This project must be done by individuals.
We know that the speed of light is very fast -- so fast, it's difficult to measure. Let's think about how one might measure the speed of light. What sort of precision is possible with simple tools?
Galileo tried to measure c, the speed of light, way back in the 1600s. His idea was similar to the method he used to measure the speed of sound:
Galileo can then use the events 1 and 2, and the distance D, to compute the speed of light.
Your job is to make reasonable estimates of the uncertainties in Galileo's measurements, and use them to estimate the uncertainty in Galileo's computed value of c.
total uncertainty in time = (uncert in t1) + (uncert in t2)to compute the total uncertainty in time
total uncertainty in c uncert in time uncert in distance ---------------------- = ---------------- + ------------------ Galileo's value of c time distanceto compute the uncertainty in Galileo's estimate of the speed of light
To be fair to Galileo, he knew very well that his measurement was uncertain. He concluded that the best he could do was to state that the speed of light was at least ten times faster than the speed of sound. That's certainly correct. Good job, Mr. G.!
We live hundreds of years after Galileo, of course, so we have much better measuring tools. Well, our special laboratories do, but what about ordinary people, like you? Imagine that you and a friend decide to measure the speed of light, using the same method as Galileo.
Instead of lanterns, though, you use flashlights, or some similar cheap and simple light source. You can't afford to fly to exotic locations, and have a total budget of just $50. In addition, you have only 3 days to perform the experiment, so you'll have to make do with nearby locations and equipment you can purchase easily and quickly (or which you already own).
How much more precise would your value be than Galileo's?
Copyright © Michael Richmond. This work is licensed under a Creative Commons License.