As the only criticism on this article has been downvoted strongly, I feel compelled to repeat my explanation of that criticism (that believing in the multiverse is like believing in heaven or hell) at a higher level, in the hopes that people will be somewhat more critical of what esteemed scientists are peddling as truth:
There is not a shred of experimental evidence for the multiverse. In fact, experimental evidence is not even possible. That places it firmly in the pantheon of metaphysics.
That there is a multiverse could be an unescapable conclusion from an otherwise very successful theory, with many experimental verifications, but that isn't the case. The article neglects to mention that there are many alternative interpretations and theories that can equally well explain 'how it all started' and still result in inflation and all associated 'best' theories for the experimental observations of the universe. This article is all unwarranted extrapolation (back to the beginning of time and before).
The main pillar of the success of the multiverse theory is that it successfully appeals to the imagination. The main reason that it is being promoted is because the great physicists promoting the idea do not realize they are not as great philosophers as they are physicists.
Assertions that take the form "X is like religion" are not enlightening. When it is prefaced with "get the facts straight" then of course it's going to get downvoted. There is nothing being "peddled" here, there is no hidden agenda by "esteemed scientists".
We have experimentally demonstrated that the universe is a really, really weird place. Time and space can bend. Whoah. But hey, we proved that beyond a shadow of a doubt. Then there's quantum mechanics. Wave functions! Entanglement! Turns out the universe really works that way. Then the universe starts looking really non-deterministic. Then we figured out that the simplest interpretation of QM implies Many Worlds, that the universe splits and splits and splits into a bazillion near-copies. The quantum events just look non-deterministic from our perspective. Do we know everything? Hell no. But we know that QM is true and that it uses some form of Many Worlds. We know that the world is deterministic. We don't know for sure how the universe came into being (but we are sure the universe is expanding). We don't know if there really is such a thing as the multiverse, but as we figure out more about the big bang, about background radiation, about black holes and dark matter and the shape of our universe there's a good chance we'll figure it all out eventually.
Physics is treading on the domain of philosophy because we're getting better at physics. Philosophers debated since the dawn of time about free will and didn't get anywhere. Now we know that non-reductionist or dualistic world views make little sense. Philosophers debated for ages about morality. Now neuroscience is starting to deliver concrete answers. Philosophers debated for ages about religion and heaven/hell. And elementary Bayesian math shows the questions are just nonsensical.
Philosophy is about reasoning about topics we don't really understand. As our understanding of physics, math, neuroscience and biology grows philosophy has to make way.
Then we figured out that the simplest interpretation of QM
implies Many Worlds
Many physicists contend this point. They do not consider this interpretation as 'the simplest'. Things hinge on such contentious points as the physical reality of 'the collapse of the wavefunction'. Again, the major thing the Many World interpretation has going for it is that it easily appeals to our imagination -- even, or especially, to the imagination of non-physicists.
We know that the world is deterministic.
Philosophers disagree. It's even the question whether this issue can possibly be settled by any experimental evidence, because of the way we, and our math, are wired to consider everything in causal chains. The evidence isn't really very compelling if you consider the fundamental problems surrounding the question.
Now we know that non-reductionist or dualistic world views
make little sense
Descartes has been critiqued extensively long before science could say anything about mind-matter interactions, because the main shortcomings of the duality argument do not depend on any experimental facts at all.
Now neuroscience is starting to deliver concrete answers.
On the subject of morality, neuroscience cannot possibly deliver any concrete answers at all. You're engaging in the naturalistic fallacy if you think it does. What is the case in the world is not argument for what should be the case in the world. Neuroscience may explain why people hold certain ethical views. It can never explain what ethical view they should hold. What view is 'acceptable', 'the best', 'right'. The answer to that question cannot be reduced to physical facts about the universe.
Philosophy is about reasoning about topics we don't really
understand.
Then we don't really understand logic and math either, do we? The foundations of logic and math are still part of philosophy after all.
And, well, Hume didn't really understand causality, did he? But fortunately, thanks to modern physics, now we do?
> Many physicists contend this point [ ... ] appeal to imagination.
