I just released my podcast conversation with physicist Daniel Schroeder on thermodynamics where we address two fundamental questions: “What is temperature?” and “What is entropy?”. Dan is the author of two revered physics textbooks *An Introduction to Quantum Field Theory* (with M. Peskin) and *An Introduction to Thermal Physics* both of which were used in my physics courses during my student days. This conversation was a lot of fun: a mix of physics, math, and philosophy of science. The first two are self-explanatory; as for philosophy, there is the perennial puzzle of the arrow of time and why entropy is increasing despite classical physics having time reversal symmetry. Our episode got a chance to delve into such conceptual issues which would ordinarily be swept under the rug in a traditional course on thermal physics.

# Ethan Siegel at the Cartesian Cafe: Dark Matter, Losing the Nobel Prize, and Theories of Everything

I had a lot of fun with my recent interview with astrophysicist Ethan Siegel, who provided much insight into many things scientific and sociological. Our 3 hour conversation got divided into three videos: a main one on dark matter

and two separate discussions on Ethan’s criticisms of Brian Keating’s book Losing the Nobel Prize (based on an earlier article he wrote)

and Ethan’s thoughts on theories of everything (inspired by the recent proposals by Eric Weinstein and Stephen Wolfram).

Detailed information about the videos can be found in their video descriptions.

# Alex Kontorovich at The Cartesian Cafe

I had a very nice discussion with Alex Kontorovich on circle packings, a subject that isn’t covered in the standard curriculum of a mathematician’s training. I’m glad we talked about it because it’s one of those subjects that has its origins in the most basic concepts in mathematics and yet continues to be a source of infinite richness as it matures over centuries (millennia in the present situation!). It’s amazing how connections to wide-ranging fields of mathematics come up in our discussion, including fractals and their dimensions, hyperbolic dynamics and limit sets, Coxeter groups and the work of Escher, and the local to global principle for quadratic forms.