What happens when several thousand distinguished physicists, researchers, and students descend on the nation’s gambling capital for a conference? The answer is “a bad week for the casino”—but you’d never guess why.

Image result for Casino images

The year was 1986, and the American Physical Society’s annual April meeting was slated to be held in San Diego. But when scheduling conflicts caused the hotel arrangements to fall through just a few months before, the conference’s organizers were left scrambling to find an alternative destination that could accommodate the crowd—and ended up settling on Las Vegas’s MGM grand.

It was an unmitigated disaster for the Grand. Financially, it was the worst week they’d ever had. After the conference was over, APS was politely asked never to return—not just by the MGM Grand, but by the entire city of Las Vegas.

Image result for MGM Grand images

Everyone knows that it’s a near-impossibility to beat a casino’s odds on a large scale. Lucky individuals’ wins are always subsidized by the unlucky masses, and everyone’s luck runs out eventually. So what happened? Maybe you’ve seen 21, and you’re picturing teams of sleek geeks using elaborate signaling systems and network analysis to gain a statistical edge over the house in blackjack. That’s been done in real life, but it wasn’t what happened at this meeting.

Image result for Casino images

When I first heard this story (it’s practically office folklore at APS), I immediately remembered a documentary I’d seen a while back, where some science-minded gamblers proved that a roulette wheel could reliably be beaten with a timer and a pocket computer…but guess again—they didn’t play roulette, either.

Some physicists have a knack for poker—the quick analytical thinking that lends itself to success in the classroom can translate well to a competitive card game: a Dutch theoretician took home a gold bracelet in the 2010 World Series of Poker. Did a group of the April ’86 attendees somehow devise an optimized betting strategy, analyzing risks and payoffs, assigning weights, hedging their bets to come out in the black? Still no—or at least not en masse.

Image result for Casino images

Instead, it turns out that the physicists found the one move guaranteed to provide an edge when the odds are stacked against you: You just don’t play.

See, usually when an organization announces that it’s holding a big conference in a certain region, it triggers a bidding war among that area’s hotels, and each tries to undersell the others and secure the group’s contract to fill up as many rooms as possible. This goes double in a gambling destination like Las Vegas, where hotels have casinos built-in; the Grand doesn’t just collect on room charges, it also gets a good portion of however much each guest was planning on taking to the tables. This is so central to the business model of casino hotels that they’ll often give rates much lower than what a non-casino hotel could afford to offer, under the assumption that they’ll recoup at the tables—it’s the same reason you can often find free alcohol and startlingly nice food at all-you-can-eat casino buffets.

Image result for Casino buffet images

So were these physicists just too busy sharing their science, seeing presentations and posters, and catching up on homework to find time for the tables? That’s one possibility. The fact that a significant portion of the attendees were broke graduate students probably didn’t help matters. On top of that, all the attendees had to have known enough about probability and statistics to recognize the “Monte Carlo* fallacy” at work: When a roulette wheel comes up black ten times in a row, it doesn’t make the ball any more or less likely to land in a red slot the next time.

Whatever the case may have been, the week of the ’86 APS April meeting found the gaming floor almost completely empty, leaving the casino with its record-low take; in the (probably apocryphal) words of one casino waitress: “They each brought one shirt and a ten-dollar bill, and changed neither.”

Image result for Casino buffet images

By staying at a gambling hotel but obstinately refusing to gamble, everyone who booked their reservation with the group effectively had their stay subsidized by guests who were lured in by the chances of a big win—which is probably why Las Vegas hotels never bid on APS conference contracts anymore. The MGM Grand learned a lesson the hard way that week: Physicists do not play dice.

—Stephen Skolnick