Original: The term '' matter '' is used throughout physics in a bewildering variety of contexts : for example , one refers to '' condensed matter physics '' , '' elementary matter '' , '' partonic '' matter , '' dark '' matter , '' anti '' - matter , '' strange '' matter , and '' nuclear '' matter .
Simplified: Matter attracts other matter with a force called gravity . Light is not matter , but its movement is changed by gravity as though it was matter .