Particles of Thought

Growth rings on trees can measure time, allowing scientists to date things from the deep past. But, paleobotantist Dr. Kirk Johnson explains why, in the tropics, some trees have no rings.
For more, check out the extended interview with Kirk Johnson.
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Nature has been solving problems for billions of years. Evolutionary biologist Sean B. Carroll reveals why scientists still turn to evolution’s inventions for life-saving breakthroughs, from GLP-1 drugs to statins.
For more, check out the extended interview with Sean B. Carroll.
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In 2024, scientists claimed they achieved the unthinkable: the birth of dire wolf pups, reviving a species that vanished thousands of years ago. Now, those pups are growing—and changing. Evolutionary biologist Beth Shapiro reveals what it’s like to watch these predators mature into modern beasts.
For more, check out the extended interview with Beth Shapiro. 
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Is AI coming for your job? AI Expert Hany Farid breaks down how AI is taking jobs once considered “future-proof” and shares his advice to prepare young people for the future.
For more, check out the extended interview with Hany Farid. 
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What does it feel like to make one of the biggest discoveries in physics? Adam Riess knows — because his work revealed that the universe isn’t just expanding, it’s accelerating. In this episode, the Nobel Prize–winning astrophysicist takes us behind the scenes of the moment that changed cosmology forever. How did his team use exploding stars as “standard candles” to measure the cosmos? Why did the data point to a mysterious force now called dark energy, making up nearly 70% of the universe? And what’s behind today’s biggest cosmic puzzle: the Hubble tension? Plus, Adam shares what new telescopes could uncover — and why the next decade might rewrite the laws of physics all over again.
 
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Guest Bio: 
Adam Riess is an astrophysicist, professor at Johns Hopkins University, and a distinguished astronomer at Space Telescope Science Institute. In 2011, he was named as a co-winner of the Nobel Prize in Physics for his contributions to the discovery that the expansion rate of the universe is accelerating. Since then, he has continued refining measurements of cosmic expansion and the Hubble constant, aiming to find and measure the most distant type Ia supernovae known, to probe the origin of cosmic acceleration.

Timestamps
(00:00:00) Introduction
(00:03:16) What Is a Type Ia Supernova? 
(00:10:52) The Discovery of Dark Energy
(00:44:39) What Is the Hubble Tension?
(00:58:59) Winning a Nobel Prize
(01:15:32) Credits