All this talk of "Carlsen accused him of cheating with no evidence" reminds me of the blowback against some athletes in the 70s and 80s who accused rivals of taking PEDs "with no evidence".

Sometimes the evidence of someone doing monstrously better than can be expected by their history is sufficient IMO. I mean, look at this article about swimmer Shirley Babashoff [1], dubbed "Surly Shirley" at the time by the media, for suggesting the East German women were on PEDs in the 70s. Nowadays we look back on those images of the East German women, looking more manly than any dude I've ever seen, and wonder how we considered with a straight face that they weren't on a boatload of drugs. Similarly, it completely baffles me how any sane person can think that Flo Jo wasn't on PEDs in the runup to the 1988 Olympics - her 100m dash record still stands today.

I'm not saying Carlsen went about it in the right way, because now Niemann is basically in an indefensible position, but I'm also not willing to quickly dismiss it because Carlsen has "no evidence".

1. https://www.swimmingworldmagazine.com/news/exclusive-shirley...

What hard evidence—exactly—do you expect Carlsen to be able to produce? Alternatively, imagine anyone in a similar position. What hard evidence can anyone produce in situations such as this?

100% serious question.

I don't know much about chess, but it seems like Niemann now has to either maintain his performance in Chess without cheating, or cheat to maintain it if he can't without - in which case he could still be caught.

That's not true. Both he and Chess.com both say that they have evidence to the extent of Hans' cheating. Both have asked Neimann for the ability to speak freely without threat of libel.

Ball is in Han's court.

Not quite. There is still a possibility that Niemann will admit cheating. If he actually cheated there may be a time—in years or decades rather then months—that he fills with remorse and admits it (hopefully with a detailed description on how he did it so we can verify). If however he didn’t cheat, we will probably never actually know the truth.