Renormalization

So I'm trying to figure out vacuum energy, and the first thing that really made any sense was renormalization, which is a method of dealing with infinite quantities in Quantum Physics.

Infinite quantities occur in three ways in the thought experiment in the Wikipedia article. They are all virtual particle situations that involve the "back reaction" of an electron's field with the electron itself:
1. a photon creates a virtual electron-positron pair which then annihilate, this is a vacuum polarization diagram.
2. an electron which quickly emits and reabsorbs a virtual photon, called a self-energy.
3. An electron emits a photon, emits a second photon, and reabsorbs the first. This process is shown in figure 2, and it is called a vertex renormalization.

So there are these closed loops of virtual particle interaction that can't be measured directly. They can't be measured indirectly because any massive particles or energies within the loop could be cancelled out by other corresponding loop aspects.

The physicists figured out that the quantities (of the electron) they were measuring didn't acutally correspond to the forces they were seeing in the lab. The virtual particle loops affected the constants of their equations. By factoring in the particle loop effects and normalizing the electron quantities by only considering relative changes, the total energy of a system could be defined, and the infinities isolated. With the infinities isolated they could be used to cancel out the troublesome infinite effects. The theory of limits is used to grant the divergences calculable values. A limit can be obtained by adding a regulator to the loop that causes convergence at high energies.

There are models that renormalization wouldn't work with, and these are said to be nonrenormalizable and don't exist in the Standard Model.