Albert Einstein did not come up with the theory to split the atom. That discovery was made by Ernest Rutherford in 1911.

Here's a breakdown of what happened:

* Rutherford's Gold Foil Experiment: Rutherford, along with his team, conducted an experiment where they bombarded a thin gold foil with alpha particles (positively charged particles). They expected the particles to pass straight through, but some were deflected at large angles. This led Rutherford to conclude that the atom must have a small, dense, positively charged nucleus.

* Nuclear Fission: The splitting of the atom, known as nuclear fission, was first observed in 1938 by Otto Hahn and Fritz Strassmann. They found that when uranium was bombarded with neutrons, it split into lighter elements, releasing a tremendous amount of energy.

* Einstein's Contribution: While Einstein didn't discover nuclear fission, he did contribute significantly to the understanding of its potential. In his famous equation, E=mc², he showed that mass and energy are equivalent and can be converted into one another. This equation provided the theoretical foundation for understanding the vast amounts of energy released in nuclear reactions.

It's important to remember: while Einstein's work was crucial to understanding nuclear fission, he did not actually discover the process. The discovery of nuclear fission is attributed to Hahn and Strassmann.