Pretty often at IFLScience Towers, we find ourselves faced with a conspiracy theory we've not seen before - and this week was no exception. "Can you believe," one of our intrepid reporters asked the office, "that some people think online gambling sites don't use random numbers?"

Well, chalk it up to mathematical nit-pickery, but technically, the conspiracists are right with this one - even if their working is wrong. It's true that the computer systems governing those sites may well not be rolling random numbers, but the reason isn't some con being run by Big Gambling - it's simply the only way computers know how to work.

"One thing that traditional computer systems aren't good at is coin flipping," explained Steve Ward, Professor of Computer Science and Engineering at MIT's Computer Science and Artificial Intelligence Laboratory, back in 2011. "They're deterministic, which means that if you ask the same question you'll get the same answer every time."

"In fact, such machines are specifically and carefully programmed to eliminate randomness in results," he said. "They do this by following rules and relying on algorithms when they compute."

When you use a machine to generate a "random" number, then, what you're actually getting is almost certainly a "pseudorandom" number - something that looks random, but technically isn't. It's typically produced by taking a "seed" number, then following some extremely complex algorithm like the Mersenne Twister or the Blum Blum Shub (yes, that's really its name; it was invented by Messrs Blum, Blum, and Shub. None of us can help our parentage.)

Now, to be fair, pseudorandom numbers are generally good enough. While it's theoretically true that, with enough luck and gumption, the system could be hacked, in practice it's virtually impossible: "[I]t's only true if you're a spy with international espionage skills," quips online gambling site BetMGM. "You'll need to get access to the software and algorithms used to create the values that drive the randomness in these games. As you might imagine, these are highly protected by the game producers[.]"

That said, there are ways computers can create truly random numbers. Known as HRNGs or TRNGs - "Hardware Random Number Generators" or "True Random Number Generators" - they depend on physical observations of natural phenomena to generate values: the decay of a nuclear isotope; the temperature or pressure; or even just random atmospheric noise.

The problem, though, is that these systems are also costly and difficult to run - and so, even when gambling sites do boast their use, they will often use them in conjunction with a pseudorandom number generator too. It's basically the best of both worlds: an element of unpredictability, with all the speed and ease of an algorithm.

For most everything else that claims to be "random", though, the addition of an HRNG would simply be overkill. So you can rest assured that no, you're probably not going crazy when you think your Spotify shuffle is repeating itself - and you're not the world's first playlist-based psychic, either. It's just pseudorandomness at play.