moorcock’s Elric series…he used the term a lot :) So, when I finally heard a scientist say it, I giggled. And I find it funny that, between the multiverse and telology, scientists would choose the multiverse :)

  • Cliff

    Nice post.

    One question thats tugged at me for quite some time, and I may as well ask it here:

    It surprises me that whenever the black hole information paradox is brought up, the explanation always seems to run afoul of the solution actually offered by Hawking himself (hep-th/0507171). He says that if you have a black hole and you throw a book into it, the information IS lost, but this does not violate unitarity because if you know for sure that a black hole exists then you are already in a highly mixed quantum state. He says that when the problem is properly formulated in semiclassical quantum gravity, the S-matrix elements have contributions from topologically trivial, information-preserving metrics, as well as topologically nontrivial metrics (i.e. black holes) that do destroy information. At asymptotically late times only, the trivial topologies actually contribute, and thus unitarity is preserved.

    I don’t consider myself enough of an expert to have a strong opinion on this, but I feel I know enough to regard this solution as highly appealing and plausible. Is there any particular reason why I almost never hear this insight discussed? It seems strange to invoke Hawkings name to answer a question that contradicts the answer that he himself offered.

  • Mike

    Thanks for this Sean. I take the QM MWI to be true for a variety of reasons that I know a little about. It’s interesting to read how this may be related to Susskind and Bousso’s approach which I know very little about.

  • Mason

    I noticed that you refered to the Copenhagen interpretation as “simplistic.” Are you suggesting that it is a bad interpretation? Or better yet, which interpretation is the best supported by experimental data?

    Questions aside, great blog post! I always enjoy your posts!

  • Roger


  • POTU

    I don’t follow how the quantum many-worlds are the same as inflationary cosmology’s pocket universes. It seems that they are separate ideas that can co-exist, which means that the universe is really big in more ways that one!

  • Liberalism’s A Sickness

    Whenever I read these astonishingly absurd cosmological theories from the “scientific” community, I am reminded of what GK Chesterton said, “When people stop believing in God, they don’t believe in nothing – they believe in anything.” This guy is so over the top, it’s just plain hilarious.

    Curiously enough, the very same people who categorically reject the relatively benign notion of a God, or even Itelligent Design for that matter, are the very same peoole who believe total crap, most of which which is infinitely less believable and equally less provable. And they have this equally silly notion that because they hold this or that science degree that their insane ideas are somehow less suspect than those of people who believe in God. Just think of all the scientifically unverifiable “beliefs” they have right out of the chute in order to come to the absurd conclusions they come to – and all under the guise of scientific inquiry!

  • Matthew Saunders

    #11: They deal with the fruits that are given them, trying to invent as little fruits as possible, but where needed :) The unknowable is unknowable and remains there to inspire and pull at all of us to want to grok with fullness, eventually :) And search for the perfect bean salad, of course.

  • QUestionmark

    Would splitting still occur as in standard MWI or would these worlds always be seperate in the wavefunction?

  • KWK

    I might be missing something here, but doesn’t the possibility of encoding information external to our universe onto our horizon mean that information from a possible multiverse would, in fact, be observable? I had thought that the existence of the multiverse was primarily motivated mathematically, and therefore (arguably) an appealing inference for what the laws of physics had actually brought about, but was in any case unobservable even in principle.
    But if observations can (again, in principle) be made regarding areas outside our horizon, how does this information get onto our horizon, since any external universes would (effectively) be infinitely far away? Would the wavefunction associated with such universes really extend to/impinge upon our own?

  • Matt

    Ah, the reason Peter disappeared in the season finale of ‘Fringe’ while the bridge remained is: Peter fading out was a rather poetic expression that there was information leakage from a localized multiverse horizon. This leakage was from a universe where Peter was to others where he was not .

    A concert of quantum events orchestrated by Peter in the machine thus created the bridge on Liberty Island in a manner analogous to Hawking radiation surrounding a black hole’s event horizon resulting in a signal in Morse code.

    So the universe(s) where Peter existed were specifically engineered (by the Observers) to make a machine that could effect other universes at a quantum level. And to create Peter so that he could use the machine to create the bridge.

  • Geoff N

    @Liberalism… your argument seems to be that since neither religion/god nor the multiverse has any evidence to support them, however religion is correct. Brilliant. Thanks for the insight.

  • David George

    I recall reading somewhere that there is a reason why Everett’s name is first on the “many worlds” interpretation. It isn’t very illuminating. The superimposed live-dead cat arises because there is no model of a spatially extended electron that explains the statistics, while the wave function as a statistical ensemble does explain the statistics. When there is a model of a spatially extended electron, the superimposed live-dead cat will disappear. Then the many worlds interpretation will disappear, then the multiverse will disappear, then inflation will disappear, the past creation moment (Big Bang) will disappear, etc.

  • Kevin

    #11: Hypotheses are different from theories. Also, see #16’s comment.

  • WWarren

    “many worlds” and “the multiverse”..might ‘compute differently’


    …is ‘absoloutely “nothing”‘ computable?

    A many worlds approach…(a many worlds computable system)…says ok…let one set of worlds be
    computable…the others “crash the system”…lets just remove the ones that cause a problem..that
    is the same way Grigory Perelman solved his problem…”cut out what you don’t like…reattach the
    rest”. Computer Science does that all the time…called “crash recovery data mining”…you can
    literally program a watch for “problem events”..and shut everything down before
    anything really nasty happens.

    A multiverse however…needs its ‘complete network working well’ (at least at first.)

    Sean in your paper <– ( see on page 30 ) you wrote

    "…the perturbations require an additional substantial fine tuning…." <–next to last

    This seems like more evidence for 'intelligent design'.

    Genesis 1:1 again anyone?


  • Matthew Saunders

    #19: Sure, John Wheeler’s ‘Participatory universe’ :) universe comes into being, observers come from universe, observers bring universe into being, observers come from universe…no beginning, no end, no first matter, all interconnected…all that groks is G_d :)

  • Phillip Helbig

    “Are Many Worlds and the Multiverse the Same Idea?”

    Well, there are some universes in which they are, and some in which the are not. :-)

  • Luke Barnes

    Great post! Is there any plan to publish proceedings or upload videos from the “Challenges for Early Universe Cosmology” conference/.

  • Baby Bones

    You know those optical illusions of facial “death” masks, where someone looking at the concave inner surface sees a convex outer surface, or those illusions where the direction of spoke rotations alternate? Our eyes can’t view both images at once so we are faced with a dichotomy that is resolved as an optical illusion with the help of an extra piece of information (we can look a little closer or touch the object to make sure). The difference between such an optical illusion and a QM experiment is that there is usually no alternation in a QM experiment to reveal the illusion immediately (although some recent ones show superpositions directly) and the variables of QM are complementary in an exclusive way. That is, in the classical physics world we have recourse to a complementary variable such as the sense of touch to determining the true state even while the illusion tricks the eye, but QM forbids the use of other variables that could be complementary to measurement via the uncertainty principle.

  • Pieter Kok

    Very nice post indeed.

