One day, Werner Heisenberg got pulled over for speeding

The officer walked up to his window and asked "Do you know how fast you were going?"

Heisenberg replied "No, but I know where I am"

......Wha?

The Heisenberg Principle relates to the speed and position of particles - by knowing one, you automatically change the other, meaning that it's impossible to know both at the same time.

I'm paraphrasing, but that's about the size of it. A good one for the Maths/Physics majors on the Forum, gylbert, but possibly to specific for this crowd

Reminds me of a Futurama joke: You change the outcome by measuring it!