Lasers at Work

From the Moon to absolute zero

An interactive lesson with 6 steps, about 5 minutes: you predict, drag and solve, with instant feedback on every answer. It runs in your browser and needs JavaScript.

What you’ll learn

• Laser ranging measures the Earth–Moon distance to millimetres.
• The Moon recedes about 3.8 cm per year.
• Laser cooling slows atoms with photon kicks, reaching microkelvin temperatures.

Steps

1. Measuring the Moon
2. Echo from the Moon
3. Blu-ray
4. Laser radar
5. A spot on the Moon
6. Cooling with light