Um, no. MWI is simplest in the strict, formal, information-theoretic, Kolmogorov-complexity sense, while fitting the data to equal precision with any competitor. That's kinda the whole point of MWI.
From your link: "This is Bayes's Theorem. I own at least two distinct items of clothing printed with this theorem, so it must be important." - Eliezer
cringe. "Here's a bunch of math so I must be really smart. Trust me guys." Math is awesome, but waving it around as if to automatically lends credibility to your argument is a poor showing IMHO.
Specifically, quantum decoherence is simply not accepted as a thing that exists on a macro scale. You're post presents no claim that is testable, despite the bold headline to the contrary.
Lets look at an example of a what physicists consider to be a falsifiable claim: The Standard Model predicts the existence of a new elementary particle, the Higgs Boson. This could be tested experimentally in theory, and later it was tested in practice, once the capability existed (LHC).
Or another example: orbital mechanics predicts the location of the asteroid Apophis will pass unusually close (<100 000KM) to earth in 2029.[1]
Now of course if Apophis fails to show up, or shows up overly late or in the wrong place etc, that doesn't necessarily invalidate the theory, but there does eventually need to be a credible explanation.
The simplest is usually measurement error, or silly human error etc. But every now and then, there are discrepancies that just don't go away, and those are often the ones that lead interesting new theories pushing science forward.
TBH I don't think your post does that.
The failing of physicists to take your above link seriously, does not epistemically speaking invalidate the claim of course, but it should be pause for concern.
MWI certainly does make falsifiable claims. It's just that different interpretations of QM are extremely difficult to experimentally distinguish with any technology we are likely to have in the foreseeable future.
The only well-known interpretation of QM that is experimentally indistinguishable--in theory--from MWI is Bohm's Interpretation. And I think it would be a difficult row to hoe that Bohm's Interpretation is simpler than MWI, as Bohm's universe contains the MWI universe as a subset in the form of pilot waves that never collapse. I.e., the only difference between MWI and Bohm is that in Bohm, one of the "worlds" is granted reality, while the others are not.
Of course, there's nothing in MWI that grants all the worlds reality either. Someone can certainly remain agnostic about that. E.g., Stehphen Hawking has said that MWI is obviously true, though he is agnostic on the reality of the other worlds.
For more information on this, including a tutorial on all the linear algebra that you need to understand, see the book Quantum Mechanics and Experience by David Albert.
Another way in which MWI is falsifiable is that it would be proven wrong if those Chinese physicists were able to show a speed limit on the spooky action at a distance. MWI says that there is no such speed limit, since there is no spooky action at a distance.
Additionally, there are collapse theories that are much easier to test than consciousness-based ones. By "much easier", I still mean fantastically difficult, but should the day come that one of these collapse theories is proven correct, then MWI will clearly have been falsified.
You can set up complicated and impractical experiments (for us, but perhaps not for inconceivably advanced aliens) that can experimentally distinguish between MWI and other interpretations of QM. (With the exception of Bohm.) Do you really want to know all the gory details? They are rather obscure.
The executive summary is that it is in theory possible to determine whether a system is in a specific superposition of states, if you know exactly what superposition of states it might be in. So, let's say you wish to see if MWI is true vs a version of Copenhagen that relies on a conscious entity experiencing the results of a measurement in order to cause the wave collapse. If you have an accurate enough model down the very last particle of the entity's brain, and everything else the entity would have to interact with for it to perform an experiment, you can in theory then experiment on the entity to determine if it (plus everything it interacted with) is in the specific superposition of states that MWI would predict.
As I said, not very practical.
Well, David Deutsch argues that it might be practical when the day comes that we have AI's living in quantum computers. (And his experiment is also a bit different from what I described, and a bit more conceivable for us to do with technology we might someday have.) A problem there, is that naysayers will no doubt claim that the AI's aren't conscious.
Also, while Eliezer does sometimes plays with the argument from authority (like in the piece of humour you cited), I have never caught him actually using it to win an argument.
Oh, and one of the points (not the main one!) is to tell that those physicists, with all their authority, are wrong. (Well, at least those in favour of the Copenhagen Interpretation.)
Physicists would hardly be intimidated by being shown the algebra of Bayes's Theorem. I will take into account your de facto information that non-physicists may see the opening as an attempt to intimidate, but it was mostly aimed at people mathematical enough to own their own T-Shirts with equations on them, and hence to laugh at the joke.
Regarding the rest of your comment, this is addressed in the second linked post.
>Physicists would hardly be intimidated by being shown the algebra of Bayes's Theorem.
Well no they probably wouldn't, but my point wasn't about intimidation and not sure how it's relevant.
Personally I'm a huge fan of Bayes theory both theoretically and practically speaking, I'm using it in two side projects I'm currently working on. My only issue was a stylistic quibble with the author, and I will have to accept it if you frame it as humor. I'll grant I probably should have left it out in retrospect, since it deals with interpersonal subject matter.
>Regarding the rest of your comment, this is addressed in the second linked post.
No you haven't I was specifically referring to the second post.
I made two central claims, neither were responded to.[1]
1. Decoherence is not a thing on the macro scale.
2. Physicists do not take your claim that MWI is falsifiable seriously.
http://lesswrong.com/lw/q3/decoherence_is_simple/
http://lesswrong.com/lw/q4/decoherence_is_falsifiable_and_te...