Is it possible to generate random numbers using physical sensors?

Question

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

Answer 1

Depends on the range, sampling frequency and sensitivity of the sensor. You can consider the sensor measurements as a bitstrings or as floats, doesn't really matter. The point is, the most significant bits / the leading decimals are not very random, they might even hardly change. Likewise, the least significant bits are unreliable sources of randomness, since they might show a step effect due to limited sensor sensitivity, and depending on the sensor they might be strongly correlated in time (e.g., temperature or voltage will have a tendency to change gradually). The middle bits/figures however might very well be a source of true random values.

Suppose you have a sensor that outputs values in the range 0 to 200 , with a precision of 0.01. Let's say it's a pressure meter, maybe a decibel meter. You'd need to test this extensively and look at the distribution of values for your specific sensor and environment, but I think that the figures at the 10^0 and 10^-1 positions might very well be distributed uniformly and without discernible order.

Best suited are sensors that can make very precise measurements but have to deal with a high level of noise anyway. This might pose a problem since most sensors aren't designed to provide an unnecessary/unreliable level of precision. Also, measurements that are roughly the same always and everywhere (except for the noise) are to be preferred of course. Cosmic background radiation is a good example of this.