The term "Modern Monetary Theory" (MMT) has been around for a while, but it has become more commonly used since the major central banks launched their money-printing sprees after the 2008 crash. (I added the "mad, maniacal" part, just to ensure that the term accurately describes the theory.)
MMT is just a grandiose term for money-printing / helicopter money. It's insane, foolish, and very destructive.
https://en.wikipedia.org/wiki/Modern_Monetary_Theory
Expect destruction.
Sure. I figure like equations that go into developing the tools used by the Fed.