Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Why Quantum Mechanics?

scottaaronson.blog

Post reply on HN
Print view View original

41–50 of 248 posts

Re: Why Quantum Mechanics?

#41

Post by MattPalmer1086 »

trixie_ wrote: post #27
EMM_386 wrote: post #24

Earlier quoted context omitted.

I strongly feel that the mystery of consciousness is somehow deeply tied into why we have things like QM and not classical physics. If it was just classical physics, then you get yourself into the thinking that you can rewind time and all the "billiard balls" knock into each other the same way, which is why you order a soup and not a sandwich every single time on that day. That eliminate free will. There is something…

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…

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

Re: Why Quantum Mechanics?

#42

Post by deltaonefour »

ketralnis wrote: post #13
deltaonefour wrote: post #3

The answer to these questions is one of those things that are beyond human understanding. It's like asking why does probability work? Why does predicate logic work? They are axioms. We have never looked beyond these axioms nor will we ever in your lifetime. I mean we may find a deeper mathematical model for quantum mechanics but the question of "why?" will never be answered. It may not even be the right question.

Why does a^2+b^2=c^2 for a right triangle? It's just axiomatic, right? Not exactly. It's only true in flat euclidean geometry. If General Relativity holds then we're only in a flat spacetime if the total energy content of the universe is in some range of values, otherwise the universe could be the 3d equivalent of a sphere or it could be a hyperbolic shape. In neither of these configurations do right triangles behave…

>Why does a^2+b^2=c^2 for a right triangle? It's just axiomatic, right?

Pythagorean theorem is not an axiom. It's a theorem.

>Not exactly. It's only true in flat euclidean geometry

It's a theorem for Euclidean geometry.

>So a^2+b^2=c^2 if and only if the big bang happened to have some particular initial conditions. It's not axiomatic, and studying _if it's even true_ tells you a lot more than you'd expect.

For theorems and the entire concept of math to even work all forms of mathematics from Euclidean geometry to hyperbolic geometry rest on universal axioms of logic. At best we have built higher forms of logic from the universal axioms and mathematics from arbitrary assumptions but we have never delved deeper than the 3 "laws" of logic.

The other weird thing that we don't understand, and this is likely connected with logic is probability. We don't know why it works. It seems foundational just like logic but the weird thing is, formally probability is just like another math theory with random axioms at it's foundation and the rest of the theorems built up from logic.

>If General Relativity holds then we're only in a flat spacetime...

This is part of science. Observed phenomena then statistically matched to a arbitrary mathematical model. The OP's article is talking about something more fundamental... he asks "why?"

When you ask that kind of question you have to really deep. Deeper than the science, deeper then the math all the way to the bottom. Everything stops at logic and probability. There is nowhere left to go to even move the needle closer to answering the question "why?"

Re: Why Quantum Mechanics?

#43

Post by deltaonefour »

moonchild wrote: post #4
deltaonefour wrote: post #3

The answer to these questions is one of those things that are beyond human understanding. It's like asking why does probability work? Why does predicate logic work? They are axioms. We have never looked beyond these axioms nor will we ever in your lifetime. I mean we may find a deeper mathematical model for quantum mechanics but the question of "why?" will never be answered. It may not even be the right question.

That is an assumption. We do not currently know of any process by which we might explain these axioms; but: 1. We may still glean insight by reflecting on them, and 2. There may be unknown processes by which we can explain these axioms

1. All axioms are assumptions.

2. You mean Logic? The foundation which axioms and theorems themselves rely on? Logic is like a recursive axiom. We assume logic is true (aka an axiom) then, logic allows us to create axioms themselves and build theorems off the axiom.

The thing with logic is that it's almost a thought driven endeavor. We don't need to observe the world to go deeper. But we can't. The buck ends here. To answer the question "why?" we have to go deeper, but there's nothing left.

Re: Why Quantum Mechanics?

#44

Post by deltaonefour »

bawolff wrote: post #10
deltaonefour wrote: post #3

The answer to these questions is one of those things that are beyond human understanding. It's like asking why does probability work? Why does predicate logic work? They are axioms. We have never looked beyond these axioms nor will we ever in your lifetime. I mean we may find a deeper mathematical model for quantum mechanics but the question of "why?" will never be answered. It may not even be the right question.

We may not find the answer, but it seems really different than say predicate logic. It seems easy to imagine a non-quantum world. I can't imagine a world where predicate logic doesn't work.

The universe seems to be built in layers. Science, Math, and logic in that order with logic at the very bottom. So logic is always PART of the answer as it's just a layer on the bottom of everything. The thing is, I would imagine the answer to the question "why?" is on some hidden layer below logic.

But the buck stops there. Even the very thought of predicting that there's a hidden layer has to involve logic. To get at the hidden layer we have to remove the upper layer of logic and therefore the process of thought itself. How is this even possible?

We can't go further. It's beyond us.

But I get what your saying. You think the answer exists on the side or the upper layers. Science and beyond.

Re: Why Quantum Mechanics?

#45

Post by trixie_ »

MattPalmer1086 wrote: post #41
trixie_ wrote: post #27

Earlier 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…

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

I'm not. Otherwise why would physicists support the concept of free will so strongly without any evidence for it. It is borderline religious. The video I posted above says as much.

Re: Why Quantum Mechanics?

#47

Post by lordnacho »

chaxor wrote: post #17
guerrilla wrote: post #12

Earlier quoted context omitted.

They're really not stable in two dimensions? Hmm [1], and another answer [2] (mentioned by Hawking apparently) but that's less convincing since there could be a 2D universe with intelligent organisms that just have their digestive systems on the outside... 1. https://www.reddit.com/r/askscience/comments/q8fmo/what_woul... 2. http://ion.uwinnipeg.ca/~vincent/4500.6-001/Cosmology/2-D_Di...

Right hand rule only works in 3d and 7d

That is rather fascinating, where can I read about this?

Re: Why Quantum Mechanics?

#48

Post by astrange »

seiferteric wrote: post #15
trixie_ wrote: post #11

Randomly found a link to this video on super determinism from his blog and found it super interesting. 100% agree, what is 'free will' anyways? A concept with no scientific definition. Why is it even used to explain anything in quantum mechanics? https://www.youtube.com/watch?v=ytyjgIyegDI

I think the question of free will is even simpler. It doesn't come down to determinism vs indeterminism because either way it's not "you" making a decision. At the lowest level (neuron or whatever) when a decision is "made" it is either deterministic (determinism) or probabilistic (indeterminism) based on physics but either way, where is the "you" in the process? Only way free will makes sense is if something superna…

There can't be a "you" with true free will even if there's a supernatural other dimension containing you, because there's still only those two options wherever you are.

The best you can do is be evolved to use true randomness (if it exists) to choose between good-enough actions, so at least nobody else can predict what you're going to do.

Re: Why Quantum Mechanics?

#50

Post by astrange »

trixie_ wrote: post #27
EMM_386 wrote: post #24

Earlier quoted context omitted.

I strongly feel that the mystery of consciousness is somehow deeply tied into why we have things like QM and not classical physics. If it was just classical physics, then you get yourself into the thinking that you can rewind time and all the "billiard balls" knock into each other the same way, which is why you order a soup and not a sandwich every single time on that day. That eliminate free will. There is something…

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…

Note, I don't think Sabine's theory in this video actually is "superdeterminism" even though she called it that. It's rather "retrocausality", which is still magical but more limited.

However, there isn't an explanation for why it's limited - seems like if the partial case could happen then the whole thing could happen too. (there's a long argument about this in the comments of Scott's post)

Post reply on HN