Boltzmann Brain (and similar) Paradoxes

[RArvay]

Not being a physicist, I confine my comments to those of a layman.

A paradox may be defined as a statement that must necessarily be true, and cannot be true. The Boltzmann Brain paradox is one of a number of conclusions to be drawn from quantum cosmology that both defy reason, and yet given the accepted rules of physics, seem not only plausible, but necessary. Is there a way to resolve the paradoxes?

The basis of these paradoxes (including “last Thursdayism”) is the well accepted principle of quantum fluctuation. Their final end product may be the Multiple Universe Hypothesis, which when closely examined, not only fails to solve the paradoxes but increases the problems associated with them.

It has been suggested that, because quantum fluctuation is purely random, there is no physical limit required for how large the fluctuation can be. In multiple universe theory, not only can a tiny subatomic particle be produced (along with its opposite pair), but indeed, an entire new universe can spontaneously be formed.

If this is true, then it is entirely possible that our own universe began as a quantum fluctuation in a theorized higher order physical existence, something called hyperspace, or a multi-verse.

In order for this to occur, the fluctuation must have produced a very tiny proto-universe, a seed or egg (so to speak), containing all the information now present in our universe. One might compare it to a molecular contingent of DNA, which in turn might be compared to a complex computer program that nobody wrote, but simply came about through random means, such as of course, quantum randomness. The “seed” or egg, then, might be thought of as an algorithm that defines and directs the physical universe.

While this algorithm must be unimaginably complex, it would require less complexity (and therefore more likelihood) than random generation of a fully formed universe. Indeed, it would be more likely than the formation of a Boltzmann brain containing sensation of that universe. On a deeper level, one might question whether there is any need for a physical universe at all to explain physics, instead of just the algorithm itself. Perhaps there is no physical universe, but only the underlying mathematics. Dr Max Tegmark has at least indirectly suggested as much.

While at first the multi-verse theory seems to explain how such an unimaginably unlikely universe as ours spontaneously arose out of a vacuum—and I do not deny that it might have occurred this way—the MUH creates more problems than it proposes to solve, as far as explaining the origin of our universe.

First, if we must resort to such explanations of the origin of the universe, then to what must we resort to explain the origin of the multi-verse? Obviously, it too must have properties, parameters, constants, natural laws, and the potential to create bubble universes. Moreover, those potentials must be specific enough to produce specific kinds of universes.

The alternative is to propose an infinitely ever higher order of random universes with no parameters at all.

The idea of a vast infinity of infinities leaves science in the lurch. It would force science to retreat to a position in which we consider our universe to be an island of order in a vast ocean of disorder, an ocean which we can never explain in any practical sense. We can explain our island of order in terms of natural law, but our only basis for that natural order is chaos. The implications of that pose further paradoxes.

Occam’s razor, however, requires a simpler solution.

Albert Einstein intuitively understood this. His personal discussions with the likes of Neils Bohr generated such iconic statements as, “God does not play dice with the universe,” with varying phraseology. Not a believer in God except in a generic, naturalistic sense, Einstein’s genius, combined with the same intuitive insight that sparked his theory of general relativity, must have told him that the universe does make sense. It seems that to Einstein, a universe that makes sense must be causal and deterministic. But other alternatives are possible, since strict causality might itself not make sense, especially as regards free and open scientific inquiry, as well as social issues such as justice and accountability.

I have heard (in online videos) scientists say that the universe does not necessarily make sense, nor need it. To me, that seems a very peculiar position for men of science to take.

Granted, the universe might not make sense to us (see JBS Haldanes’s famous comment that the universe might be queerer than we can suppose). But it seems an unavoidable axiom that the universe at its most fundamental basis does indeed make sense, even if we cannot find it. To avoid that axiom is to concede the possibility that all is ultimately absurdity, and that science at its heart is only an attempt to make scientific sense of a few lines of “Through the Looking Glass,” while ignoring that the context of those seemingly sensible lines is rooted in irrational fantasy.

To allow that reality may itself be absurd is to relegate science to a meaningless, futile endeavor. Would it not be amazing if the pinnacle of scientific theory were to discredit science entirely?

[Q-reeus]

If I understand it right, the 'need' for outlandishly improbable BB's (Boltzmann Brains) stems from an interpretation of QM that requires conscious observers in order to 'actualize' a given universe. Other interpretations do not require that baggage.

As for an eternal self-reproducing multiverse, it has an undeniable attraction but some knowledgable folks also find it to have a fatal Achilles' heel - it can't actually be 'past eternal':
http://www.technologyreview.com/view/42 ... beginning/
http://arxiv.org/abs/1403.1599

And the idea that unitarity (absolute conservation of information) can be remotely reconciled with a point-sized big bang origin just seems too stupid for words imho. One or the other or both must be false and imho unitarity fails bigtime somewhere along the way.

[RArvay]

I don't think that the Boltzmann brain necessarily requires consciousness to explain the universe.
The BBrain theory simply says that we are already conscious, and then attempts to explain why and how we are conscious of the universe around us,
whether or not that universe exists as we perceive it.

If the universe is infinitely large, and if it operates on quantum probability, then it is not a stretch to say (and I disagree with the saying by Guth)
that anything that can happen, must happen, and it must happen infinite times.

If this is so, (and I repeat that I do not think it is), then in a universe of random chance, a brain can (and must) spontaneously form for at least a brief moment,
complete with memories, perceptions of an external universe, and so on. One cannot disprove that he came into existence just an instant ago, and that his consciousness is a composite of infinite BBrains stringing together a chain of perceptions, somewhat like random pages out of order torn from a large number of books, strewn about, and then pieced together after the fact.

IMHO, this absurdity is why there is something wrong with the BBrain theory. The premise that leads to it must be false.

The false premise, IMHO, is that there is such a thing as quantum randomness, or true randomness.
Einstein said that there is no true randomness, and while I also disagree with his proposal of rote determinism, I think he had a correct intuition about randomness.

My own proposal, which is based only on my intuitive assumption, is that there is a sort of Cosmic Intent. If so, then that eliminates the need for chaotic randomness, and it imposes order and reason on the universe, reason which underlies our own faculties of consciousness and indeed, free will.

Of course that borders on the theologic, but as physics ever more closely encounters questions of ultimates and absolutes, we must replace the inevitable theories such as BBrain, multi-verse and "last Thursdayism" with proposals that at least explain, if not prove, that the universe is founded, rock solidly, in a natural law and a natural order that prevents absurd conclusions.