IMAX film is twice as wide as standard film. 70 mm instead of 35 mm. The IMAX film platters are physically ginormous. All that extra film gives you a bunch of extra resolution compared to regular film.
The first catch is that "IMAX standard" may not be real IMAX. I don't know exactly what that means. Perhaps it could even be digital projection that aims to be comparable to IMAX in some ways?
Second catch is that a lot of films that are shown in IMAX theaters were not actually shot on IMAX originally. If a film was shot on 35mm, say, and then printed onto IMAX, you don't get all of the resolution benefits, and you may also get letter boxes or pan-and-scan because the aspect ratio isn't the same. IMAX cameras are massively more expensive and logistically difficult than regular film cameras.
The proof is not that ancient. Pi was proven to be irrational in 1761, and proven to be transcendental in 1882.
For a long time the problem was known as "squaring the circle": Given a circle in a plane, construct a square with the same area using a compass and straightedge. This was a famous unsolved problem in mathematics from antiquity all the way through the renaissance.