What are neutrino imprints?
814385
A neutrino is an elementary particle that has been considered massless for many years, but recent experiments have shown their mass to be extremely small, but non-zero. This basically means that the neutrino is very much like a ghost particle that hardly ever interacts with normal matter. One analogy I've heard is that a neutrino can pass through matter a light-year thick and not get absorbed or have a collision. So it's hard to see how the neutrino can make any imprint on anything.\n\nHowever, it's been determined that when the Universe first formed, most of the matter in the Universe was in the form of a neitrino, about 41%. Currently scientists believe that the Cosmic Background Radiation (whch is the leftover of the Big Bang) may have neutrino imprints, and that these imprints may tell us more about the nature of matter/energy in the Universe, and eventually what will become f the Universe.
523517
A neutrino.  You don't need a charge to get it to accelerate in a magnetic field.  You just can't have mass.
46009
Some of these overlap.\n\nSorting by Weight:\n-------------------\n\n1. Baryons: heavy particles. They are always fermions, so have half integral spin. (protons and neutrons are baryons)\n\n2. Muons: medium weight particles (intermediate weight between lepton and baryons, such as muons, kaons, pions, etc)\n\n3. Leptons, light particles (neutrinos and electrons are leptons)\n\n\nSorting by Spin\n----------------\n\n1. Bosons: having integral spin and satisfying Bose-Einstein  statistics (helium-4 atoms and photons for example)\n\n2. fermions: having half integral spin and satisfying Fermi-Dirac statistics (electrons, protons, etc)\n\n\nCharacterization by Force Influence\n------------------------------------\n\nHadrons: subject to the strong force (protons and  neutrons for example). These are of two types: the baryons and the mesons (intermediate weight between lepton and baryons, such as muons, kaons, pions, etc)\n\n\n\nOf course, there is  HUGE amount of other information about these.
196869
You get an antineutrino from the decay of a neutron, giving a proton, an electron and an antineutrino. The reason you get those decays is that heavy nuclei (like Uranium, Plutonium) have many more neutrons than protons. Light stable nuclei have about the same number of protons as neutrons. So after a heavy nucleus undergoes fission, you get lighter nuclei with too many neutrons compared to protons. It is energetically good for them to change some of the neutrons into protons through beta decay. Hope it helps.
526456
No, it's evidence of combustion.  Radioactive decay is usually invisible unless you have film there to see the particles given off.
420044
I'd imagine it refers to a flash exhibited in a particle detector in certain circumstances - more precisely, when the interaction between a neutrino and pure water produces a particle moving faster than the local speed of light.  In this case, Cerenkov radiation is produced, in the form of a small ring of light which is detected by the photomultiplier tubes.  The 'telltale flash' in question.\n\nFor a bit more info, search for 'SuperKamiokande' and see what you turn up.
510041
To realize the existance of massless particles, one needs to come out of the orthodox classical visualization. Quantum mechanically, mass is not the necessary property for the existance of a particle, it could be just one of the properties! So, the statement that 'neutrino is matter and must have mass' is not correct (although, now it is known that they do have some mass).\n\nNeutrino is a chargeless particle that has half (plus or minus) spin (hence, a fermion). Postulated by Pauli (1931)in order to remove the descripancies associated with the explanation of beta-decay observations, the neutrino-theory successfully explained the beta decay.\n\nHowever, experimental discovery of neutrino wasn't that easy. For a particle whose interactions with matter are extremely limited (neutrinos are subjected only to weak and gravitational interactions), it required a lot of planning, very huge detectors and very accurate counters to detect neutrino. Nevertheless, a few neutrinos have been successfully detected. For example, the first experimental detection of neutrinos took place in 1956 by Clyde Cowan, Frederick Reines, F. B. Harrison, H. W. Kruse, and A. D. McGuire, a result that was rewarded with the 1995 Nobel Prize. Also, although they had been considered massless for many years, recent experiments (e.g.: Super-Kamiokande, Sudbury Neutrino Observatory, KamLAND and MINOS) have shown their mass to be non-zero (around 0.05 eV, can not be more than 0.3 eV). \n\nNote:\n1. Writing the unit of mass as eV (unit of energy) is a common practice in nuclear physics, and it actually corresponds to the energy associated with the mass (E = mc^2).\n2. The example of 'burning' as a proof of mass-energy equivalence, as given by one of the user is foolish. Burning is just a chemical reaction. In burning, a given mass is converted into other masses (gases, solid ash, etc.), and heat is generated (exothermic process).
637538
thatoneguy is confusing alpha decay with beta decay.\n\nWhen a beta particle is released one of the neutrons of the parent becomes a proton and the electron is released to conserve charge (and carry away some mass).  The daughter recoils because of the electron and an anti-neutrino that is released during the decay.
