nothing, they appear to contradict each other.
Because they do not iclude quantum mechanics and general relativity
Albert Einstein developed the theories of general relativity and special relativity. He also did work in quantum theory. (He won a Nobel prize for his work with light.)
Quantum Mechanics
The distinction is sometimes made to distinguish normal quantum mechanics (which does not incorporate special relativity) and quantum field theory (relativistic quantum mechanics). Since we know special relativity is correct it is the relativistic form of quantum mechanics which is true, but non-relativistic quantum mechanics is still used, because it is a good approximation at low energies and it is much simpler. Physics students typically study regular quantum mechanics before moving on to quantum field theory.
Einstein's theories were General and Special Relativity. Hawking put forward a theory combining relativity with quantum mechanics.
Albert Einstein is famous for his theory of relativity, which revolutionized our understanding of space, time, and gravity. He also made significant contributions to the development of quantum mechanics and the photoelectric effect. His most famous equation, E=mc^2, demonstrates the relationship between energy and mass.
Relativity has two parts: General relativity and special relativity, general relativity describes gravity as a geometric property of spacetime and special relativity is the physical theory of measurement in inertial frames of reference. Now quantum mechanics, in it's wave formulation, deals with describing things on the atomic scale as a wavefunction.
Einstein's work on the Photoelectric effect, which won him the Nobel prize in 1921 was a bulwark of Quantum Mechanics. Einstein went off in another direction because of his inate suspicion that Quantum Mechanics has severe internal difficulties. Quantum Mechanics and Relativity have not yet been reconciled--but they are moving together slowly. Quantum Gravity seems to be key to the issue and may be resolved by String Theory.
Physics Branches: Classical Mechanics Mathematical Physics Classical Electrodynamics Quantum Mechanics Thermodynamics and Statistical Mechanics Condensed Matter Physics Nuclear Physics Quantum Field theory Non-Linear Dynamics Astronomy and Astrophysics General Theory of Relativity and Cosmology
Physics Branches: Classical Mechanics Mathematical Physics Classical Electrodynamics Quantum Mechanics Thermodynamics and Statistical Mechanics Condensed Matter Physics Nuclear Physics Quantum Field theory Non-Linear Dynamics Astronomy and Astrophysics General Theory of Relativity and Cosmology
the theory of relativity & quantum mechanics.
The related link Wikipedia article lists some. Probably his most famous are his theories of Special Relativity and General Relativity. He laid the groundwork for quantum mechanics and other modern physics concepts.Special Relativity, General Relativity and the beginnings of Quantum Mechanics.