Why Quantum Mechanics? • Hacker News Board

Re: Why Quantum Mechanics?

#131

Post by MathCodeLove » Fri, Jan 28, 2022, 1:59 PM UTC

Dumblydorr wrote: post #127

Q1: Why didn’t God just make the universe classical and be done with it? What would’ve been wrong with that choice? Why mention God? If you're attempting a scientific stance, starting your initial question with an unproven deity who doesn't want us to eat meat on Fridays part of the year, why? Why include that, it's an instant turnoff to any evidence-based reader.

I think your assumption that he meant the Christian monotheistic god may be the problem. Maybe that's precisely what they meant, but I find more often in these kind of discussions its meant as a placeholder for "The event/entity/unknown source of the universe."

I'm an atheist myself and find no issue in the use of the word God here. We don't know with any certainty how the universe was spawned into being, using God as a sort of shorthand to state as much isn't a problem.

Re: Why Quantum Mechanics?

#132

Post by alecst » Fri, Jan 28, 2022, 2:00 PM UTC

EMM_386 wrote: post #95

MattPalmer1086 wrote: post #41

Earlier quoted context omitted.

Physicists don't largely choose physical theories on whether they make life meaningful or not. I think you're thinking of religious people.

> Physicists don't largely choose physical theories on whether they make life meaningful or not. I think you're thinking of religious people. I disagree, I think quite the opposite. Physicists often seem to adhere to a "religion" of sorts, that being atheism. Anything to get rid of the "God problem". It's not all so cut and dry. > “I believe in Spinoza's God, who reveals himself in the lawful harmony of the world, no…

In my physics PhD a meaningful portion of the department was religious. Had more to do with country of birth than the thing they were studying.

Re: Why Quantum Mechanics?

#133

Post by platz » Fri, Jan 28, 2022, 2:13 PM UTC

Dumblydorr wrote: post #127

Q1: Why didn’t God just make the universe classical and be done with it? What would’ve been wrong with that choice? Why mention God? If you're attempting a scientific stance, starting your initial question with an unproven deity who doesn't want us to eat meat on Fridays part of the year, why? Why include that, it's an instant turnoff to any evidence-based reader.

Religion isn't relevant to the question scott is pursuing and neither is your aversion to it.

Re: Why Quantum Mechanics?

#134

Post by platz » Fri, Jan 28, 2022, 2:20 PM UTC

_Nat_ wrote: post #92

> 4. To keep the discussion focused, in this post I’d like to exclude answers along the lines of “but what if QM is merely an approximation to something else?,” [...] imagine that, as fantastical as it sounds, QM were not only exactly true, [...] Seems like an absurd, conceptually-crippling stipulation, analogous to asking why [the fine-structure-constant is exactly 1/137]( https://en.wikipedia.org/wiki/Fine-structur…

#4 isnt about the accuracy of the fine structure constant.

#4 is about limiting the discussion to QM as opposed to dealing the claim that QM is incomplete - that maybe the only reason it gives us probabilities for events is because its incomplete, and maybe theres a deeper theory that would supersede QM; this line of reasoning would not be productive to scott's initial question, which is focused on the nature of QM, given that it is true in a fundamental way.

Re: Why Quantum Mechanics?

#135

Post by stared » Fri, Jan 28, 2022, 2:23 PM UTC

> 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-relativistic, low-energy approximation of Quantum Field Theory.

It is like asking why God created clouds, not just "waters above the filament"?

That said, Q2 minus Q1 is an interesting question.

Re: Why Quantum Mechanics?

#136

Post by ninkendo » Fri, Jan 28, 2022, 2:23 PM UTC

> As in, “I’m 100% fine with living inside a Matrix … I just want to understand why it’s a _unitary_ matrix!”

Best quote from the article right there. I love Scott's writing style... highly recommend his book "Quantum Computing Since Democritus" if you're into his blog.

Re: Why Quantum Mechanics?

#137

Post by platz » Fri, Jan 28, 2022, 2:27 PM UTC

guerrilla wrote: post #5

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.)

Scotts question is better because it asks to explain why the universe as we see it needs QM.

Your question is unbounded because you're asking us to imagine an alternative that doesn't exist; there could be infinitely many reasons because there could be infinitely many alternative possibilities you're asking us to imagine with no constaints

Re: Why Quantum Mechanics?

#138

Post by platz » Fri, Jan 28, 2022, 2:32 PM UTC

breuleux wrote: post #7

Given the infinite number of ways the universe could have been, it seems kind of a mathematical truth that whatever it ended up being was incredibly improbable to begin with. I would tend to say that unless it is logically necessary for the universe to be what it is, the question of why it is what it is necessarily lacks an answer. We should expect the universe to be improbable.

This assumes a differnt universe could have been possible. What pool are you sampling from? What notion of probability are you relying on?

scott is not asking what other universes were possible. he's asking to explain why QM must be true in the universe that we do observe.

Re: Why Quantum Mechanics?

#139

Post by platz » Fri, Jan 28, 2022, 2:40 PM UTC

stared wrote: post #135

> 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…

It seems like you misunderstood the actual question. It attempting to get at why QM might be inevitable, not why classical mechanics is

Re: Why Quantum Mechanics?

#140

Post by platz » Fri, Jan 28, 2022, 2:41 PM UTC

ninkendo wrote: post #136

> As in, “I’m 100% fine with living inside a Matrix … I just want to understand why it’s a _unitary_ matrix!” Best quote from the article right there. I love Scott's writing style... highly recommend his book "Quantum Computing Since Democritus" if you're into his blog.

agreed!