Niels Martens DPhil Candidate Philosophy of Physics Oxford
University Why Philosophy of Physics is Awesome!
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Phil of Physics Quantum (info) Thermodynamics/ Statistical
Mechanics Gravity, Space, Time & Space-time Specific sciences
Phil of Biology Phil of Mind Phil of Physics Phil of Mathematics
Philosophy of Science Epistemology Scientific method Specific
sciences (Anti)-realism Metaphysics
Is space real? Einsteins Relativity Theory Time slows down!
Space contracts! Cosmology/Big Bang Emergent Space(time)
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Leibniz-Clarke Correspondence Space exists! It makes sense to
talk about empty space Even if there is no play tonight, the
theatre is still there All talk about space is reducible to talk
about relations between particles Compare with family relations
Newton Clarke Leibniz SUBSTANTIVALISMRELATIONALISM
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Leibniz shifts: space must be relational Principle of
Sufficient Reason
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Immanuel Kant: Lets use your left and right hands There is a
difference between your right and left hand The relationalist
explains the different handedness of two objects via relations What
about a single hand in an empty universe?
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Newtons bucket: lets look at science! The relative motion
between bucket and water is the same in picture 1 and 3, but the
relative motion with respect to the stars is not! Problem: physics
becomes nonlocal Ernst Mach
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Philosophy of Quantum Mechanics
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Metaphysics: What does the world look like according to quantum
mechanics? Quantum information Probability/determinism/free
will
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Interpreting Quantum Mechanics Does light (and everything else
in the world) consist of particles? Or waves? Photo-electric effect
(Einstein Nobel Price): particles Double split experiment:
waves
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Double slit experiment
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Does each photon (light particle) go through both slits at the
same time? Can we measure which slit it goes through? Even if you
only send one photon through the slits, we still get a
(probabilistic) interference pattern! Photons are waves (and
electrons, and protons, and all other matter) You cannot say that
there is a localised particle that goes through one of the two
slits: there is a wave that goes through both slits: the photon is
in a SUPERPOSITION of going through the left and the right slit at
the same time
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This is absurd! So, at the smallest scale, our world consists
of quantum waves: light, electrons, protons, everything is a
quantum wave, meaning that the `particles are at several places at
the same time. Schrdinger (Magdalen College Alumnus): This cannot
be true. If it would be true, it should also apply to large objects
(since they are made up out of small objects), and it would be
absurd to have a large object - like a table - being here and
somewhere else at the same time! We never see tables in
superpositions!
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Schrdingers cat
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Ways out Instrumentalism (or the shut-up-and-calculate school)
Measurement `collapses the wavefunction If you measure with a big
apparatus, you will find the particle or cat in one specific
location/state: the probability of that location/state depends on
how big the wave is at that point. Consciousness `collapses the
wavefunction Pilot-wave theory Many-worlds interpretation