Thanks for the link. :up:

My take away: Michio Kaku ontologizes an interpretation of quantum theory whereas Sabine Hossenfelder finds this speculation (re: 'platonizing' the wave function) experimentally unwarranted and Roger Penrose suggests it's an ad hoc confused muddle which doesn't help explain anything that he thinks needs explaining (e.g. "inconsistencies in quantum theory of Schödinger's equations or the measurement problem"). Old school – harsh but apt.

Overall, I tend to agree with Sabine cautioning us to carefully distinguish philosophy from physics in order to avoid proposing pseudo-scientific "fictions" such as Michio's notion of "the (macro) multiverse" (and the like fetishized by e.g. our resident Quantum-Woo Crew).

So Michio assumes too much might be possible when there isn't enough to open that door, or he is fantasizing too much on impractical ideas that might not serve us anytime soon? What is his fault?

Dr. Kaku is heavily invested in M-string theory, so much so that he, IMO, exaggerates the salience of its untested experimental predictions. Worse he popularizes his exaggerations to sell books. I enjoy his pop-sci books though since they provide good fodder for writing science fiction stories (which I do occasionally). As Dr. Hossenfelder noted: Kaku's quantum pronouncements make "good fiction."

Isn't M theory a good thing? It tries to combine all aspects of previous string theories into a single thing? Also what else can a theoretical physicist do except make predictions? They generally don't do the experiments?

If you're promoting as "true" a model which makes predictions that – so far? – can't be tested by experments, then you're promoting pseudo-science (or, in the case of M-string theory, platonizing its mathematics – metaphysics, not physics). Just because one is a theoretical physicist doesn't mean one's work does not require experimental testing of its predictions by experimental physicists. For now at least, Dr Kaku's untested – untestable? – work on M-string theory is indistinguishable from, as Dr. Hossenfelder says, "fiction". That's neither a "good thing" nor bad thing, it's just not yet a 'scientific theory of quantum gravity'.

Who would've, even in his wildest imaginings, thought things so small as atoms would require us to posit things so large as multiverses?

@180 Proof is on target but que saise-je?

I've always thought that "multiverse" is a wildly extrapolated misunderstanding of Hugh Everett's many worlds interpretation of the interference pattern from the double-slit experiment. It just doesn't seem to follow that 'classical n-counterpart (parallel) universes' from 'planck superposition (n-worldlines) of a photon', does it? Physicists like David Deutsch seem to suggest this ... but like you say, Smith, what do I know ... :nerd:

The Everett Solution to Paradoxes

Hugh Everett is the guy who proposed the Many Worlds Interpretation. Basically, Schrödinger's cat is both dead and alive but in 2 different universes. The Schrödinger's cat scenario is no longer a contradiction.

Paradoxes: True contradictions (p & ~p). Visit Wikipedia for more.

The Everett Solution to Paradoxes: If a contradiction (p & ~p) arises, it follows that the universe splits into two, one in which p and the other in which ~p.

A penny for your pensées ... — Agent Smith

It all boils down to the 3^rd law of thought (the law of noncontradiction/the LNC). If A and not A are both true, we need at least 2 worlds/universes.

I think you're way off. Schrödinger's cat thought-experiment was proposed in order to show that quantum theory (re: superposition, measurement problem) is inconsistent, or incomplete, and not as a claim of "a true contradiction". Certainly, Everett's MWI was not proposed to account for "simultaneous X & not-X", Smith, and the "multiverse" add-on unparsimonously occludes the problems raised by Schrödinger and others.

Oh! I remember now, Schrödinger's cat was Schrödinger's gibe at QM as it was probably being interpreted during his day. Not, it seems, to reveal profundity, but rather to expose stupidity.

:smirk: