Summary
Overview
Hannah Fry and Michael Stevens explore listener questions about gravitational waves, space debris, and stair-climbing physics before diving deep into obsidian—the sharpest naturally occurring material on Earth. They discuss its volcanic origins, historical significance as humanity's oldest trade good, and remarkable properties that make it sharper than surgical steel.
Cancer Research Through Evolution's Lens
This segment discusses Cancer Research UK's approach to studying unusual species like Greenland sharks, which can grow over six meters long, weigh more than a small car, and live for 400 years while remaining cancer-free. By understanding how evolution has conducted natural cancer prevention trials over millions of years, scientists hope to unlock new pathways for tackling over 200 types of cancer in humans.
- Greenland sharks can grow over six meters long and live up to 400 years while remaining cancer-free
- Evolution has been running the world's most successful cancer prevention trial over millions of years
- Cancer Research UK's work has helped double survival rates in the UK over the last 50 years
Gravitational Waves and Human Perception
The hosts tackle a fascinating question about whether humans could feel gravitational waves from colliding black holes. They explore the terrifying scale of cosmic events and calculate exactly how close you'd need to be to sense these ripples in spacetime. The discussion reveals that even the most powerful black hole collisions detected from 1.3 billion light-years away only compressed Earth by the width of a dozen protons, demonstrating both the weakness of distant gravitational waves and the remarkable sensitivity of LIGO detectors.
- The first gravitational wave detected by LIGO came from black holes 1.3 billion light-years away, compressing Earth by about a dozen protons
- If the same collision occurred at the sun's distance (93 million miles away), Earth would expand and contract by about one meter
- You would likely hear gravitational waves before feeling them, as your eardrum is your most sensitive vibrational detector
- High-frequency gravitational waves from close collisions could disrupt blood flow and cause physical harm through differential acceleration
" I am so in the mode of control because of our modern world where I can pause a streaming show. I can resume it later. I can rewind that. I just feel like I get to control everything. I click on the links that I want. I scroll when I want, but what the solar eclipse does not work that way. It's going to happen when it happens and you know when it's going to happen and there's nothing you can do about it and that is so alien to our world today that it freaks me out. "
" Almost nothing cares about us, Michael. Almost nothing. "
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