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Peter Conn

True Random Numbers

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Hiya I was talking to my maths teacher, and we're currently doing statistics and picking samples using random number tables and we came onto the point "How are random numbers generated?" - I know that computers make pseudorandom numbers using some sort of table and an algorithm and I've also heard that humans are useless with random numbers (stuff like subconcious decisions and picking the number 7 too much), so is there any way to get true random numbers? Also if anyone could explain to me a bit more indepth about computers pseudorandom numbers I'd be very grateful.

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It's my understanding that random numbers are generated predictably from a seed value, which is typically the previous random number. The first random number is often generated from the time at that moment. Therefore, the numbers are predictable provided you have enough information on the system.

Other attempts to create less predictable random numbers have involved everything from line noise, quantum state measurements, ground vibrations, and cosmic rays.

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The name "random number generator" is actually a bit of a misnomer. Pseudo-random number is better, seeing as on a computer you can't actually generate random numbers. It's important to remember the difference between something that we can't predict, and something that's truly random(read a good article about it somewhere). You can use the time, unique identifiers based on the specific computer, whatever you want, but it's all completely deterministic. Mersenne twister tends to come up a lot.

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CPU temp, inter-thread timing (as taken from the CPU clock), unitilized variables (not very good, but you might as well use it), elapsed time since last user action (mouse click, button press, etc), anything variable and "undefined" that won't crash your system...

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Quote:
Original post by DaBookshah
The name "random number generator" is actually a bit of a misnomer. Pseudo-random number is better, seeing as on a computer you can't actually generate random numbers. It's important to remember the difference between something that we can't predict, and something that's truly random(read a good article about it somewhere). You can use the time, unique identifiers based on the specific computer, whatever you want, but it's all completely deterministic. Mersenne twister tends to come up a lot.

It could be argued that everything is deterministic, so "random number generator" would be appropriate (depending on your viewpoint).

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This is a fun article that shows how to build a random number generator from a webcam and the radiation source from a smoke alarm.
link
Maybe not what you are looking for but... its cool :)

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Quote:
Original post by stevenmarky
It could be argued that everything is deterministic, so "random number generator" would be appropriate (depending on your viewpoint).


I'm out of my depth here, but I think the current idea is that we live in a probabilitistic universe(E.g. the wave function interpreted as a probability density function, or something like that. Oh yeah, and I'm contradicting the point about being deterministic, but just ignore that ok). Appparently you can get random number generators relying on some sort of external source of entrophy.

Better stop, the previous thread I saw on this topic in a different forum went for 80 pages.

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Quote:
Original post by Riviera Kid
is anything ever truly random for sure?

are the only things which are random the things we cant explain?


Gah, this is the whole point. You have to make a distinction between things which are random, and things which we can't explain, and therefore might possibly call "random", but which are deterministic.

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