1. The Cosmic Speed Limit
Suppose you launch a pod at ½ c from a rocket traveling at ½ c relative to the Earth.
How fast will it go?

2. The pod travels at ½ c relative to the rocket.
Which line is the pod’s? A B C D t t’ x’ x

3. The pod must cover one unit of space in two units of time.B C D t t’ x’ x

4. How fast is it moving relative to the Earth?x’ x

5. How fast is it moving relative to the Earth?
It travels at 4/5 c t t’ x’ x

6. The relativistic equation for velocity addition is v = (v’ + vrel)/(1 + v’ vrel)
How fast is the pod moving relative to the Earth according to the equation?
v = (½ + ½)/(1 + ½ *½) = 4/5

7. The relativistic equation for velocity addition is v = (v’ + vrel)/(1 + v’ vrel)
How fast is the light of the rocket’s headlights moving relative to the Earth according to the equation?
v = (1+ ½)/(1 + 1 *½) = 1

8. Reality Check #1: The cyclotron at Triumf can form pions moving at 0
Reality Check #1: The cyclotron at Triumf can form pions moving at 0.96 c which decay by emitting muons and neutrinos.

9. Many of these emitted particles go faster than 0
Many of these emitted particles go faster than 0.96 c, but none go faster than light.

10. Reality Check #2: At CERN, neutral pions were accelerated to c. When these pions decayed, they emited light.

11. All the light emitted by the pions traveled at c.