This document discusses our current understanding of matter at the quantum scale based on developments in physics over the past century. It outlines how classical physics broke down in the face of experiments like blackbody radiation and the photoelectric effect. This led to the development of quantum mechanics, which describes reality in strange ways like wave-particle duality and quantum entanglement. While highly successful, quantum mechanics raises philosophical questions about determinism, observation, and the nature of reality that are still debated today. It also explores implications for understanding the mind and consciousness.

1. How We See the
Matter That Makes
All Things
Steven Spencer
Applied Mathematician
Philosophers Corner
2nd October 2012 1

2. Outline
• The world of classical physics
• Things don’t quite add up!
• Enter the quantum
• The mechanics and the quantum
• Stranger and stranger
• What does it mean?
• Where is the mind in all this?
• Are you sure? 2

3. The world of classical physics
• Deterministic (Laplace 1749 - 1827)
• External observer and isolated experimental
systems
• Particles (Newton 1642 -1727)
• Waves (Hooke, Huygens, Young, Maxwell)
3
• Atomic theory (Dalton)

4. Things don’t quite add up
• Black-body thermal radiation → colours
• Stable atoms
• Line emission spectra
• Photoelectric effect
4

5. Enter the Quantum
• The physics of atomic and sub-atomic scales?
• Energy is emitted in ‘bits’ (quanta) (Planck,
1900) → tricky maths?
• Energy in light is in ‘grainy bits’ (photons)
which are particles with wave properties →
photoelectric effect (Einstein, 1905)
5

6. Two views of EM radiation
• Light is a wave! Light is a particle!
6

7. The Mechanics and the Quantum
• Orbital atomic theory (Rutherford, 1911)
• Quantised electron orbit atomic model
(Bohr, 1913) → ‘flights and perchings’
• Particles are waves! (de Broglie, 1924) →
orbiting electrons have integer
wavelengths!
• Matrix mechanics (Heisenberg, 1925) →
unanschaulich atomic world! 7

8. • Wave mechanics (Schrodinger, 1926) → how the
quantum state of a system evolves with time.
Anschaulich atomic world?
• Complementarity – wave-particle duality
• Deterministic description for wave functions +
Statistical description of matter and energy.
• Uncertainty principle (Heisenberg, 1927)
Momentum and position cannot be simultaneously
measured with unlimited precision. 8

9. The observer and the system
• The role of the classical observer
(measurement) of a quantum system becomes
central and hotly contested –
“We are not only observers. We are
participators. In some strange sense, this is a
participatory universe.” – John A. Wheeler
9

10. The Quantum World?
• Wave function evolution U(objective &
deterministic) + measurement R(subjective) =
confusion?!?
10

11. Electron Double Slit Experiment
(Feynman)
• Detector ‘D’ turned
on or off by observer
→ affects pattern on
screen by double slit.
Observer affects
outcome of experiment!
11

12. Stranger and stranger
• Superposition of states → possible in quantum
but not classical world (Schrodinger’s cat).
• Quantum emtanglement → Many particle
systems have a complicated combined
wavefunction even at ‘large’ distances!
• Einstein-Podolski-Rosen (EPR) effect – QM is
either ‘non-local’ (faster than light influences)
or is not a complete theory!
12
• Bell inequalities – QM wins again!

13. Schrodinger’s Cat Thought Experiment!
• Quantum
superposition
affects the
classical
world?
13

14. ‘Spooky action at a distance’ (Einstein)
• Before detection the electron wave is
‘everywhere’, at detection the wave function
collapses throughout the universe! 14

15. • Single source of two photons – ‘spin’
observation method at one end affects
observation at a distant point! Do particles
communicate with one another or are they
one entity ?!? 15

16. • Standard QM violates Bell’s theorem. Separated
particles are connected (entanglement)!?!
• Result confirmed by experiment (Aspect, 1982)!!
16

17. What does it mean?
• Starting point – no experiment has ever been
found that concludes against QM maths!
• Whatever happened to determinism?
“God does not play dice” – A. Einstein
vs
“A physical object has an ontologically
undetermined component that is not due to
the epistemological limitations of physicists’
understanding” – A. Eddington 17

18. • Ontologies (interpretations) –
a) Copenhagen (Bohr, Heisenberg and Born, 1927) –
Complementarity + uncertainty principle +
measurement + correspondence principle.
QM describes knowledge NOT reality!
“There is no quantum world. There is only an
abstract physical description.” - N. Bohr
“The idea of intermediate kinds of reality was just
the price one had to pay” – W. Heisenberg 18

19. b) Many-worlds / relative state (Everett, 1957) –
universal wavefunction never collapses → multiverse
c) Environmental decoherence – rapid disappearance
of quantum superpositions by interaction with
environment (useful for many interpretations).
d) Ensemble (Einstein) – Minimalist, statistical –
wavefunction for large numbers of particles only.
e) Relational – different observers see different
quantum states.
19

20. f) Pilot-wave (de Broglie, Bohm) – Particles guided by
wavefunction. Non-local, holistic universe, hidden
variables.
g) Objective collapse (Penrose) – physical mechanism
of collapse – extended QM.
h) Conciousness collapse - subjective reduction (von
Neumann/Wigner) & participatory anthropic principle
(J.A. Wheeler)
g) New theories (many!) – objective R wave function
collapse / non-linear U function. 20

21. Where is the mind in all this?
• What is a brain?
• Dense network – more
than 104 cell bodies and
km of wiring per cubic mm!
• Multiple cell types: spiking Q: Is the mind
neurons (1011 cells) for info (consciousness)
processing, analog neurons highly organised
& ‘supporter’ cells . brain activity?
21

22. Neuronal Behaviour
⇒
22

23. Quantum Theory of Mind
• Non-algorithmic thought → cannot be modelled by a
digital (Turing) computer.
• Consciousness as a quantum mechanical phenomenon
(Penrose & Hameroff) –
Hypothesis: Neuron microtubules within neurons support
quantum superpositions (non-computable behaviour) +
macroscopic quantum entanglement across brain.
• Highly controversial – decoherence counter-argument!
• Physical collapse of quantum wavefunction of
microtubules essential for consciousness (Orch-OR). 23

24. Complex Dynamical Behaviour Theory
of Mind
• Intrinsic non-linear dynamics of each individual neuron +
network dynamics (attractors, bifurcations of behaviour,
small changes in inputs lead to large changes in outputs).
• ‘Simple’ non-linear models found for behaviour of
individual spiking neurons → reproduce complex bursKng
behaviour.
• Apparently non-algorithmic behaviour (sometimes chaos)
from algorithmic (deterministic) components.
• Consciousness as an emergent phenomenon from a neural
network complex dynamical system of the physical brain.
24

25. Are you sure?
• An underlying level of reality?
• Quantum state decoherence and gravitons?
• Non-linear quantum theory
• The classical-quantum divide - looking for
decoherence
• To be continued… 25

26. THANK YOU!!!
26