Whose equations united electricity, magnetism, and light?

James Clerk Maxwell, a Scottish physicist, developed the equations in the 1860s and 1870s that describe how electric and magnetic fields interact. The equations predicted electromagnetic waves, including visible light, radio waves, and X-rays, all traveling at a constant speed in vacuum. This was one of the great unifications in physics. Maxwell’s work laid the theoretical foundation for modern communications and much of 20th-century physics.