Diego Garza Astrophysicist in Training

The Physics of the Dark Universe

Here I share the resources from my Physics of the Dark Universe course taught by Gordan Krnjaic (GOAT’d). I think this was the first time this course was taught and it was also his first time teaching. Both went really well: the first couple weeks was virtual but the in person lectures were great because he was so engaging.

He spent the first 15 minutes of each lecture motivating the day’s topic and reviewing the previous lecture. This was great because it allowed anybody to ask clarifying questions we hadn’t thought of yet. With a hard course like this, you needed to review topics frequently to make sure you understood the topics. However with that, the class was very difficult conceptually. I felt like I could follow along, understand, and even ask questions about the topics in lecture, but each problem was basically asking students to analyze a completely new Universe. Looking back though, it was pretty cool and fun.

The class covered the following topics:

  1. Natural Units
  2. Special & General Relativity
  3. Freedmann-Robertson-Walker (FRW) Universe Model & Thermodynamics
  4. Multi-Component Universe (Radiation, Matter, Dark Energy)
  5. Entropy, Degrees of Freedom, Effective DoF
  6. Hubble Rate & Temperature
  7. Cosmic Inventory (Standard Model Particles)
  8. Inflation
  9. Baryogenesis
  10. Electroweak Phase Transition
  11. Quantum Chromodynamics Phase Transition
  12. Neutrino Decoupling
  13. Phase Space Function for Particle in Equilibrium
  14. Electron Positron Annihilation
  15. Big Bang Nucleosynthesis (& chemical potential)
  16. Matter-Radiation Equality
  17. Recombination (Hydrogren Formation)
  18. Cosmic Microwave Background
  19. Boltzmann Equation for Particles not in Equilibrium
  20. Dark Matter Thermal Freeze Out
  21. Matter Power Spectrum
  22. Dark Matter Direct & Indirect Detection

This class was really a mesh of particle physics, general relativity, thermodynamics, and cosmology. We went through the entire history of the Universe to finally reach how we’re currently trying to detect Dark Matter. Like Gordan said in first lecture, this class prepared me to go to the ArXiv and be able to understand most of an astrophysics or high energy physics paper. The main textbooks referenced in the class were a lecture notes from Daniel Baumann, Barbara Ryden, and Tongyan Lin.

This was one of my favorite astrophysics I took at UChicago. I felt out of my depth partially because the prerequisites included Statistical & Thermal Physics, which I would take the following school year, but he reviewed most of what was needed.

Here are my lecture notes:

Lecture 1

Lecture 2

Lecture 3

Lecture 4

Lecture 5

Lecture 6

Lecture 7

Lecture 8

Lecture 9

Lecture 10

Lecture 11

Lecture 12

Lecture 13

Lecture 14

Lecture 15

Lecture 16

Lecture 17

Lecture 18