Sean Carroll: General Relativity, Quantum Mechanics, Black Holes & Aliens | Lex Fridman Podcast #428

Sean Carroll argues Einstein deserves credit for understanding quantum entanglement, and that black hole information is preserved in Hawking radiation — not destroyed.

• Carroll argues Einstein understood quantum mechanics better than commonly credited, with his objections to it largely correct and his work essentially anticipating quantum entanglement.
• A black hole of solar mass takes roughly one microsecond to traverse from Event Horizon to singularity — the singularity is a future moment in time, not a location in space.
• The single black hole at the Milky Way center (Sagittarius A*) has entropy of 10^90 — more than the entire observable universe had before stars formed (10^88).
• Carroll is skeptical of alien civilizations despite finding the premise reasonable: Fermi-style self-replicating probes could fill the galaxy in far less than its multi-billion-year age.
• The holographic principle (Maldacena’s AdS/CFT) posits that a gravity theory in N+1 dimensions is fully encoded in an N-dimensional theory without gravity on its boundary.
• Carroll is working on a research program called ‘complexogenesis’ — how complexity arises from a universe governed by reversible, entropy-increasing physics.
• Carroll’s third book in the Biggest Ideas trilogy is titled Complexity and Emergence, intentionally covering only established science rather than speculation.

Guests: Sean Carroll, theoretical physicist at Johns Hopkins and host of the Mindscape podcast · 2024-04-22 · Watch on YouTube