Particles of Thought

How did animals first make the giant step from water to land? Evolutionary biologist Sean B. Carroll explains how the discovery of Tiktaalik—a fossil with both fish and limb-like features—revealed a key moment in evolution. For more, check out the extended interview with Sean B. Carroll. Learn more about NOVA and subscribe to our YouTube channel. 

Black holes aren’t the cosmic monsters Hollywood makes them out to be. Astrophysicist Janna Levin explains why they’re so hard to detect, why they’re not as destructive as you might assume, and how you could safely orbit much closer than you think. For more, check out the extended interview with Janna Levin. Learn more about NOVA and subscribe to our YouTube channel. 

Could the universe be governed by a law we haven’t discovered yet? Mineralogist Robert Hazen and astrobiologist Michael Wong propose a new rule—the law of increasing functional information—to explain why complex systems evolve and why complexity keeps emerging over time. For more, check out the extended interview with Robert Hazen and Michael Wong. Learn more about NOVA and subscribe to our YouTube channel. 

AI isn’t just coming for office jobs—it’s coming for some hands-on blue collar professions, too. AI expert Hany Farid explains which jobs are safe, and which are at risk.  For more, check out the extended interview with Hany Farid.  Learn more about NOVA and subscribe to our YouTube channel. 

Scientists claimed in 2024 that they "de-extincted" the dire wolf… so what’s next, and what determines whether a species can be brought back? Evolutionary biologist Beth Shapiro explains some of the factors that go into deciding what to try and bring back.  For more, check out the extended interview with Beth Shapiro.  Learn more about NOVA and subscribe to our YouTube channel. 

Dinosaurs might not have been the roaring beasts many imagine. Neuroscientist Erich Jarvis explains why modern birds—living dinosaurs—offer clues about vocal learning and why dinosaurs could have been singers. For more, check out the extended interview with Erich Jarvis.  Learn more about NOVA and subscribe to our YouTube channel. 

If the universe is expanding, why aren’t galaxies stretching apart? Cosmologist Adam Riess breaks down the physics behind cosmic expansion, the forces that resist it, and why dark energy dominates the vast spaces between. For more, check out the extended interview with Adam Riess. Learn more about NOVA and subscribe to our YouTube channel.

Why does thinking too hard ruin your rhythm? Neuroscientist Heather Berlin unpacks the science of flow states, explaining why mastery means trusting your brain’s hidden systems to do what they do best. For more, check out the extended interview with Heather Berlin. Learn more about NOVA and subscribe to our YouTube channel. 

Black holes can be bigger on the inside than they are on the outside. Astrophysicist Janna Levin explains how this is possible, and what that means about how black holes work.  For more, check out the extended interview with Janna Levin. Learn more about NOVA and subscribe to our YouTube channel. 

What’s the difference between a fact, a law, and a theory? Mineralogist Robert Hazen and astrobiologist Michael Wong unpack the hierarchy of scientific ideas and reveal how laws of nature elegantly unify the universe. For more, check out the extended interview with Robert Hazen and Michael Wong. Learn more about NOVA and subscribe to our YouTube channel. 

Sorry, Beyoncé, it turns out microbes rule the world. Microbiologist Peter Girguis explains how to conceptualize just how many microbes are on Earth… and how understanding this helps us look for life on other worlds.  For more, check out the extended interview with Peter Girguis. Learn more about NOVA and subscribe to our YouTube channel. 

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. Learn more about NOVA and subscribe to our YouTube channel. 

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. Learn more about NOVA and subscribe to our YouTube channel. 

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.  Learn more about NOVA and subscribe to our YouTube channel. 

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.  Learn more about NOVA and subscribe to our YouTube channel. 

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.  Learn more about NOVA and subscribe to our YouTube channel.  ————————— 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

The universe isn’t adding up—and it’s creating a crisis in cosmology. Nobel Prize winner Adam Riess explains why measurements of the universe’s expansion rate from its earliest light and from nearby galaxies don’t match, and how this growing gap threatens the foundations of our standard model of the cosmos. For more, check out the extended interview with Adam Riess Learn more about NOVA and subscribe to our YouTube channel. 

Discovering dark energy wasn’t just thrilling—it was terrifying. Nobel Prize Winner Adam Riess explains the nerve-wracking process behind confirming that the universe’s expansion is accelerating and why Einstein’s so-called “biggest blunder” turned out to be anything but. For more, check out the extended interview with Adam Riess Learn more about NOVA and subscribe to our YouTube channel. 

