# Tag Info

0

As a note on the randomeness of quantum mechanics (though this might not be what you're directly asking in your question). Time evolution of a state/system is perfectly deterministic in quantum mechanics. It's only measurements that give "random" results. In a certain perspective, that's an effective model for our ignorance of how measurements work (for eg: ...

1

I've never heard about a non deterministic theory in physics, classical physics is, quantum theory is (if I take the wave function of the universe its evolution is deterministic), general relativity is ... And about the wave function collapse, it means that something not well understood happens when a system interact with another one which posses much more ...

1

The easy answer is "noone knows". The Schrödinger equation is just an equation that old Erwin threw together that happened to fit the experimental data. It is not even consistent with relativity theory (second derivative of space but only first of space) so clearly something is wrong with it. It just happens to work real well for engineering.

15

You're right; the Schrödinger's equation induces a unitary time evolution, and it is deterministic. Indeterminism in Quantum Mechanics is given by another "evolution" that the wavefunction may experience: wavefunction collapse. This is the source of indeterminism in Quantum Mechanics, and is a mechanism that is still not well understood at a fundamental ...

0

If one understands the 0-norm to be the intersection of the 1 and 2-norms, shouldn’t the trilemma really be the following (for any universe with very generic properties)? 1. Determinism, classical probabilities and quantum mechanics are all true. 2. Classical probabilities is true; the other two are false. 3. Quantum ...

-1

My opinion is that searches for alternatives are made because their proponents do not give sufficient weight to the message coming from representation theory. This message is the following. In classical physics the state of a system is a vector $x \in V_{2m}$ in a $2m$ dimensional phase. The physics is encoded by the symplectic group $Sp(2m,R)$. Classical ...

1

I once heard from one of my professors one convincing argument about QM being a non fundamental theory. If you look at Classical Mechanics, for example, you have just one dynamics governing all systems at any time. If it explained every experiment it would be a pretty nice fundamental theory. In Quantum mechanics, instead, one of the weirdest things from a ...

0

Below is my answer to a different question, but I think most of the points I make there are relevant here as well. My answer can be summarised as "there might not be an underlying theory, but then again there might, and if we don't look for it then we'll never find it." Not everybody has to participate in such a search, but it would be foolish not to take ...

2

Jim Graber says he can't speak for 't Hooft, Smolin or Penrose. Neither can I. But surely these physicists can and do speak for themselves. 't Hooft lists some "motivations for studying the ontological nature of quantum mechanics" (http://arxiv.org/abs/quant-ph/0701097), among them - the problems related to the "collapse of the wave functions" and the ...

1

In my opinion it is not only philosophy that is powering these alternative searches but also the human psychological set up. Inherent in us, and particularly the great technicians in the sample, is the drive to invent a better mousetrap. 't Hooft for example has great mathematical tools which he used brilliantly in his early career. Such honed tools "ask" ...

2

Obviously, I can't speak for 't Hooft, Smolin or Penrose, but I think that they and many other physicists think the inability to reconcile quantum mechanics (QM) and general relativity (GR) (the so-called quantum gravity problem) indicates that it is at least worth considering possible alternatives to QM. The fact that, as you note, QM is spectacularly ...

2

Possibly this is just a different way of making the same points Nathaniel alluded to in his comment. A physical theory is just a mathematical model. When constructing the theory we devise some mathematical model, compare it with experiment, and if our model predicts the correct results we announce it to the world. If our model fails to match observations we ...

0

Different types of theories are more suitable for describing different physical phenomena. The fact that you cannot use Newton's laws to describe an atom does not mean that you should not use them to describe your bicycle. Of course, some theories are more powerful than others. In fact, the three theories you mention form a hierarchy:  \text{deterministic} ...

-1

The answer is simple: classical mechanics is macroscopic (Planck's constant zero) and quantum mechanics is microscopic (Planck's constant not zero). It is a myth that any hidden variable theory that underpins quantum mechanics must be classical. They cannot be. Local realism uses non-classical ideas. Locality is not a quantum notion of course but is ...

-2

After conducting a 12 year experiment to see if events are predetermined, i.e., super-deterministic as John Bell had postulated, the evidence obtained absolute and precise results to substantiate that absolute determinism exists. I recently applied this discovery to the recent Higgs boson preliminary discovery and found a fundamental omission error has been ...

1

While quantum mechanics might not be as weird as we used to think (classical wave-particle systems exhibit many quantum-like properties - see eg this article), there's a fundamental disconnect between quantum and classical theories and various no-go theorems that go along with it (Bell, Kochen-Specker, Greenberger–Horne–Zeilinger are probably the most famous ...

Top 50 recent answers are included