Not so. The vast majority of quantum physicists now agree Many Worlds has won, including Feynman, Gell-Mann and Hawking. The concept of 'collapse of the wavefunction' is silly and shouldn't even be considered for reasons outlined here: http://lesswrong.com/lw/q8/many_worlds_one_best_guess/
> Determinism; Philosophers disagree.
It's just basic reductionism. There are absolutely no fundamental problems surrounding this.
> On the subject of morality, neuroscience cannot possibly deliver any concrete answers at all.
All moral thought and all moral beliefs up to now have happened inside the human brain. Most moral thought is confused and self-contradictory. If we want to figure out why we are moral the way we are, what our "true" moral beliefs are, and how to build societies that flourish, we have to look inside the brain to see how it all works. Either morality has bearing on the real world and is therefore subject to measurement or it has no bearing on the real world and is therefore irrelevant.
> Then we don't really understand logic and math either, do we? The foundations of logic and math are still part of philosophy after all.
Where the line is drawn between math/philosophy isn't a very interesting question.
> And, well, Hume didn't really understand causality, did he? But fortunately, thanks to modern physics, now we do?
Firstly, [1] disagrees with you. Secondly, there is a difference between accepting MWI above other interpretations and actually believing in multiple parallel universes. A difference between accepting the physical and the metaphysical consequences. Thirdly and crucially, MWI depends on QM. Everyone acknowledges QM is probably not a definite description of the universe and non-locality, non-contextuality or another kind of modification would wreak havoc on MWI. If physicists subscribe to MWI but also acknowledge QM seems incomplete, they are being inconsistent.
Concerning determinism:
You say "it's just basic reductionism". But in fact it presupposes reductionism as a viable strategy to determine 'the truth' about determinism. It isn't [2]. Specifically, the question whether we can even determine whether our fundamental theories are deterministic is still wide open. None of the theories, from classical mechanics to quantum mechanics, is clearly deterministic and it remains a question whether it can even be determined whether they are deterministic.
Concerning morality:
No matter how well you can 'measure' my 'true' ethical views on abortion: no measurement will ever tell you what my ethical view on abortion should be. No collection of measurements will ever tell you what a governments policy on abortion should be. At most you can hope to be able to say: in this particular case we should allow it, because that will be best for everyone: the average happiness, productivity and insert-factor-of-importance will be highest if we allow it. However, that kind of judgment presupposes a certain moral system. You can never determine which factors should be important. At most you can measure which factors people rate as most important on average. But again, you presuppose a certain moral system if you choose to use that measurement to determine what to do. If you feel otherwise, there's a large philosophical nut left for you to crack.
I think you underestimate the complexity of these subjects and that your verdicts are premature.
BTW, you guys keep talking about MWI, while the original article is categorically not about MWI. The author describes a Tegmark Level I Multiverse[1], the most conservative of the multiverse models. MWI is Level III, and the author himself says in a subsequent comment[2]:
What I've presented, above, is the argument for the first
type of Multiverse, which I think is correct, and hence,
which I believe in.
I think that anything beyond that is too speculative to be
believed at this point, at least with any sort of
confidence. At least, by me.
The author responds to this point in one of the comments; I quote:
this is -- and I make no pretensions otherwise -- theoretical physics. It's not airy-fairy pie-in-the-sky speculation, but it also isn't proven the way you would prove that a * b = b * a. You may want to read this recent guest essay (http://scienceblogs.com/startswithabang/2011/10/guest_essay_...) that does a wonderful job of explaining, with some brilliant metaphors, what this sort of theory is (and isn't).
There is not a shred of experimental evidence for the multiverse. In fact, experimental evidence is not even possible. That places it firmly in the pantheon of metaphysics.
That there is a multiverse could be an unescapable conclusion from an otherwise very successful theory, with many experimental verifications, but that isn't the case. The article neglects to mention that there are many alternative interpretations and theories that can equally well explain 'how it all started' and still result in inflation and all associated 'best' theories for the experimental observations of the universe. This article is all unwarranted extrapolation (back to the beginning of time and before).
The main pillar of the success of the multiverse theory is that it successfully appeals to the imagination. The main reason that it is being promoted is because the great physicists promoting the idea do not realize they are not as great philosophers as they are physicists.