In one of the strangest music stories in recent memory, Atlanta rap hitmaker B.o.B. recently posted a long string of conspiracy-theory tweets about how the earth is actually flat, not round. (He also believes that powerful interests are trying to keep you from realizing just how flat the earth is.) It’s easy to dismiss this as attention-grabbing trolling, especially since B.o.B. just dropped a new mixtape, but his Twitter musings are so strange and sincere and extensive that we might have to believe that he actually believes this stuff. (Mental illness seems like a real possibility here, which makes the whole thing a bit less funny.) When B.o.B. was off on that tangent yesterday, scientist and celebrity factchecker Neil DeGrasse Tyson jumped on Twitter to debunk some of his claims:

@bobatl Earth's curve indeed blocks 150 (not 170) ft of Manhattan. But most buildings in midtown are waaay taller than that.

— Neil deGrasse Tyson (@neiltyson) January 25, 2016

@bobatl Polaris is gone by 1.5 deg S. Latitude. You’ve never been south of Earth’s Equator, or if so, you've never looked up.

— Neil deGrasse Tyson (@neiltyson) January 25, 2016

@bobatl Flat Earth is a problem only when people in charge think that way. No law stops you from regressively basking in it.

— Neil deGrasse Tyson (@neiltyson) January 25, 2016

@bobatl Duude — to be clear: Being five centuries regressed in your reasoning doesn’t mean we all can’t still like your music

— Neil deGrasse Tyson (@neiltyson) January 25, 2016

This has led to something even stranger: A rap beef against Neil DeGrasse Tyson. B.o.B. has just posted a new song called “Flatline” about how the world is flat, and it features a sample of Tyson talking about the world’s shape. A choice line: “Neil DeGrasse Tyson need to loosen up his vest / They’ll probably write that man one hell of a check.” Also: “They divided the seas up into 33 degrees / Feeding kids masonry, be careful what you read.” Also, bafflingly: “Stalin was way worse than Hitler / That’s why the POTUS gotta wear a Kipper.” We should be clear here: He is rapping about a Jewish conspiracy to brainwash the world. He recommends that his audience “do research” on famous Holocaust denier David Irving. On a rap song. I don’t even know, man. Here’s the song:

You can read the lyrics to the thing at Genius.

UPDATE: Neil DeGrasse Tyson has now fired back. Rather than rapping a response at B.o.B. he’s recruited his nephew, TYSON, to rap a bunch of scientific corrections over Drake’s “Back To Back” beat. The new song is called “Flat To Fact,” and it is bad. Check it out below.

@bobatl As an astrophysicist I don’t rap, but i know people who do. This one has by back: https://t.co/BbMi4tzHLz

— Neil deGrasse Tyson (@neiltyson) January 26, 2016