Difficulties in Understanding Quantum Physics,
or What does the Wave Function Describe?
Quantum mechanics is very successful!
- Good calculational tool!
- A framework in which we express our physical theories.
- No failures yet found, despite many tests (still ongoing)
- BUT: (what) does Quantum Mechanics (QM) tell us about the physical
Features difficult to understand:
- Wave/particle duality, interference effects, non-locality, etc, as we all
- But there are more questions:
- Does anything actually happen? Are there actual events independent of
our immediate experience?
- Are all measurements really position measurements, even though precise
positions are never measured!
- What happens after measurements?
- Are actual and virtual events the same or different?
- Are all events really interactions?
What happens after a measurement?
- If we measure a ‘system’ described by wave function y=a1u1+a2u2
to discriminate between the ui, and u1
is found to occur:
- What happens after to the ‘unphysical’ u2?
- Equally as real as u1? many
- Exists, but has no effect? decoherence
- Dynamically reduced? new physics!
- If it occurs: When and Why?
- Large sizes? No: large superconductors
- Large distances? No: photons 20km apart
- Energy differences? No: we do see DE
- Spontaneous? (GRW) ad hoc
- Mind? (Wigner, Stapp) cat? virus?
- Gravity: is spacetime classical? (Penrose)
- Scope for new physics!? » tests ongoing.
- Any law should be Lorentz-invariant!
Does wave function describe anything?
- Relation between observations / experiences?
- Does it tell us what exists? What is a ‘system’?
- We agree that
- cannot use naive models of particles or waves
- assuming a ‘material world’ leads to problems, if ‘material’ means
‘solid’ or ‘fluid’
- I claim that: if we cannot find any idea of quantum existence, this shows
not that there is no underlying world, but that we lack imagination!
There are many references I could give for this section, to a wide range
of books and articles in both physics and philosophy.