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Why Quantum Mechanics?

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Re: Why Quantum Mechanics?

#231

Post by ninkendo »

EMM_386 wrote: post #203
ninkendo wrote: post #177

Earlier quoted context omitted.

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.

> Nothing about superdeterminism says you can't find ways out of suffering Actually it does. Your movie is going to play out the way it plays out, regardless of whatever you do. Throw your feet up in the recliner or struggle for that next promotion, doesn't matter. Brain cancer. I just find this rubbish.

Do you find it rubbish because you don’t want to believe it’s true? Or because there’s holes in the logic?

You rejecting superdeterminism, deciding that your fate is up to you, and making positive decisions to improve your life, is great. Do that.

It may be though, that those positive decisions and deciding your fate is up to you, etc, was already printed on the film. Or if instead you just throw your feet up on the recliner and decide to do nothing, then that would have already been printed on the film as well.

If in a trillion years the universe ends and there’s a complete story to tell about everything that happened, and some external observer were to watch that story, they’d see you making whatever decision you made and your life turning out in a particular way. But they wouldn’t expect that if they rewound the film that things would somehow turn out differently.

Re: Why Quantum Mechanics?

#232

Post by cannabis_sam »

platz wrote: post #194
cannabis_sam wrote: post #152

>Why didn’t God just [MAKE THE PLANETS ORBIT AROUND EARTH] and be done with it? What would’ve been wrong with that choice? Okay then, can you explain the math behind that solution? How in the world does the words “God”, “just” and “be done with it” in anyway whatsoever help elucidate this issue…?

You're either getting caught up in the incidental religious reference, or failed to interpret Scott's conciseness. See this comment for elaboration on exactly what kind of counterfactual Scott is asking https://news.ycombinator.com/item?id=30117928 . He's asking about a hypothetical alternative in a very specific way, which is to see whether it sheds any light on the logical foundation of QM, not just to consider alt…

>he's asking about a hypothetical alternative in a very specific way, which is to see whether it sheds any light on the logical foundation of QM

Could easily be done without any references to an omniscient, omnipresent and omnipotent concept with exactly zero scientific evidence. Even worse the whole concept of God literally defies logic, so mixing god into this discussion is laughable, if it didn’t come from an authority in the field of QM. I have a lot of respect for Scott, but IMHO he would be more persuasive if he left his religious beliefs out of this argument.

>Scott's aim is to understand QM better.

How does referencing god help with this endeavor?

Btw, the comment you linked commits the exact same fallacy of assuming anthropomorphic qualities behind whatever created the universe…

Re: Why Quantum Mechanics?

#233

Post by nurettin »

seiferteric wrote: post #29
nurettin wrote: post #23

Earlier quoted context omitted.

I thoroughly enjoy these discussions where someone wants to talk about a bat, a natural occurrence, and people immediately produce a man with a bat costume and start talking specifically about their construction, completely oblivious to the aforementioned bat.

I get your point, it is a vast simplification, perhaps inaccurate, it is possibly that more exists in nature that we don't yet understand that could make free will possible (even God) but is not much more than speculation or chimera.

I want to show an example of what I mean. News: "Wow look how that tachyon beam exceeded speed of light!"

Commenters: "So are humans going to be able to travel FTL? Let's talk about that hypothetical for 200 comments!"

Completely ignoring physics. Everything must be human centric, everything must be dumbed down and anthropomorphised and become absolutely boring to the core until there is no more low hanging fruit left to pick.

Re: Why Quantum Mechanics?

#234

Post by posterboy »

CTmystery wrote: post #168
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…

I don't think the author was proposing that classical mechanics is something sacred. Rather, are there prohibitive consequences to a world where our invented model of classical mechanics perfectly matches reality?

Yes, classical mechanics suggests infinity, eg. the Newtonian method and infinitesimals, which is just as problematic as a Turing Machine's infinite tape or Maxwell's Demon. Really classical, platonic geometry requiring atoms with hard bounds is also inconceivable.

The uncertainty principle and stuff like Noether's theorem should nicely limit how to ask the right questions. Now I'm not sure if Noether's is a proof by contradiction that would answer the question directly, I rather doubt it.

It's a valid question for the sake of didactics at least, how much can be simplified and explained in classical terms without catastrophic loss of precision. Conversely, the slit-experiments for example are a probably the most prominent display of quantum effects in the experiential domain.

Re: Why Quantum Mechanics?

#235

Post by posterboy »

pontus wrote: post #112
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.)

I know you explicitly asked for non-string theory answers, but I have to give one anyway -- sorry! There's an argument in string theory called the brandenberger-vafa mechanism that I think is pretty clever: Imagine that a bunch of particles and antiparticles travel along in one dimension. Because they can't spread out, they'll eventually collide and annihilate. However in 2d that's not the case: they're more likely t…

> Imagine that a bunch of particles and antiparticles travel along in one dimension.

Haha, thank you, hahaha, but no, thank you very much.

> If you analyze this carefully you can show that in fact three of the spatial dimensions will tend to expand while the six remaining ones will remain compactified.

While 1 is the domain of time, I pressume.

