# Are these articles proof that wave function is real?

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1. Dec 24, 2014

### Nick V

2. Dec 24, 2014

### Doug Huffman

Depends on your standard of proof and definition of science. Informed by Popper's The Logic of Scientific Discovery, I suggest that technology may be validated, as here, but that science must be falsifiable and beyond mere ad-hockery. It is an image artifact of some instrument.

3. Dec 24, 2014

### vanhees71

From the article on physicsworld.com:

"The group observed several hundreds of thousands of ionization events to obtain the results, with the same preparation of the wavefunction for each."

This shows that the experiment is in full accordance with the minimal statistical interpretation of the wave function. You have to prepare and measure a large ensemble of equally and independently prepared atoms in order to get the probability distribution for the electron's position and compare it with the prediction from quantum theory. So you cannot conclude from this that the wavefunction is necessarily ontic. The experiment is fully consistent with the usual epistemic view of the minimal interpretation.

4. Dec 24, 2014

### Nick V

So it doesn't prove or give evidence for the wave function being real?

5. Dec 24, 2014

### vanhees71

No! By the way, the wave function is complex ;-).

6. Dec 24, 2014

### Nick V

So your saying that it doesn't show/prove that the wave function is real. Also, what do you mean that it is complex? And do you think that the wave function is a real thing or just a mathematical tool?

7. Dec 24, 2014

### vanhees71

For me the wave function (or better quantum theory as a whole) is a physical theory allowing me to calculate probabilities for the outcome of measurements given an equivalence class of real-world preparation procedures. Whether there is an ontic interpretation of the quantum theoretical states or not for me is a purely metaphysical question without much implications for physics.

The thing with "complex" was a joke. Of course the wave function is a complex valued function in Schrödinger quantum theory (beyond that, i.e., in the relativistic context it's anyway only of approximate nature; there's no consistent interpretation of relativistic wave functions for interacting particles).

8. Dec 24, 2014

### Nick V

So you believe that it is just a mathematical tool and is not a real thing, correct?

9. Dec 24, 2014

### Staff: Mentor

That's a physicist's inside joke. In mathematics, the complex numbers are the ones that are of the form $a+bi$ where $i^2=-1$ - these are what laypeople call "imaginary" numbers. The real numbers are the subset in which $b$ is zero. The value of the wave function is a complex number, not a real one.

10. Dec 24, 2014

### Staff: Mentor

It does not. It's the result of combining a large number of individual measurements and no more shows that the wave function is real than a pie chart showing that the average American family has 2.2 children proves the existence of fractional children.

11. Jan 4, 2015

### Ilja

I disagree. In QFT, the wave function is, of course, a function on the configuration space, which is a space of functions. Thus, we have a wave functional. But this is clearly not a decisive problem - anyway, Haag's theorem tells us (roughly) that only some finite-dimensional regularizations make sense, say, a lattice theory with periodic boundary conditions so that as the UV, as the IR infinities are regulated away. And for these lattices the "wave functional" is again a simply wave function on a high- but finite-dimensional configuration space.

12. Jan 4, 2015

### vanhees71

Well, that's strictly speaking true. The only problem with that seems to be that space-time is not a discrete lattice, at least not within the resolution of our current observations.

13. Jan 4, 2015

### bhobba

It doesn't matter what Vanhees believes, or even me for that matter, the thing is the wave-function is complex so whatever it is a picture of it cant be a wave-function. Complex numbers are specified by two real numbers so you cant take a picture of it.

Nugatory gave its real explanation.

Thanks
Bill

Last edited: Jan 4, 2015