Fundamental interaction

A fundamental interaction is a mechanism by which particles interact with each other, and which cannot be explained by another more fundamental interaction. Every observed physical phenomenon, from galaxies colliding with each other to quarks jiggling around inside a proton, can thus be explained by these interactions. Because of their fundamental importance, understanding of these interactions has occupied the attention of physicists for over half a century and continues to do so.

Related Topics:
Physical - Galaxies - Quark - Proton - Physicist

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Traditionally, modern physicists have counted four interactions: gravity, electromagnetism, the weak nuclear force, and the strong nuclear force. Their magnitude and behavior vary greatly, as can be seen in the table below. Yet, it is strongly believed that three of these interactions are manifestations of a single, more fundamental, interaction, just as electricity and magnetism are now understood as two aspects of the electromagnetic interaction. Electromagnetism and the weak nuclear forces have been shown to be two aspects of a single electroweak force. Somewhat more speculatively, the electroweak force and the strong nuclear interaction have been combined using grand unified theories. How to combine the fourth interaction, gravity, with the other three is still a topic of research into quantum gravity.

Related Topics:
Physicist - Gravity - Electromagnetism - Weak nuclear force - Strong nuclear force - Electroweak force - Grand unified theories - Quantum gravity

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These interactions are sometimes called "fundamental forces," although many find this terminology misleading because one of them, gravity, is no longer explained by a "force" in the Newtonian sense: no "gravitational force" is acting at a distance to cause a body to accelerate (as it was falsely assumed until a century ago in the Newtonian theory of gravitation). Instead, general relativity explains gravity by the curvatures of spacetime (composed of the gravitational time dilation and the curvature of space).

Related Topics:
Newtonian sense - General relativity - Gravitational time dilation - Curvature of space

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The modern quantum mechanical view of the three fundamental forces (all except gravity) is that particles of matter (fermions) do not directly interact with each other but rather exchange by virtual particles (bosons) called interaction carriers or interaction mediators (as, for example, virtual photons in case of interaction of electric charges). This coupling of matter (fermions) with force mediating particles (bosons) is believed to be the result of some fundamental symmetries of nature.

Related Topics:
Fermions - Virtual particles - Bosons - Photons - Electric charges

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