47603
Good question. It depends on whether you count exchange particles (ie particles associated with the fundemental forces of nature), if you count antiparticles, and which particle physics model you are using.\n\nIn the "Standard Model" of particle physics there are the follwing fundemental particles (the word's in CAPTIALS are the type of particle):\n\nLEPTONS:\nelectron, muon, tau.\nelectron neutrino, muon neutrino, tau neutrino.\n\nQUARKS:\nup, charmed, top.\ndown, strange, bottom.\n\nGAUGE BOSONS:\nphoton, W+, W-, Z0 (note the +, - and 0 are superscripts)\n8 different gluons.\n\nand finally... the Higgs Boson (still undiscovered).\n\nThis doesn't count antiparticles, of which there are 12 (6 anti-leptons and 6 anti-quarks).\n\n\nSome theories introduce a whole host of new particles, but none of these extra particles have been discovered either.
341412
There are some theories that suggest that quarks and leptons are composed of smaller "fundamental" particles known as Preons or Rishons (depending on the theory you read). The rishon theory nicely shows why electrons and quarks always have a charge that's a multiple of e/3 by having the same rishons or antirishons inside them.\n\nAlso they have a hypercolour property similar to the colour property of quarks that explains why the particles we see (leptons or confined quarks) always have an integer multiple of e charge.\n\nThese theories also have downsides too, such as Heisenbergs uncertainty principle stating that a particle that small must have a large amount of energy, which is more than the mass of an electron!
1069017
Hmm.... I can't seem to find one on the sites I've checked, but based on inference, I would guess it would be something like Argmt. or Agmt. These aren't official, mind you, but with a little hard work they could be ;) .
255787
What kind of a symbol?
258993
This looked interesting but I am still very confused ?!?!?!\n\nWeighing the Universe \n\nThere are obvious contributions to the density of the Universe, e.g., planets, galaxies, ... , however, there are also other not so obvious contributions. We need \nrho = rho(baryons) + rho(neutrinos) + rho(photons) + ... \n\nUsing the above, we define \n\nOmega = Omega(baryons) + Omega(neutrinos) + Omega(photons) + ... \n\nSo the issue becomes what are all of these contributions to Omega? \n\nBefore we go on, photons are in there, but why? Aren't photons massless? And what if neutrinos turn out to be massless? Why are they there? \n\n\nAccording to Einstein, E = mc2, and mass and energy are equivalent. They are just different forms of a single entity \n===> mass = Energy / c2 \n\n\nCMBR ===> rho(photons) = 4.7 x 10-34 gm per cubic centimeter << than any reasonable rho(critical) \n\nThe neutrinos are more problematic. \nFor the Cosmic Neutrino Background Radiation (CNBR) \n\n====> rho(neutrinos) = 0.3 rho(photons) and if neutrinos are massless (like photons) then the CNBR does not make a large contribution to the density of the Universe. \n\n\nWhat if neutrinos are not massless? \n\nnumber of neutrinos per c.c. is N(neutrinos) ~ 375 per c.c. ===> rho(neutrinos) ~ 375 m(neutrino) gm per c.c. \n\nTo get an idea about when neutrinos are important, let's use H(now) ~ 25 [km/s] per Million light years ===> rho(critical) ~ 1.2 x 10-29 gm per c.c. ===> rho(neutrinos) > rho(critical) if m(neutrino) > 3.2 x 10-32 gm ~ m(electron)/300,000 (or so). \nNeutrinos can either be important or not depending upon whether they have a significant rest mass. \n\n\nGalactic Masses (Individuals and Groups) \nI will discuss galaxies as probes of the mass of the Universe. In some cases, there will be direct counting of galaxies, in other cases, the galaxies will be used as test particles. Define \n\n\nOmega(gal) = Omega(baryon) + Omega(other?) \nWe will measure Omega(galaxy) using light and dynamical techniques \n\n\nLight Method \nThis is straight-forward. We simply count up galaxies. The complication is that we observe primarily the galaxies which are easy to see. However, there are also many galaxies which are hard to see. These hard to see galaxies are the ones with low surface brightness (which means that they are very hard to see against the pervasive background of the night sky. The number of these low surface brightness galaxies is not yet well-established, however, the current density distribution of galaxies is interesting. But anyway, let's press onward under the assumption that we may be making a factor of 2 error or so by only considering the bright galaxies in our discussion. \n\nRecall, galaxies are divided up into different types: \n\n\n \nThe different types of galaxies have different Mass-to-Light (M/L) ratios. To get a feel for what M/L tells us, consider: \n\n\nA galaxy made of 1011 stars like the Sun. We then have M/L = 1011 M(Sun) / 1011 L(Sun) ===> M/L = 1 M(Sun)/L(Sun). If we measure M/L in units of solar masses to solar luminosities, then this galaxy has M/L = 1. \n\nSuppose that this same galaxy had in addition to its stars, 1011 black holes of mass 1 M(Sun) ===> M/L = 2 x 1011 M(Sun) / 1011 L(Sun) ===> M/L = 2 \n\nSuppose that we had a galaxy composed of 1011 stars of mass 10 M(Sun) and 104 L(Sun) ===> M/L = 1011 x 10 M(Sun) / [1011 x 104 L(Sun)] ===> M/L = 0.001 \n\nThe Mass-to-Light ratio depends on the types of stars that populate galaxies and how much unseen matter exists in the galaxies. \nThe typical M/L for the visible parts of galaxies are: \n\n\nEllipticals: (M/L) ~ 7 - 20 \nSpirals: (M/L) ~ 3 - 5 \n===> Omega(gal,visible) ~ 0.007 (factor of 2 uncertainty) << 1 \n\n\nDynamical Methods \nThe dynamical methods are indirect in the sense that you do not count-up things. You rely on Newton's laws of physics and gravity. The dynamical methods are applied on all scale
481479
Strings are indeed very small but I'm going to have to agree with the neutrino answer here. They are so light that they were thought to have no mass until the late seventies (I think).
