Because Shrödinger's theory of the quantum wave didn't include special relativity, it ignored this "borrowing" of energy and only gave approximate values. In the 1930's and 40's, physicists attempted to take energy fluctuation into account.

The first attempt led to the creation of quantum electrodynamics, the quantum version of Maxwell's electromagnetic field. Then came the creation of the quantum field theories for the strong and weak forces, called quantum chromodynamics and the quantum electroweak theory. Quantum electroweak theory actually united the quantum field descriptions of the electromagnetic and weak forces. In the 60's and 70's, Sheldon Glashow, Abdus Salam, and Steven Weinberg showed that, at a high energy and temperature level (like right after the Big Bang) the two fields dissolve right into each other. At low temperature levels, they crystallize out into separate forms through symmetry breaking. Unfortunately, if we do a problem using quantum mechanics and general relativity mixed, we get an nonsense answer like the probability of infinite. So no one has been able to create a quantum field theory for gravity.

Today the smallest particles we know of are called quarks. They make up the protons and neutrons inside the nuclei of atoms. There are at least six "flavors" of quarks: up, down, strange, charmed, bottom, and top. Each "flavor" can be one of three "colors": red, green, and blue. Protons and neutrons are made up of three quarks, one of each color. Protons have two up quarks and one down, neutrons have two down and one up. Other flavors besides up and down can be used to create particles, but they quickly decay into protons and neutrons. The matter particles are divided into three different families, each with two quarks, the electron or one of its cousins, and a type of neutrino.

Messenger particles are virtual particles that transmit force. Photons carry the electromagnetic force. They are virtual in the sense that they don't really exist but can be seen when an electron moves to a smaller orbit around an atom's nucleus and light is given off. Gluons transmit the strong force, and the weak gauge bosons are used for the weak force. A messenger particle for the gravitational force is predicted to exist and is called the graviton, but it has not actually been observed yet. Gravity is the weakest force and is described by general relativity. The electromagnetic force is a combination of electricity and magnetism and the weak nuclear force is responsible for radioactivity. The strong nuclear force holds together protons and neutrons in the nuclei of atoms and the quarks together in the protons and neutrons. The three quantum field theories, matter particles, and force particles together make up the standard model. The predictions made by the standard model match remarkably well with experimental results using energy capable of smashing bits of matter into pieces as small as a billionth of a billionth of a meter, the current technological limit.