Last week's puzzler got some interesting results: exactly half the people who answered got the right answer (picking a random number), and the other half all picked the same wrong answer (computing the angular distances between all the stars in the sky).
Despite experiences you may have had with a computer that seem like random events, computers are actually deterministic devices – for a given set of inputs, they always produce the same results. Computers have no capability that is the equivalent of rolling a pair of dice; they simply don't know how to. Some very clever programmers have developed some very clever approximations to random number generation, but even the cleverest of them is still repeatable: given the same set of starting conditions, they generate the same darned numbers, every time.
It is possible to build special-purpose computer hardware to generate truly random numbers. Such hardware usually depends on some natural phenomenon (such as radioactive decay) that is, so far as anyone knows, truly random. Some innovative folks in recent years have developed other, less expensive techniques. For example, one such technique involves a lava lamp and a digital camera watching it; the image is then compressed to generate random numbers. To my knowledge, nobody has yet proved whether these systems are truly random…
This weeks puzzler is another history factoid...
Hi, Simon... Someone else wrote me with much the same argument. The key issue is whether there are an "infinite" number of stars, for if there were, clearly your point would be correct. However, as I understand (possibly incorrectly!) the best understanding of astronomers and cosmologists today, the number of stars is NOT infinite, though it is very large, and it is not known to us today with any precision. Still, if there are a finite number of stars then the problem is solvable by a computer in finite time...
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