## Episode 050 - Craig Lent: decoherence, entropy, and faith

0:00 - Three issues: entropy, decoherence, Schrodinger vs. Dirac equations

2:30 - Schrodinger uses a non-relativistic Hamiltonian, with a p^2/2m kinetic energy

3:00 - Dirac equation absorbs special relativity by shifting from scalar to spinor field

4:00 - Quantum field theory as a further extension, accommodating fields that include many particles

5:00 - Field Lagrangian and all the particles and interactions in the Standard Model

6:00 - Even "everyday" gravity is in some sense accommodatable in the theory, just not extreme gravity capable of "separating out the vacuum"

8:00 - Decoherence, not to be confused with the measurement problem

9:00 - Decoherence arising from the interaction of a simple system with other systems

10:00 - Reduced density matrix begins to look classical

11:00 - Zurek and the work on decoherence: states that are "chosen" to survive interaction with the environment

11:30 - Measurement problem not solved by this work

12:30 - Entropy: the proposal that entropy is most fundamentally lack of information

progress from the special case of thermodynamic entropy, to statistical mechanics,

to von Neumann's quantum definition, to Shannon's information theory

21:00 - Craig's career: why is an engineer so interested in the fundamentals of physics?

24:00 - Journey of faith

30:30 - People of Praise in Indianapolis

31:20 - Final thoughts