Everything is electromagnetism. Electromagnetism's vector has a static magnitude, aka the speed of light, and all energy is the change of direction of this vector; the magnitude is static and does not change. Electromagnetic waves such as light have zero movement along the time axis, and as such have maximum magnitude along the three space axes. Electromagnetic waves with mass (aka matter) are moving diagonally, along both the time axis and at least one space axis. The combined total of directional magnitude and time magnitude equals the speed of light; as you approach light speed, you are shifting your electromagnetic vector closer to the space axes and reducing the amount of magnitude on the time axis, which results in the phenomenon known as time dilation. Hypothetically, electromagnetic waves that travel solely along the time axis should exist.