What You Need to Know About the Weak Force

What You Need to Know About the Weak Force The weak nuclear force is one of the four fundamental forces of physics through which particles interact with each other, together with the strong force, gravity, and electromagnetism. Compared to both electromagnetism and the strong nuclear force, the weak nuclear force has a much weaker intensity, which is why it has the name weak nuclear force. The theory of the weak force was first proposed by Enrico Fermi in 1933 and was known at that time as Fermis interaction. The weak force is mediated by two types of gauge bosons: the Z boson and W boson. Weak Nuclear Force Examples The weak interaction plays a key role in radioactive decay, the violation of both parity symmetry and  CP symmetry, and changing the flavor of quarks (as in beta decay). The theory that describes the weak force is called quantum flavourdynamics (QFD), which is analogous to quantum chromodynamics (QCD) for the strong force and quantum electrodynamics (QFD) for the electromagnetic force. Electro-weak theory (EWT) is the more popular model of the nuclear force. Also Known As:  The weak nuclear force is also referred to as: the weak force, the weak nuclear interaction, and the weak interaction. Properties of the Weak Interaction The weak force is different from the other forces: It is the only force that violates  parity-symmetry (P).It is the only force that violates charge-parity symmetry (CP).It is the only interaction that can change one kind of quark into another or its flavor.The weak force is propagated by carrier particles that have significant masses (about 90  GeV/c). The key quantum number for particles in the weak interaction is a physical property known as the weak isospin, which is equivalent to the role that electric spin plays in the electromagnetic force and color charge in the strong force. This is a conserved quantity, meaning that any weak interaction will have a total isospin sum at the end of the interaction as it had at the beginning of the interaction. The following particles have a weak isospin of 1/2: electron neutrinomuon neutrinotau neutrinoup quarkcharm quarktop quark The following particles have a weak isospin of -1/2: electronmuontaudown quarkstrange quarkbottom quark The Z boson and W boson are both much more massive than the other gauge bosons that mediate the other forces (the photon for electromagnetism and the gluon for the strong nuclear force). The particles are so massive that they decay very quickly in most circumstances. The weak force has been unified together with the electromagnetic force as a single fundamental electroweak force, which manifests at high energy (such as those found within particle accelerators). This unification work received the 1979 Nobel Prize in Physics, and further work on proving that the mathematical foundations of the electroweak force were renormalizable received the 1999 Nobel Prize in Physics. Edited by Anne Marie Helmenstine, Ph.D.

5 Sentences Repaired by Correct Use of Commas

5 Sentences Repaired by Correct Use of Commas 5 Sentences Repaired by Correct Use of Commas 5 Sentences Repaired by Correct Use of Commas By Mark Nichol 1. â€Å"Students write a third essay regarding the impact of geography on history and culture.† The implication of this sentence is that students produce three essays on the topic in question. But if the preceding text refers to differing topics for the first two essays, the sentence suffers from insufficient differentiation. This revision specifies that the third essay’s topic differs from those of the others: â€Å"Students write a third essay, this one regarding the impact of geography on history and culture.† 2. â€Å"Students participate in a workshop on learning to research effectively and refine their search with a professional researcher.† The relationship between the verb phrases in this sentence is unclear: Do students first participate in a workshop and then refine their research, or do they participate in a workshop about researching effectively, during which they also refine their search? Either way, the sentence, because of the ambiguity, is erroneously organized. If the former meaning is intended, the sentence should read, â€Å"Students participate in a workshop in which they first learn to research effectively and then refine their search with a professional researcher.† If the latter meaning is the correct interpretation, it should read, â€Å"Students participate in a workshop on learning to research effectively, and then refine their search with a professional researcher.† 3. â€Å"He invoked the dreaded comparison with Mary Smith, only Jones has been more successful in her sport than Smith.† Because of the paucity of punctuation in this sentence, the sentence could be read as containing a comma splice, an error in which a comma is incorrectly employed in place of a more substantial punctuation mark. But if a semicolon or a period separates the two clauses, and the second element (depending on which punctuation mark is used, an independent clause or a separate sentence) seems to imply that no one other than Jones has been more successful than Smith, a non sequitur results. It’s much more likely that only serves as a less formal synonym for however. However, just as when that word is used, the sentence still requires stronger punctuation to clarify its function: â€Å"He invoked the dreaded comparison with Mary Smith; only, Jones has been more successful in her sport than Smith.† The semicolon seems too formal for the casual only, though; a dash seems more appropriate. Either way, however, only must be set off from the following statement by a comma: â€Å"He invoked the dreaded comparison with Mary Smith only, Jones has been more successful in her sport than Smith.† 4. â€Å"She also uses a Geiger counter, which measures radiation; motion detectors; barometric-pressure monitors; and thermometers.† This sentence, containing four listed elements only one of which, the first, is modified is hampered by the notion that because of that extra phrase, the usual commas must be promoted to semicolons to bear the burden of supporting the sentence’s structure. When used with such short phrases, however, the semicolons seem overbearing. The simple insertion of the conjunction plus, which serves to provide more distance between sentence elements than the standard and, obviates the complicating semicolon solution: â€Å"She also uses a Geiger counter, which measures radiation, plus thermometers, motion detectors, and barometric pressure monitors.† (Notice that, for euphony, I’ve reordered the additional list items according to the number of syllables in each item.) 5. â€Å"The majority has upheld the act in whole, not by relying on an expansive reading of the commerce clause, but on Congress’s firmly rooted power to tax.† The initial proposition in this sentence, â€Å"The majority has upheld the act in whole not by relying on an expansive reading of the commerce clause . . .,† is a continuous thought, and there is no reason to include punctuation within it. But there’s a larger problem: The sentence is not parallel. Relying should be repositioned to serve both propositions (those beginning â€Å"not on† and â€Å"but on†), because the structure of the two phrases, in the original sentence respectively headed by â€Å"not by† and â€Å"but on,† is discordant. The solution, which (like â€Å"not only . . . but also† constructions), requires no internal punctuation: â€Å"The majority has upheld the act in whole by relying not on an expansive reading of the commerce clause but on Congress’s firmly rooted power to tax.† Want to improve your English in five minutes a day? Get a subscription and start receiving our writing tips and exercises daily! Keep learning! Browse the Punctuation category, check our popular posts, or choose a related post below:How to Format a US Business Letter44 Resume Writing TipsOne Scissor?