There are definitely rankings in science and engineering departments. To find out what they are, just look at where faculty in a given field at any university got their PhD. 99% will be from the same 3-5 institutions. For example, in Chemical Engineering the top schools are (in nor particular order) MIT, Berkeley, Stanford, Cal Tech, Wisconsin, and Minnesota.

The OP was pointing out that his wife had the academic cred to compete for faculty positions, but chose not to do so. There's no need to be the next Einstein in order to become faculty, or to change the world for that matter.