    This may be due to Sean’s write-up, or with the original idea, but it seems to me that this idea works very well for the quantum superposition of vacuum states, but what about superpositions of other degrees of freedom that all sit happily in the same vacuum? So rather than the MWI and the multiverse being the same, isn’t it more accurate to say that the multiverse is a consequence of MWI and the existence of multiple vacua?

    PS. as a liberal I denounce corporal punishment in all cases but one: superposition jokes.

  • ophu

    @”Liberalism is a disease”: The “null hypothesis” is traditionally used when an answer is unwanted.

  • Pala

    That was an incredibly well written post. Thanks.

  • Pieter Kok

    Don’t feed the troll, people.

  • Jason Dick

    I somewhat wonder if this idea might have a corollary in dealing with gauge invariance: in a number of theories in physics, there are ways to change the equations that have no impact whatsoever on the underlying physics. With basic, Newtonian gravity, for instance, you can add a constant number to the gravitational potential and nothing at all changes. Many theories have much more complicated ways of changing the math that leave everything about the physical behavior unchanged. In General Relativity, for instance, you can make any change in coordinates, and there is no change to the underlying behavior.

    This becomes very important when performing sums over all possible configurations, such as one often does in statistical mechanics or when doing path integrals in quantum field theory: we have to be very careful not to sum up multiple configurations that are just the same thing related by a simple gauge transformation. If we do do this, we will get the wrong answer (often an infinite one), because we have counted up the same physical state many times.

    So maybe this idea has an application here: after we’ve summed over all of the many worlds within a single cosmological horizon, we have already summed over all physical configurations, so attempting to sum over the configurations of neighboring regions of space-time would just be multiply-counting the same configuration all over again. And just like in gauge theory, it’s just not something you can do and get a reasonable answer.

  • Jason Feather

    I doubt there are multiple universes, I suspect consciousness collapses the wave function and does so because we and the universe are actually a simulation running on a computer. This solves the distinction between mind & matter, neither exist, ultimately all is information.

  • Giotis

    “Eventually it strays so far that it climbs right over the barrier in the direction of the true vacuum.”

    I thought climbing was related to Hawking-Moss instanton and tunneling through the barrier Coleman-de Luccia.

  • Axel

    Good food for thought .. Good thoughtexperiments .. Physical meditations ..

    Thank you ..

  • Toppie

    What we see as the universe is in fact the multiverse. It’s the most probable outcome of probabilities. There are no other universes like ours, it wouldn’t make sense. The universe is the universe. There are no parallel worlds that are almost the same as ours, including ‘copies’ of ourselves. The universe is a game of infinities. The probability of differences vastly outnumbers the probability of similarity. Branching takes place at quantum mechanics level, contained within boundaries. In our daily world we don’t see any effects and everything seems logic and solid.

    What we see as the universe is in fact a natural model in our brains. Light, colors, sound, senses, 3D depth, time, consciousness, logic, anything is basically a projection of our brains, in our brains. The universe itself may be totally different in nature as how we perceive it in daily life. The universe may be an infinite number of fractals without volume, size or dimensions, except within itself. And we happen to be part of that ‘super fractal’, are within that fractal, made of fractals. The universe is probably the outcome of simple mathematical laws. In a “nothing, nowhere and never” (as some people seem to look for as the origin of everything) mathematical laws would ‘still’ be valid, a true “nothing, nowhere and never” simply cannot exist. Existence by itself is a contradiction. To me it makes sense that there is ‘mostly nothing’ instead of absolutely nothing. What the basic nature of this something is? Nothing we can relate to in daily life. Infinite space maybe, or just infinity.

    A Mandelbrot-like fractal is infinitely complex and has an infinite long boundary. Since the Mandelbrot lives within a small square on an infinite 2D plane the fractal cannot be ‘just’ 2D. It implies it has more than 2 dimensions.

    3D fractals like the Mandelbox are fascinating. A simple function based on Mandelbrot projects an infinitely complex 3D structure with mathematical patterns and things that strongly resemble city landscapes, nature landscapes, microscopic images, coral, living creatures, art, architecture. Yet this Mandelbox fractal has no volume. It’s impossible, but if you were able to see the fractal after infinite iterations there wouldn’t be anything left. Calculated coordinates would have escaped the 3D coordinate space. Thin air so to speak. What you see depends on your position and zoom level. Basically, you only see something when you are ‘part’ or strongly related to the fractal. Explore the Mandelbox yourself with Mandelbulb3D. Maybe it’s a quite accurate but extremely simplified simulation of our universe.

  • Phillip Helbig

    “Rather, everything that you think might be going on outside can be encoded in the form of information on the horizon itself, just like for black holes!”

    A big difference is that the interior of a black hole is finite, whereas the volume outside the cosmological horizon can be infinite, which could imply the encoding of an infinite amount of information. Discuss.

  • Igor Khavkine

    I find that appeal to a speculative idea (black hole complementarity) which may or may not be supported by an unsubstantiated hypothesis (string theory) is not a good way to build an argument in support of conflating two other speculative ideas (distinct, though related: bubble universes of eternal inflation and anthropic ensembles of cosmologies) with a third rather down-to-earth and reasonably well supported idea (MWI = no true collapse in QM).

  • Ryan


    That’s a great comment. I myself have toyed with the idea of the zero-worlds (as opposed to many worlds) hypothesis.

    In fact, if someone more qualified than I could comment on this:

    I’d be interested to see a debunking.

    My personal feeling is that the organization of the brain constitutes a Turing machine, and as such, must construct the universe in a certain (Turing computable) way. Literally all information present in consciousness must be ordered this way. Our experiments increasingly show the quantum nature of matter exists at higher and higher masses, but the behavior is simply less relevant and apparent.

    The insight, then, is that evolving a classical computer is much easier than a quantum one.

  • Jim Cross

    So apparently when I die, I don’t really die but just somebody observes me dead while someone else in a different space observes me still alive. And in the that different space when I die, I don’t really die…

    So apparently there is life after death or life along with death or something like that.

  • Liberalism’s A Sickness

    Um, Geoff, my argument wasn’t that “since neither religion/god nor the multiverse has any evidence to support them, however religion is correct.” The fact is I didn’t make an argument for either. Nice try.

    However, what I did mean to suggest, though, is that much of what now passes for science these days is (1) every bit as preposterous and bizarre as what is believed in most mainstream religions and (2) every bit as unverifiable, untestable, and empirically undocumented. Sometimes the numbers and data are even cooked and manipulated, as in the “science” of meteorology, our new state religion with Al Goreleone as its high priest.

    The real point, sir, is that this would not otherwise deserve comment except that it’s your gang who generally ridicule people of faith, people who actually believe things far less bizarre and preposterous than much of what I read in these blogs and forums.

    Incidentally, I happen not to belong to any organized religion, but I do believe in Intelligent Design. Where do you think all those beautiful equations and immutable, physical Laws you deal with came from? The tooth fairy?

  • Matt Lehman

    I’m not a physicist, so I’m sure I’m out of my depth, but I have some thoughts.

