Is there any rational reason to care about rationality?

[The Atheist]

I think you need to do more research on this, because just about every modern area of science is pointing towards multiple universes, as there is too much that doesn't make sense without them. The recent theory of Inflation, eg, which explained how the visible universe was rendered flat (something necessary for life), predicts multiple universes and was recently corroborated by examinations of the CMBR.

I try to stay fairly up to date with theoretical physics from an amateur perspective, but I have yet to see anything compelling - even Hawking's analysis seems too silly for serious contemplation.

The worst thing about it is we're putting the cart before the horse. Given our lack of understanding of quantum physics and dark energy/matter, why posit a question that may not even be required? Not to mention that if we have interacting, external universes, the mere fact they interact would make them part of this universe anyway.

In the case of multiverses, it is an extraordinary claim, and therefore requires extraordinary evidence. So far, nothing like that exists.

I was actually thinking about how our models for gravity break down inside black holes and at the singularity. We can still model them via quantum physics, but we lose General Relativity as the numbers come out to infinities, so something is clearly wrong. The attempt at reconcile QP and GR has taken up a huge chunk of theoretical physics for around the last century, and, so far, the only thing that has been successful at reconciliation is the many-worlds interpretation of QP, that solves a couple other mysteries as well and is actually much simpler. String Theory (and practically every other quantized gravity theory out there) has yet to be really tested, much less proven/disproven. Right now all we have are theories with a logical consistency but without an ability to test them against each other. We may be able to when quantum computing becomes available, but we're looking at several decades if current trends hold.

Well, the universe still has several billion years of existence left at the very least, so a few decades either way aren't going to matter much.

In the meantime, the questions are purely theoretical and I'm happy to wait until the extraordinary evidence appears. Those things that, as you note, don't fit into our present physics could equally have a mundane explanation that we just aren't aware of yet.

[cafolini]

As predicted by me on several ocassions, Catholic fake Stephen Hawking (commissioned by the Roman Catholics to fabricate a new genesis with the Bang) now boycotts Israeli talks, etc.

[MorpheusSandman]

Given our lack of understanding of quantum physics and dark energy/matter, why posit a question that may not even be required?

One thing I think many misunderstand about the proposed "multiverse" is that it has, most commonly, come about as a predictive consequence of theories being used to answer other, unrelated questions. I already mentioned inflation, but many-worlds exists primarily to explain the so-called wavefunction collapse, as well as the other mysteries of QP that doesn't allow it to be reconciled with GR. For years, physicists thought that there must be some "split" between the quantum and macro levels, but increasingly large objects have been put in a state of quantum superposition without any split being found, so it's starting to look like there isn't any such split, and, if there's not, many-worlds would be a consequence of everything just being quanta all the way down (or up, however you want to look at it). Elsewhere, on might look at the similarity between the singularity and black holes, which lead some to think that a universe may be the product of black holes. If you can, check out the writings of Max Tegmark and David Deutsch, the former on multiverse theories, in general, and the latter on many-worlds and especially the ability of quantum computing to test it.

I'm not going to outright claim that there is a multiverse, but I will claim that it's looking more and more likely in almost every arena of cosmology and QP. I'm not sure why, though, a multiverse would be an "extraordinary claim;" why is it any less extraordinary to assume we're the only universe? Lawrence Krauss, who is not a big fan of various multiverse theories, has stated that given what we know about quantum fluctuations, it was inevitable that a universe would form; so, if one, then why not many? He's also begrudgingly said he's been pushed into multiverse theories because of the growing evidence, though he, like you, is still rather skeptical.

[The Atheist]

... which lead some to think that a universe may be the product of black holes.

There'd be a kind of ironic justice in that - the universe is a Disney film.

(Good, coherent posting, by the way.)

[MorpheusSandman]

@ "universe is a Disney film"

Thanks.

[YesNo]

I'm not going to outright claim that there is a multiverse, but I will claim that it's looking more and more likely in almost every arena of cosmology and QP. I'm not sure why, though, a multiverse would be an "extraordinary claim;" why is it any less extraordinary to assume we're the only universe? Lawrence Krauss, who is not a big fan of various multiverse theories, has stated that given what we know about quantum fluctuations, it was inevitable that a universe would form; so, if one, then why not many? He's also begrudgingly said he's been pushed into multiverse theories because of the growing evidence, though he, like you, is still rather skeptical.

I think you are mixing up two very different multiverse ideas. The multiverse that Krauss is probably referring to, I would accept. The one that the Many Worlds Interpretation (MWI) of quantum physics promotes, I would not.

To tie this back to the OP, reason can be used to show the likely existence of reality that we do not have any way to experience directly. As one example, that reality could be a quantum object such as the Higgs boson, which was recently found. If it turned out that the Higgs boson could not be found where it was expected, the theory supporting quantum mechanics would have to be modified.

The multiverse that I would accept, and that I think Krauss refers to, is based on the mediocrity principle and the evidence for the Big Bang. The basic argument is if the Big Bang happened once, it happened many times since there is nothing special about our Big Bang. It is unlikely that ours was the only one. This would imply the existence of a multiverse of universes, totally disconnected that we have no other evidence for, that are like ours. Of course, ours might be the only one, but I personally accept that it is reasonable to assume it is not.

