In 1926, Erwin Schrödinger modified the general wave equation to apply to single particles.Erwin Schrödinger was not a lazy man laying in a bathtub dreaming up equations, he worked very hard to achieved Habilitation (venia legendi) by 1914 (Or did he?). Or was he?
This modification and it's postulates, reducing the general wave equation to apply to single particles , converted the general wave equation to an approximation, the Schrödinger equation, which is used for the foundation of many experimental and technological fields. All approximations that work well within experimental error (experimental error masks theoretical error).
Thus shut up and calculate.
Thus, super computers are needed to solve the equations.
Likely, since there is so much fighting over how to "science" and whoever controls funding wants to keep it this way, and the point is so subtle yet so huge, it has taken up until now to bring a little light to the situation.
The General Wave equation derivation is an approximation already - having to do with concepts of linear vs. non-linear systems and validity of superposition or summing momenta, and other details. In the general case, momenta do not sum just like velocities do not add (in special and general relativity?), so a modification combined with postulates, is an approximation and misses the behavior of the whole. So, a modification to an approximation is the Schrödinger equation. Nice work fellas.
This is at the root of the problem with Western science - reductionism and isolated systems. This is not an accurate way to model Nature.
(but it works good for technology, AI, singularity, while abusing Nature)