Fame can hijack the brain like a drug—activating the same reward circuits that fuel a relentless chase for dopamine highs. Neuroscientist Heather Berlin reveals the antidote—and why even social media fame can trigger this cycle. For more, check out the extended interview with Heather Berlin. Learn more about NOVA and subscribe to our YouTube channel. 

Fossilization isn’t luck - it’s geology. Paleobotanist Kirk Johnson explains how fossils only form in certain conditions, the tricks to finding them, and why one fossil leaf can lead to thousands more.  For more, check out the extended interview with Kirk Johnson. Learn more about NOVA and subscribe to our YouTube channel. 

Speech is rare in the animal kingdom because it requires a very specific brain architecture. Neuroscientist Erich Jarvis explains how duplicating neural pathways for movement unlocked language, dancing, and even advanced problem-solving in more than just humans. For more, check out the extended interview with Erich Jarvis.  Learn more about NOVA and subscribe to our YouTube channel. 

How does evolution invent entirely new things, like limbs, wings, and venom? Evolutionary biologist Sean B. Carroll joins us to reveal the hidden rules behind nature’s creativity and the genetic toolkit that makes it possible. Carroll explains how the same set of genes can build wildly different creatures — from fruit flies to lobsters — simply by rewiring their genetic circuits. Discover why developmental biology holds the key to understanding evolution, how snake venom evolved, and why medicines like GLP-1 drugs and statins trace their origins to nature’s own innovations. Plus, what the emergence of new species tells us about life’s future and the surprising power of evolution to repurpose old parts in new ways.  Learn more about NOVA and subscribe to our YouTube channel.  ————————— Guest Bio:  Sean B. Carroll is a renowned evolutionary biologist and author whose work has inspired a deeper public understanding of evolution and the natural world. He is an Investigator at Howard Hughes Medical Institute (HHMI), where he was formerly Head of HHMI Tangled Bank Studios, and led the Department of Science Education from 2010-2023. He is also a Professor of Biology at the University of Maryland. His research focuses on genes that influence the evolution of animal diversity. Timestamps (00:00:00) How Does A New Species Evolve? (00:12:54) The Process of Speciation: Use It or Lose It (00:36:22) Development: What the Fruit Fly Taught Us (00:55:37) The Evolution of Defense Mechanisms & Developing Medications (01:19:55) The Role of Chance in Evolution (01:24:22) Credits

From legs on heads to missing eyes, fruit fly mutations exposed the genetic toolkit that builds all animals. Evolutionary Biologist Sean B. Carroll shows how these discoveries rewrote our understanding of evolution. For more, check out the extended interview with Sean B. Carroll. Learn more about NOVA and subscribe to our YouTube channel. 

From snakes to jellyfish, venom is one of evolution’s most lethal inventions. Evolutionary Biologist Sean B. Carroll reveals how this deadly innovation emerged—and the new science behind antivenom inspired by nature’s own defenses. For more, check out the extended interview with Sean B. Carroll. Learn more about NOVA and subscribe to our YouTube channel. 

The edge of a black hole isn’t what you think. Astrophysicist Janna Levin dives into the event horizon, the one-way transition where space and time warp so much that escape becomes as impossible as reversing the clock. For more, check out the extended interview with Janna Levin. Learn more about NOVA and subscribe to our YouTube channel. 

There’s no single ‘smoking gun’ for life beyond Earth. Microbiologist Peter Girguis explains the subtle fingerprints scientists hunt for—and why finding them on Mars could change everything. For more, check out the extended interview with Peter Girguis. Learn more about NOVA and subscribe to our YouTube channel. 

Scientists are editing genes for human speech into mice to see if they can learn vocal patterns. Neuroscientist Erich Jarvis explains how this could unlock not just speech—but entirely new ways of thinking. For more, check out the extended interview with Erich Jarvis.  Learn more about NOVA and subscribe to our YouTube channel. 

Can we bring extinct species back to life? Evolutionary biologist Beth Shapiro claims we just did. As Chief Science Officer at Colossal, her team made headlines in spring 2025 with the announcement of the de-extinction of the dire wolf. She takes us behind the headlines to explain how this is no “Jurassic Park” fantasy. She breaks down exactly how her team used ancient DNA, CRISPR genome editing, and the genomes of modern relatives to bring back lost traits and create animals capable of thriving in today’s ecosystems. Along the way, she dives into the surprising challenges of this work — from the quest for artificial wombs to the ethics of genetic engineering — and reveals how the same tools powering de-extinction are already helping endangered species survive.  Learn more about NOVA and subscribe to our YouTube channel.  ————————— Guest Bio:  Beth Shapiro is an evolutionary biologist and Chief Science Officer at Colossal, a company notably responsible for the de-extinction of  the dire wolf. She is also a professor of Ecology and Evolutionary Biology at UC Santa Cruz. Her research focuses on species evolution and the continued impact of human activities, considering questions about domestication, speciation and pathogen evolution. She is also exploring techniques to recover trace amounts of DNA from samples and the possible role of genomic technologies in the fields of conservation and medicine. Timestamps (00:00) What is De-Extinction? Reviving the Dire Wolf (29:45) Ethics and Backlash for Cloning  (38:10) Modifying DNA to Bring Species Back to Life (45:31) The Future of De-Extinction (54:30) Credits

