Anyone who’s washed dishes knows that eggs stick to pans. Egg white is mainly made up of water, and a water soluble protein called albumin. As the egg is heated, a familiar popping sound occurs, as water comes off rapidly as steam.
When albumin loses water, it coagulates and works into the many minute crevices in the surface of the metal pan. Further heating causes the embedded protein to expand in the crevices. Hence it sticks firmly on the surface. If the pan is pre-coated with cooking oil, the imperfections in the pan’s surface get filled with fat, so the albumin can’t enter the crevices.
A more efficient and healthier solution to the problem is to use a pan coated with Teflon. Teflon is thermally stable to higher temperatures than your stove can reach. In Teflon coated pans, eggs slide over the pan as easily as two lubricated metals slide past each other.
A sticky egg is only one example of a general problem. Almost everything in nature has a natural tendency to stick. If you took two pieces of absolutely pure metal, which were perfectly smooth and completely clean, they would do more than stick together if they were brought into contact in the absence of air. They would actually bond into one piece, because a metallic bond would form between them. Then it would be impossible to break them apart.
So next time, save yourself some work and use a coated pan.