Electroweak interaction. In particle physics, the electroweak interaction is the unified description of two of the four known fundamental interactions of nature: electromagnetism and the weak interaction.
Although these two forces appear very different at everyday low energies, the theory models them as two different aspects of the same force. Above the unification energy, on the order of 100 GeV, they would merge into a single electroweak force. Thus if the universe is hot enough (approximately 1015 K, a temperature exceeded until shortly after the Big Bang) then the electromagnetic force and weak force merge into a combined electroweak force. During the electroweak epoch, the electroweak force separated from the strong force. Fundamental interaction. Fundamental interactions, also called fundamental forces or interactive forces, are modeled in fundamental physics as patterns of relations in physical systems, evolving over time, that appear not reducible to relations among entities more basic.
Four fundamental interactions are conventionally recognized: gravitational, electromagnetic, strong nuclear, and weak nuclear. Everyday phenomena of human experience are mediated via gravitation and electromagnetism.
Electromagnetism.