Jurassic Park got it all wrong. Beth Shapiro would know… she’s Chief Science Officer at Colossal, the genetic engineering company that recently made headlines for bringing back the extinct dire wolf. She breaks down how de-extinction is really done, and why Jurassic Park can never happen. For more, check out the extended interview with Beth Shapiro. Learn more about NOVA and subscribe to our YouTube channel. 

The deepfake game is getting real. Deepfake detective Hany Farid gets under the hood of AI and explains exactly how it can now make such convincing fake content –  so convincing that he himself has trouble identifying his own real voice from an AI-generated fraud. Can you spot the deepfake? For more, check out the extended interview with Hany Farid. Learn more about NOVA and subscribe to our YouTube channel. 

Ever wonder why you get déjà vu? Or why you keep losing your keys? Your brain does some weird stuff. Neuroscientist Heather Berlin explains the surprising science behind these everyday mysteries. For more, check out the extended interview with Heather Berlin. Learn more about NOVA and subscribe to our YouTube channel. 

Space itself rings with gravitational waves when black holes collide—the most powerful events detected since the Big Bang. Astrophysicist Janna Levin reveals why, when the cosmic symphony fades, the merged black hole is stripped to flawless simplicity. For more, check out the extended interview with Janna Levin. Learn more about NOVA and subscribe to our YouTube channel. 

Could a Martian rock hold the most promising sign of life beyond Earth? Microbiologist Peter Girguis unpacks NASA’s stunning discovery of ‘leopard spots’ on a rock from Mars’s Jezero Crater—and why they look eerily like the handiwork of microbes on our own planet. For more, check out the extended interview with Peter Girguis. Learn more about NOVA and subscribe to our YouTube channel. 

A sinkhole can become a time capsule full of skeletons - layers upon layers of beasts that once walked the Earth - and Florida’s landscape is full of them. Discover the surprising science of how Florida’s sinkholes form, what they really are, and what can be found inside them. Come along with Dr. Kirk Johnson, Sant Director of the Smithsonian Institution National Museum of Natural History, as he describes what he calls "the best sinkhole experience For more, check out the extended interview with Kirk Johnson. Learn more about NOVA and subscribe to our YouTube channel. 

In a world flooded with fake videos and voice recordings that seem real, how can you detect deepfakes? Turns out, there are some aspects of the physical world that are not yet known to artificial intelligence - and those gaps are the key. Expert Hany Farid reveals techniques that can be used to detect AI-generated media. For more, check out the extended interview with Hany Farid.  Learn more about NOVA and subscribe to our YouTube channel. 

What do deep-sea microbes and Martian “leopard spots” have in common? Marine biologist Peter Girguis thinks they might both hold clues to finding life beyond Earth. In this episode, he joins Hakeem for a journey from the ocean floor to outer space, sharing stories from his dives aboard the Alvin submersible and exploring how Earth’s most extreme lifeforms could help us find the first ETs. Along the way, he explains how Earth is truly a microbial planet — teeming with enough microbes to stretch across the galaxy –  reshaping how we think about life, both here and out there.  Learn more about NOVA and subscribe to our YouTube channel.  ————————— Guest Bio:  Peter Girguis is a professor of Organismic and Evolutionary Biology at Harvard University. His research focuses on marine organisms, and how they adapt to extreme environments. He also works on developing novel technologies like deep sea autonomous laboratories and microbial fuel cells. Girguis appears in NOVA’s Ancient Earth series Timestamps (00:00:00) Microbes Rule the Planet (00:13:45) Deep Ocean Exploration (00:36:30) Signs of Life on Mars (00:54:18) Other Life in Outer Space (01:01:23) Two Truths and a Lie: Science Headlines (01:07:00) The Future of Working With Microbes (01:11:22) Credits

