How can a computer be random?

I'm a pretty logical/mathematical thinker, and I've always wondered how computer programs can generate random numbers. Obviously, a processor doesn't have a will, so it can't just "pick" a number, and yet so many functions in computer programs require the computer to make a random choice. How is that possible? (Try to keep it in Laymen's terms, I'm not a programmer)

hehe, good question. The answer is it can't. In the absence of this, 'pseudorandom' is good enough. If it appears random to us, what's the difference? A common technique used is, when a function requests a random number it uses an equation where the current CPU tick is the independent variable. Every time an instruction executes, the tick is incremented by 1. Another technique is to use the current system time, as it will always be different when a random number is requested.

Look up 'pseudorandom number generation' for some more complicated ways of doing this. Obviously, trying to generate many 'random' numbers quickly using the above techniques will create a linear pattern, which is not random.

The quick answer is that it cannot be. If you have a program that generates random variables, it will tend to generate the same numbers each time it is run. Long ago though, programmers found ways around this, such as tieing the random number generation into the clock, so that the number that is seeded into the random number generator is based on the number of seconds in the day so far or something similar. This allows for the appearance of randomness. The more complex a program is, the more random it is going to appear as well.

The real answer is: it can't. Computer software can only produce a pseudo random number.

My guess is that it is probably time based. If a computer processor can produce a key let's say 100 times a second. Then it would probably just keep producing those keys untill a specific time is given. For instance, if it was told to randomly pick a number out of a list of 1000 numbers, it would probably keep cycling through that list a gazillion times until it hit a certain time.....maybe 5 seconds? Then after 5 seconds wherever it is on that list when the time is up is the "random key"
Sorry if my guess does not please you :)
Just trying to help

Actually, most computers can generate random numbers by sampling thermal noise in a simple circuit. This is a quantum mechanical phenomenon, and is truly random. Unfortunately, it doesn't produce random numbers very quickly.

Most "random" numbers in computer programs come from a pseudo-random number generator (PRNG). Wikipedia has a good reference:
http://en.wikipedia.org/wiki/Pseudorando...