/sci/ - Science & Math

>5 live listener Matthew in Wolverhampton wrote to Stephen Hawking in 1990.

>Matthew was serving in the army, when he and his friend had a question:

>"If you've got two cars, travelling at the speed of light, and the car at the back turns its headlights on, would the light reach the car in front?"

>Matthew said it wouldn't - his friend said it would.

>He wrote to Stephen Hawking - and this was the reply: [pic related]

>Matthew said "ever since then, when I've run the London Marathon, I've run it for motor neurone disease as a thank you."

I am out of my depth trying to comprehend this