People I (Mostly) Admire 164. Unravelling the Universe, Again
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Aug 16, 2025 
Adam Riess, an astrophysicist at Johns Hopkins University and Nobel Prize winner, revolutionizes our understanding of the cosmos with insights into dark energy and cosmic expansion. He discusses how methods like Cepheid variables and type 1A supernovae have shaped distance measurement in space. Riess also addresses the challenges of the Hubble Tension and rethinking the standard model of the universe. Their candid journey through skepticism highlights the emotional impact of groundbreaking discoveries in modern cosmology.
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Hubble's Law And The Expanding Universe
- Edwin Hubble showed the universe is expanding by correlating galaxy distances with their redshifts.
- The farther a galaxy, the faster it appears to recede, like raisins in rising bread.
Cepheids Unlock Cosmic Distances
- Cepheid variable stars provide a period-luminosity rule to measure distance.
- Henrietta Leavitt used stars in the Small Magellanic Cloud to calibrate that relationship.
Why Type Ia Supernovae Behave Uniformly
- Type Ia supernovae are uniform because white dwarfs explode near the Chandrasekhar limit.
- That uniformity makes them standard candles visible across billions of light years.