**Quantum theory** may mean:

In science:

- Quantum mechanics: a subset of physics explaining the physical behaviours at atomic and sub-atomic levels
- Old quantum theory under the Bohr model
- Quantum field theory, a generic type of relativistic quantum theory, which includes:
- Quantum electrodynamics
- Quantum chromodynamics
- Electroweak interaction

- Quantum gravity, a general term for theories intended to quantize general relativity
- Quantum optics

In popular culture:

- "Quantum Theory", the final song from
*Jarvis (album)*, by Jarvis Cocker - Quantum Theory (video game) is also the name of a console video game for PS3 and Xbox 360, released in 2010

### Famous quotes related to *quantum theory*:

“But how is one to make a scientist understand that there is something unalterably deranged about differential calculus, *quantum theory*, or the obscene and so inanely liturgical ordeals of the precession of the equinoxes.”

—Antonin Artaud (1896–1948)