everytime I hear parallel world being taken seriously I cringe.Scott Aaronson replied:parallel worlds is just pure bs, nothing useful has ever come out of it.
people who like it tend to have particular attitudes towards life itself, so to my eye it is more like they are looking for something that is aligned with their attitude towards life than real hypnosis that they try to find evidence to rule out or support. it is for people who cannot handle random processes, so they have to assume that if you have a random process and an observation of the outcome, to achieve symmetry you need a parallel world in which the other possible outcomes occur. it is a confusion of possibility with actuality.
the issues with quantum physics that parallel world interpretation is trying to answer, point out actually to witnesses in the foundations of quantum physics, and point towards not talking quantum physics too seriously and physicists did with Newtonian physics for centuries.
a lot of physics theories are built upon unrealistic simplifications, assumptions that are needed because otherwise doing physics becomes too hard for our human brains computationally. we need to assume that we have isolated systems but in reality there is no small isolated system. etc. etc.
like many sciences, physics is built on top of some practical lies, and that is ok, but if we forget that and take the theories too seriously that is a problem.
who knows, many in 100 years we will learn that quantum physics breaks under particular conditions and the nice simplified theoretical foundation needs to be made much more complex to reflect better how reality works.
the idea that all the time infinite number of parallel universe get created out of no where is such a bizarre belief, it is completely against the Occam’s razor to believe in existence of such things.
anon #38: Since you’re so confident about these matters, surely you’ll be able to enlighten all of us novices. What is true about the world, such that we should describe it using the quantum formalism? What decides when unitary evolution is suspended and the wavefunction collapses instead? If not many-worlds, do you advocate Bohmian mechanics? A dynamical collapse mechanism? Perhaps some new view of your own invention? Don’t hold back!This reply misses the point. Bohmian and dynamical collapse theories are objectionable for other reasons.
The point is that there is no need to subscribe to such theories. Maybe in 100 years we will learn of a need for a more complete theory, but there is no such need today.
Many worlds theory does not solve anything. There is no point to it. It is based on misguided beliefs.
Aaronson seems to be only about 80% on board with Everettian Many-Worlds here. Sometimes he is more fully accepting. He does endorse it to the extent that it helps explain how quantum computers work, and that it helps give confidence that they will work.
All this leaves me scratching my head. Aaronson is a smart guy, and he shows a fair amount of skepticism about other matters. But many-worlds is so wrong and misguided that if he gives it any credence at all, then I have serious doubt about anything he says about quantum mechanics. It is not a reason to accept quantum computers. Not even a little bit.
He concedes that one can believe that Shor's algorithm can work on a quantum computer, without believing in many-worlds. Okay, so why does he keep bringing up many-worlds?
His blog motto for years has been:
If you take nothing else from this blog: quantum computers won't solve hard problems instantly by just trying all solutions in parallel.Okay, I accept that. A lot of physicists try to explain quantum computers by saying that they try all possible solutions in parallel. He jumps on them, and insists that is erroneous thinking. The explanation should not be given.
So why does he push the many-worlds explanation? It is even more erroneous.
I posted a similar comment on his blog. He posted this reply:
I agree that many-worlds isn’t necessary to explain quantum computing — and unlike Deutsch, I’ve never claimed that it is.The ideas pay rent! Wow, I did not expect him to explain it that way. Here is more of his response to the anonymous commenter:On the other hand, in two decades of actual on-the-ground experience teaching quantum computing to undergrads, I’ve seen again and again how confused they get by the fact that a CNOT from |ψ⟩ to an ancilla qubit, has exactly the same local effect on |ψ⟩ as if someone had measured it, mapping a pure state to a mixed state. And again and again I’ve found myself saying: “look, imagine if you like that the one qubit measures the other qubit! what did you think measurement was in the first place, if not the measured state getting entangled with the measuring apparatus and the larger environment?” And I’ve seen how much this Everettian way of thinking helps pedagogically, even if the student doesn’t want to swallow the full Everettian metaphysics, as I’m not sure that I do. So these ideas do pay rent, even if they aren’t logically indispensable.
But Sean Carroll, David Deutsch, Stephen Hawking, Don Page, Wojciech Zurek, and Lev Vaidman all are (or were) hardcore many-worlders. From that alone, we deduce that there can’t be anything trivial about quantum mechanics (or math and physics more generally) that the many-worlders simply fail to understand.Hmmm. He cites authority for many-worlds being valid, and then cites Galileo for the Church authority being wrong.Indeed, given certain axioms about what a scientific theory is supposed to do for you, what we mean by the “simplicity” of a theory, etc., you’re led inevitably to many-worlds, as an almost “conservative” picture of whatever reality the Schrödinger equation is describing. And given those same axioms, your retort that “it’s just math, there doesn’t have to be any picture of reality behind it” sounds just as dumb as when the Church said the same to Galileo about heliocentrism.
He also includes Saunders and Wallace (PhD mentor and student, resp., at Oxford) in the list of the proponents of MWI.
