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Home > 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, their understanding has occupied the attention of physicists for over half a century, and continues to do so.

Traditionally, physicists have counted four interactions : gravity, electromagnetism, the weak nuclear force and the strong nuclear force. The magnitude and behavior varies greatly as can be seen in the table above. Yet, it is strongly believed that three of them are manifestations of a single, more fundamental, 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.

They are sometimes called "fundamental forces" although many find this terminology misleading because one of them, gravity, is not explained anymore by a "force" in the Newton sense : no "gravitational force" is acting at a distance to cause a body to accelerate (as it has been falsely assumed 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 ).

The modern view of the 3 fundamental forces (i.e. all 4 except gravity) is that objects do not directly interact with each other but rather generate a field which affects the behavior of distant objects. From quantum field theoryQuantum field theory (QFT) is the application of quantum mechanics to fields. It provides a theoretical framework widely used in particle physics and condensed matter physics. In particular, the quantum theory of the electromagnetic field, known as quantu these fields are associated with one or more particles and are believed to be the result of some fundamental symmetries of nature.

1 The interactions

1.1 Gravity

Main article : Gravity

Gravity is by far the weakest interaction, but it is the interaction that has the largest range. The term "long range" refers technically to the falling off of the interaction with distance r at a rate equal to 1/r². Unlike the other interactions, gravity works universally on all matter and energy. Because of its long range, and property of depending only on the mass of objects, and independent of their charge etc., most interactions between objects separated by length scales larger than that of a planet, for example, are predominantly due to gravity.

Because of its long range, gravity is responsible for such large-scale phenomena as the structure of galaxies, hypothetical black holeThis article is about the astronomical body. For other uses, see Black hole (disambiguation). roche limit. Infalling matter forms an accretion disk, with some of the matter being ejected in highly energetic polar jets. A black hole is a concentration of ms and the hypothetical expansion of the universeAlternate uses: See Universe (disambiguation In the first half of the 20th century, the word universe was used to mean the whole spacetime continuum in which we exist, together with all the energy and matter within it. Attempts to understand the universe, as well as phenomena closer to everyday experience such as the orbitFor other meanings of the term "orbit", see orbit (disambiguation In physics, an orbit is the path that an object makes, around another object, whilst under the influence of a source of centripetal force, such as gravity. History Orbits were first analyses of planetA planet (from the Greek , planetes or "wanderers") is a body of considerable mass that orbits a star and that produces very little or no energy through nuclear fusion. Prior to the 1990s only nine were known (all of them in our own solar system); as of 3s and falling apples.

Gravitation was the first kind of interaction which was explained by a mathematical theory. Isaac Newton's law of Universal Gravitation was a good approximation of the behaviour of the gravity. In 1916, Albert Einstein published the General Theory of Relativity, a more accurate description of gravity in terms of the geometry of space-time.

An active area of research today involves merging the theories of general relativity and quantum mechanics into a more general theory of quantum gravity. It is widely believed that in a theory of quantum gravity, gravity would be mediated by a particle which is known as the graviton. Gravitons are hypothetical particles not yet observed.

Although general relativity appears to present an accurate theory of gravity in the non-quantum mechanical limit, there are a number of alternate theories of gravity. Those under any serious consideration by the physics community all reduce to general relativity in some limit, and the focus of observational work is to establish limitations on what deviations from general relativity are possible.

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Topics: Fundamental Interaction Force Gravity Theory Quantum Strong...

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Fundamental interactionName of InteractionRelative MagnitudeBehavior Strong nuclear force10401/r7 Electromagnetic force10381/r2 Weak nuclear force10151/r5 to 1/r7 Gravity1001/r2 A fundamental interaction is a mechanism by which particles interact with each other, and which cann Fundamental groupIn mathematics, the fundamental group is one of the basic concepts of algebraic topology. It is a group associated with every point of a topological space and conveying information about the 1-dimensional structure of the space. The fundamental group is t Fundamental frequencyThe fundamental tone often referred to simply as the fundamental is the lowest frequency in a harmonic series. The fundamental frequency of a periodic signal is the inverse of the pitch period length. The pitch period is, in turn, the smallest repeating u Fundamental theorem on homomorphismsIn abstract algebra, for a number of algebraic structures, the fundamental theorem on homomorphisms relates the structure of two objects between which a homomorphism is given, and of the kernel and image of the homomorphism. For groups, the theorem states Fundamental theorem of arithmeticIn mathematics, and in particular number theory, the fundamental theorem of arithmetic or unique factorization theorem is the statement that every positive integer can be written as a product of prime numbers in only one way. For instance, we can write :6 FundamentalismFundamentalism is a movement to return to stricter adherence to founding principles, usually in religion. In comparative religion, fundamentalism can refer to anti-modernist movements in various religions. In many ways religious fundamentalism is a modern Fundamental analysis Fundamental theorem of calculus Fundamental theorem of algebra Fundamental unit Fundamentalist Christianity Fundamentals analysis Fundamental attribution error Fundamental justice Fundamental Baptist Fellowship of America