Let me see if I can help at all. I wrote a paper on particle physics for my senior year physics class and touched on this. Hopefully it's understandable (sorry for the length):
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Currently there exist four fundamental forces: gravity, electromagnetism, strong, and weak. The standard model deals with the latter three forces, disregarding gravity because of the force’s infinitesimally small affect at the short distances under which the standard model is used. The gravitational force between two particles is so weak compared to the other forces that it is generally ignored by particle physicists. Gravity is as influential as it is because of the large distances over which it can act (Kane 60).
The most familiar, and second strongest, force described in the standard model is electromagnetism. This force binds electrons and nuclei into atoms, and is responsible for the interaction between atoms and molecules. The mere fact that people do not pass through floors no matter how hard they push, caused by the atoms repelling each other, plainly displays the strength of electromagnetism (Kane 61). The strongest force, aptly named the strong force, is also both attractive and repelling. The strong force binds quarks together to form baryons and mesons to create the multitude of hadrons that exist. Although the strong force is thousands of times stronger than gravity, it acts only over a very short distance and its effects cannot be felt in everyday life (66). The third force, the weak force, acts over even smaller distances and is the weakest force in the standard model (63). Responsible for radiation, the weak force triggers radioactive decay by transforming a neutron into a proton or vice versa (NOVA).
In 1927, Austrian physicist Werner Heisenberg proposed what would soon be known as the Heisenberg Uncertainty Principle. This principle states that for a particle, “the more precisely the position is determined, the less precisely the momentum is known in this instant, and vice versa” (Cassidy). The more accurately the position is known, the more energy that was used to discover that position. Any energy used excites the particle and changes its momentum, causing a larger change if more energy is used and thus a less accurate view of the particle’s momentum if a highly accurate view of the position is known. Similarly, to find the momentum of a particle, small amounts of energy are used as to leave the particle unmoved. This causes an inaccurate view of the position, becoming more inaccurate as the amount of energy lessens (Cassidy).
Originally intended to explain the uncertainty of knowing both the position and momentum of a particle, the principle can also be applied to energy and time (Gell-Mann 178). Heisenberg also showed there is a similar uncertainty in the precision of energy measurements and how long one takes to do the measurement. It is impossible to say precisely that a particle has certain energy at a certain time; ever increasing precision of energy measurements take ever-longer durations to complete (Greene 115). Over a short enough time interval, the energy of system or particle can wildly fluctuate, with important consequences (116).
When a person pushes a table with their hands, it is plain to see how the force is applied. The person’s hands act directly on the table, applying a force. However, the fundamental forces – gravity, electromagnetism, strong, and weak – seem to act at a distance, and it has been found that particles actually mediate the forces between the matter particles. These particles, known collectively as gauge bosons, are “virtually” exchanged between fermions to mediate the four forces. The various quarks and leptons are able to “borrow” energy for an extremely short interval of time to create a gauge boson. The borrowed energy is then reabsorbed by the receiving quark or lepton. This sequence of events does not violate the law of conservation of energy because energy is returned quickly enough to create an overall equilibrium (Close 46).
The two farthest-reaching bosons are the graviton, the gauge boson for gravity, and the photon, the gauge boson for electromagnetism. Neither has mass and can act over infinite distances. The low energies and zero masses of the graviton and photon allow them to exist for infinitely long duration of time (Kane 55). Alternatively, the strong and weak forces work only on very small scales (10^-13 cm or less). The strong force is mediated by the gluon (which comes in eight flavors), which binds quarks together to form baryons and mesons and protons and neutrons together to form nuclei (66). The weak force is mediated by three particles named W-plus (W+), W-minus (W-), and Z-zero (Z0); the particle used depends on the weak charge of the fermion (57). Gluons also have no mass but large energies while the weak bosons’ masses average ninety times the mass of a proton (55). Because of these large energies and masses, the weak and strong bosons can only exist for short durations of time and thus act over short distances. The gluons and weak bosons can be thought of as massive boulders that can only be pushed for very short distances, while the graviton and photon easily dash around the universe (Greene 124). |
