I've always liked these kinds of questions. Myself, I always wondered why specifically three dimensions. (Please don't start telling me about string theory.)
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Why Quantum Mechanics?
171–180 of 248 posts
Re: Why Quantum Mechanics?
#172> Why didn't God just make the universe classical and be done with it? What would've been wrong with that choice? I hear it over and over and still don't understand the premise. Classical mechanics is not something sacred. It is our first serious model of physics. Our first approximation is based on the scales at which we operate and our senses as humans. Furthermore, even "regular" quantum mechanics is a non-relativ…
> Classical mechanics is not something sacred. It is our first serious model of physics.
Just a sidenote: it is at most our second serious model. Aristotle's Physics has a bad rap, but it's "a correct and non-intuitive approximation of Newtonian physics in the suitable domain (motion in fluids), in the same technical sense in which Newton theory is an approximation of Einstein's theory". See "Aristotle's Physics: a Physicist's Look" by Carlo Rovelli (https://arxiv.org/abs/1312.4057).
Re: Why Quantum Mechanics?
#173> Why didn't God just make the universe classical and be done with it? What would've been wrong with that choice? I hear it over and over and still don't understand the premise. Classical mechanics is not something sacred. It is our first serious model of physics. Our first approximation is based on the scales at which we operate and our senses as humans. Furthermore, even "regular" quantum mechanics is a non-relativ…
To elaborate on this a bit: One may argue that "a state" is a simpler concept than "a superposition of all state". Even in pure mathematics [1], I don't think that (say) real numbers are less fundamental than natural (unlike Kronecker in "Natural numbers were created by God, everything else is the work of men"). What's true for the set theory route, does not need to be true for any possible mathematics, including tho…
> One may argue that "a state" is a simpler concept than "a superposition of all state".
What would that mean in the context of QM?
"A superposition" is "a state".
Re: Why Quantum Mechanics?
#174>> By my age, Einstein had completed general relativity, Turing had founded CS,
won WWII, and proposed the Turing Test, and Galois, Ramanujan, and Ramsey had
been dead for years.
I fee confused when an article begins with a blatant exaggeration about a subject I am cognisant in right off the bat because then Idon't know how much I can trust it when it speaks of subjects I don't know.
To wit, Turing did not win WWII and didn't found CS. Turing wrote a seminal paper in early computer science, but he didn't found the field of research called "computer science". To be honest, I have no idea who would rightfully deserve to be recognised as the founder of computer science, when there have been many contributions of the same value as Turing's, the most obvious examples being Church and Von Neumann, less well-recognised ones being Charles Sanders Peirce and Henry M. Sheffer, Claude Shannon, Conrand Zuse and others (Church described a theory of computation equivalent to UTMs; Von Neumann proposed the accursed Von Neumann architecture; Peirce and Sheffer described logic gates and showed the completeness of the NAND gate; Shannon proved the completeness of Boolean logic circuits; Zuse made the first programmable computer -Babbage only designed the first). And so on. In my mind, trying to ascribe feats to heroes that they never performed, diminishes, rather than exalts, the hero. Turing doesn't need any extra serving of praise for things he didn't do to be known for ever as one of the greats of CS.
Re: Why Quantum Mechanics?
#175> Why didn't God just make the universe classical and be done with it? What would've been wrong with that choice? I hear it over and over and still don't understand the premise. Classical mechanics is not something sacred. It is our first serious model of physics. Our first approximation is based on the scales at which we operate and our senses as humans. Furthermore, even "regular" quantum mechanics is a non-relativ…
> waters above the filament
*firmament
Re: Why Quantum Mechanics?
#176Earlier quoted context omitted.
It seems like you misunderstood the actual question. It attempting to get at why QM might be inevitable, not why classical mechanics is
Well, the very quotation treats classical mechanics as a reference. Q2 minus Q1 is much more interesting: why this specific theory (i.e. quantum mechanics), rather than anything else.
> Well, the very quotation treats classical mechanics as a reference.
