A Boost For Quantum Reality

Eponymous Hero sends this excerpt from Nature: "The philosophical status of the wavefunction — the entity that determines the probability of different outcomes of measurements on quantum-mechanical particles — would seem to be an unlikely subject for emotional debate. Yet online discussion of a paper claiming to show mathematically that the wavefunction is real has ranged from ardently star-struck to downright vitriolic since the article was first released as a preprint in November 2011. ... [The authors] say that the mathematics leaves no doubt that the wavefunction is not just a statistical tool, but rather, a real, objective state of a quantum system."

Comments

Re:Heh

[steelfood]

It certainly knows.

It knows, but you don't. You don't because you haven't measured it yet. And until you measure it, the answer is not the simplified version of the cat being dead and alive at the same time, but that there's a probability it's dead, and a probability it's alive, but it'll never be more than probability until you actually confirm it. Once you confirm it by measurement, the probability of one state goes to one, and the probability of the other state goes to zero.

This goes back to the age-old question: If a tree falls in a forest and no one is around to hear it, does it make a sound? It certainly makes a noise, but does it make a sound?

If there's nothing to observe reality, does it still exist? That's the essence of Schrodinger's cat.

Re:Elephants!

[maxwell demon]

the mathematics leaves no doubt that the wavefunction is not just a statistical tool, but rather, a real, objective state of a quantum system.

If that's the case, I would suppose that wavefunctions have wavefunctions.

Yes. That's known as second quantization.

Re:I get it now

[History's Coming To]

The argument used to be whether the wave function was "real" or whether it was a mathematical artifact, in other words is a particle actually smeared out or does it exist at one point and we're just limited in our observations of it (aka a "hidden variable"). These days the argument is whether the (Copenhagen interpretation) wave function actually exists or whether it's a mathematical artifact of a different theory, such as Everett's "Many Worlds" interpretation. Personally I go with Everett, but for philosophical/anthropic arguments rather than anything testable at the moment.

Re:Heh

[jd]

Try this as a thought experiment. Imagine your brain and your DNA scanned into a computer. This is used to generate a simulated you. This simulated you is placed in a simulated room in which all the known laws of physics are simulated to a high degree of precision.

You are placed in an identical, but real, room. The two rooms are connected via a terminal (or, in the copy's case, a simulated terminal).

You and the simulated you can ask for any scientific equipment that can fit into the room. Both of you can conduct whatever experiments you like. The only requirement is a unanimous agreement between you, your copy and those running the experiment as to which of you is physical and which is virtual.

If no observation, experiment, or set of experiments, exists that can prove which is real, then you cannot prove what is "real" - there'd be nothing so unique to reality that would allow you to unquestionably establish that something belongs to reality and not to something else. If, however, you CAN through experimentation reach a unanimous verdict, then an objective reality is provable.

It is my opinion that it is the first case that would turn out to be true.

Re:It makes sense when compared to string

[jd]

I am not convinced that the particles regarded as fundamental actually are. I'm not even completely convinced that "particles" at that level even exist in the normal sense, since we know interference patterns exist when the gap is in time rather than in space. That makes no logical sense when using a corpuscular model.

It is my suspicion (IANAQMPBTIBO) that in precisely the same way that matter is merely energy that has "condensed" and entangled, particles are merely waves that have "condensed" and entangled. This is based on the fact that fundamental particles of the same type are totally interchangeable and no two particles of the same type are in the same state. To me, that does not appear distinguishable from saying that a single wave appears to be every particle of that type, since that would give you what is observed without having to have any new or excessively complex physics to explain it.

If that is correct, then neither space nor time are particularly important in QM. Which has been theorized by better minds than mine. You would be able to map everything into waveforms and not need spacetime for them to exist in. Rather, spacetime would be one way an observer could interpret those waveforms - it would be subjective, not objective. The waves themselves would be the only "reality". Again, there's a branch of QM based on just such a notion.

To answer your question as to what is "vibrating", in this line of thought there wouldn't be anything TO vibrate, per-se, no time for it to be vibrate in and no space in which the vibrations could take place. You'd simply have a multidimensional waveform where if you made some axis space and another one time, you could treat it as though something was vibrating. In practice, though, it would be a static n-dimensional waveform whose existence was logical rather than physical.

I like this particular branch of QM, as it means physics is a branch of mathematics, a specific group with specific properties and specific operations, and that the universe is a specific set of functions that wholly reside in that group. It makes maths the "ultimate" reality, which means these sorts of philosophical musings about the world can be answered through mathematical analysis (although maths permits that answer to be rigorously undefined).