StarTalk Radio · Neil deGrasse Tyson

Cosmic Queries – Understanding Infinity with Stephon Alexander

February 6, 2026·46 min·3 clips

Physicist Stephon Alexander confesses he doesn't know what infinity is, leaving Neil deGrasse Tyson speechless.

The archive frame comes first. Neil reminds StarTalkians that the catalog runs deep, then sets up Cosmic Queries as the fan-powered format where Patreon listeners can join in. Then infinity gets put to work. Alexander uses resisting magnets to show how classical physics can predict infinite force and energy in a place where real life stays annoyingly normal. The magnets touch. Nothing explodes. That gap is the point: infinity can be a sign that a theory has run out of road. Neil sharpens it. If ordinary strength can push two resisting magnets together, a calculation demanding infinite force is missing something. Feynman enters the conversation, and Alexander points to quantum physics as the next layer, with light as the quanta mediating the force and photons carrying the interaction. Then comes fuzzify. Nagin calls it out immediately, which is exactly why the joke lands. The word sounds fake, and infinity can sound fake too when it is tossed around casually. Neil lets the laugh sit for a beat, then pulls it back to the science: what does quantum mean in this magnet case? The answer stays grounded. Quantum behavior softens the classical picture, so the math stops pretending an ordinary magnet interaction contains infinite energy. The closing beat shifts into celebrity banter, with Hillary Clinton, Apple TV's Gutsy, and a favorite-astrophysicist joke giving the episode a loose landing before Neil signs off.

As heard by us

A playful infinity lesson that turns a magnet puzzle into a doorway to quantum physics.

Infinity is treated here less as a mystical endpoint than as a warning light in the math. Neil deGrasse Tyson and Stephon Alexander use Cosmic Queries to move from the big idea to a concrete problem: why two magnets can touch even when a classical calculation seems to demand…

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Why you'd press play

You've always half-suspected infinity is just what physicists say when the math refuses to behave.

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