Simplified 3A covers
the first half of Volume 3 and chapters 37 and 38
of Volume 1 of The Feynman Lectures on Physics. The
topics we explore include:
will greatly benefit from a prior understanding of the material in
Feynman Simplified 1A, 1B and 1C. A familiarity with elementary
calculus is assumed.
- Why the Micro-World is Different
- Quantization and Particle-Wave Duality
- Indeterminism and the Uncertainty
- Probabilities and Amplitudes
- Identical Particle Phenomena
- Bosons and Spin One
- Fermions and Spin One-Half
- Time Evolution and the Hamiltonian
- The Two-State Ammonia Maser
Y & P Measured by a Barrier
a parallel beam of particle-waves incident on a barrier with a small
aperture that is followed by a detection screen, as shown in Figure
3-1. Let D be the aperture width, L be the distance between barrier and
screen, and let y=0 on the horizontal axis of symmetry.
Figure 3-1 Plane Wave
from Barrier with Aperture
the incident particles have momenta py=0 and pz=p0. What do we know
about the particles after they pass through the aperture?
Particles exiting the aperture must have y values
between +D/2 and –D/2.
cautions: we might assume the particle’s exiting y momentum is zero
with zero uncertainty, “but that is wrong. We once knew the momentum
was [entirely] horizontal, but we do not know it any more. Before the
particles passed through the hole, we did not know their vertical
positions. Now that we have found the vertical position … we have lost
our information about the vertical momentum!”