You're looking at StableBuild's Deleted PyPI mirror - where we index all deleted packages from the Python package registry.

nimblephysics
0.9.28

This version was deleted from PyPI around 2023-12-21. Installing fails with:
$ pip3 install nimblephysics==0.9.28 ERROR: Could not find a version that satisfies the requirement nimblephysics==0.9.28