# Physicist reveals how to win at roulette (until the casino bans you for life)

There are three ways to play roulette. Option one is that you can play it safe and bet exclusively on red or black, which gives you odds of slightly below a 50/50 chance of winning any given roll (because as well as the 36 black and red segments, there are two greens). Option two is far weaker odds, but far greater rewards, where you bet on a specific number, where your odds are 38-1 against. The third option is the safest – until you get kicked out – use physics to stack the odds in your favour and beat the house.

A short history lesson: back in the 1970s, a mathematician named J. Doyne Farmer built a machine that would help him win at roulette. It turns out the machine was a touch too effective, as the upshot was that the casinos all banned him – not because they could prove he was cheating, but because he was significantly beating the odds, and that’s reason enough in Vegas.

How he did it may have been explained just four short decades later, in a Q&A on Quora, asking the simple question “What do physicists know that let them win at casinos?”

Richard Muller, professor of Physics at UC Berkeley explained how a colleague managed to beat the house at its own game:

“To encourage people to bet at roulette, it has been traditional to allow bets to be made after the wheel is spun and the ball is flung, but only before it begins to drop. In that second or two, there is enough information to allow a measurement and computation that will, for example, double your odds of winning. If the computation simply rules out half of the wheel as unlikely, then the odds jump up highly in your favor. Whereas before, your odds of winning might be 98:100 (so you lose), if you exclude half of the numbers, your odds become 196:100; you win big!

You don’t have to predict the number where it will fall. You only have to increase your odds by 3% to go from losing on average to winning on average.

He built a device with a switch for his toe in which he tapped each time the ball spun around; with a separate switch he tapped each time the wheel turned. This provided enough information for his small pocket computer to signal him back (with a tap to his leg) where he should place his bet. (He had to calibrate each wheel, but he did that by watching and testing before he started betting.)”

Said colleague went on to win “almost enough money to pay for the roulette wheel he had purchased to perfect his instrument at home”, before he was banned from the casino, but how was he caught?

Well, as mentioned above, casinos don’t have to catch you cheating – and they don’t have the right to search you in any case – but they do have the right to exclude any person without cause, and if they see someone beating the odds consistently, you’re marked. As Muller explains, “they can’t get their money back, but they can stop losing.”

Fun fact: roulette is also known as the Devil’s Game, because if you add all the numbers on the table together, you come up with 666 – the number of the beast according to the book of revelations. This has nothing to do with physics, but consider it a free bonus for getting to the end.

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Images: Zdenko Zivkovic and David Fischer used under Creative Commons

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