One of the earliest attempts at unifying the forces of nature was made in the 1920s, when German physicist Theodor Kaluza melded Einstein's gravitational theory with the electromagnetic theory of James Clerk Maxwell. (newscientist.com)
c. Evolution is on equally solid ground as other scientific theories such as gravitational theory (gravity), heliocentric theory (earth orbits the sun), germ theory (disease is caused by germs), atomic theory (matter is composed of atoms). (religion.blogs.cnn.com)
The Penn researchers intend to use the method to figure out how fast voids are kicking matter out, and then see which gravitational theory comes closest. (discovermagazine.com)