This is such a poorly written article. I can't even begin to point out the mistakes. I'm sure Scott Aaronson will write a response and strike this down.
Macroscopic quantum objects cannot exist if P ≠ NP?
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Re: Macroscopic quantum objects cannot exist if P ≠ NP?
#22I'm not buying it 1 - P=NP is a mathematical problem. It has nothing to do with Physics. Physics has to do with Mathematics but one should be very careful when extrapolating (range, constraints, etc). 2 - Nature has no problem whatsoever solving complicated equations. Our mathematical models are the ones who suffer to model simple everyday stuff in Physics. Turbulence and Navier-Stokes equations, electromagnetic prop…
There is no evidence that nature can globally solve NP-hard problems. At best, nature finds locally optimum solutions to these problems.
Re: Macroscopic quantum objects cannot exist if P ≠ NP?
#23"Nobody knows why we don’t observe these kinds of strange superpositions in the macroscopic world." Yeah, why can't we observe processes that rely on lack of observation?
We can observe processes that rely on lack of observation in the microscopic world. Look up the one-slit and two-slit experiments[0]. In the two-slit experiment, we don't observe which slit the photon takes, but we can observe the interference pattern on the screen. The two-slit experiment works with photons, but not with bullets, or cars, or baseballs. [0]: http://en.wikipedia.org/wiki/Two_slit_experiment
Hmm, probably fair.
Re: Macroscopic quantum objects cannot exist if P ≠ NP?
#24I hope Scott Aaronson blogs about this article, because it espouses several of the wrong-facts he complains about and then cites him.
- Limitations on computers within physics are not limitations on physics itself. Analogously, you can simulate system so simple that a computer can't be made in them without your computer unmaking itself. Relevant: xkcd.com/505
- We do understand why we don't observe superpositions. It all comes down to this thing we call "quantum mechanics", which precisely describes those sorts of situations.
- The article consistently mixes up NP-Hard and NP-Complete.
> "And how does the universe decide whether a system is going to be quantum or not?"
Seriously, is this article a satire?
Re: Macroscopic quantum objects cannot exist if P ≠ NP?
#25Wait what? What this article is arguing is totally absurd - just because we can't model certain physical objects, they cannot exist?! That's like saying that since we can't model three gravitational objects interacting (i.e. the numerical solutions diverge, therefore to properly model the system, we would require increasing amounts of memory and time), therefore they cannot exist. I'm not saying that the physical cla…
If something can neither be modeled nor observed, in what sense does it exist?
We observe n-body systems continuously. We are all participants in n-body systems continuously.
Re: Macroscopic quantum objects cannot exist if P ≠ NP?
#26I'm not buying it 1 - P=NP is a mathematical problem. It has nothing to do with Physics. Physics has to do with Mathematics but one should be very careful when extrapolating (range, constraints, etc). 2 - Nature has no problem whatsoever solving complicated equations. Our mathematical models are the ones who suffer to model simple everyday stuff in Physics. Turbulence and Navier-Stokes equations, electromagnetic prop…
Your comments are non-constructive. This second point was almost religious.
To say that a mathematical problem has nothing to do with physics would not be right, since physics' major theories of today are essentially maths.
Re: Macroscopic quantum objects cannot exist if P ≠ NP?
#27Wait what? What this article is arguing is totally absurd - just because we can't model certain physical objects, they cannot exist?! That's like saying that since we can't model three gravitational objects interacting (i.e. the numerical solutions diverge, therefore to properly model the system, we would require increasing amounts of memory and time), therefore they cannot exist. I'm not saying that the physical cla…
I'm a simulationist. I believe that the universe we're experiencing is a simulation made by a far-advanced civilization. So in my reality, if something can't be modeled, it can't exist.
Not saying that this is the truth, just the way I choose to understand things.
Re: Macroscopic quantum objects cannot exist if P ≠ NP?
#28Wait what? What this article is arguing is totally absurd - just because we can't model certain physical objects, they cannot exist?! That's like saying that since we can't model three gravitational objects interacting (i.e. the numerical solutions diverge, therefore to properly model the system, we would require increasing amounts of memory and time), therefore they cannot exist. I'm not saying that the physical cla…
If something can neither be modeled nor observed, in what sense does it exist?
That's not the question. Macroscopic behavior as described by Schrodinger's equation has never been observed. Because of having no observations, we assume it does not exist.
The linked paper is arguing, "Because solving Schrodinger's equation is non-polynomial, and such solutions are infeasible when N is large, then they can't exist." The linked paper is stating that the phenomenon has not been observed, assuming it does not exist, and then trying to explain why.
tomp's point is that we observe systems in our Universe that we can't model efficiently all the time. Hence, the line of argument in the paper doesn't hold up.
Re: Macroscopic quantum objects cannot exist if P ≠ NP?
#29I'm not buying it 1 - P=NP is a mathematical problem. It has nothing to do with Physics. Physics has to do with Mathematics but one should be very careful when extrapolating (range, constraints, etc). 2 - Nature has no problem whatsoever solving complicated equations. Our mathematical models are the ones who suffer to model simple everyday stuff in Physics. Turbulence and Navier-Stokes equations, electromagnetic prop…
Your comments are non-constructive. This second point was almost religious. To say that a mathematical problem has nothing to do with physics would not be right, since physics' major theories of today are essentially maths.
"To say that a mathematical problem has nothing to do with physics would not be right, since physics' major theories of today are essentially maths."
No
Physics depends on mathematics, not the opposite.
Math exists regardless of physics.
Re: Macroscopic quantum objects cannot exist if P ≠ NP?
#30We can't directly observe superpositions (macroscopic or otherwise) because when doing so, we become entangled with the state of the observed object. The only thing special about macroscopic objects is that it is difficult to prevent or postpone their entanglement with the environment.
Think about Schrödingers' gedankenexperiment from the cat's point of view. It finds itself to be either comfortable or dying by toxic fumes; it can't see the superposition because it is inside of that superposition. The same thing happens to any observer trying to look at a quantum superposition.