My post at: http://www.sciforums.com/showpost.php?p=1818401&postcount=17 I observe that the Helium nucleus (2P & 2Ns) is stable DESPITE the Coulomb interaction between the two protons, P. I concluded that post with: If anyone can educate me on why P = 0 & N = 4 does not exist, I would appreciate it. After some thought on this, I began to wonder how we know that what I will call N4 does not exist? By which of the four fundamental forces could the existence of N4 be detected? Answer (I think): Only by gravity. Certainly not by the Coulomb (electric interaction). I cannot see how the strong force would give any observable except by some scattering experiment, but how do you make an accelerator for N4 beams or an N4 target to “throw” protons at? The “weak force” would disclose the existence of N4 only if one of the neutrons were to decay. That might be possible, but there are many nuclei in which the neutrons are stable against beta decay etc. Alternatively, perhaps N4 does decay with very long half life. – Could that be where some of the tritium comes from? Certainly, each N4 produces a gravity field, but it is surely much too weak to be detected. This line of thought leads to the wild idea that there is lots of N4 in the universe. Perhaps more than 90% of the universe is N4. I.e. what we call “dark matter” is mainly N4. Now I know that the “dark matter” experts state that “dark matter” cannot be any form of “ordinary matter.” I do not fully understand this, but think this statement may related to the lack of “dark matter” scattering of distant star light, etc. Having no way to interact with any EM radiation, N4 would not scatter starlight. Thus, if no one can answer my original question above, its extension becomes: How do we know that “dark matter” is not “zillions” of N4 particles? Comments? Zephir, whose posted ideas (which I think are nonsense) my post cited above was a replying has kindly provided me the following link: http://www.cnrs.fr/cw/en/pres/compress/noyau.htm
Quite easily. Because we safely know, the tetraneutrons aren't stable particles and here's no mechanism, how to regenerate them in the void of cosmic space. Every particle, which is supposed to form the very old structure of dark matter must be extremely stable - this effectively excludes all these WIMPS and other less or more abstract and unstable artifacts, which are expected to appear in expensive experiments in accelerators. Sometimes the theorists appears to lose the sense of reality at all. Here exists a few controversial hypothesis, the dark matter is formed by larger objects, like the tiny black holes or strangelets, but I don't believe in it. After all, we can observe the dark matter effects even inside of solar system by Pioneer anomaly, where no such artifacts were ever observed and its evident, if dark matter exists, it must be dispersed quite finely. The explanation of dark matter can be a much more trivial. The main portion of so called "cold dark matter" is caused by omni-directional Universe expansion, which results into violation of Lorentz symmetry at cosmological scale. Please Register or Log in to view the hidden image! So called "hot dark matter" is formed most probably by heavily ionized atom nuclei, stripped of theirs electrons. At the case of heavier atoms it's often more difficult to free atom nuclei of electrons, then to achieve the fission, because the electrons are binded to protons very strongly, so they lack the electron spectra at all. These nuclei are repelling mutually, so they can defy a gravity of galaxies. We can even observe them as a spherical haze by X-ray dispersion in X-ray telescopes, like Chandra. Surprisingly enough, the most trivial hypothesis are considered at the very end, by the same way, like the dense aether hypothesis.