Talking, singing, even dancing — they all trace back to a rare superpower: vocal learning. But humans aren’t the only animals that have it. Neuroscientist Erich Jarvis has spent his career decoding the mysterious ability to imitate sounds, a key ingredient in spoken language. In this episode, he joins Hakeem to explore why only a handful of species — like parrots, dolphins, and bats — can do it, how it evolved, and what it reveals about the brain, consciousness, and culture. Plus, Erich shares how AI is helping decode animal communication  and why engineering our pets to talk might actually be possible… but could fundamentally change the way they think.  Learn more about NOVA and subscribe to our YouTube channel.  ————————— Guest Bio: Erich Jarvis is a neuroscientist investigating the mysteries of speech and vocal learning through groundbreaking research on birdsong and brain evolution. As a professor at The Rockefeller University and head of the Jarvis Lab, he explores how complex behaviors like human language arise from brain circuits and genetic pathways. Jarvis was also profiled in NOVA Wonders: What are Animals Saying. Timestamps (00:00:00) Language in Animals vs. Humans (00:10:37) Music and Vocal Learning (00:20:15) Can You Genetically Engineer Animals to Speak? (00:27:48) How Did Speech Evolve? (00:36:09) Can We Translate Animal Language?  (00:42:27) Brain Size and Speech (00:48:14) Writing & Symbolic Communication  (00:57:00) Conclusion (01:04:02) Credits

Your brain does all kinds of strange things — and neuroscientist Heather Berlin wants to explain how it works. In this episode, she joins Hakeem to explore the mysteries of the mind: how consciousness works, how your brain constructs reality, and how you might be able to hack it to live a better life. They dive into the effects of psychedelics and meditation, and explore the future of thought in a world shaped by AI. This episode is no placebo – it really will expand your mind.  Learn more about NOVA and subscribe to our YouTube channel.  -------------------------- Guest Bio: Heather Berlin is a neuroscientist, clinical psychologist, and associate clinical professor of psychiatry and neuroscience at the Icahn School of Medicine at Mount Sinai in New York. She is interested in how consciousness and creativity work within the brain and is also the host of NOVA’s "Your Brain" two-part special. Timestamps (00:00:00) What is Consciousness? (00:09:38) Perception Box (00:22:18) What's My Brain Doing? Deja Vu, Goosebumps & More (00:34:45) Cognitive Behavioral Therapy & Ketamine Treatment (00:44:55) Thoughts and Creative Flow States (00:58:02) Aversive Conditioning: Addiction, Anxiety, and Behavior (01:08:06) Fame & Fulfillment (01:18:02) The Future of Neuroscience (01:29:09) Credits

The universe loves making things complicated. From minerals and microbes to languages and societies, complexity keeps showing up — but why? Astrobiologist Mike Wong and mineralogist Bob Hazen think we’re missing a law of nature to explain this phenomenon. Hakeem sits down with them to understand – and kick the tires on – their bold new idea: what they call a Law of Increasing Functional Information. They break down how it works, why it matters, and how it could reshape our understanding of everything from life to language to the universe itself. Learn more about NOVA and subscribe to our YouTube channel.  -------------------------- Guest Bios: Robert Hazen is a mineralogist and astrobiologist at Carnegie Science and George Mason University. His pioneering research explores the origins of life and the evolving diversity of minerals on Earth. A prolific author and public communicator, Hazen has written widely on science, complexity, and the deep connections between the physical and biological worlds. Mike Wong is an astrobiologist and planetary scientist at Carnegie Science whose work focuses on how life begins and evolves on worlds like our own. He is also a science communicator, hosting the podcast Strange New Worlds, where he brings complex cosmic ideas to broad audiences. Wong’s research and outreach bridge cutting-edge science with big-picture questions about life in the universe. Their new book Time's Second Arrow: Evolution, Order, and a New Law of Nature will be available in February 2026. Timestamps (00:00:00) Introduction (00:05:28) Laying Out the "Law of Increasing Functional Information" (00:22:50) Functional Information: Explained (00:30:17) What is Selection? Discussing the Law (00:51:34) Testing the New Law (01:11:24) Credits

