Episode 51 - From Atoms to Quarks
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Goodstein - propose theories - prove them wrong - necessary for progress
theory becomes fact - e.g. special relativity, evolution (!)
models for atoms - kinetic theory, bond formation, an atom
to be seen, object has to reflect light, won’t work for atom or nucleus
Fermilab, machinery of quantum mechanics
Bohr model of atom - electron exists only in certain orbits
deBroglie’s explanation of Bohr model - 2r = n
not final word
Schrodinger - model successful
quantum mechanics of Schrodinger gave same precision as Bohr atom,
and beyond - entire periodic table
application of Heisenberg uncertainty principle - based on mass size larger mass, smaller region; P(r) graph - rmax = Bohr radius - electron
cloud
E(n) n = 1 sphere, n = 2, l=0; n=2, l=1 - “orbital” - donut - component of
angular momentum along vertical axis is 0, +/- h-bar : ml = 0, 1
n=3; - l=0, l=1, l=2, m=2
n>0, l=0...n1, m=+l...l
c.f. earth, air, fire, water -> periodic table
electron has spin
Pauli exclusion principle - not mentioned by name
atom = ion + one outer electron
building the periodic table - bringing in the electrons one by one
proton + neutron + electron ... three different parts
many many more elementary particles
“the eightfold way” - not mentioned by name - particle, antiparticle,
higher mass
experimental physicists and theorists
“quarks” - up = red, down = blue
up, down, strange; charm, top, bottom + antiquark ... will they be found?
Goodstein - Giordana Bruno - Copernicus’s idea -> life in other planets Bruno executed in 1600.
new knowledge can be threatening - lack of determinism - 1920's dangerous knowledge
closing credits
end
level:
no calculus
some angular momentum concepts used
difficult-to-understand business of spin projection along vertical axis
Episode 52: The Quantum Mechanical Universe
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principle
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begin
Goodstein intro
we don’t yet have all the answers
governed by QM in small scale
cosmic scale - general relativity
ultimate rules not yet known (GR contradicts QM)
optimism - end of physics?
All of the solutions of the TOE wouldn’t help - we already have the entire
universe
The real job of physics isn’t to find out everything - understanding,
insight, connections between things, intuition - what’s important and what
isn’t in a given phenomenon - abstract the simple out of the complicated approximations,
patterns noticed for first time, e.g. Kepler’s laws, Balmer series,
cannonball/moon similarity, arrangements
- result of hard work, trial and error; debates
connections are never forgotten
mechanical universe tale began with Copernicus; ends with QM revolution
solar system - mechanical
the atom - completely different
F=ma
electricity - Franklin - Leiden jar
Faraday - lines of force - Maxwell’s equations
Maxwell
problem with tape - jumpy, but still mostly intelligible
few details that didn’t fit - Michelson; Planck; Rutherford
Einstein, 1905
Lorenz
special relativity
general relativity
photoelectric effect explanation via photons
Young’s interference demonstration of waves
light particles
Ernest Rutherford
why did electrons not radiate away their energy and collide with nucleus
Bohr, deBroglie; matter waves
particle/wave duality
Heisenberg uncertainty principle
cause for motion; for change in motion
results of given set of circumstances not determined
c.f statistics - in principle still predictible, but QM says it’s impossible in
revolutions - but:
energy, momentum, angular momentum still conserved
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note:
E=mc2
spin - quantum mechanical gyroscope
Goodstein
Copernicus, Newtonian, new revolution - comparing the two
Newton’s laws not true - why teach - wrong laws replaced with right ones
still true - but not ultimate truth - arise out of deeper more profound laws
we ask new kinds of questions
human/divine authority - replaced with observation, measurement
We don’t believe in the mechanical universe, but the quantum mechanical
universe
“goodbye and good luck”
this episode makes very many connections to earlier ones; so is definitely
not a stand-alone episode
level: includes some calculus