By 1930, quantum mechanics had been further unified and formalized by the work of David
Hilbert, Paul Dirac and John von Neumann[11] with greater emphasis on measurement, the
statistical nature of our knowledge of reality, and philosophical speculation about the 'observer'.
It has since permeated many disciplines including quantum chemistry, quantum electronics,
quantum optics, and quantum information science. Its speculative modern developments include
string theory and quantum gravity theories. It also provides a useful framework for many
features of the modern periodic table of elements, and describes the behaviors of atoms during
chemical bonding and the flow of electrons in computer semiconductors, and therefore plays a
crucial role in many modern technologies.[citation needed]
While quantum mechanics was constructed to describe the world of the very small, it is also
needed to explain some macroscopic phenomena such as superconductors,[12] and superfluids.[13]