NVIDIA is proud to announce PhysX SDK 4.0, available on December 20, 2018. The engine has been upgraded to provide industrial grade simulation quality at game simulation performance. In addition, PhysX SDK has gone open source, starting today with version 3.4! It is available under the simple 3-Clause BSD license. With access to the source code, developers can debug, customize and extend the PhysX SDK as they see fit.
I’m not well-versed enough in this area to gauge how big of a deal this news it, but regardless, it seems like a good contribution to the open source community.