This episode is with Abhay Ashtekar. He is Evan Pugh Professor of Physics at Penn State, where he also holds the Eberly Chair. In 1993, he founded the Institute of Gravitation and the Cosmos. Ashtekar’s scientific work focuses on theoretical aspects of general relativity, cosmology and quantum gravity. Here we talk about what is gravity?, loop quantum gravity, The big bang, The big bounce, Singularities, Black holes and gravitational waves.

Guest info: 

Website: https://science.psu.edu/physics/people/abhay-ashtekar 

Biography: https://www.aip.org/history-programs/niels-bohr-library/oral-histories/45807

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Timestamps:

00:00:00 Introduction

00:00:52 What is gravity?

00:10:50 Einstein's equivalence principle

00:15:34 Importance of geometry in physics

00:19:04 Introduction to quantum field theory

00:23:50 Einstein's work on quantum mechanics

00:25:04 Quantum field theory to explain reality

00:33:10 Scale of theory of relativity and quantum field theory

00:37:50 Introduction to loop quantum gravity

00:52:44 Gravity is a weak force

00:54:45 'Loops' in loop quantum gravity

01:05:20 Difference between strings and quantum threads

01:07:04 Status of Gravitons

01:10:58 Importance of gravitons

01:15:12 Gravitational waves

01:17:34 What is a black hole?

01:21:16 Black holes and loop quantum gravity

01:27:12 The Big Bounce

01:38:00 Loop quantum cosmology

01:39:07 Big bounce and the universe

01:41:31 Validating loop quantum gravity

01:45:25 Recommended reading

01:49:51 Thank you!

Recommended reading:

The Story of Loop Quantum Gravity- From the Big Bounce to Black Holes https://www.youtube.com/watch?time_continue=1042&v=x9jYH5VIF9E Before the Big Bang 1 - Loop Quantum Cosmology Explained https://www.youtube.com/watch?v=IFcQuEw0oY8&feature=c4-overview&list=UUtOgKmAM4MeFu-jd-HB3_cg A 

Short Review of Loop Quantum Gravity, by A. Ashtekar and E. Bianchi, https://arxiv.org/pdf/2104.04394.pdf 

Quantum Space-time: Beyond the continuum of Minkowski and Einstein, by A. Ashtekar, https://arxiv.org/pdf/0810.0514.pdf 

Clip: New Meaning of the Big Bang.

https://www.youtube.com/watch?v=U7kvjTRW-tw&feature=youtu.be