575368
Well, there are 3 families of sub-atomic particles, namely:\n\nQuarks, containing:\n1. up quarks (charge + 2/3)\n2. down quarks (charge - 1/3)\n3. charm quarks (charge + 2/3)\n4. strange quarks (charge - 1/3)\n5. top quarks (charge + 2/3)\n6. bottom quarks (charge - 1/3)\n7. all six anti-quarks\n\nQuarks interact with each other by the STRONG INTERACTION, which involves the exchange of virtual particles called gluons. Virtual particle exchange cannot be actually observed, hence the name "virtual".\n\nSTRONG INTERACTION: The particles that result from applying quantum principles to one set of FIELDS are called quarks.\n\nFIELD: The universe's fundamental building blocks, (according to the Standard Model). [I don't know what this means :)]\n\nLeptons, containing:\n\n1. electrons (charge -1)\n2. electron neutrino (charge -1)\n3. muon (charge -1)\n4. muon neutrino (charge 0)\n5. tau (charge 0)\n6. tau neutrino (charge 0)\n7. all six anti-leptons\n\nLeptons interact with each other by the ELECTROWEAK INTERACTION, by exchanging virtual particles called the photon, two W's and one Z\n\nELECTROWEAK INTERACTION: The particles that result from applying quantum principles to another set of fields are called leptons.\n\nBosons, containing\n1. photons\n2. Z boson\n3. W+ boson\n4. W- boson\n5. gluon\n6. Higgs boson\n\nWell, I'm not a physicist or scientist, just the normal person, so I can only tell you what I know:\n\nAccording to the Standard Model, Quarks or Leptons are tiny packets of energy.\n\nBosons are other types of energy packets, but cannot be observed because of the "virtual" thingy resulting from uncertainty considerations.\n\nWe don't really know what an electron is like, but it forms an electron cloud wherever its orbit is situated. The Heisenberg Uncertainty Principle states that there is a limit on the mathematical product of the position uncertainty and the momentum uncertainty of any particle and a corresponding limit on the product of the uncertainty in energy and the uncertainty in time. [I don't understand a single phrase of that :)]. Anyway, we know that the more precisely the position of an electron is known, the less precisely its momentum can be known, and vice versa. There's another strange thing about electrons. In p-type orbits, the orbits form a figure of eight, but with teardrop-shaped electron clouds replacing the eight with their tips facing the center. At this precise center, no electron can exist for any given time. That is, our probability of finding an electron here at any given time is zero. However, an electron can always travel from one teardrop to another. How, you ask me? I don't know, but it's explained in the wave theory.\n\nAs for photons, scientists explain its particle-like properties and wave-like properties by saying that spheres and wave-lines are far too simplistic diagrams to express the nature of photons. And, you'd probably like to know, that a photon's antiparticle is still a photon. So, scientists cannot know that whether a particular photon is actually matter or antimatter.\n\nProtons are made up of 2 up quarks and 1 down quark, hence the charge of 1+. Neutrons are made up of 1 up quark and 2 down quarks, hence the charge of zero.\n\n(Whew), that's about all I know. Sorry I couldn't explain everything, because I simply don't know anymore.
1154361
Hi Decisiveliu\n\nThe most recent observations indicate the following:\n\n* about 70% of the energy density of the universe is dark energy (for physicists this is an omega value of 0.7, where omega is the ratio of the actual density to the critical flatness density)\n* about 30% (omega = 0.3) of the energy density is normal mass-energy\n\n* of this 30%, about 27% is dark matter, and the remaining 3% is baryonic or luminous matter\n\n* about 20% of the total dark matter mass is likely to be massive neutrinos (small weakly interacting particles), about 10% large non-luminous objects (eg black holes, neutron stars, brown drawfs, etc) and the remainder unsure as yet\n\n* of the visible matter the vast majority is hydrogen (as suggested above), followed by helium, and then (relative) traces of other elements.\n\n\nHope this helps!\nThe Chicken
765187
The symbol for sopper is Cu\nThe symbol for Nickel is Ni