    In trying to reconcile this seeming duality between the ‘exterior’ inflationary multiverse and the ‘interior’ QM multiverse, shouldn’t we appeal to good old Occam’s Razor, which should suggest they’re identical? Developing the topology to make the two isomorphic would seem to be an interesting exploration. The non-orientable Möbius strip and Klein bottle, come to mind.

  • AnotherSean

    I think the holographic solution to unitarity is right. Still, the principle of complementarity has never meant anything more to me than the Heisenberg Uncertainity, so I’m skeptical by approaches that implicity elevate it to a status of fundamental law.

  • martin g

    re: #37- Intelligent Design theory contradicts the theological axiom that god is perfect and created a perfect universe. One interpretation would have it that god found it impossible to make a seamlessly perfect world and left behind messy fingerprints on the work- tattletales if you will.

    It also denies a basic and necessary characteristic of doing science at all- knowledge and understanding are cumulative over time (Newton stood on the shoulders of giants). One of the seminal proponents of ID theory reasoned that a complex bio-mechanical phenomenon could not have arisen naturally (at least he couldn’t figure it out) therefore it must be “artificial”. If that were true no one would ever be able to add to past knowledge and gain a better understanding of nature. Let us not call it a “sin” but rather the “error” of arrogance- “If I can’t do it, no one can!”.

    As consolation, “Liberals are Evil” might contemplate that Hawking falls into a similar error when he came to the conclusion that it isn’t possible to “know the mind of God” and therefore it must be “turtles all the way down”- the Many Turtles Model if you will (though it’s not very nice to take consolation in the limitations of others- just your own.)

  • Jesse M.

    Sean, do you have any definite ideas about how this relates to your ideas on the arrow of time (which depend on eternal inflation), or is that still up in the air?

  • jtravers

    There may in fact be many Universes. Apparently though if they exist they are completely undetectable. Therefore it is meaningless and useless to even bother pondering such a thing. We should instead continue studying and working with our Universe to gain a better concept of how it works. As an alternative to Quantum Theory there is a new theory that describes and explains the mysteries of physical reality. While not disrespecting the value
    of Quantum Mechanics as a tool to explain the role of quanta in our universe. This theory states that there is also a classical explanation for the paradoxes such as EPR and the Wave-Particle Duality. The Theory is called the Theory of Super Relativity and is located at: superrelativity. This theory is a philosophical attempt to reconnect the physical universe to

    realism and deterministic concepts. It explains the mysterious.

  • Liberalism’s A Sickness

    Very prescient comments, Martin G; you’re a very, very bright man. You are quite right that ID contradicts the theolgies of most mainstream religions, but one can reconcile the notion of an Intelligent Designer with good and evil, or with an imperfect world, as it were.

    A good start is by reflecting on the incontrovertible fact that nothing can exist (at least in this universe) without contemplating its mirror opposite. It’s only in this context that ANYTHING makes sense. For instance, good, or goodness, makes no sense at all as a behavorial model unless evil exists to give it meaning. Otherwise, it could not be said to be “good” in any meaningful sense. The same can be said for perfection as an abstract concept. It has no meaning unless we view the “flawed” in juxtaposition to perfection as an abstract notion..

    There is something much deeper at play here, and perhaps we will all have to visit the other side, if there is one, to grasp what it’s all about. But thanks for your very wise and polite response.

  • H.

    What most people fail to appreciate is that black hole complementarity is actually one step weirder than quantum mechanics. In usual quantum mechanics, macroscopic observers will agree with each other whenever they compare their observations. The current distance separating them doesn’t matter because they can always meet up in the future. When we introduce general relativity however, there are some metrics where this can never happen and both observers can never compare notes. This gives us room for letting their observations disagree. This goes beyond what Bohr ever dreamed of.

    In the Susskind and Bousso’s article, their complementarity is with respect to a supersymmetric terminal state with zero cosmological constant with no upper bound on its number of degrees of freedom.

    If complementarity happens with respect to the causal patch horizon in the inflationary phase, with the stretched horizon at the apparent horizon, the holographic bound to the entropy of the causal patch will be smaller than the possible entropy of its child bubbles. Only entanglement entropy can solve this conundrum, and coarse graining over it will give rise to the second law of thermodynamics in the bubble.

  • Sean

    Jesse, I don’t have any definite ideas, just some vague ones. There’s also some discussion in Nomura’s paper.

  • Lord

    Can a wormhole cross an event horizon?

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  • Nullius in Verba

    There’s a simpler way. According to QM, everything that can happen at a place, does happen, in superposition. If the laws of physics are the same throughout the universe, and the initial state was uniform (translational symmetry) then everything that can happen does happen everywhere, and the wavefunction is identical at every point.

    That this includes false vacua is just one special case. You and your entire history are another possible quantum event, that therefore occurs everywhere simultaneously. Although it is difficult to work out what it means to talk about a definite point in space in a relativistic, translationally symmetric universe…

    To answer #4 on where the mass comes from – the answer is that it doesn’t, because the universe doesn’t really split. It’s just an analogy to explain the concept in everyday language. If you think about a single electron as it passes through a pair of splits, does the electron passing through one slit see itself passing through the other? The different possible paths the electron can take are the different “worlds” of the MWI. A wavefunction spread out across space is a superposition of many instances of a single particle each at a single place, surrounded as far as it can tell by empty space. Components of the wavefunction for a single particle don’t ‘interact’ (for example, a charged particle wavefunction doesn’t repel itself electrostatically), in the same sort of way that ripples on a pond pass through one another without affecting one another. It’s all still one universe, but bits of it act independently, as if the rest of it didn’t exist.

    “Many Worlds” is really just a bad metaphor for a very routine bit of quantum mechanics that has already been accepted by anyone who accepts that the electron really does – in some sense – go through both slits at once.

  • David George

    # 48 Nullius in Verba — The electron does not – in any sense – go through both slits at once. The electron goes through a single slit. However, its path is influenced by the field disturbance it creates by its motion. The field disturbance takes the same interference form in passing through the slits as a light wave. So a series of electrons — which can be separated not only in time but also in space so long as the equipment is identical — will over many impacts build up an interference pattern, so long as the possibility of interference is not destroyed by a detector. But the pattern is due to the electron influencing its own path, not to the electron going through both slits at once.

  • Nullius in Verba


    That sounds like the DeBroglie-Bohm ‘pilot wave’ interpretation. It’s non-local in its handling of EPR-type situations, and MWI would say the particle part was superfluous given that the pilot wave does everything the MWI says the wavefunction does, but as an interpretation of QM has exactly the same observational predictions as all the others.

    I can’t tell you which interpretation of QM is “correct” – it’s arguably an unscientific question. (Depending on how you evaluate issues like parsimony, aesthetics, and explanatory power in science.) But what I was talking about above was what the claims of the Many Worlds interpretation were, not whether it was true.

  • David George

    #50 — Why should anyone accept that an electron goes through two slits at once, when there is a reasonable explanation for the electron to go through only one slit at a time while building up an interference pattern? It sounds like giving an unrealistic explanation the same status as a realistic explanation. There is no reason in nature why an electron, a material body, should be in two different places at the same time. The wave function is a statistical ensemble. I don’t think what I am describing is the “pilot wave” but I’m not sure how you would equate a collective motion with the statistical ensemble that gives the probability for each location that the electron is there.

