Explore Related Concepts

Best Results From Yahoo Answers Encyclopedia Youtube


From Encyclopedia

Particles, Fundamental Particles, Fundamental

Fundamental particles are the elementary entities from which all matter is made. They have no known smaller parts. As recently as 1900 most people believed that atoms were the tiniest particles in the universe. By the 1930s, however, it was clear that atoms were made up of even smaller particles—protons, neutrons, and electrons, then considered to be the fundamental particles of matter. (A proton is a positively charged particle that weighs about one atomic mass unit [1.0073 AMU]; a neutron has about the same mass [1.0087 AMU] but no charge; and an electron has a much smaller mass [0.0005 AMU] and a negative charge.) Protons and neutrons make up the tiny nucleus of an atom, while electrons exist outside the atomic nucleus in discrete energy levels within an electron "cloud." By 1970 it began to appear that matter might contain even smaller particles, an idea suggested in 1963 by American physicist Murray Gell-Mann (who called the particles quarks ) and independently by American physicist George Zweig (who called them aces ). There are in actuality hundreds of subatomic particles that have been observed, but many of them are unstable. At the start of the twenty-first century, scientists believe that all matter is made up of tiny particles called fermions (named after American physicist Enrico Fermi). Fermions include quarks and leptons. Leptons include electrons (along with muons and neutrinos); they have no measurable size, and they are not affected by the strong nuclear force. Quarks, on the other hand, are influenced by the strong nuclear force. They are the fundamental particles that make up protons and neutrons (as well as mesons and some other particles). Both protons and neutrons are classified as baryons, composite particles each made up of three quarks. Quarks come in six different types, or "flavors": up and down, top and bottom, and charm and strange. Protons and neutrons are made of up (u) quarks (which have a charge of +⅔) and down (d) quarks (which have a charge of −⅓). A proton is made from two u quarks (+⅔)(+⅔) and one d quark (−⅓), giving a total charge of +1. A neutron contains one u quark (+⅔) and two d quarks (−⅓)(−⅓) for a total charge of zero. There are also fundamental forces acting on matter; these have their own sets of fundamental particles. The forces are the strong nuclear force (or strong interaction), the weak nuclear force (or weak interaction), and electromagnetism (which includes light, x rays, and all the other electromagnetic forces). All these forces are transmitted by particles called fundamental bosons (named after Indian physicist S. N. Bose). Fundamental bosons differ from fermions in spin and the number of quarks they contain. Fermions have spins measured in half numbers, and they contain an odd number of quarks. Bosons have whole integer spins, and they contain an even number of quarks. The bosons that transmit the strong nuclear force are called gluons, those that transmit electromagnetic forces are photons, and those transmitting the weak force are known as weak bosons. A fourth force, the gravitational force, is believed to be transmitted by particles called gravitons; however, the particles have not yet been observed. Still another kind of boson, called a Higgs boson, is thought to be the source of mass in other particles, but this particle also has not actually been observed. The study of fundamental particles often involves speeding up charged particles, such as protons or electrons, and then letting them collide with targets so as to produce other particles for further study. The particle accelerators used to do this are devices that force the charged particles to jump over longer and longer space gaps per unit of time, until the particles are moving at speeds approaching the speed of light. The earliest of such devices were the linear Cockcroft-Walton accelerator (1929), the circular cyclotron (1930), and the Van de Graaff generator (1931). Modern synchrotrons are large machines that have both linear and curved sections. The most powerful synchrotron is the Tevatron proton accelerator at the Fermilab located near Batavia, Illinois (just outside of Chicago); it lies inside an underground circular tunnel that measures almost 6.4 kilometers (4.0 miles) around. The longest accelerator is the collider at the CERN research center in Geneva, Switzerland—it has a circumference of about 27.3 kilometers (17.0 miles). Detection of fundamental particles is difficult because the particles are so extremely tiny. The earliest detector was just photographic film, since particles passing through would expose the film and become evident when it was developed. The first device designed for the purpose of detecting tiny particles was the "cloud chamber" (invented by Scottish physicist Charles Wilson in 1911). It was a glass container filled with air saturated with water (or alcohol) vapor. Charged particles passing through the chamber formed ions leaving fog tracks—the heavier the particles, the wider their tracks. The "bubble chamber" (invented by American physicist Donald Glaser in 1952) was similar to a cloud chamber, except that it was filled with a liquid (usually liquefied helium or hydrogen) held at a temperature just below its boiling point. Moving particles would disturb the liquid, causing bubbles to form along their paths. There was also a "spark chamber" (invented in Japan in 1959) that contained a series of parallel metal plates and produced an electrical discharge along the ion trail left by a charged particle. Although all of these devices were once important for detecting subatomic particles, they have largely been replaced by more modern detectors. In the twenty-first century fundamental particles are studied using detectors such as tracking chambers (which trace the path of a particle with electrical signals), sampling calorimeters (which track the particle's path by its energy of motion), scintillators (which give off light when particles strike them), or magnetic detectors (which cause charged particles to move in curved paths). Many instruments use combinations of these various kinds of detectors. The inspiration for C. T. R. Wilson's expansion, or cloud, chamber came from his interest in meteorological sciences. His initial intention was to recreate cloud formations. This led to an interest in studying atmospheric electric fields and the vapor trail of ions. For his work he shared the Nobel Prize in 1927. —Valerie Borek To further complicate the subject of subatomic particles, each kind of particle has an antiparticle. For example, for each kind of quark there is an antiquark of the same mass and spin, but of opposite charge. The first antiparticle to be observed was the positron, an electron with a positive charge. An antiproton is like a proton, but it has a negative charge. Antiparticles can be observed, and molecules of antimatter can even be generated. A positron orbiting an antiproton, for example, is an antihydrogen atom. Many scientists believe that there must be some areas of the universe that are completely made up of antimatter, the exact opposite of the kind of matter found on Earth. If that is true, such areas would not be very compatible with areas made of matter—when a particle and its antiparticle make contact, they destroy each other and are converted into energy. According to Einstein's special theory, E = mc2, which means that energy is equivalent to mass times the speed of light, squared. In other words, a tiny speck of matter can be converted to a considerable amount of energy. The conversion can also go the other way. Large releases of energy that occur when high-energy particles collide can produce new particles and antiparticles of matter. Much modern research in particle physics involves high-energy collisions between beams of particles, such as protons, so as to generate other kinds of particles. Some collisions involve interactions of particles with antiparticles (e.g., electrons with positrons). Particle accelerators have been turned into giant colliders in which beams of particles moving at speeds approaching the speed of li


