Transcript Philosophy of Physics PHL 356 S (2016) Department of Philosophy University of Toronto

Philosophy of Physics
PHL 356 S (2016)
Department of Philosophy
University of Toronto
General information
Wednesday, 6:30 - 9:00
UC 256
http://www.chass.utoronto.ca/~jrbrown/WeeklyReadings356Physics.htm
James Robert Brown
170 St. George St, Room 514
Cell: 519-854-0131
[email protected]
Office hours: After class or by appointment. Email is often best and fastest.
Course Outline
This course will examine some of the fascinating issues in
contemporary physics. The general theme of the course will be:
What is objectively real and what is not (in modern physics)?
The first part will be devoted to space and time: Does time pass,
or is the flow of time an illusion? In the light of special and
general relativity, are temporal order and geometrical structure
facts about the world or are they conventions? Is space an
entity in its own right or just a system of relations among
physical bodies? The second part of the course will be devoted
to problems in quantum mechanics: Does QM offer a complete
description of reality? Do observers discover an already
existing reality or do they somehow create it by measuring and
observing? The focus will be on the Copenhagen interpretation,
the EPR argument, and the Bell results concerning non-locality.
Some mathematical background, such as first year calculus is
recommended (but it can be rusty).
Texts & Requirements
• TEXTS:
Various articles will be assigned.
Books (available in Bookstore):
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Huggett (ed), Space From Zeno to Einstein
Rae, Quantum Physics: Illusion or Reality
• REQUIREMENTS:
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Two short in-class tests (25% each)
Mid-term (50%)
Main themes
Space & time
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Does time pass, or is passage an illusion of some
sort?
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Does space have a geometry, or is it a (convenient)
convention?
•
Do space and time exist independently of other
things, or are they some sort of system of relations?
Quantum Mechanics
•
•
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Do we discover reality or do we somehow
create it by measurement?
Are there different “realities”, ie, micro-,
macro-, physical, mental?
If measurement has some effect, does it
violate special relativity by sending signals
faster than light?
General Theme
The unifying theme in the course:
How much of current physics is about
independent, objective reality, and how
much is (in some sense) our creation?
Metaphysics and Epistemology
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Philosophy of physics is largely the metaphysics
and epistemology of a special topic, physics.
•
The same could be said for the philosophy of
biology, mathematics, and so on.
•
What do these terms mean?
Metaphysics
•
Metaphysics = the study of the more general features of reality,
especially those that are not clearly empirical. (The boundary is fuzzy;
there is no sharp line between metaphysics and physics.)
•
For some people, “metaphysics” is a term of abuse.
•
Examples
–
are space and time absolute or relational?
–
determinism or chance (in physics)? (determinism or freewill (people)?
–
laws of nature – are they just regularities, or a form of causal necessity, or
relations among abstract entities?
–
do chemistry, biology, psychology really reduce to physics (ie, QFT or to
strings)?
–
is there any other way to conceptualize reality than in terms of substances
with properties?
–
is there a boundary between physics and metaphysics?
Epistemology
• Epistemology = the study of knowledge. What is
knowledge?, how it is acquired?, what justifies a
belief?, and so on.
•
Most scientists and most philosophers are
empiricists.
•
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Empiricism = all knowledge is based (sometimes indirectly)
on sensory experience.
Problem: What about non-scientific knowledge:
mathematics, ethics, philosophy (eg, the doctrine of
empiricism itself), religion?
What about thought experiments?
Do bodies fall at different rates?
Without experiment, I am sure that the effect will
happen as I tell you, because it must happen that way.
- Galileo
L
H
H+L
Galileo’s Reasoning
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Aristotle and common sense claim: H > L.
Thus, H+L > H
But, H > H+L
This is a contradiction.
• Galileo’s resolution: H = L = H+L.
• In other words, all bodies fall at the same rate,
regardless of their weight.
What is our job?
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Physicists are very good at doing physics. (By contrast, astrologers
are terrible at doing astrology.)
•
For the most part we will take relativity and quantum mechanics as
given.
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Our job is to make sense out of the best theories going and to try to
answer philosophical questions that arise.
•
We might also make a contribution to foundational issues, that is, sort
out conceptual confusions.
•
Sometimes we can criticize (philosophers occasionally see
conceptual problems that others don’t see), but this will be rare.
(Rare in physics, perhaps more common in the social sciences.)
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We will meet each week at 9:30 pm and go until noon.
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Short break?
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I will usually hang around for those who want to talk more.
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Office hours? By appointment. Email is generally fastest.
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Lectures will be available on-line two or three days in advance. Also
posted: required readings and/or links to other papers and possibly
interesting things.
•
Each week before class check:
http://www.chass.utoronto.ca/~jrbrown/WeeklyReadings356Physics.htm
Questions?
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Math anxiety?

Physics background?
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Philosophy background?
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What will tests/exam be like?
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Other questions?