> Why didn’t God just make the universe classical and be done with it?
He did. Physicists just never managed to properly grapple with the concept that classical mechanics involves action-at-a-distance.
Why Quantum Mechanics?
161–170 of 248 posts
Re: Why Quantum Mechanics?
#162> 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…
QM/QFT is radically simpler to simulate than classical mechanics. It's infinitely more expensive though in terms of pure CPU speed though.
With classical mechanics you need to timestep and integrate F=ma and all kinds of associated issues. In QFT you just generate all possible 4D configurations of all fields, assign a weight to each by a prescription, and estimate the ones you're interested in finding the probability for by adding together the weights, take their square, and normalize by the total sum of weights.
Re: Why Quantum Mechanics?
#163Earlier quoted context omitted.
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…
You can't possibly hope for eliminativism to be meaningful? Like a computer is not on the level of a transistor, "you" is not on the level of a neuron, but on a higher integrative level.
I mean I am saying it does not matter. If "you" is the sum of your experiences, genes and your environment programming your brain over time, but decisions are either deterministic or probabilistic, then "you" really had no input on how your brain/body would ultimately develop. It does not matter how complex your program is, each decision ultimately comes down to a process on the lowest level that you don't control.
Re: Why Quantum Mechanics?
#164Earlier quoted context omitted.
I wondered that for a long time myself and recently stumbled on what I believe is (or at least is a good candidate for) the correct answer: planetary orbits are stable in three dimensions, but not any other dimensions. The anthropic principle therefore selects for three-dimensional slices/subsets of the wave function.
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 can conclude if life, then 3D.
Re: Why Quantum Mechanics?
#165Given 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.
I mean, if QM wasn't true we would observe something else, wouldn't we? I don't understand how this is a meaningful question.
Re: Why Quantum Mechanics?
#166> 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…
QM/QFT is radically simpler to simulate than classical mechanics. It's infinitely more expensive though in terms of pure CPU speed though. With classical mechanics you need to timestep and integrate F=ma and all kinds of associated issues. In QFT you just generate all possible 4D configurations of all fields, assign a weight to each by a prescription, and estimate the ones you're interested in finding the probability…
That does even transcend the meaning "simple" is used with in SNMP...
Re: Why Quantum Mechanics?
#167Earlier quoted context omitted.
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…
It's not that easy, unfortunately. The problem lies in the relationship between a mind - the system of patterns of connections and processes that constitute whatever it is that allows a subjective experience to occur as an emergent property - and the external world. That singleton which has experience, and the infinite outside which it experiences. Free will could be framed as unpredictable behavior arising from the…
It seems like a difference between a scientific philosophy definition of free will vs a common or theological one. I don't think most people would find the unpredictability definition very satisfying, even if philosophers or scientists use it. Lots of very simple systems can be unpredictable, like a decaying atom, but it is not exhibiting free will. I do think most people have an idea of "self" that is not predetermined, or probabilistic, but instead has some form of definite control (whatever that means) over their decisions. As such they can feel "good" about making the "right" decision and "bad for the "wrong" decisions etc. If each decision, no matter how complex the circuitry in your brain has become (remember you didn't have any control over that, it just happened) comes down to a deterministic or probabilistic process, I just don't really find it satisfying to call that "free will".
Re: Why Quantum Mechanics?
#168> 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?
Re: Why Quantum Mechanics?
#169> Why didn’t God just make the universe classical and be done with it? He did. Physicists just never managed to properly grapple with the concept that classical mechanics involves action-at-a-distance.
Nothing in classical mechanics can explain the double-slit experiment; nor the relativity of simultaneity.
Furthermore, action-at-a-distance (non-locality) makes classical mechanics inconsistent even with itself, so it's a non-starter (it implies grandfather paradoxes).
Re: Why Quantum Mechanics?
#170Because we're in a simulation. And they used a quantum computer to run it.