Black holes get a bad rap. They’ve been cast as the monsters of the cosmos — gobbling up stars and stretching anything that gets too close into cosmic spaghetti. But Black Hole expert Janna Levin has spent her career decoding these mysterious objects, and she thinks they’re just misunderstood. In this episode, she dives into the strange physics of black holes: what they are, what they sound like, what happens if you fall into one, and how there’s a lighter side to every black hole. Janna shares why black holes might not be the end of everything — but the beginning of something even weirder. Learn more about NOVA and subscribe to our YouTube channel.  -------------------------- Guest Bio: Janna Levin is a professor of physics and astronomy at Barnard College of Columbia University, where she explores the profound mysteries of black holes, cosmology, and the nature of the universe. She is also the founding scientific director of Pioneer Works, a nonprofit cultural center in Brooklyn that fosters collaboration across science, art, and education. An award-winning author and renowned science communicator, Levin has written several acclaimed books, including Black Hole Blues and Other Songs from Outer Space, and has spent her career making the strange and beautiful realities of the cosmos accessible to a wide audience. She is host of NOVA’s two-part special Black Hole Apocalypse. Timestamps (00:00:00) Introduction (00:04:12) Black Holes Get a Bad Rap (00:09:08) Gravity and Free Fall (00:12:04) Black Holes 101 (00:14:48) Warping Space Time (00:21:25) Is the Universe a Black Hole? (00:23:33) This Is the Century for Black Hole Discoveries (00:25:53) Ligo & Gravitational Waves (00:39:55) Black Holes Are Hairless (00:47:50) 2 Truths & a Lie, Black Hole Edition (00:52:35) Hawking Radiation (00:58:11) Black Holes Can Be Bigger on the Inside Than the Outside (01:01:15) Holography and Black Hole Information Paradox (01:04:57) Quantum Entanglement (01:12:30) Black Holes Helping to Understand Fundamental Laws of the Universe (01:16:27) Extra Dimensions (01:20:01) Credits

In a world flooded with fake images, manipulated videos, and AI-generated voices, how do we know what’s real anymore? Hany Farid has made it his mission to find out. A leading voice in AI research and digital forensics, Hany works to authenticate digital media and expose the fakes. In this episode, Hakeem and Hany dive into how we got here. How does AI really work? How are deepfakes detected? And what does the future hold for truth in the digital age? Plus, Hakeem puts Hany to the test: can he tell the difference between real and AI-generated headlines? And can Hakeem tell a deepfake version of Hany from the real thing? Subscribe to our YouTube channel for more content and exclusive videos.  -------------------------- Guest Bio: Hany Farid is a Professor at the UC Berkeley School of Information. In addition to teaching at UC Berkeley, Hany is Chief Science Officer at GetReal Security, a company that focuses on the authentication of digital media. His research focuses on digital forensics, forensic science, misinformation, image analysis, and human perception. He has published dozens of papers on how humans relate to AI and technology. Timestamps (00:00:00) Introduction (00:06:06) What is Artificial Intelligence?  (00:11:47) What are Deepfakes and How Are They Made? (00:19:30) Can You Detect a Deepfake?  (00:38:51) Will AI Take Away Our Jobs?  (00:52:00) The Concerns of AI  (01:08:19) What Does the Future of AI Look Like? (01:25:03) Credits

What do fossilized leaves, an asteroid, and Florida sinkholes have in common? Dr. Kirk Johnson oversees one of the largest natural history collections on the planet, and he has the answers. He’s spent his career digging into the story of life on Earth across millions (and billions) of years. In this episode, Hakeem and Kirk explore the science of “deep time,” how fossils actually form, and the surprising origins of Earth’s oceans. Plus, Kirk shares some hot tips on fossil hunting and how to count the number of leaves on a tree … because you never know when you might need these skills. Subscribe to our YouTube channel for more content and exclusive videos.  -------------------------- Guest Bio: Dr. Kirk Johnson is Sant Director at the Smithsonian Institution, National Museum of Natural History, home to one of the largest natural history collections in the world. A paleobotanist by training, his research explores ancient climates and extinct ecosystems through the study of fossil plants. He has authored more than a dozen books on paleontology and natural history and has traveled extensively in search of fossils on every continent. As a science communicator, Dr. Johnson has brought the natural world to millions through hosting acclaimed NOVA documentaries such as Polar Extremes and Making North America, blending deep scientific expertise with an engaging, accessible storytelling style. Timestamps (0:00:00) Introduction (00:01:32) What is Paleobotany? (00:03:36) How Do Fossils Form? (00:10:02) The Bennu Asteroid Sample (00:17:57) Early Earth: Evolution and Extinction (00:41:58) Trees and Fossil Leaves (01:06:53) Fossil Reefs and Sinkhole Formation (01:15:53) Excavating Teen Rex (01:25:46) What Does the Future of Earth Look Like?  (01:37:19) Credits

What happens when brilliant minds collide? In Particles of Thought, astrophysicist Hakeem Oluseyi is obsessed with understanding not just what the world's greatest scientists know, but how they think. From quantum mechanics clashing with general relativity to fossil memories written in ancient rocks, each conversation captures those electrifying moments when curiosity sparks new understanding. Join Hakeem as he explores the downright bizarre, the subatomic, and the furthest reaches of the universe through the minds that dare to question everything. Subscribe to our YouTube channel for more content and exclusive videos.