1. What was the original quark model of elementary particle physics and how does Lie group theory relate the masses of the pion, eta, and kaon mesons in this model? (p.659)

2. How does algebraic topology influence whether one can maintain an electric current in a closed wire loop that sits in a curved three dimensional space? (p.122)

3. How is the air pressure in an irregular soap bubble related to its curvature? Which curvature? (p. 227)

4. How does the observed fact that there are nearby thermodynamic states that cannot be connected adiabatically imply the existence of entropy, and why does entropy increase? (p. 183)

5. What are the Cauchy and the Piola-Kirchhoff stress tensors of elasticity (p. 618) and how does Lie group representation theory show that the 36 elastic coefficients reduce to 2 when the elastic body is isotropic? (p.663)

6. How does Jacobi's metric and the topology of the configuration space influence the existence of periodic motions in a dynamical system? (pp. 284 and 331)

7. In Kirchhoff's electric circuit laws, why are currents "chains", voltages "cochains", resistances "scalar products", and what roles are played by Poisson's equation and Weyl's method of orthogonal projection? (pp. 645 and 647)

8. Gauss invented "intrinsic" curvature (p. 232) and equated it to his "extrinsic" curvature for a surface in Euclidean space; how does Einstein's general relativity generalize this? (p. 318)

9. In what sense is a full rotation about an axis "something" whereas two full rotations is "nothing" and how is this related to Dirac's equation? (pp.499 and 517)

10. How does Weyl's "principle of gauge invariance" lead to the conservation of electric charge in quantum theory? (p. 536)

11. How are properties of fluid flows (Euler's equations, circulation, vorticity, Woltjer's theorem of magnetohydrodynamics) described via the Lie derivative. (p.144)

12. What do "relative homology groups" have to say about boundary value problems in physics and engineering? (p.381)

13. What does special relativity have to say about the physical significance of the Lagrangian and the relation between the Lagrangian and the Hamiltonian? (p.436)

14. What do the magnetic field, "Berry phase", and the "Aharonov-Bohm" effect have to do with parallel displacement and curvature? (pp. 442,554, and 472)

15. How does special relativity show that the magnetic flux law div B=0 implies Faraday's law, and that Gauss' law implies the law of Ampere-Maxwell? (p.200)

16. What is the Yang-Mills analogue of Faraday's law? (p. 550)