From Yahoo Answers

Question:

Answers: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 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). The modern view of the three fundamental forces (all 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 theory these fields are associated with one or more particles and are believed to be the result of some fundamental symmetries of nature.

Question:Unification of force equivalent to Unification of Energy?

Answers:Now four forces have been resolved into 3 forces. The Gravitational, Electromagnetic and Nuclear force. How can it be four energies? This was what struck Einstein, But he could not give the combined eqn fo all the three. Gravity and Electrical force follow more or less the same principle. F=GMm\r.r or F = q1q2\r.r

Question:Which of the 4 fundamental forces of nature (gravity, weak force, strong force, electromagnet force) does friction go into? yes, i understand that friction is not one of the fources.... but which one is friction an example of?

Answers:Friction is not a "Fundamental Force." Friction is not an example of a fundamental force.

Question:What are some of the results that will benefit humanity by unifying the 4 forces of nature?

Answers:There probably wouldn't be too many practical uses for unification. It would be an enormous triumph of the human intellect though. Just think about it, according to a unified theory all the forces of nature would be manifestations of just one fundamental force....thats pretty cool. We would be one step closer to "knowing the mind of God". However it is possible that some practical devices may come from such a theory. Things like the artificial gravity that you see in Star Trek. Maybe even antigravity....thats a big maybe though.

From Youtube

CalTech: Fundamental Forces of Nature P3 :The four known fundamental interactions, all of which are non-contact forces, are electromagnetism, strong interaction, weak interaction (also known as "strong" and "weak nuclear force") and gravitation. With the possible exception of gravitation, these interactions can usually be described, in a set of calculational approximation methods known as perturbation theory, as being mediated by the exchange of gauge bosons between particles. Gravitation: is by far the weakest of the four interactions. Hence it is always ignored when doing particle physics. The weakness of gravity can easily be demonstrated by suspending a pin using a simple magnet (such as a refrigerator magnet). The magnet is able to hold the pin against the gravitational pull of the entire Earth. Yet gravitation is very important for macroscopic objects and over macroscopic distances for the following reasons. Gravitation: is the only interaction that acts on all particles having mass; has an infinite range, like electromagnetism but unlike strong and weak interaction; cannot be absorbed, transformed, or shielded against; always attracts and never repels. Electromagnetism is the force that acts between electrically charged particles. This phenomenon includes the electrostatic force acting between charged particles at rest, and the combined effect of electric and magnetic forces acting between charge particles moving relative to each other. Electromagnetism is infinite-ranged like gravity, but vastly stronger ...

CalTech: Fundamental Forces of Nature P1 :The four known fundamental interactions, all of which are non-contact forces, are electromagnetism, strong interaction, weak interaction (also known as "strong" and "weak nuclear force") and gravitation. With the possible exception of gravitation, these interactions can usually be described, in a set of calculational approximation methods known as perturbation theory, as being mediated by the exchange of gauge bosons between particles. Gravitation: is by far the weakest of the four interactions. Hence it is always ignored when doing particle physics. The weakness of gravity can easily be demonstrated by suspending a pin using a simple magnet (such as a refrigerator magnet). The magnet is able to hold the pin against the gravitational pull of the entire Earth. Yet gravitation is very important for macroscopic objects and over macroscopic distances for the following reasons. Gravitation: is the only interaction that acts on all particles having mass; has an infinite range, like electromagnetism but unlike strong and weak interaction; cannot be absorbed, transformed, or shielded against; always attracts and never repels. Electromagnetism is the force that acts between electrically charged particles. This phenomenon includes the electrostatic force acting between charged particles at rest, and the combined effect of electric and magnetic forces acting between charge particles moving relative to each other. Electromagnetism is infinite-ranged like gravity, but vastly stronger ...