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Monday, August 26, 2024

Albert explains Weirdness of Quantum Mechanics

David Z. Albert is one of the leading popularizers of quantum mechanics, and is on this podcast:
David Albert is the Frederick E. Woodbridge Professor of Philosophy at Columbia University, director of the Philosophical Foundations of Physics program at Columbia, and a faculty member of the John Bell Institute for the Foundations of Physics. This is David’s eighth appearance on Robinson’s Podcast.
I think he is mostly known for trying to give a philosophical defense of string theory, in the absense of any evidence.

He tries to explain what is weird about QM

24:01 what's often considered striking and unsettling about quantum 24:08 mechanics is that at the beginning of the 20th century people start doing all 24:15 kinds of experiments where unlike in the Newtonian case where we're just taking 24:20 it for granted that yeah there're you know you look at these little dust Moes 24:26 or something like that how they're moving around they themselves presumably consist of billions upon billions of 24:33 these Elementary Point particles which we can't actually see we're sort of taking it for granted that things are 24:38 going to work out in the beginning of the 20th century people fooling around with cathode ray tubes and and stuff 24:46 like that begin to be able to keep track 24:51 of the Motions of individual Elementary particles 24:58 and these particles um um are behaving in ways that are almost 25:08 inconceivably bizarre okay in 25:13 particular people manag to convince themselves by doing lots of experiments 25:19 with these Elementary particles that things like electrons for 25:26 example could be in you you know um it's possible for an electron to be located 25:31 at this point in space and possible for an electron to be located at that point 25:37 in space those are the familiar Newtonian possibilities here or here or 25:42 here or here or here what these experiments at the beginning of the 20th century suggested 25:49 to people and I'm condensing here 30 years or so of wrestling with 25:56 the with the results of these experiments in the beginning of the 20th century there are certain sets of 26:03 experiments so-called interference experiments um double slit experiments 26:10 if you can read about this want to read about this in the literature Neutron interferometry experiments stuff like 26:16 that there's a whole um family of of experiments which 26:23 slowly persuades people that um 26:29 um that apparently there are certain states that 26:34 electrons can be in electrons and neutrons and all elementary particles 26:41 can be in um once again there's a possible state where the electron is at 26:46 Point a there's a possible state where the electron is at point B what people became convinced of is that in addition 26:54 there are possible states of electrons such that the very question is it 27:01 located at Point a or is it located at point B or is it located at neither of 27:07 them fails to make sense okay that um that the question that there are certain 27:15 situations in which the question is the electron in box a or in box b or in 27:22 neither of the boxes is like um is is is is like a 27:32 question of the form um um is the number five Married 27:38 okay or or what is the weight in grams of Catholicism okay or something like 27:45 that um questions that philosophers often refer to as category mistakes okay 27:51 um that there can be situations of a material particle an electron okay where 27:59 asking whether or not it's in box a is somehow like asking what the marital 28:06 status of the number five is or what the weight and grams of Catholicism is okay 28:12 um this strikes people is absolutely bizarre people felt forced to 28:18 conclusions like this because if you tried to tell the story of these 28:23 experiments in a way that used locutions like well at this this point in the story the electron I suppose must have 28:30 been here or at this point in the story the electron must have been there or even if you just insist that at this 28:37 point in the story there must be some place where the electron was because after all it got from here in the 28:43 beginning of the experiment to there at the end of the experiment it must have gone by some particular route either 28:51 through this route or through that route you try to insist on that you try to tell yourself a story about how these 28:59 experiments went okay that's consistent with the results you got you find that 29:05 every particular Claim about which route the electron might have taken somehow collapses into nonsense becomes 29:13 inconsistent with certain of the results of these experiments that you actually did okay so an idea grows 29:21 up um um that it appears to be a feature 29:28 of the way these fundamental particles behave that for every pair of states 29:34 that such a particle could be in that is the state of being located at a and the state of being located at B there's also 29:42 another radically unfamiliar but physically possible state which is 29:47 referred to as the superposition of being located at a and being located at b or the quantum 29:54 mechanical superposition of being located at a or being being located at and being located at B which is which 30:03 which we can we can argue from our experiments is not a case of being 30:08 located at a and not a case of being located at B and not a case of being 30:14 located at both A and B as you often find in the popular literature when they 30:19 try to talk about superposition and that's very bad too and that would reduce the mysteriousness of this way 30:27 below what it actually is what these experiments suggest is that it is wrong 30:33 to say under those circumstances that the electron is located at a and that it's wrong to say that it's located at B 30:40 and that it's wrong to say that it's both at A and B and that it's also wrong 30:45 to say that it is neither at a nor is it at B okay if you think there must always be a 30:53 fact of the matter about where the electron is that exhausts the line iCal 30:58 possibilities okay um um and so people felt 31:04 forced um to acknowledge that what these experiments seem to be screaming at us 31:12 okay is that for any two states that an electron could be in A and B there are 31:18 other physically possible States in in in you know which can't be rightly 31:25 characterized by saying that they're at a can't be rightly characterized by saying it's a b can't be rightly 31:31 characterized by saying it's a both and can't be rightly characterized by saying it's a neither okay and rather you seem 31:41 to be confronted with a situation in which um asking whether the 31:47 electron is at A or B is like asking about the marital status of the number five okay it's just a 31:55 nonsensical question good um
No, this is not weird. The same thing happens in classical mechanics. If you put a ball in a box and shake it up, you do not know where it is. When you open the box, you find it in one position, and not others.

Why is it surprising that electrons behave this way, when classical balls do also?

He goes on to strongly attack Bohr for saying that it does not make sense to talk about the exact location of an election in a box, until you open the box and look at it. Then he praises various alternatives, such as hidden variables and many-worlds.

Bohr was right, and Albert is wrong. The electron is not a particle. If you ask for the exact location of the election, you are basing the question on the faulty premise that the electron is a particle, and it has no answer because it is a meaningless question. As Albert complains, the Physics community accepted Bohr's philosophy about a century ago.

Albert is one of many QM expositors who argue that the textbooks do not make sense so there must be something better. They are just wrong. The textbooks present a perfectly good theory, and all the alternatives have horrible defects.

Sabine Hossenfelder is another one. She just posted a podcast on Can Quantum Physics Explain Consciousness After All? Her answer is No, of course, as she ends up saying Bell's Theorem requires superdeterminism.

She is a free will denier, but see the new paper Decision theory presupposes free will. You have to reject a lot of good science, if you reject free will.

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