title: Is it possible to generate random numbers using physical sensors?
body: <p>I've heard about people using light sensors, geiger counters, and other physical sensors to generate random numbers, but I'm skeptical.  Is there really a way to generate random numbers from taking measurements of the physical world (using an Arduino or any other microcontroller)?  If so, would these numbers ever be really random?</p>
  
  <p>to clarify: the question is about the feasibility of using microcontroller-gathered data to generate random numbers that could be applied soundly to cryptography-- an alternative to relying on a device's entropy.</p>