Need to know how many leaves are on that tree? Paleobotanist Dr. Kirk Johnson shares the surprisingly nerdy method—because you never know when leaf math will come in handy.

For more, check out the extended interview with Kirk Johnson.

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What engineering secrets lie within the Great Pyramid, and who really built it? Innovations like rope‑sewn boats, laser‑precise alignments, and hidden internal chambers reveal a building team with knowledge far ahead of its time. Uncover clues buried around Giza that point to a surprising truth about the workforce responsible for one of history’s greatest construction projects.

To watch the full film, visit https://www.pbs.org/wgbh/nova/video/decoding-the-great-pyramid/

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Long before trees and grass, microbes were shaping our atmosphere. Evolutionary biologist Peter Girguis explains how ancient bacteria learned to split water for energy, and why their waste product changed Earth forever.

For more, check out the extended interview with Peter Girguis.

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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.

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What if whales had legs? Once upon a time, they did. Sort of. An astonishing fossil trail shows that modern whales actually evolved from hooved land mammals. Whales still carry the fingerprints of this past, from their stomach anatomy to their swimming gait. Dive in to discover the wild story of how whales traded legs for fins, as we uncover clues about their ancestors, as well as their unlikely present-day relatives.

To watch the full film, visit https://www.pbs.org/wgbh/nova/video/when-whales-could-walk/

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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.

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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.

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What happens when the Arctic’s ancient freezer starts to fail? Scientists have uncovered the truth behind giant sinkholes exploding from the frozen ground in Siberia, and a vast lake bubbling with methane in Alaska .They are pointing to a dramatic shift beneath our feet – one driven by thawing Arctic permafrost, the vast frozen layer that stores nearly twice as much carbon as the entire atmosphere. Learn why these geological curiosities reveal a dangerous climate wildcard – one powerful enough to accelerate global warming in ways current models don’t yet predict.

To watch the full film, visit https://www.pbs.org/wgbh/nova/video/arctic-sinkholes/

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