Learnfold

Free course · 6 lessons · 20–30 min

Black holes, without the math

A place even light can't leave, and how we know it's really out there.

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What you’ll learn

Explain in plain words what a black hole is, how one forms, what falling in would do to you, and how astronomers know they exist.

Before you start

No physics or math needed. If you've ever thrown a ball in the air, you have the background.

Course outline

  1. Chapter 1

    What a black hole is

    Squeeze enough mass into a small enough space and light can't get out. See how nature does it, and what crossing the edge would do to you.

    1. A place light can't leaveEscape velocity, and what happens when it passes the speed of light.3 min
    2. How a star becomes a black holeWhy heavy stars collapse, why the Sun won't, and the giants at the centers of galaxies.3 min
    3. What falling in would be likeThe event horizon, spaghettification, and why a bigger black hole is gentler at the edge.3 min
  2. Chapter 2

    Seen and unseen

    Watch time slow near a black hole, see how astronomers found things that give off no light, and meet the questions nobody has answered.

    1. Clocks that run slowGravity slows time, near Earth and enormously near a black hole.3 min
    2. How we see something blackOrbiting stars, glowing disks, gravitational waves, and the first pictures.3 min
    3. What nobody knows yetHawking radiation, the information paradox, and where physics runs out.3 min

Where people go next

Questions this course tends to raise. In Learnfold, any of them becomes a course of its own.

  • How do neutron stars work?
  • Explain Einstein's general relativity without equations
  • What is dark matter, and how do we know it's there?
  • Why don't quantum physics and gravity fit together?
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