HPS211H1 Lecture Notes - Quantum Field Theory, Mechanics

2 pages75 viewsWinter 2013

Department
History and Philosophy of Science and Technology
Course Code
HPS211H1
Professor
Curtis Forbes

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LEC Feb 12
MISSED FIRST PART
Stern Gerlach Experiment
Electron being represented by wave function in nature
two distinct probability functions
superposition of states
cannot find electron
Schrodinger's Cat
How far can we take superposition
box with cat and radioactive material- probability that it will decay is 1/2
when it finishes enables hammer to hit a gong which releases gas and kills cat
how do we know if cat is dead or live
some ppl claim it is in a superposition of state- one half dead, one half alive
but schrodinger claims it is ridiculous to apply quantum mechanics (with superposition of states
and indeterminism) to macro world (determinism)
no scientific theory that est at what scale you have quantum and what is macro
Einstein
formulated rules of general and special relativity
special relativity claims nothing can go faster than the speed of light
Einstein-Podolsky-Rosen Paradox: two observers; we have a neutron- which has slight
probability of decaying into proton- electron; the particle that is made from it must also be
neutral; after the decay can be both arrows up or both arrows down (spin); before one side
measures the proton it is in superposition of both states up and down but the moment he
measured it was up (from his side); moment you measure it changes state of ; the lines between
quantum and macro actually exists;
quantum field theory makes quantum mechanics relativistic by removing all observables-spin,
etc.
clear contradiction between our understanding of determinism and finiteness of nature that is
being challenged
A Quantum Mechanical Worldview
it is an approximate theory but never been proven wrong
What was the quantum revolution?
The dawn of the 20th century saw a buildup of experimental anomalies- disproved wave theory
and particle theory of light
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