The Digest.

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What If summaries

Every long episode from What If, read in minutes: the key takeaways, the chapters, and a digest of the whole conversation. An epic exploration of possibilities. Join Peter and explore science-based hypothetical worlds across space, technology, Earth, and prehistoric history. Each episode begins with a simple “what if” question and follows real scientific theory, physics, biology, and astronomy to see…

Nothing in This Universe Is the Right Size

Exploring extreme scales, from shrinking to atomic size to planets becoming stars, reveals fundamental physics and biological limits.

April 3, 2026