Last week Magnus Carlsen, the world chess champion, directly accused Hans Niemann, a U.S. grandmaster, of cheating during their game at the Sinquefield Cup, in St. Louis, Mo. He thus made plain an accusation he had been hinting at for weeks.

Carlsen has so far provided no evidence to back up his charge, nor has he specified how the cheating took place. Everyone agrees, however, that if there was cheating, then it must have involved computers, because nothing else could dismay Carlsen, whose rating of 2856 is higher than that of any other player. And everyone seems to have chosen sides.

Those who back Carlsen point to Niemann’s own admission that he used computers to cheat in online play at least twice—once at age 14 and again at 16; Niemann is now 19. Others note that his performance has risen very rapidly in the past two years. Still others raise an eyebrow at the large number of games he has played in recent years that get a score of nearly perfect from computer analysis. And behind it all are statements from leading players that they are convinced that cheating happens all the time nowadays, though hardly anybody ever gets caught.

Last week Magnus Carlsen, the world chess champion, directly accused Hans Niemann, a U.S. grandmaster, of cheating during their game at the Sinquefield Cup, in St. Louis, Mo. He thus made plain an accusation he had been hinting at for weeks.

Carlsen has so far provided no evidence to back up his charge, nor has he specified how the cheating took place. Everyone agrees, however, that if there was cheating, then it must have involved computers, because nothing else could dismay Carlsen, whose rating of 2856 is higher than that of any other player. And everyone seems to have chosen sides.

Those who back Carlsen point to Niemann’s own admission that he used computers to cheat in online play at least twice—once at age 14 and again at 16; Niemann is now 19. Others note that his performance has risen very rapidly in the past two years. Still others raise an eyebrow at the large number of games he has played in recent years that get a score of nearly perfect from computer analysis. And behind it all are statements from leading players that they are convinced that cheating happens all the time nowadays, though hardly anybody ever gets caught.

Computers loom so large because they now play chess like gods.

What makes the scandal so big is not merely the level of the players. In 1961 the great Bobby Fischer wrote an article for Sports Illustrated titled “The Russians Have Fixed World Chess.” He alleged that Soviet chess players arranged draws to ensure that one of them would win a tournament.

Nor is the scandal notable for flagrancy. In 1967 Milan Matulović, a Yugoslavian grandmaster, shockingly took back a move he had just played and only then said “J’adoube,” the French phrase uttered when a player merely adjusts the position of a chessman. Players thereafter called him “J’adoubavić.”

No, what makes today’s accusations resonate is the pervasive role of chess computers. They give children around the world sparring partners that earlier generations couldn’t have dreamed of facing, even if they’d lived next to the Moscow Central Chess Club. No wonder prodigies of the game have gotten younger and younger.

And computers do so well in helping the home preparation of the opening, the early moves of a game, that players, including Carlsen, will sometimes deliberately play a second-best move just to force the opponents out of “book.”

Finally, computer analysis offered during Internet broadcasts of ongoing tournaments will look 12 moves ahead within a second or two. They show the amateurs in the audience much that the grandmasters miss, creating the illusion that the amateurs actually understand what’s going on. Of course, any viewer could give illicit help to a player if provided a means of communication.

Several things are at stake. There is the prize money, which runs in the hundreds of thousands of dollars for the circuit of which the Sinquefeld Cup tournament is a part. There are the invitations to future events, which are often contingent on doing well in qualifying events. Then there are the rating points. Carlsen cares deeply about this metric: Although he recently declined to contest his World Championship title in 2023, he insists that he will continue to play in the hope of raising his rating to an unprecedented 2900.

The cheating to which Niemann does admit—in his younger years, during online play—was itself detected with the aid of computers of Chess.com, the online playing forum in question. Recently, however, the Wall Street Journal reported that an internal investigation by Chess.com has found that Niemann in fact cheated in more than 100 online games, most recently when he was 17. The company did not impugn the grandmaster’s over-the-board play.