dark matter might cause fundamental constants to change over time /

(Phys.org)—The fundamental constants of nature—such as the speed of light,Planck's fixed, and Newton's gravitational fixed—are thought to be fixed in time, or as their name suggests. But scientists have questioned this assumption as far back as 1937,when Paul Dirac hypothesized that Newton's gravitational fixed might decrease over time.

Source: phys.org