Create index.md

added description and wiki url to physics topic

Author: williamdavie

topics/physics/index.md

@@ -0,0 +1,8 @@
+---
+display_name: Physics
+short_description: A natural science concerned with the properties of matter and energy
+topic: physics
+wikipedia_url: https://en.wikipedia.org/wiki/Physics
+---
+
+Physics is one of the most fundamental scientific disciplines, with its main goal being to understand how the universe behaves.