I think Sean is doing us all a major favour by pushing this idea in order to help us start asking the right questions again. Bless him if he doesn’t even fully ‘believe’ in many worlds, but is championing it at risk of being a fall-guy for the benefit of future generations of physicists. For this, he needs a stack of medals. And yes, giving credit to Everrett makes him seem respectful for ousted thinkers of the past – but he has a difficult task in explaining many worlds to layman, like me, without confusing us by adding the maths. (Btw America, unlike the universal wave function there is more than just one math).

Why hasn’t he convinced my confused but open mind yet? Well, after watching and listening to everything I can find that he works tirelessly to put out (including the BBCs infinite monkey cage that just added more woo) and especially his fab great courses plus series on time (actually it was about entropy, but hey…) I talked to a bunch of people and many get “stuck” on the same handful of points he raises. None of us could find answers to a few things he states time and again, without actually explaining them in a way that resolves our questions – for example:

1 – Maybe entangled electrons are just like a pair of socks. You know, one is a righty so you can infer the other is a lefty – without any information travelling spookily. If this isn’t the case, I need to know which experiment actually shows they are undecided wave functions before they collapse into left or right (or spin up and down)?

2 – Different worlds that “don’t talk to each other” is a phrase he uses a lot but that is just a phrase, he doesn’t describe what this really means, like the Copenhagen interpretation it glosses over without giving a satisfactory explanation, just a soundbite, no? and if the world splits rather than makes new worlds, wouldn’t it already be thinner than the equivalent of a ‘many worlds’ plank length already. How far can this actually go without sharing out all the universe’s energy?

3 – He explains how the observation problem is totally misunderstood because people think it involves humans observing things, which will cause the wave function to collapse, ie decoherence. He explains that any particle of light or matter, or whatever, that can ‘sense’ where a particle is (or which way it is spinning for example), is enough to count as an observation. However, I have problems understanding when it is that light or matter DOESN’T sense another particle’s spin or position. Ie when is it where a wave function doesn’t collapse? Maybe he means only light that has never landed on something? (yet).

I would love him to take 5 minutes out to answer these as I am “in” if he can explain what he means properly without going into Hawking mode and just clicking the same phrases out again and again. However, I don’t think a couple of tweets would do the job.

Too shy to ask but if anyone can shed any ‘light’, on this ‘matter’ let me know. I will keep following his every word to see if he goes into more detail without adding maths. If you ever get to talk to him, thank him for all the hard work and inspiration. PS that blasted cat is surely an x cat now – stop flogging it in universities, just admit you don’t know the answers, thats what everyone else does, surely a university would be the first to express this, its what inspires new minds to come up with new ideas.

Sean Carroll Thinks We All Exist on Multiple Worlds

Link: https://www.wired.com/story/sean

In his book Something Deeply Hidden, the physicist explores the idea of Many Worlds, which holds that the universe continually splits into new branches.

Scientific American, making it sound like Carroll is the only guy to belive quantum mechanics is real and not just an idea: “Aim an instrument at the electron to determine where it is, and you’ll find it in just one place. You might reasonably assume that the wave function is just a statistical approximation of the electron’s behavior, which can’t be more precise because electrons are tiny and our instruments crude. But you would be wrong, according to Carroll. The electron exists as a kind of probabilistic blur until you observe it, when it “collapses,” in physics lingo, into a single position.”

Multiverse Theories Are Bad for Science

Link: https://blogs.scientificamerican

New books by a physicist and science journalist mount aggressive but ultimately unpersuasive defenses of multiverses