The Rest Is Science The Device That Maps The Heavens
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Dec 18, 2025 Discover the ellipsograph, a fascinating device that turns complex geometry into motion on paper. Explore how ellipses relate to planetary orbits and Kepler's historical shift in understanding celestial motion. Delve into the science of color mixing with translucent CMY cubes and learn the truth about the infamous goldfish memory myth. The hosts also share intriguing tales of iconic mathematicians like Galois, Archimedes, and Pythagoras, adding a humorous twist to the serious side of science.
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Ellipse Defined By Two Foci
- An ellipse is the set of points where the sum of distances to two foci is constant.
- Hannah Fry demonstrates mechanical methods like the ellipsograph to turn that abstract rule into precise motion.
Brass Ellipsograph Demo
- Hannah shows an ellipsograph that uses sliding arms and magnets to draw ellipses.
- Michael admires the brass craftsmanship and the way linear tracks produce curved drawings.
Ellipses Replaced Celestial Circles
- Kepler replaced the long-held circle model with ellipses, a major leap in astronomy.
- Hannah emphasizes how reluctantly accepting ellipses advanced understanding of planetary motion.