  • Rob Wayman

    Ok, so Just to clarify things as I see them. These questions are still being explored today by Extra solar and interdimensional travelers who are expanding the research of the theories we are postulating today. But i guess it’s good we think about things and questions now so they can be answered in the future. Which technically is now and “they” are from what you might call the future. “They” go back and forth conducting timeline specific research on these and more advanced theories. It’s a never ending process of discovery, and it drives all societies to step forward and look for answers to their questions; what ever they may be.

  • Nullius in Verba


    Because trying to maintain only a single electron results in a mathematically more complicated theory, and requires disturbances in it to propagate faster than light (and hence backwards in time). It was while arguing about the pilot wave theory that Bell came up with his inequalities, to show that any interpretation that claimed a single definite classical state throughout had to be non-local (i.e. involve faster-than-light). You also have to introduce a new field, and an interaction law between the electron and this field, and new physics to describe what happens to the field when you observe the electron.

    Or to put it another way, the pilot wave theory is also an unrealistic explanation – it’s just unrealistic in a different way.

    The basic problem is that our intuitions about the way the world is have been built up around classical physics, so anything else looks weird and unrealistic. Even the physicists developing it struggled with the idea that the world we lived in wasn’t really classical. Bohr’s Copenhagen interpretation tried to fudge it by saying it was quantum up to the moment of observation when it “collapsed” into a classical outcome. DeBroglie and Bohm tried to say it was a classical world that got pushed around by this quantum thing when nobody was looking. Einstein tried to say that it was classical throughout, it was just there were interactions and hidden states we hadn’t yet discovered that gave the illusion that it was quantum. Others said the question was meaningless, QM didn’t tell you how the world really works, it only told you the outcome of experiments, so you should “just shut up and calculate”.

    Everett simply pointed out that if the world was quantum at every level, that what we would see as quantum objects ourselves would be precisely a classical looking world. From the outside, it looks like a wave, but from the inside it should look like billiard ball particles bouncing off one another.

    So he said, why invent two entirely separate physics, a quantum world and a classical world, and then tie yourself in non-local knots trying to glue the two together, when a purely quantum world already does the job?

    The quantum picture predicts everything we observe, except that it also predicts a bunch of other stuff should be going on where we can’t ever see it. Since we can’t see it, we’re inclined not to believe it exists. Trying to come up with a mechanism by which it can disappear as required has led to a huge amount of debate. But we’ll never know, because we can’t see it to check.

    If you’re saying that your theory is your own idea, rather than the DeBroglie-Bohm theory, then you’ll have to develop the details some more for anyone to offer an opinion. You’ll need to come up with an equation for the electron-field interaction, another for the propagation of the field, say how it electrons/fields interact with other charged particles, and show how it explains experiments like EPR, Bell’s inequalities, the delayed choice quantum eraser, and so on. But at the end of the day, it won’t prove that MWI is wrong, only that it’s not the only option. You have a choice.

  • David George

    #53 — I may not understand what you mean by “trying to maintain only a single electron” (or the sentence), but I take it you mean that the real path of an electron is not calculable without taking into account its other possible paths which are not real. I would describe that as a kind of half-entanglement. It implies acknowledgement of a previous history which cannot be traced (even under the most controlled experiment), but whose influence does not diminish: if the unlikely previous history did happen, then the electron will take that unlikely path. So the probability is really accounting for unknown previous history. When electrons can be tracked, they can be seen to become “fully” entangled (spin up-down) so that neither electron can be considered without the other. But I don’t think the MWI-multiverse idea is anything to do with that.

    However a wave is a wide area “disturbance in the field” (of whatever kind). It may be treatable as following a path but its effect is over a large area. An electron is a spatially extended but tiny and local material entity, and it doesn’t make sense to demand, because of the math, that an electron in physical reality can be in two places at once (or act like a wave). One of the places is not a real place (it is an unreal path). The interference pattern, which is a statistical pattern independent of time and space (provided the equipment is identical), is not due to the electron being in two places at once when no one is looking. I do not believe anyone who thinks this over for even a short time will say it is reasonable for an electron to be in two places at once. The fact that this is demanded by the math does not mean it is demanded by physical reality. It is an indication that the physical reality is not understood. The task then is to find out a physical mechanism that can reproduce the q.m. results. But this has not been done for 100 years – entanglement seems to have mesmerized people, they forget there is no realistic spatially extended electron model. Such a model still must recognize entanglement, but gives the possibility of ending the fruitless debate over different interpretations, because it will give the local realistic hidden variable machinery by which the q.m. results are found. I have indeed worked on this model and am convinced by it. However, there should be “real scientists” looking down this path. A realistic electron model will undoubtedly clear up the problem of interpretation. I am not saying the world can go back to being “classical”, but it can come to an understanding of q.m. results that doesn’t involve electrons being in two places at once, many worlds, multiverses, etc. Describing a triaxially rotating sphere (of rotating space) rotating at c at a radius from the proton (also a sphere) between the classical and Bohr radii (separated from each by inverse alpha), and showing how that sphere of rotating space will move when there is a disturbance in the field its vicinity, will lead to a new and more explanatory model for atomic and nuclear systems than the SM. And eventually the interpretational problems of quantum mechanics will disappear.

  • Sean Strange

    Is physics turning into some kind of a joke? I find it comical how physicists follow intellectual fashions and subscribe to occult belief systems like multiverse and string theory, while claiming to hold the intellectual high ground as the arbiters of ultimate truth. Please be aware of your absurd hubris! To the unindoctrinated, multiversal quantum theory sounds no more credible than ancient mystical ideas about astral planes and reality-as-illusion.

    More than a century ago, the great philosopher Nietzsche predicted that science would eventually turn its lens upon itself and self-destruct, and it seems that yet again he was prophetic!

  • http://(none) G. E. Hahne

    I published a paper some years ago (arXiv:gr-qc/0611098 and references therein)
    proposing another kind of parallel (or antiparallel, with reversed
    time evolution) worlds. The main idea was to use the
    direct sum of weakly interacting quantum fields to represent
    parallel worlds, as distinguished from the usual procedure
    of taking direct products of fields for the various particle
    families. One observable correlate that I proposed
    was that a huge cancellation of vacuum energies occurs
    between our world and a hypothetical weakly connected one with a reverse
    evolution in time. Another was that of the existence of gravitational waves converging
    on future events in space-time.

  • JonJ

    @55: No, it’s no kind of joke, and it’s not mysticism. And Nietzsche didn’t really understand science, certainly not 21st-century science.

    These “intellectual fashions” of physicists are basically proposals for possible ways of understanding the theories which developed to solve real problems with real empirical observations. If you go through a text like Roger Penrose’s The Road to Reality and manage to stomach all of the mathematics (good luck with that), and brush up on the history behind the development of quantum theory, relativity theory, and quantum theory, you will see that it all rests on real observations and real scientific problems which those observations threw up. It’s just that trying to talk about these subjects without using the math you will find in Penrose’s book, as Prof. Carroll is very courageously trying to do, makes it sound rather weird, perhaps.

