Fundamental Forces

Forces that govern the various interactions between particles. The four fundamental forces, or interactions, are (in order of increasing strength): gravitational forceOne of the four fundamental forces, gravitation is the force of mutual attraction that is exerted between massive bodies and between particles that have mass. Although gravitation is far weaker than the other three fundamental forces over short ranges, it is the dominant force on large scales because its range, the weak nuclear forceFundamental force which accounts for some particle interactions. The weak nuclear force causes radioactive decay, and, in particular, governs β decay whereby a neutron breaks up into a proton, an electron and an antineutrino., the electromagnetic force, and the strong nuclear forceFundamental force binding nucleons within an atomic nucleus and preventing like-charged protons from flying apart. Particles that are acted on by the strong nuclear force (including protons and neutrons) are known collectively as hadrons. The strong nuclear interaction between individual hadrons is believed to be a remnant of a more. The strong and weak nuclear interactions are short-range forces that are effective only within atomic nuclei. The range of the strong force is ~10^-15 m and that of the weak force ~10^-17 m. In contrast, the electromagnetic and gravitational interactions are long-range forces, their strengths inversely proportional to the square of distance (1/r²). Although the effect of gravitation on particles is far weaker than the electromagnetic force, because matter tends to be electrically neutral, gravitation controls the overall dynamics of planets, stars, and galaxies. According to quantum theories, fundamental forces are conveyed between real particles by means of “virtual” particles called gauge bosons.

In the present-day universeThat which contains and subsumes all the laws of nature, and everything subject to those laws; the sum of all that exists physically, including matter, energy, physical laws, space, and time. Also, a cosmological model of the universe., at common energy levels, the four forces are separate and have different strengths. However, at very high energies (more than ~10¹¹ eV), the weak and electromagnetic forces merge into a single electroweak force. According to Grand Unified Theories (GUT), the strong nuclear and electroweak forces will behave as a single unified force at particle energies in excess of ~10²⁴ eV (~10¹² times higher than achievable experimentally). The fundamental forces may be summarized as follows:

• Gravitational Force – Acts on matter and energy; mediated by gravitonHypothetical force-carrying particle (gauge boson) for gravitation. Although there is, as yet, no generally accepted quantum theory of gravity, it is widely believed that it should be possible to formulate gravitation in quantum terms with the gravitational interaction between particles of matter conveyed by gravitons. The hypothesized graviton has zero; experienced by all particles
• Electromagnetic Force – Acts on flavor; mediated by γ; experienced by charged particles; component of electroweak force
• Weak Nuclear Force – Acts on electric charge; mediated by W⁺, W^–, and Z⁰; experienced by quarks and leptons; component of electroweak force
• Strong Nuclear Force
  • Fundamental – Acts on color charge; mediated by gluons; experienced by quarks and gluons
  • Residual – Mediated by mesons; experienced by hadrons