The Arrow of Time and How to Reverse It
Summary
PBS Space Time explores why the arrow of time exists despite fundamental physics laws being time-symmetric. The episode explains how the Second Law of Thermodynamics and entropy increase break this symmetry, using the Big Bang’s low-entropy state to define the direction of time. It also discusses the speculative possibility of a symmetric universe where entropy increases in both directions from a central minimum.
Topics discussed
Sponsor: LinkedIn Hiring Pro
Sponsor: Uber Eats Game Day Delivery
Introduction: The Arrow of Time and Physics Symmetry
Perceiving Time: External Entropy vs Internal Memory
Reversibility of Motion: Electrons and the Block Universe
The Second Law of Thermodynamics and Entropy Definition
Sponsor: LinkedIn Hiring Pro
Sponsor: Uber Eats Game Day Delivery
Energy Distribution and Statistical Entropy Increase
Entropy Fluctuations and the Origin of Time's Arrow
Cosmic Expansion and the Low Entropy Big Bang
Sponsors: LinkedIn and Uber Eats
The Big Bang as an Entropy Minimum
Speculation: A Symmetric Universe and Reverse Time
Transition to Comments and Thanksgiving Break
Comment: Electroweak Theory and Vacuum Decay
Sponsor: LinkedIn Hiring Pro
Sponsor: Uber Eats Game Day Delivery
Comment: Free Will, Information Theory, and Compatibilism
Outro: QED Joke and Final Sponsors
Listen ad-free on Castria