    These remark also apply to “Liberalism”‘s attempt to equate physics and religion.

  • Paul Firebrand

    No predictions, no science.

  • Sean Strange

    OK JonJ, but what empirical observations is multiverse/string theory based on, and what testable predictions can it make? And how is your advice distinguishable from an occultist telling me that if I study various magical texts and follow certain esoteric practices for several years, I will be able to understand his mystical teachings? I think the physics priesthood is facing a huge crisis if the best they can come up with going forward is untestable, mystical-theological string/multiverse theories, and by extension the entire scientific paradigm may be in deep trouble!

  • Nullius in Verba


    For the empirical observations, you’ll need to follow JonJ’s advice and get some good books on the experimental history of quantum mechanics. Or better, do a course where you get to try it out for yourself in the lab.

    But to answer your question about how they are distinguishable to a layman who doesn’t want to learn the maths – the answer is that physics works, and occultism doesn’t. You can play Sonic the Hedgehog on the products of quantum physics, which you can go out and buy in the shops. If it didn’t work, it would soon be noticed.

    Other than that, your question makes as much sense as asking how you can tell if Japanese Haiku make sense when you don’t speak Japanese. I have met people who pretended to be speaking Japanese when they were actually making up nonsense syllables, but the basic test is to drop them in the middle of Japan and see if they can make their way. Even if you don’t know what they’re saying, you can see whether or not it works. Complaining that they all sound the same to you is not an effective test.

  • Sean Strange

    OK please demonstrate to me the multiverse in action, or cosmology, or string theory. I’m not questioning whether quantum effects are real, I’m questioning whether these multiverse and cosmological ideas are even science, as opposed to some kind of non-empirical mathematical theology.

  • Paul Firebrand

    The physical world is far too messy and uncooperative for our celebrity Platonists.

    They like to wax eloquent in the purely abstract.

    The better to avoid that crackpot naysayer: nature.

  • Shantanu

    Curious to know what you think about ‘T Hooft’s latest paper

  • Nullius in Verba

    “I’m not questioning whether quantum effects are real”

    Jolly good. The MWI is simply the assertion that quantum effects are really real, and apply to the entire universe, us included. So if you’re not questioning it, we’re done, right?

    (Oh, and string theory is an entirely separate matter, for which the fundamental basis is that point particles don’t work, because an inverse square law gives severe mathematical difficulties at zero radius. If points don’t work, there has to be an extended structure, and the simplest alternative to a point is a string. If you want to disprove it, all you have to do is explain how the inverse square law operates at the electron’s actual location.)

  • David George

    #64 Nullius in Verba (at the risk of disrupting the current conversation), if you decide that spatial extension is necessary, a string does not seem such a likely candidate since it has only two dimensions, is that not right? Is this due to the demands of the math? A more likely spatially extended particle would be a sphere, and it has recently been discovered that an electron is indeed an almost perfect sphere. In the model I follow, the sphere besides rotating also oscillates — breathes in and out. If your requirement of an explanation of the inverse square law is a generally recognized requirement, the charge would be spread out over the entire sphere, and then you would have a charge per square meter. As the sphere oscillates (its frequency change is equal to the frequency of 13.6 eV), I do not know how you would handle that mathematically. In this model the electron sphere surrounds the proton sphere, and when they are in that system there is no force between them. When they are separated (the electron is ejected from its orbital space) the electromagnetic force emerges. (And an atom is rotating spheres, all the way in!)

  • Nullius in Verba


    Disrupt away! The other conversation wasn’t going anywhere.

    While string theory did start with string, it has extended to include higher-dimensional entities – membranes and n-branes and so on, in what is now known as M-theory. So yes, they’ve considered more than just strings.

    The articles about the electron being a sphere are a bit of a simplification – what they’re actually saying is that the charge distribution so far as we can measure it is spherical (the electric dipole moment is close to zero – the extent to which the charge is spread out along an axis), although it is not expected to be exactly so, as there are influences of asymmetric physics that are expected to influence it. However, this is measured at a scale far, far larger than strings are thought to be, so it doesn’t really say much about string theory, at least, not directly.

    Supposing the electron to be a uniformly charged sphere, you might like to think about what force holds it together against the self-repulsion of the charge. Is the charge uniform throughout the volume, or concentrated on the surface? Is it flexible or rigid? Is the charge fixed in the solid body, or can it flow? What effect does the spin of the electron have – is it like a metal sphere spinning, or something else? When an electron and positron collide, what happens to the charge? And how can you reliably distinguish between all these options?

    The size of the electron is usually thought of as being much smaller than a proton, although in atoms its wavefunction is spread out over a larger space. Experiments in colliders find the inverse square relationship for the nucleus breaks down at a certain point – when the particles come into physical contact – but electrons have been pushed together much closer with no breakdown of the inverse square to suggest such a limit has been reached. You would need to think about why that would be.

    Try reading Penrose’s book, as JonJ recommended. It would give you the background in what has gone before, so you will know what sort of things to try, and all the many features your theory will need to explain.

  • Sean Strange

    “The MWI is simply the assertion that quantum effects are really real, and apply to the entire universe, us included.”

    To which I say: who cares? If there are no testable consequences of this model, what possible difference does it make? I find it amusing that people are actually willing to pay the salaries of these modern day theologians so they can travel around the world to conferences discussing the scientific equivalent of how many angels can fit on the head of a pin. Enjoy it while it lasts, because I suspect this secular priesthood’s days are numbered…

  • David George

    #66, I have read “The Road to Reality”, as thoroughly as possible given no physics and little math training. It was very useful but, naturally with quantum mechanics, unphysical when it came to the processes. But it explained a lot, more than any other book I have read (I have also read “Six Easy Pieces” and “QED” and they are also first rate).

    You have given some meaty suggestions and questions, which I appreciate very much.

    “Supposing the electron to be a uniformly charged sphere . . . what force holds it together against the self-repulsion of the charge.”

    I think the first thing to address is “charge”. I believe the actions and reactions due to what is called charge are a spatial phenomenon. The proton and electron when separated are connected by some motion of space, some rotational alignment (wide area in effect). That is the electromagnetic effect. It does not exist within an electron-proton system. However, the “charge” can be deconstructed into its physical units, and there is then a current totalling the elementary charge. The current is timed at one second. So one second of current totalling the elementary charge is part of the structure of the system. The “energy” gives a frequency in the Planck equation, etc. So the electron is a massless current — and for experiment it can be in amperes, etc. The current in this model is simply rotating space. In other words, in this model there is no hyphenated spacetime-energy complex. Spacetime is energetic; energy is spacetime, which in turn is motion. Without the energy then the field disappears just as in general relativity. So “rotating space” is spatially oriented motion, or spatially oriented energy.

