'''Quantum field theory''' is a mathematical theory in physics which extends [[quantum mechanics]]. Field theory describes the interactions between subatomic particles, such as electrons, protons, quarks and photons. However, it predicts a cosmological constant that is 120 times larger than the observed value. <ref>http://www.aip.org/pnu/2006/split/781-2.html</ref> Simply put, quantum field theory is [[liberal claptrap]].
The differences between basic QM and Field Theory are these: in QM, the interactions between more than two particles are increasingly difficult to model, and the creation and destruction of particles cannot be modeled at all. In contrast, Field Theory can describe states containing arbitrary numbers of particles of different energies, masses, charges and types. Field Theory also provides an elegant framework for describing the interactions between particles, and the creation of new particles and destruction of old ones-- for example, the emission and absorption of photons by electrons, and vice versa<ref>Bjorken and Drell. <i>Quantum Field Theory</i> Chapter 3; McGraw Hill Inc. (1980)</ref>.