The MWI claims that the underlying quantum reality of our universe decoheres into alternate universes for every possible alternative. The reason this has been promoted is because the Schrodinger wave function implies Heisenberg's uncertainty principle which means that the universe at the quantum level is not deterministic. To save determinism, MWI claims that there are many worlds so every possibility is achieved. One of the things I've learned since the last time this topic was discussed on these forums, is that the mathematics underlying the wave function does not require the existence of many worlds. One world would do just fine. The reference for this would be Roland Omnes, Quantum Philosophy. That means that the wave function does force one to accept the uncertainty principle, but it does not force one to accept many worlds.

Reason can justify the existence of almost anything from Santa going down a chimney to alternate universes decohering from a common quantum reality to the existence of many universes that also started with a Big Bang to even the existence of weapons of mass destruction in a country we want to invade. Each of us has to make a choice whether we want to accept these consequences or not.

[MorpheusSandman]

I'm not mixing up multiverse ideas; I clearly stated there are multiple, often quite different, multiverse theories, and I was merely mentioning a few different ones. MWI can be considered a type of MV theory, though it is a very distinct one. Obviously, someone can agree with MWI without agreeing with other MV theories and vice-versa. There's nothing mutually inclusive or exclusive about these various theories. FWIW, Krauss seems to have come around to the multiverse after the observations of the CMBR that supported an Inflationary universe, and inflation predicts a multiverse.

I remember the last QP/MW thread in which you participated, and you demonstrated an obvious bias against MW from the very beginning, lacking even a rudimentary understanding of what was being discussed. Perhaps you've learned more since then, but you're still doing nothing to actually contradict MW. You claim that MW was proposed to "save determinism," but this simply isn't true; the fact that it saves determinism is only a side-effect of it solving non-locality, non-reality, and reconciling QP with GR. Of course QP doesn't require MW and can be worked into a single world interpretation, but then you're left with the same problems: non-locality, indeterminism, non-realism, and its incompatibility with GR. If you treat the wavefunction as an observer-independent object and assume it always follows the wave equations at all times, you end up with MWI. Obviously you can continue to assume that particles effect others at great distances, that the position or velocity can't be predicted, and that collapses only happen if there's an observer, but why in the world that makes more sense than assuming that the wavefunction is real and is simply acting in accordance with its inherent equations is beyond me.

[Ecurb]

“The whole is more than the sum of its parts” may be reasonable mathematically in light of Godel’s “Incompleteness theorem” that we have just now been discussing. This from the article in the New Yorker I linked:

In fact, as Gödel showed, a numerical formula could even be made to say something about itself. (Goldstein compares this to a play in which the characters are also actors in a play within the play; if the playwright is sufficiently clever, the lines the actors speak in the play within the play can be interpreted as having a “real life” meaning in the play proper.) Having painstakingly built this apparatus of mathematical self-reference, Gödel came up with an astonishing twist: he produced a formula that, while ostensibly saying something about numbers, also says, “I am not provable.” At first, this looks like a paradox, recalling as it does the proverbial Cretan who announces, “All Cretans are liars.” But Gödel’s self-referential formula comments on its provability, not on its truthfulness. Could it be lying? No, because if it were, that would mean it could be proved, which would make it true. So, in asserting that it cannot be proved, it has to be telling the truth. But the truth of this proposition can be seen only from outside the logical system. Inside the system, it is neither provable nor disprovable. The system, then, is incomplete. The conclusion—that no logical system can capture all the truths of mathematics—is known as the first incompleteness theorem. Gödel also proved that no logical system for mathematics could, by its own devices, be shown to be free from inconsistency, a result known as the second incompleteness theorem.

In other words, the “whole” (all of the parts) can only be seen as consistent or complete when viewed from outside the system.

However, in a more general way looking at the whole as more than the sum of its parts is more practical than philosophical. Reductionist explanations for complicated phenomena tends to be simplistic and naïve (in practice). That’s why the sciences of chemistry, biology and psychology exist. Although it is perhaps true that these sciences, given perfect knowledge, could be “reduced to” or “explained by” principles of physics, we aren’t there yet. If we study (for example) human culture, we can understand it in a more sophisticated way by creating “laws” of economics or of linguistics, rather than trying to “reduce” these cultural institutions to the laws of physics, or chemistry, or biology, or even psychology. It’s simply a practical matter – by looking at the whole as an abstraction (instead of as a sum of the parts), our understanding of it often improves

[cafolini]

When the modernist hears that the whole is more than the sum of the parts, he nods "yes" like a baboom because he/she feels that achieving a whole is some kind of marvel. When you say the same thing to a postmodernist, he thinks that a lot has been missed in determining the whole of the parts. He/she doesn't think that there is in fact a whole anywhere. She/he knows the whole is unachievable outside the imagination. She/he's coming from awareness of what can be done, not from idiotic wholism.

[YesNo]

I was reminded about the whole being more than the sum of its parts when in a meeting today a company partnership was described as a situation where 1 + 1 = 3.