Quantum Theory The worst scientific theory of all time Dr Mark J Hadley Dept of Physics.
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Transcript of Quantum Theory The worst scientific theory of all time Dr Mark J Hadley Dept of Physics.
Quantum Theory
The worst scientific theory of all time
Dr Mark J Hadley
Dept of Physics
Plan
• Introduction to QT
• Why it is bad
• A bad theory of classical Mechanics– Classical probability
• Why the quantum world is different– Why QT is a bad response
• An alternative to QT
Quantum theory
• Predictions are intrinsically probabilistic.
• A state is represented by a vector, , in a complex Hilbert space.
contains the maximum possible amount of information.
• A rule to get probabilities from .
• A rule to describe the evolution of .
Includes
• Quantum mechanics
• Quantum Field Theory
• String Theory
How bad?
1. Quantum Theory
2. Genesis
3. ..
4. .
5. .
Why is it so bad?
• Fails to explain Nature– What is an elementary particle
• Particle spectrum• Fundamental forces
– What is happening in an experiment
• Prevents progress
(x)
• Gives probability information only.
• It is not the particle.
• It does not exist.
• It requires a new meaning to probability
• Cannot say what a particle is..• where it is…• what it is doing.
A bad theory of classical mechanics
• Throwing a projectile at a target.(r,) describes the probability of a
certain result.(r,,z,t) describes the evolving wave-
packet.
• Nothing else can be said about the projectile
A dice throw
(n) gives the probability of a particular result.
• The throw is governed by classical mechanics.
(n) = 1/6
• Why?
(n)
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
0.16
0.18
1 2 3 4 5 6
0
0.05
0.1
0.15
0.2
0.25
1 2 3 4 5 6
0
0.05
0.1
0.15
0.2
0.25
1 2 3 4 5 6
0
0.1
0.2
0.3
0.4
0.5
0.6
1 2 3 4 5 6
evens
high
lucky
(n)= 1/6
• Not from Newtonian mechanics
• Structure Phase space of initial conditions
+ Deterministic evolution
= Space of final conditions
• Symmetry
• Nothing else
Structural Implications
1
2
3
4
5
6Phase-space of initial conditions
(n)
Boolean Logic
Deterministic evolution
Classical Probabilities
• Satisfy Boolean Logic
• Are a measure of our ignorance of initial conditions.
• Can always be represented as Volume integrals.
Quantum Theory Probabilities
• Do not satisfy Boolean Logic
• Are represented by projections of a vector
• Are an intrinsic feature of Nature
A completely new meaning to probability
Classical and Quantum worlds are very, very similar.
For a single experiment– Can use classical probabilities
• Boolean Logic• Individual trajectories• No complex wave function
For incompatible experiments– Cannot construct a single phase-space of
initial conditions that gives the observed results.
The quantum World is context dependent
• QT is one response– It hides the difference
• State => Evolution => results
– At a cost• A new meaning to probability• No underlying explanation
The quantum World is context dependent
• Explain it with an existing theory– Sensible
• Explain it with a brilliant new theory– Genius
• Don’t explain it– Pragmatist
• Deny that anything needs explaining– Philosopher
The quantum World is context dependent
• Explain it with an existing theory– lazy
• Explain it with a brilliant new theory– insane
• Don’t explain it– loser
• Deny that anything needs explaining– bad loser
Using an existing theory
• Choice between:1. GR
2. GR
3. GR
GR and QT
• Can GR explain context dependent effects?– Yes
• Will it agree with QT predictions?– Yes it has to
Structure + Symmetry & Continuity = all equations of QT
Using GR
• GR allows a non-trivial causal structure– Measurement apparatus can set additional
boundary conditions
• Any Geometric theory of spacetime can have the same structure
From GR to QT
• Can GR get the equations of QT directly?– No (Not yet)– But remember (n)= 1/6
ProgressThe Logic of Quantum Mechanics Derived From Classical
General Relativity Foundations of Physics Letters Vol 10, No.1, (1997)
43-60.
• Topology change and context dependence International Journal of Theoretical Physics Vol. 38
(1999) 1481
• Charge and the topology of spacetimeClass. Quantum Grav. 16 No 11 (November 1999)
3567-3577
• Spin half in classical general relativity Class. Quantum Grav. 17 No 20 (October 2000)
4187-4194
• The orientability of spacetime Class. Quantum Grav. 19 (August 2002) 4565-4571
The Quantum World
• Explain it with an existing theory– GR (sensible)
• Explain it with a brilliant new theory– insane
• Don’t explain it– loser
• Deny that anything needs explaining– Quantum Theory (bad loser)