    So there is no force holding a rotating charge against its self-repulsion. What there is, in this model, is a force creating and maintaining the rotating sphere. This force takes the form of a (constant) acceleration due to change of direction. It dissipates the energy of a (the) really fundamental universal physical field. This energy takes the form of pressure against both the interior and exterior surfaces of the sphere; the pressure is relieved by rotation, but the rotation must be on the equivalent of three axes in order to absorb pressure from every direction.

    This means then that there is a “vacuum pressure” which in this case creates (in a creation scenario) the massive bodies of the universe. If there is no e.m. force between the system electron and proton (i.e. when they are together as a hydrogen atom), similarly there is no force between the multiple spheres that exist in heavy atoms. But there is a constant and complex action-reaction sequence among the relative motions of each sphere that strikes me at the moment as hopelessly complex (even uncalculable). Anyway the idea is that nuclear radiation is a net effect of the juggling of the ever less stable assemblies of rotating and oscillating spheres (as the atoms get bigger). An “electron” emerges from the nucleus because that is the form that emerges after all the juggling is done. (Maybe the juggling would be transfer of momentum.) And the bottom line is that the really fundamental universal physical field has a limit of available energy, and it is possible to create systems that exceed this limit for short periods of time (like a neutron) by juggling the motions of the intermediate fields (between spheres). So there is a kind of “vacuum expectation value” here but I’m not sure it is a q.m. kind.

    This scenario is then for a constantly “powered” universe.

    “What effect does the spin of the electron have – is it like a metal sphere spinning, or something else? When an electron and positron collide, what happens to the charge? And how can you reliably distinguish between all these options?”

    In this model the spin determines the path of the electron through a magnetic field, just as “normal”. The main feature of this model is that the electron rotates on two of three possible axes. One of the axes is the “electric” axis; the other is one of two possible “magnetic” axes. Which is electric and which is magnetic, no one can ever know, because it is a spatial orientation process — there is a spatial motion “key” which is equivalent of the recognition of “charge”. But note that the electron can take one of two possible magnetic axes — there are three possible axial relations. I believe this will give the superposition style q.m. statistical result. The spin here is real, actual, physical rotation. The electron is not a tiny dot but a rotating sphere with a radius between the classical and Bohr radius. So it is a large region of space. The proton is eighteen hundred times smaller. The inertial mass of the bodies is due to the spatial origin of their rotation. Space is moving toward the body from every direction (the external field is infinite in space but the internal field is finite). That net motion of space toward it holds the body in place.

    When an electron and positron collide, their “charge” (which is really a temporary phenomenon) is extinguished. I do not know what form the resulting energy will take. And in general I don’t know whether this model can be tested, but it does give the electron magnetic moment to seven calculator decimal places, with no spin-g factor. That to me is almost like “proof”, but other people may not agree.

    How the inverse square law would apply to a sphere like the one here, I don’t know. But the current is simply a spatial current – a motion of space – and as well as forming a rotating spherical structure it also oscillates in and out, and this is due to the temporary depletion and renewal of the field in the vicinity. It seems to me this means it cannot be a perfect sphere. Now try to imagine this rotating and oscillating sphere responding to pressure variations arriving in waves at its surface. This would be “electromagnetic radiation” and would have two pressure components or vectors, at 90 degrees. The response of the electron to the “applied energy” depends on the direction and internal structure of the wave, and also on the specific rotational pattern of the electron. So it is pretty well uncalculable. But somehow some specific form of spatial disturbance will be retransmitted by the electron, and it will bear the mark both of the electron’s rotation and of the previous wave’s “polarity”. Can this be visualized or animated? I don’t know, but it seems to me somebody should take it on. (It won’t be me, I tried it and went mad.)

  • THE

    Instinctively I like it Saun.
    I too am troubled by the increasingly “metaphysical”, almost theological trends in Mathematical Physics.

    Anything that grounds physics more-firmly in observable reality gets my interest at least, if not my support.
    Empiricists need to take back physics from the Platonists.
    The mystics need to driven back to the Math Dept where they belong.
    Physics belongs among the empirical sciences.

    The deeper question is: whether there are actual laws of Nature that impose this rigorous empiricism on us? Actual discoverable laws? One feels there could well be.
    How could you have an philosophically-complete physics that didn’t have its rigorous empiricism built in to its axioms?
    A nature that isn’t profoundly closed is a nest of spooks.

    What is known must be a subset of what is knowable. Must be. Couldn’t be anything else.

  • NF Bates

    MWI is not at heart consistent with the Born probability rule. Simply, MWI has as many “branches” as choices, but the BR requires squared amplitudes for e.g. superpositions with unequal amplitudes. After say 100 trials, counting up branches gives 50/50 type frequentist statistics, which is wrong if you need other ratios.

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  • Rich Murray

    Joel Goldsmith: “God is the substance of all being.”

    Individual being-awareness is God-Being-Awareness.

    Each of us already being all of single entire unified creative fractal
    hyperinfinity, always shimmering along all possible corridors of
    meaning, the putative present, the constantly evolving pasts, the
    entire manifold of ever increasingly fabulous futures, with “sideways”
    causality among all streams of probable history world lines,
    “vertical” causality among an ascending (Georg Cantor) infinite
    hierarchy of levels of infinity realms — every most infinitesimal
    point in intimate rapport with every other — jus’ ussens, folks…..
    prodigious smidgons of nonduality…..

    CSICON — Murray’s Law — Eternal Exponential Expansion of Science:
    Rich Murray 1997.04.05, 2001.06.22, 2011.01.03
    Tuesday, January 3, 2011
    [ at the end of each long post, click on Older Posts ]
    [ you may have to Copy and Paste URLs into your browser ]

    Rich Murray CSICON April 5 1997
    Communion for the Subjective Investigation of Claims of the Normal

  • Rick


    I’d rather assume the Born Rule than assume a Collapse of the Wave Function. At least there are some decent arguments that the MWI is no worse off than classical mechanics when it comes to probability. There are no decent arguments that the Wave Function actually collapses — and as a result it is an assumption too far in my view.

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  • Andrei Ștefănucă

    Very nice article . It leaves some loose ends but on the other hand both physics itself and our perception of the universe will always leave some holes to fill considering that:

    a) the universe is not intrinsically finite, it is only observed empirically to be finite – the idea of finite is first of all a man made concept, therefore the universe cannot ever be said to have an intrinsic ‘boundary’ other than the obvious observation-based one;
    b) we constantly, continuously and collectively modify the universe by our actions and our words (both of which are based and dependent on perception and imagination). However, any action can be infinitesimally divisible on the axis of (time-dependent and time-independent) perception therefore the entirety of the universe will be unknown by at least a finite and infinitesimally small amount;
    c) our perception, reasoning, feeling and acknowledgment of the universe and ourselves is constantly expanding both in x,y,z,t coordinates, in microscopic and macroscopic depth and in all the rest of inner dimensions with each successive generation as is our extended perception (technologically aided one). However, even if we could in a very very distant future let’s say, empirically observe infinity, we cannot empirically observed the middle of a star or even approach it past a certain distance, unless we’re either in a ‘moving black hole’, in an impermeable protective bubble or the observation itself is purely imaginary (or unconscious);
    d) our ability to measure is intrinsically linked to our ability to observe (which is itself exponentially related to our ability to observe with an aid). The exponential curve of perception would be even steeper if our technological aids could build their own aids, but we still have to wait a little before that happens – although programming software programmers (meta-programming) or programming genes that program genes (meta-genetics) are a couple of inches away. however, because of this intrinsic link and because of point a), the possibility of a microscopic bottom or a macroscopic upper boundary of the universe is null, a boundary of this sort can only exist conceptually.

