Why don't water and oil mix?

This is an example of vegetable oil and water not mixing together.

In order for a substance to dissolve in another substance they have to have similar electric dipole moments. An electric dipole moment is the measure of separation of positive and negative electrical charges in a system of charges. Which is a measure of the charge systems polarity. An electric dipole has both a positively charged end and a negatively charged end. One of the ends may be bigger than the other. The distance between the ends and the magnitudes of the 2 charges determines the strength of the dipole. Therefor, dipoles with similar strengths dissolve in each other way better than dipoles with drastically different strengths. Oil and water do not mix because they have very different dipole moments. Therefor, they do not dissolve in each other.