APPLIED PHYSICS/PHYSICS COLLOQUIUM: Chao-Lin Kuo, Stanford University - “Knowing the Unknowable — The Experimental Study of Inflation”

Date Range
Tue February 22nd 2022, 3:30 - 4:30pm
Event Sponsor
Applied Physics/Physics Colloquium
Department of Physics

Stanford University


Tuesday, February 22, 2022

3:30 p.m. on campus in Hewlett Teaching Center, Rm. 200

Light refreshments served in Varian lobby at 3:15 p.m. Please register to attend:

Please wear face coverings and practice social distancing

In-person attendance limited to Stanford affiliates

Zoom webinar link:

Password: email dmoreau@stanford for password

Chao-Lin Kuo Stanford University

“Knowing the Unknowable — The Experimental Study of Inflation”

Inflation as the physical process of Big Bang explains many properties of the observable universe, including the density fluctuations and the large-scale geometry. In the first part of the talk, I will discuss how measurements of the cosmic microwave background (CMB) polarization can provide a crucial piece of information on inflation – its energy scale. I will discuss the status of the South Pole-based BICEP experiment and its recent results that limit the tensor-to-scalar ratio r to <0.036 (sigma=0.009). This direct measurement of inflationary energy scale rules out many once-promising models. I will describe the future of the project, which looks to improve this measurement by a factor of 3 in the next few years.


Inflation also has an unfortunate tendency of making the universe boring. It wiped out everything – exotic particles, topological defects, etc. leaving little memory of the early universe. In the second part of the talk, I will discuss other research activities in the Stanford CMB group that could shed light on the physics of inflation through effects on axion dark matter.