Actually though, the universe is flat spread out, as is the surface of the earth, so the vertical axis, ie. gravity, also needs explained for the human experience to make sense. There are these types of questions like why is my right arm the left arm in the mirror but the head stays up?

I forgot the canonical answer but it's evidently the case that the brain automatically creates a recibrocal to the mirror image which denies the fact that the "left" arm is still on your right side.

Re: Why Quantum Mechanics?

#236

Post by messe »

posterboy wrote: post #235
pontus wrote: post #112

Earlier quoted context omitted.

I know you explicitly asked for non-string theory answers, but I have to give one anyway -- sorry! There's an argument in string theory called the brandenberger-vafa mechanism that I think is pretty clever: Imagine that a bunch of particles and antiparticles travel along in one dimension. Because they can't spread out, they'll eventually collide and annihilate. However in 2d that's not the case: they're more likely t…

> Imagine that a bunch of particles and antiparticles travel along in one dimension. Haha, thank you, hahaha, but no, thank you very much. > If you analyze this carefully you can show that in fact three of the spatial dimensions will tend to expand while the six remaining ones will remain compactified. While 1 is the domain of time, I pressume. Actually though, the universe is flat spread out, as is the surface of th…

> I forgot the canonical answer but it's evidently the case that the brain automatically creates a recibrocal to the mirror image which denies the fact that the "left" arm is still on your right side.

Generally the argument goes as follows: the mirror doesn't invert left and right. The image of your right arm is still on the right hand side of the image, just like your head remains at the top of the image. Instead it just inverts front and back.

Re: Why Quantum Mechanics?

#237

Post by dekhn »

Huh. What he's not talking about is QM, he's talking about the enormous math industry that built up around QM. Actual QM is experiments in labs with lasers and cryocooling. You can sit around with your complex amplitudes and fancy math but none of that is really necessary to appreciate or make forward progress in the actual underlying physics.

Sort of like string theory. Not exactly, but sort of.

Re: Why Quantum Mechanics?

#238

Post by grog454 »

deltaonefour wrote: post #227
grog454 wrote: post #222

Earlier quoted context omitted.

> 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. Can you elaborate on this or provide further reading?

Probability theory is just a bunch of theorems and axioms, it's a logical game we play just like graph theory or any other mathematical theory. If we roll a dice many times the dice follows a probability distribution. We don't know why this occurs in reality. Or in other words we don't know why this random mathematical theory some how is applicable to repeatedly observing a "random" process many times. We're not even…

I've always thought of probability, teleologically, as an approximation of deterministic processes that are too complicated to calculate explicitly.

Under very carefully controlled circumstances, even a die becomes deterministic and feasible to predict. Just drop it sufficiently low to the ground with as close to 0 angular and linear velocity as you can. Does something intrinsic or fundamental change as you increase the height at which you drop the die? I'd say no.

Re: Why Quantum Mechanics?

#239

Post by deltaonefour »

grog454 wrote: post #238
deltaonefour wrote: post #227

Earlier quoted context omitted.

Probability theory is just a bunch of theorems and axioms, it's a logical game we play just like graph theory or any other mathematical theory. If we roll a dice many times the dice follows a probability distribution. We don't know why this occurs in reality. Or in other words we don't know why this random mathematical theory some how is applicable to repeatedly observing a "random" process many times. We're not even…

I've always thought of probability, teleologically, as an approximation of deterministic processes that are too complicated to calculate explicitly. Under very carefully controlled circumstances, even a die becomes deterministic and feasible to predict. Just drop it sufficiently low to the ground with as close to 0 angular and linear velocity as you can. Does something intrinsic or fundamental change as you increase…

>Under very carefully controlled circumstances, even a die becomes deterministic and feasible to predict.

You aren't thinking deep enough. WHY is it an approximation? How come this random mathematical set of theorems and axioms happens to approximate these things?

When we DON'T look at the experiment in a controlled circumstance what is the fundamental process driving it to follow the laws of probability?

We in fact do not know. The phenomenon of probability is assumed... aka axiomatic. We have no further explanation for it. In fact it's encoded into a fundamental physical law. The second law of thermodynamics: Entropy must increase.

It's actually a misnomer. Increasing entropy is not the law, it is the consequence. Entropy increases because disordered configurations of particles are more probable then ordered configurations. Thus over time the more probable configuration dominates the system. Hence the system becomes more and more disordered. Note the word "Probable." Thus Probability is the fundamental axiomatic law here.

I understand why this is hard to process. It's because seemingly it seems like that if we understand the exact physics of a single particle it means we will understand the aggregate macro behavior of a billion particles by deriving the macro behavior from the physics of each individual particle. Turns out the aggregate behavior obeys axiomatic laws of entropy that we have no deeper explanation for. Even if you have a physics engine simulate the rolls of 10000000 physical dice approximately 1/6 of those dice come out to be 6. Why? We don't even know why the simulation behaves that way let alone the real world.

Re: Why Quantum Mechanics?

#240

Post by GoblinSlayer »

pontus wrote: post #179
guerrilla wrote: post #164

Earlier quoted context omitted.

> 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 multi…

When you assume 3D, there's no need to explain it, because it's assumed from the start. 3D needs to be explained if it's not assumed.
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