    This being said, it seems almost obvious that the universe itself is not finite and that our perception of it fades to black (or to nothing, to be more precise). Now what exactly is this nothing? Let me ask you one thing. Imagine the Big Bang. If it ever happened, then that means that all the astral bodies in the universe should be radially diverging from a point of origin. Any physical emergence has a point of ignition, a center, a source if you will, even in swarm behavior based emergence (consider how a predator spreads a bank of fish, the fish radially diverge from the predator). Considering that any measurement that is not continuous, real-time and constant (a flux) is an incomplete measurement, and considering that everything is constantly moving, has anybody tried to measure if the astral bodies in the universe that we have managed to observe so far are indeed radially divergent from this hypothetical point Origin (i.e. the source of the Big Bang)? To make such a measurement, one would need to continuously measure the motion of the centers of gravity of 3 (any 3) galaxies over a certain period of time. Let’s say that we measure Galaxies A, B and C.

    Consider the 3 measured distances A to B, B to C and A to C. They form a triangle, obviously. By observing how A to B varies in relationship to B to C, how B to C varies in relationship to A to C and how A to C varies in relationship to A to B while keeping in mind that they are points on the same expanding three-dimensional wave of force radiating from the hypothetical Big Bang, one can find out if a hypothetical CENTER of the universe (i.e. the source of the Big Bang) exists. In simpler words, 3 Galaxies, when measured and observed from their centers of mass, form a triangle. Any triangle, in a three-dimensional wave of force expanding from the Big Bang (an expanding sphere) scales over time, except if all three points are in the center of the radiating wave of force in which case the triangle itself doesn’t exist. Any scaled triangle, in three-dimensional space, maintains its angles at the same values. Therefore if the Big Bang happened, any 3 Galaxies that we continuously, coherently and constantly (over time) measure according to the rules above, will maintain the angles of their composite triangle. If they don’t, the Big Bang never happened. If the Big Bang did not happen, then Universal entropy does not exist and the Universe can be thought of as an application of Bernoulli’s rule of thermal agitation on a homogeneously stochastic space filled with hydrogen atoms and that presents local emergence (i.e. other chemical elements). If this measurement yields non-consistent results (i.e. the angles do not remain constant) one could either hypothesize dark matter or, better yet, ask how did the hydrogen atom appeared and what exactly it is to begin with. Furthermore, consider that we can simulate our own galaxy (even the past position of our planet in our galaxy, relative to its center of mass), and that we can calculate the distances between the 3 galaxies to be measured and make the necessary calculations and corrections so that the measurements are time consistent for all of the galaxies involved in relationship to one another (i.e. they are at the same position in objective time, for all 3 measured galaxies).

    Now please consider everything written so far. It is safe to assume that hydrogen is the oldest element in the universe other than nothing, due to its huge, observed proportions in physical reality. Consider that carbon dating cannot measure the age of hydrogen, consider that the big bang can be epistemologically and ontologically questioned and verified through the measurement described above, consider the supposed existence of dark matter.and consider the following: whatever “oldest astral body” we will find, there will always be the possibility of an even older astral body outside of our current area of perception, because of the fact that the origin point of the big bang cannot be defined (due to the posited existence of dark matter). Therefore even if we could measure the age of hydrogen in the observable universe, the constant “even older” astral body would have at least one even older hydrogen atom in its vicinity. Does the age of the universe depend on human perception and human measurement as and extension of human observation and perception? Is what is believed to be the Big Bang the birth of our empirical perception of the universe?

    Moreover, all current ways to measure the age of hydrogen are flawed because they are based on the supposition of the Big Bang:…7…39K. They are all distribution based, and take into account the Big Bang as a given when the Big Bang itself was never proven empirically through the measurement described above.

    Considering everything written so far, and considering that everything can be described geometrically, including the wave function, including physical reality, including every possible force, is it possible that reality is the “virtual” emergence of a hydrogen based, self sustainable, autopoietic universal processor?

  • Daniel

    In your article you said that one can draw a slice in spacetime that contains both the infalling book and the outgoing radiation. But can this slice of spacetime be really seen as slice of simultaneity? What if it in fact cannot?

  • Daniel

    I think there is still a difference: the many-uninverses together with the horizon complementarity implies that everything outside the horizon can be described by the Hilbert space of our universe, more specifically, its state now becomes a superposition of our universal states.
    Whereas in multiverse, the total Hilbert space is the tensor product of the individual universal Hilbert spaces. The dimension difference is HUGE.

  • Stefanbanev

    The picture is getting elegant and natural once we recognize that it is not universe splits apart (it’s always in superposition state) but observer is constantly branching. Our memory perceives a single path from root to current node. In fact the time from this point of view is not one dimensional – it seems one-dimensional only thanks to our perception.

  • uberK

    Are we not a “causal patch” that promotes decoherence for another, or perhaps every other, “causal patch”?

    It still seems to be a bit of a subjective perspective.

  • http://none Vincent

    Brian Green’s book title ‘The Hidden Reality’ gets at the ontological or metaphorical aspect of many worlds (or call them many multiverses – that might yoke the two concepts together). But Green does not go far enough: the ‘reality’ of many worlds is not hidden in the way dark energy or the Higgs boson may be; it is a way of doing thought experiments about simultaneity and the nature of existence, old philosophical chestnuts that many physicists balk at. It doesn’t matter whether the many worlds are near or far, they exist as determinable realities that can exist simultaneously, not least for measurement purposes. The cosmological approach needs to go a little softer on the hard science and look at the issue as a conceptual one that has very little to do with boundaries or horizons, or even (meta)physical spaces. The problem started as a thought experiment that went wrong for Bohr and Heisenberg – Everett simply proposed a way of rethinking reality that is almost pre-Socratic in its elegance.

  • Mike

    In one sense the MW of QM and the Multiverse of Susskind et al can’t be the “same”, since in the former the worlds affect each other through interference, while in the later, if I understand correctly, the various universes are separated and non-interacting.

    What I found intriguing about both the Susskind and Nomura papers was the bit about deriving probability from the physical theories themselves, and that the MWI is not the problem, rather it is the solution. I just found it ironic that while critics point to the probability measure in MWI as being a “problem”, these papers point to the MWI as the “solution” to assigning probabilities over their multiverse schemes.

  • doloop

    David George, do you have a website or blog? Can you post a link here? I would like to follow your comments on issues like these. You clearly have an intelligent approach.