Yes, as a reference for an alternative possible world. Other alternatives discussed are cellular automata.
Re: Why Quantum Mechanics?
#177Earlier quoted context omitted.
That's why physicists are so opposed to super determinism because like you say it would make life 'utterly meaningless' (I dont agree, a bit dramatic). Super determinism is the unpopular answer that solves many problems in quantum mechanics and relativity. It also makes a lot of sense if you think of the universe as pre-rendered, just like you would a CGI movie. Determine where all the particles land upfront througho…
> Life can still be fun even it is pre-rendered. Like a movie you don't know what's going to happen next anyways. What if my life isn't "fun"? A lot of people live out lives of complete suffering. Childhood cancer? Poverty? Disease? Genetic mental health issues? Inbreeding? Childhood trauma? That list goes on and on. That isn't a movie I signed up for. Does determinism think this is supposed to be a lesson of some so…
Nothing about superdeterminism says you can't find ways out of suffering... to use the movie example, the movie may play out such that your life gets better! Or it won't... superdeterminism just says that those frames are already printed on the film, we just don't know what they look like yet because we can't perceive the future.
Re: Why Quantum Mechanics?
#178Earlier quoted context omitted.
> I have a lot of trouble imagining any experiment which could completely rule out every other influencing factor It's called Bell's theorem and it can even be tested at home[4]. There are no local hidden variables in quantum mechanics.[1][2][3] 1. https://en.wikipedia.org/wiki/Bell%27s_theorem 2. https://en.wikipedia.org/wiki/EPR_paradox 3. https://en.wikipedia.org/wiki/Hidden-variable_theory 4a. https://www.youtube…
Thanks for this, hidden variable theories are very seductive but Bell's Theorem is definitive.
It's definitive that you have to give up locality (Bohmian mechanics), counterfactual definiteness (Copenhagen and others), or statistical independence (Superdeterminism). It's not definitive at all about local hidden variables.
Re: Why Quantum Mechanics?
#179Earlier quoted context omitted.
Anthropic arguments only work if there's a mechanism for generating other versions besides the one you're observing. For example, you could use the anthropic argument to explain why earth is in the "goldilocks zone" because there are plenty other planets out there at varying distances from their sun. So, if you want to make the argument that 3d is preferred for some reason you need to acknowledge that there are other…
> So, if you want to make the argument that 3d is preferred for some reason you need to acknowledge that there are other universes out there with 2d, 4d, etc that just can't sustain life and that therefore life only finds itself in the subset of universes that have three dimensions. Or you can make the argument that no other universes other than a 3D one can support life, i.e. that 3D is necessary for life. Then you…
I disagree. If there really is only one universe which is 3D, this argument does not in any way explain why it is 3D.
If you use Bayesian probability, you would in this case start with p(3d) = 1 since there's only one universe which is 3d and then end with p(3d | life) = 1. In other words, there's no explanatory power in the observation that there's life.
If instead you say that p(3d) = 1/1000 because maybe the multiverse has all sorts universes out there but you also say that life is only possible in 3d, i.e. p(life | 3d) > 0, but p(life | not 3d) = 0, then you go from p(3d) = 1/1000 to p(3d | life) = 1. In other words, the observation of life does have explanatory power.
Re: Why Quantum Mechanics?
#180>> By my age, Einstein had completed general relativity, Turing had founded CS, won WWII, and proposed the Turing Test, and Galois, Ramanujan, and Ramsey had been dead for years. I fee confused when an article begins with a blatant exaggeration about a subject I am cognisant in right off the bat because then Idon't know how much I can trust it when it speaks of subjects I don't know. To wit, Turing did not win WWII a…
Perhaps this comes down to having more context on Scott Aaronson's work and writing, but this section to me came off as humorous front matter, not some attempt to precisely characterize the history of computer science. See the front matter of his book (Quantum Computing Since Democritus) for more context on this.
On the actual meat of the post, Scott Aaronson is a definite authority figure (among others) on these topics especially as they relate to computing.