JRE 1428 · February 19, 2020

Brian Greene

sciencephilosophytechnologyphysics

Who is Brian Greene?

Brian Greene is a theoretical physicist, mathematician, and string theorist. He has been a professor at Columbia University since 1996 and chairman of the World Science Festival since co-founding it in 2008. His new book "Until the End of Time" is now available: https://amzn.to/2ug680o

Topics and Timestamps

01Brian Greene explains string theory and why it's so difficult for the human brain to visualize 11 dimensions
02Discussion of entropy, time's arrow, and why the universe tends toward disorder and chaos
03Greene breaks down how quantum mechanics and general relativity don't play well together despite both being true
04Exploration of the heat death of the universe and what happens trillions of years from now
05Brian discusses his book 'Until the End of Time' and the philosophical implications of cosmology
06Joe and Brian dive into whether consciousness and time are fundamental to physics or emergent properties
▶Brian explains why visualizing 11 dimensions is impossible for the human brain0:05:30
▶Discussion of entropy as the fundamental reason time flows forward, not backward0:18:45
▶Greene breaks down why quantum mechanics and general relativity contradict each other0:32:15
▶Exploration of the heat death of the universe and ultimate cosmic fate0:48:20
▶Brian discusses consciousness and whether time might be an illusion or fundamental reality1:02:10

The Show

Joe sits down with theoretical physicist Brian Greene to explore some of the deepest questions in modern physics. Greene, a Columbia University professor and co-founder of the World Science Festival, brings his gift for making complex ideas accessible to the average person.

They start by discussing string theory and the challenge of conceptualizing the extra dimensions that string theory predicts exist beyond the three spatial dimensions and one time dimension we experience. Greene explains how our brains evolved to navigate a three-dimensional world, so imagining 11 dimensions is genuinely difficult even for physicists. He uses analogies and mathematical frameworks to help Joe understand why physicists believe these dimensions exist even though we can't perceive them.

The conversation shifts to entropy and the arrow of time. Greene explains that time appears to move forward because entropy always increases, meaning disorder in the universe always grows. This is why we remember the past but not the future, and why eggs break but don't unbreak. Joe finds this fascinating because it grounds the human experience of time in physical law rather than just perception.

Greene tackles one of the biggest unresolved problems in physics: the incompatibility between quantum mechanics and general relativity. Both theories work incredibly well in their domains, but they give contradictory answers when you try to apply them simultaneously, like at the center of black holes. This is why physicists are desperately searching for a theory of quantum gravity.

They explore the far future and what happens to the universe trillions of years from now. Greene paints a picture of the ultimate fate of the cosmos, discussing possibilities like heat death where all energy is evenly distributed and nothing interesting can happen anymore. It's heavy stuff that really puts human existence in perspective.

Throughout the episode, Greene discusses his new book 'Until the End of Time,' which explores these cosmic questions and their philosophical implications for how we understand consciousness, meaning, and our place in the universe. Joe keeps the conversation grounded and pushes Greene to explain things in ways that make sense to regular people, not just physicists.

Best Quotes

“Our brains evolved to navigate three dimensions, so asking us to visualize 11 is like asking a goldfish to understand calculus”

— Brian Greene