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  • David George

    #82 doloop –I have no website (due to illiteracy, inertia, and funds). This is the only place I usually will comment. However I am willing to contribute the equations and explanations I have discovered during the last few years if there is somewhere to send them. Things keep changing but since I started reading “Big Bang science” (would that be creation “science”, or non-creation “science”?) in the 1990’s I have doubted the orthodox version. About the first “thought experiment” I did (before I even heard of a thought experiment) was to play God. If I were God, and I had one command, given what we know about the universe, what could it be? The answer is, “Expand!”. The result of this command is the universe we experience with our senses. The immediate consequence of this simple initial condition is a finite rate of expansion. We must assume God has an infinite bank of “energy” (unlike the Big Bang, where the window closes and it is all downhill from there). Now, from this infinite bank of energy God (or Zeus) pulls whatever amount Mother Nature (or Mrs. Zeus) wants. However, time intervenes. There may be an infinite amount of energy available, but there is not an infinite speed of time (i.e. infinite speed of light). The energy can be doled out only at a specified rate. The rate can be designated as c. This imposes a limit on the profligate Mrs. Zeus, who (naturally) wants more of everything, all at once, now! The expansion rate c defines both a rate of expansion of the universal ball of space, and the movement of disturbances through it. And the expansion rate has other consequences.

    The amount of energy/space created per constant time unit of expansion continually grows by the cube of the radius (times 4/3 pi). This is like an acceleration upon an acceleration. This to me gives a truer picture of God as an infinite creative power than the other infinitudes I have seen (“Finite but unbounded? Infinite but bounded?” etc.).

    Here the first consequence of expansion emerges. The only region of space where the field (the real, universal, whole, physical, energetic spatial field) expands (according to its initial condition or command) at its full potential (c) is at its outer surface. Everywhere within the field, space cannot expand at its full potential (because the space it would expand into is already occupied by itself). The easiest way to visualize this is to imagine a sphere expanding from a point (a tiny but finite point). After one second the outer shell of the sphere will have expanded at the distance covered by light in one second. In a region halfway from the shell of the sphere to the center point, (i.e. half the radius), the expansion is only half the distance covered by light in one second. So in this region there is an unused potential for motion equal to the amount of motion that is used. So expansion creates some “pressure of space” virtually everywhere throughout the universe. And on average, everywhere, no matter that the universe is expanding at its full potential at its limit, there is a constant pressure of unused space equal to the amount of space that exists. (That is, there is always twice as much energy in the universe as we think there is, which explains the failure of classical equations for magnetic moment.)

    The universe responds to the pressure by rotating. I believe the matter particles form as bubbles in larger rotational motions (galactic dark matter size and maybe larger). Inside each bubble is a region of space trying to get out; outside each bubble is the universe trying to get in. And so on. I believe the initial bubbles are neutrons. The field can hold a neutron bubble together for about 15 minutes before it separates into two bubbles (with an intermediate field — I said there is no force between electron and proton, but it can be modelled as exchange of a magnetic flux quantum.)

    This “creation scenario” gives the natural result that an electron (and protonA) can be modelled as a rotating sphere, because its charge is spread out over one second, etc. You then can get frequency, circumference, and from Planck and Einstein you get h and q. And with f (frequency of rotation, not of oscillation), h and q you will find v (Volts, or the equivalent of eV). You then have two massless current spheres. There are I believe significant coincidences: V(e) x V(p) = approx. 2 q / h (Josephson constant); and f(e) / v(p)^2 = 140.35 (approx. inverse of fine structure constant). By designating the exact values, you come up with a system proton-electron ratio that is 1860.308707, not the approx. 1836 of the conventional model. That is, in their system state the proton and electron have different masses than in their free state. And there is much more to be found out from there.

    This “model” can be attached to the conventional models by conversion factors — which themselves involve the spin-g factor! There is something here that has not been discovered by anyone except me — it is a mystery to me because I am not a scientist and don’t know the terminology (apart from the general ideas). I think it only came about because I am not a scientist and didn’t know what I was doing. But each step along the way it seemed to come clearer — the end (for the scientists) being a world of research into triaxial motions of space!

    As I said, I have more equations, but I think anyone can get them given the information here. And then a different world opens up. I have done only the electron and proton, also the Ballmer series, etc. for spectral emission/absorption lines. Someone other than me will end up doing something like this sometime because the current models are so far out it isn’t funny. So eventually someone would have to do it. I have written (to myself, as it turns out) many words on this subject (it comes down to EPR), I am tired of rewriting. In general I think the answer is to go back to the 1920’s where Einstein tried to figure out a hidden variable equation and couldn’t, Bohr’s model didn’t work, the probability amplitude for locating a material point worked, and a spatially extended model wasn’t needed. But from there you can trace how point particles in fields have bedevilled physics. Einstein said not to put particles in your fields, and he was right. Quantum mechanics is not a complete description of the physical reality of electrons, protons, light, etc. It is far past the time to consider a realistic model.

  • Rick

    82 doloop,

    Well, you asked for it 😉

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  • Phil

    I don’t understand how the many worlds interpretation can possibly be true. Actually, I think it’s nonsense. When I open the box and find a dead cat, why am I living in the universe harboring a dead cat and not one that’s alive? What governs which universe I am aware of? You see my point? MWI is pure nonsense. The universe doesn’t magically split whenever an “observation” is made.

  • Alvin

    I’ve read (, and have a few comments. First, there are only 2 possible alternatives that I can see that agree with all aspects of reality. First, that time and space are lineal, but causality works both from past to future and future to past, and where decoherence is entirely reversible (that is, nothing ever really happens, kind of like existence from the point of view of a photon, where creation and annihlation occurs at the same time) over time. This would solve quantum entanglement action at a distance. The second would be a multiverse as described with the following caveats: 1) there must be a probabillity axis with a dimensional magnitud between 1 and 0, describing parallel universes with all possible probabillity states. 2) the intersection point between the probabillity axis and time-space, can only have two “real” states: interaction and non-interaction. 3) all intersection points in time-space for the same particle, are the same intersection point in the probability axis.

  • http://google edward s. andrews

    does time stay time in other universes and if a paraell universe colaspes what happens to the time in the universe beside it and if one runs backwards and the other forwords what happens

  • http://google edward s. andrews

    can anyone anwser my question

  • pollywog

    here’s my answer ed…

    Everything is now and You are here!!!

    That only leaves one other option if it were not true. You are not here and everything is not now, meaning you are dead !

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  • geogeo

    Per MWI: the universe in state A (call it #A) can ‘split’ into #B and #C; could #C (say) ‘join’ with #D to make #F? If not we have (at last!) a truly unidirectional temporal process; if not, then information is lost, and quantum determinism (so dear to the heart of Leonard Susskind) fails. And yes, the two- multiverse and MWI- could be the same idea, because we couldn’t possibly know enough at this point to say otherwise.


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Cosmic Variance

Random samplings from a universe of ideas.

About Sean Carroll

Sean Carroll is a Senior Research Associate in the Department of Physics at the California Institute of Technology. His research interests include theoretical aspects of cosmology, field theory, and gravitation. His most recent book is The Particle at the End of the Universe, about the Large Hadron Collider and the search for the Higgs boson. Here are some of his favorite blog posts, home page, and email: carroll [at] .


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