ReplyDeleteDear Roger,
ReplyDeleteI've a ``theory'' about it --- why Scott behaves this way. I mean, not theory, not even a ``theory,'' but just a ``conjecture''... Actually, not even that, but just an idle guess. I'm not too serious about it either. FWIW, I'll *share* it, here.
So... Early on, Scott gets into maths. Then, he also goes to Berkeley, and there, he gets into not just TCS but also into the QC. (May be, even before Berkeley.) So, sometime somewhere, he runs into Feynman (late in his career lecture) and Deutsch (early in his career work), exhales sharp ``wow!''s at both. And, begins idolizing both. So, he accepts the entire package deal --- the maths algorithm and the MWI. Particularly because it seems, to him, a ``buy one, get one for free.'' The combo pack stays in his mind. It begins to inform his thought processes.
As time passes, he learns QM better. (Who gets QM right the first time?) And so begins issuing alerts to himself: Only maths, no favoured interpretation --- not even MWI.
Some time later, he now begins to *teach* QC. But then, as it so happens, we often tell stories that are at least coloured (if not fully informed) by our own earlier conclusions.
Maths, being a very narrow science (in the sense, broadly it only deals with only those *meta-categories* or *meta-classes* of quantitative relationships that are already known), and also very carefully defined, mathematical ideas, once proved, and then, also with the proof *fully* understood, are next to impossible to reject. Indeed, the very process of full understanding has already internalized the truth of what they say. So, it's easy to revise one's beliefs when proofs to the contrary come in the view.
Attitudes in maths (and mathematical physics too) are a little more vague, and so, harder to revise. Just as an example, once you burn the midnight oil not just one night but nights after nights, solving problems from Jackson, all the time using advanced and creative analytical methods that give you ``exact'' solutions, then, you also become not so receptive to conclusions coming from the use of those *mere* numerical methods. [A related bit, I just noted in my latest blog post].
The more philosophical attitudes, as prevailing in science, are still harder to revise. For instance attitudes towards physics vis-a-vis maths.
As to attitudes pertaining to deeper and more general philosophic issues: They are extremely hard to revise. In fact, I do sincerely doubt if any one can really change his most basic philosophy --- provided that he *has* taken efforts to *have* any. ... But of course, one can always be utterly wrong, even in all sincerity. ... I also sincerely hope that I was wrong, here.
[continued in the next reply]
[continued from the previous reply]
DeleteBut coming back to Scott, and my idle musings... They shall now also touch on psychology, not just philosophy. I shall write.
When Scott teaches QC, issues like entanglement and measurement problem (MP) come up, and in confronting the problem of how to cover it (MP) in the class --- or to skirt it altogether (so as to get back to maths at the earliest possible instance) --- he ends up falling back on his ... err... ``earliers.'' (I won't call them the ``priors.'' Not yet, anyway.) So, his explanation (rather, the escape from MP) naturally acquires a flavour of MWI over any other ``interpretation'' or ``explanation.'' Deutsch, remember? Also, Oxford? The refined intellectual atmosphere ``east of the pond''?
But of course, Scott also has a lot of academic integrity, and he keeps on issuing all those caveats regarding the MWI too. But he also keeps coming back to MWI (+ the caveats). The point is: Unless he has settled the matters for himself (specifically, for MP and all), mere caveats simply won't be (actually, *can't* be) as effective, practically speaking, as the ``earliers.'' Those ``earliers'' will keep on slipping in.
Plus, look at it ``realistically''. Deutsch still has not retired. He still is at Oxford. Students can be placed. Sabbaticals can be exchanged. If not for oneself, then at least for friends and the influenced people.
Students, unprepared, catch it all, too. That's why, when prodded (especially by him / likes of him), many of they do say that MWI is the most straight-forward way to make a sense of how the QC works. (Note: They're talking about QC, not MP.)
But of course, Scott is reporting on what his students tell. Or, the students of people like him. At least, students who talk.
There are always many students who have no opinion, but silently go along with those who say something --- any thing. There also are others who might have some opinions/thoughts, but won't mention these to their professors --- no matter how utterly friendly and helpful a professor otherwise might be. And then, of course, there are those smart ones, in both categories, who *choose* to stay silent: If the issue isn't settled in the larger professional community, why create a ``back-link'' for the future? Aren't reco's important? Etc. [The ancients knew it too. They said: ``Silence is golden.'']
And of course, there are other students of other professors, too. Or perhaps even of Scott himself (and of other professors like him). They talk. Even if it doesn't agree with their professor.
I am not at all sure if ``anon'' was a student, a professor, or even an AI. But I do know that there always are students --- specifically, students --- who do talk back. Some times, even with very good elements of logic and reason.
[No, I don't believe that professors learn from their students. That's a hyperbole. But it *is* true that some students do prod their professors to learn for themselves.]
All in all... Especially in reference to MWI in academia and all...
Given the entrenched position that MWI enjoys for at least three academic generations (if not more), the only solution now possible is to have an objective solution to issues like the MP (and, I might as well add: for other issues like the exact *physical* nature of the QM -- QC correspondence).
--Ajit
PS: Does Scott read your blog? Just wondering ... Might as well post this reply at my blog or elsewhere too...
I doubt that Scott reads my blog.
ReplyDelete