Friday, September 1, 2023

Where are we?

Unless something like the Bohmian interpretation or a spatial collapse theory is right, quantum mechanics gives us good reason to think that the position wavefunction of all our particles is spread across pretty much all of the observable universe. Of course, except in the close vicinity of what we pre-theoretically call “our body”, the wavefunction is incredibly tiny.

What are we to make of that for the “Where am I?” question? One move is to say that we all overlap spatially, occupying most of the observable universe. On a view like this, we better not have position do serious metaphysical or ethical work, such as individuating substances or making moral distinctions based on whether one individual (say, a fetus) is within the space occupied by another.

The other move is to say I am where the wavefunction of my particles is not small. On a view like this, my location is something that comes in degrees depending on what our cut-off for “small” is. We get to save the intuition that we don’t overlap spatially. But the cost of this is that our location is far from a fundamental thing. It is a vague concept, dependent on a cut-off. A more precise thing would be to say things like: “Here I am up to 0.99, and here I am up to 0.50.”


Zoe said...

Wolfgang Smith's interpretation of quantum mechanics has resolved the various quantum enigmas by pointing out that the physical world is *less real* than the corporeal one.

On this view QM doesn't give us anything to answer the question, "Where are we actually?" Only "Where are we potentially?" But the latter question doesn't appear to pose any problems with regarding 'position' as a fundamental thing or to any so-called ethicist in favour of child murder.

William said...

Another way is to recognize that the space around us can be seen as a sea of atmospheric atoms and, beyond that, virtual particles. As soon as the influence of the waveform of us cannot be distinguished from that of the waveform of the virtual particles and the atmospheric molecules -- less than a meter-- we have enough of a border. This is similar to the "bounds" of the solar system, where there is no end that is sharp, but at some point the gravity of the sun is not easily distinguishable from the gravity of other stars, etc.

Fr M. Kirby said...

I also think Wolfgang Smith's perspective in this area is helpful.

Too many physicists reify the quantum fields and their dispersed oscillations so much that they forget 2 things:
1. What the oscillations actually represent in terms of empirical reality.
2. The difference between concrete and abstract (with the latter firmly grounded in the former for physics operationally).

Re: 1, the "waves" in the QM realm interact to give probability amplitudes. Probabilities of what? (The answer to that is what theorists often forget is the key.) Probabilities of measured observable, "particulate" properties. So, all the popular nonsense of questioning whether particles are real results from forgetting what the waves are waving, so to speak! QFTs cannot dissolve the wave-particle duality in favour of waves because, whatever their mathematical shape, the meanings of their equations' components are tied to particles' measured states.

Re: 2, If concrete observables are incorrigibly particulate and the derived abstractions that describe or predict their ordering are inescapably "wavy", it is foolish to deny the reality of the concrete bodies to elevate ontologically the abstracted waves, since that would require cutting off the branch one is sitting on, epistemically.

Wesley C. said...

@Zoe and @Fr M. Kirby

I wonder how Wolfgang Smith accounts for quantum indeterministic behaviour of particles? Does anyone know? Because certainly the probabilities of the wave function are the probabilities of SOMETHING, namely the corporeal particle. Yet those probabilities also describe the behaviour of particles, which turns out to be most likely intrinsically indeterministic, so not just that we can't completely determine or predict what the particles will do next, but that the particles own actions are not strictly determined in any specific direction, so that they COULD HAVE behaved otherwise in the same external and internal circumstances.


smrtn said...

in the eternal moment