Graviton

In physics, the graviton is a hypothetical elementary particle that transmits the force of gravity in most quantum gravity systems. In order to do this, one theory posits that gravitons have to be always-attractive (gravity never pushes), work over any distance (gravity is universal) and come in unlimited numbers (to provide high strengths near stars). In quantum theory, these requirements define an even-spin (spin 2 in this case) boson with a rest mass of zero.

Related Topics:
Physics - Elementary particle - Gravity - Quantum gravity - Quantum theory - Spin - Boson - Rest mass

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Gravitons are postulated simply because quantum theory has been so successful in other fields. For instance, the electromagnetic interaction can be very well explained by the application of quantization to photons, a science known as quantum electrodynamics. In this case photons are being continually created and destroyed by all charged particles, and the interactions between these photons produce the familiar effects of electricity and magnetism. In the same way, the strong nuclear force and the weak nuclear force are mediated by gluons and by W and Z bosons, respectively.

Related Topics:
Photon - Quantum electrodynamics - Charged particle - Electricity - Magnetism - Strong nuclear force - Weak nuclear force - Gluon - W and Z bosons

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Given the widespread success of quantum theory in describing the basic forces in the universe except for gravity, it seemed only natural that the same methods would work well on gravity as well. Many attempts finally led to introduction of a so-far unseen graviton, which would work in a fashion somewhat similar to the photon, the gluon etc. It was hoped that this would quickly lead to a quantum gravity theory, although the mathematics became convoluted and no internally consistent theory has yet emerged.

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