There's a huge scandal going on in the chess world right now. Magnus Carlsen, a five-time World Chess Champion and the current top chess player in the world, played a match at the invite-only Sinquefield Cup in St. Louis against Hans Niemann, a chess grandmaster who only earned that title in the last two years. After a grueling match in which Carlsen played as white and should have had the advantage, Carlsen instead lost and immediately dropped out of the tournament. This was huge news! In addition to the fact that this tournament hadn't seen a withdrawal before, Carlsen himself had never withdrawn from a major chess event in his career.

That was four weeks ago, on September 4th. And the drama has only gotten worse.

On September 19th, Carlsen and Niemann started a much-anticipated online "rematch," with both players on webcams. However, one move in, Carlsen resigned from the game. No explanation was given.

On September 26th, Carlsen finally posted an official statement on Twitter accusing Niemann of cheating. His accusation has merit. Earlier in the month, Niemann explained that he'd previously been banned from Chess.com for cheating during online chess games. One of those times had been when he was 12 and participating in an online tournament, while the other had been at age 16 during unrated games. But he'd never cheated in an over-the-board game, he claimed, and he offered to play fully naked to assuage cheating concerns. (StripChat, an adult entertainment webcam platform, then offered Niemann $1 million to follow through.) His former coach, Maxim Dlugy, was also banned from Chess.com for cheating in 2017 and in 2020. Dlugy eventually confessed to using computer assistance.

Has cheating happened before?

Cheating happens all the time at the amateur level, but it's rare among elite chess players. A well-known accusation happened during the 2006 World Chess Championship, when Vladmir Kramnik took an excessive number of bathroom breaks and was accused of using computer assistance during those breaks, since no video or audio is recorded in the bathrooms. However, after thorough analysis of the games, Kramnik's name was cleared. The incident is now referred to as Toiletgate.

Why is cheating suspected?

In Niemann's case, Carlsen says that Niemann's playing style is unusual and that Niemann doesn't seem to need heavy concentration, even during critical points of the game.

Others have done analysis of Niemann's games and found that he plays perfectly more often than other elite players. Here, a "perfect" game is one in which a player chooses the best move every time, as determined by a computer program. Percentages are used to describe how many of a player's moves in a game are so-called perfect. So while Magnus Carlsen has played two 100% games and two other games that were above 90%, Niemann is well-above the average at ten 100% games and twenty-three above 90%. Hikaru Nakamura, another grandmaster, elaborated on how suspicious this is in longer chess games and followed up later with additional evidence to suspect foul play.

How could Niemann cheat?

No one really knows.

Matches are recorded behind closed doors and then shared to the public on a lag, so it's difficult to involve outside parties in cheating schemes. Some grandmasters (partially) joked about the use of anal beads, sparking memes all over the internet. But the truth of the matter is that it's difficult to come up with mechanisms for cheating over-the-board.

Online cheating is much easier for players to do, so Chess.com employs several techniques for detecting cheating on its site. They use information about how long players take to respond, how well players are performing compared to their historical performance, and how well players are performing compared to computer engines.

That last point is an especially big one. In 1996, Garry Kasparov played and lost 2 out of 3 matches against the AI Deep Blue, thereby cementing people's confidence in a computer's ability to outplay even the best chess players in the world. Since a person's ability to consistently play perfectly is unheard of, repeated matches or moves with perfect performance are attributed to cheating.

So what's next?

Carlsen has said that he refuses to play Niemann anymore, but only time will tell what happens. Either way, I eagerly await Niemann's next move.