Two! one to change the light bulb and the other to rotate the universe!
One.
A. 3. 1 to find the bulb 1 to find a ladder and 1 to find a man.
Only one, but the light bulb has to want to change.
THAT'S NOT FUNNY!
The mathematician says "2" The Physicist says "2, plus or minus 0.1" The engineer says "Probably around 2, but let's say 3 to be on the safe side".
They have the ability to penetrate both holes at the same time. explanation(http://en.m.wikipedia.org/wiki/Double-slitexperiment)
Because they thought that they were the center of the universe.
At the university.
Two. One to hold it in place, another to rotate the universe around it.
I'm sorry, but the video you filmed is imaginary. Please rotate your phone 90 degrees and try again.