Monday, June 19, 2023

Carroll says Many-Worlds is Falsifiable

Physicist Sean M. Carroll is a guest on another podcast, and goes into detail on some of his favorite topics, like the Many-Worlds theory of quantum mechanics. If you are a fan of his, you have probably heard it all. I just want to mention a couple of things where he is way off base.

He says there are a lot of "bad worries" about Everett MW, such as it being not falsifiable. It postulates other worlds that we cannot visit.

His answer is that you can believe in the worlds because they can be described by the Schroedinger equation. MW could be falsified by disproving that equation. He then refuses to give any more arguments against MW, as he just wants to say what is good about it.

This argument is really stupid. Say you have a cat in a superposition of alive and dead. Then you observe it dead. QM nows says you have a wave function of a dead cat. MW says you still have a live cat in a parallel universe.

Somehow that live cat has to be postulated and taken on faith, as it is impossible to observe.

Carroll would presumably say that QM cannot predict whether the cat is alive or dead, so MW is not a postulate, but just continuing to believe in that uncertainty even after you determine that the cat is dead.

Got it? Idiotic.

Many-Worlds is just like the following fantasy: There is no such thing as probability. Every time you say that there is a chance of several things happening, and you see one, then what really happened was that the world split into parallel worlds, with each thing happening in its own world. All things happened, and probability is just the illusion of getting disconnected from the other worlds.

He goes on the argue that last years Nobel Prize committee got this wrong:

The Northern Irish physicist John Stewart Bell (1928–1990), who worked at CERN, the European particle physics laboratory, took a closer look at the problem. He discovered that there is a type of experiment that can determine whether the world is purely quantum mechanical, or whether there could be another description with hidden variables. If his experiment is repeated many times, all theories with hidden variables show a correlation between the results that must be lower than, or at most equal to, a specific value. This is called Bell’s inequality.
And also:
John Clauser developed John Bell’s ideas, leading to a practical experiment. When he took the measurements, they supported quantum mechanics by clearly violating a Bell inequality. This means that quantum mechanics cannot be replaced by a theory that uses hidden variables.
This is saying that Bell showed how QM can be distinguished from classical theories, and the prize was given for the experiment confirming QM.

Carroll says this is wrong because Bell believed in the Bohmian hidden variable theory. He says that theory is wrong, but some people believe in it, so experiments do not rule it out.

Bell's Theorem is a mathematical theorem, so it has technical hypotheses. Violating the hypotheses gives loopholes. The main ones are: action-at-a-distance, retrocausality, multiple outcomes, and superdeterminism. These are all outlandish, and my guess is that no one on the Nobel committee believes in any of them. The Nobel description is correct. It just skips over the unphysical loopholes.

There is no need to go into any of this in a Nobel press release. They are clear that the prize is only being given for experimental work, and not for any endorsement of theoretical interpretaions by Bell or anyone else. Clauser thought that he would disprove QM, but instead he confirmed it.

1 comment:

  1. Mathematicians have a long and illustrious history of being card cheats and often going bat shit crazy. Nice to see them striving for such consistency.

    Mysterious box, mysterious content, wave the magic equation past a human observer and POOF! Lookie lookie! We can mathematically produce an answer...any answer. Sure you can! In fact, if you squint your eyes, look constipated and believe you can divide by zero, pretend mass has EVER been measured or detected at a diagrammatical point, or that two dimensional number lines can carry physical forces and be physically indestructible (a la super-string), If you can believe these ....entirely made up things... I'm sure you can also believe the Wizard of Oz is just a few planes of reality away.

    You see, 'truth' is, the cat isn't really dead at all, it's just Toto taking a nap in an otherworldly black box.

    Stay Tuned for Next week, where Sean Caroll pulls an abacus out of his ass and calculates the probability that he (and the rest of us sadly) is just a figment of a dead cat
    s imagination! Oh what fun we will have!

    “You can get so confused
    that you'll start in to race
    down long wiggled roads at a break-necking pace
    and grind on for miles across weirdish wild space,
    headed, I fear, toward a most useless place.
    The Waiting Place...”
    ― Dr. Seuss, Oh, the Places You'll Go!