You supplied a link (and it is at end of OP also) that makes your "we safely know" at least questionable, even if it is probably true that N4 does not exist. I quote from it: "... a system made up of only two neutrons is not bound… but it is very nearly: a slight increase in the attraction between the two particles would result in a bound structure, the "dineutron," being formed. Finally, research into nuclei having more than two neutrons shows that, very often, adding a further neutron increases the stability of the structure. The question then arises as to whether a neutron system made up of more than two neutrons could exist. On the basis of current knowledge of interactions between nucleons, the theoretical answer is probably not. In fact, for 40 years now, all attempts to show experimentally that such a system could exist have failed. However, over the last ten years, with the advent of high-energy exotic nuclei beams, it has been possible to design new experiments since it is thought that nuclei that are very rich in neutrons could contain clusters made up of neutrons only. ..." They had 6 events (in 2002) which seem to suggest N4 does exist. Basically scattering of protons off dense collections/ clouds of neutrons. If the protons "rebounds" 180 degrees from a collision with a single neutron, it has very little energy, but if the collision was with an assemble of neutrons in N4 it has most of the energy returned to it. That is there approach and they claim 6 events. I cannot read their paper in Physical Review C and do not know good reference for it. (Link at end of OP is only a "press release" but the primary author seems to be: Geneviève Edelheit / Tel: +33 1 44 96 47 60 / e-mail: edelheit@admin.in2p3.fr and I have made no effort to contact her, I assume.) I hope others, more knowledgeable than me, may know something about this. I certainly agree that for N4 to be a major part of the dark matter, it must be stable and I would also think it must be a delayed product of the "big bang" condensed out of the energy only some protons, neutrons, and electrons with considerable temperature initially. Obviously some nuclear binding did take place as the temperature dropped (at least if it is true that Helium was not all formed in stars.) I am still at a loss to understand why Helium is more stable than N4, as seems to be the case, despite the Coulomb forces trying to destroy He nucleus but not N4 nucleus. It must be true that the strong force between N and P is not identical to that between P & P or N & N. I do not think this necessarily implies that the strong force depends directly on the charge of the nucleon, as the quark structures of N & P are different. Hope someone jumps in here with some mechanistic explanations. Your assertion that N4 is “unstable” is not what I am looking for; and possibly is not even true.
This is logical, isn't it? If the tetraneutrons would be more stable, then it would be a much more common. It's like the tiny clusters of water vapor molecules, which are quite metastable. The surface tension of cluster will stabilize the neutrons itself, but it will increase the speed of neutron evaporation from cluster. The smaller such cluster is, the faster is the decomposition of it. This is the reason, why the tetraneutron clusters are so rare. You'll need the very rich source of cold neutrons to prepare such stuff. You can imagine the neutron fluid as a reflecting droplets (of density in range ten thousands of tons per cubic millimeter), penetrating the ordinary matter like ghosts in glowing holes. It's highly improbable, such superdense matter would be of insignificant surface tension. After then we can ask, how large such surface energy can be and how it will affect the stability of neutrons inside? You should forget the nuclear forces, the surface tension is macroscopic effect. U can imagine it as a result of uncompensated isospin charge between up- and down- quarks at the curved surface of neutron droplet.
Yes, how dare they predict something never seen before but which they have working models which lead to precisely testable physical predictions! It's almost as if they are following the scientific method. Not that you'd know. Except they don't behave like a liquid in the sense of an aether. The protons in nuclei produce a stablising effect. The precise mechanism isn't know but it's something to do with pseudo-Goldstone exchange.
Well, this is the moment of 2nd order phase transition inside of supercritical fluid. The density fluctuations previously formed are sufficiently heavy and strong to form a sort of four-dimensional meta-fluid, even with its own "surface". Such meta-fluid exhibits a quite complex interactions between its particles, but its still nothing, what cannot be derived from inertial particle models and what violates the dense Aether concept. Please Register or Log in to view the hidden image! The fact some fluid composed of irregularly shaped particles is behaving like the "non-Newtonian fluid" doesn't mean, it cannot be described by the Newtonian dynamics under consideration of its particular geometry. By such way, we can convert a whatever theory of your personal preference into another just by consideration of some specific geometry. Sorry, no "WIMPS" were detected so far. And if these WIMPS aren't detected, it simply means, they're unstable and they cannot form the dark matter streaks, which exists for billions of years. This is quite trivial conclusion.
Wikipedia - Tetraneutron Says that the theory says they're unstable. Letter to the Editor in Journal of Physics G: Nuclear and Particle Physics: Do multineutrons exist? Says: "Summarizing, due to the small probability for a pair of neutrons to be in the singlet even state, the two-body NN force cannot by itself bind four neutrons, even if it could bind a dineutron. Unrealistic modifications of the NN force would be needed to bind the tetraneutron." Other scholarly abstracts: Further Evidence for the Nonexistence of Particle-Stable Tetraneutrons (1965) Can Modern Nuclear Hamiltonians Tolerate a Bound Tetraneutron? (2003) Is the tetraneutron a bound dineutron–dineutron molecule? (2003) On the existence of a bound tetraneutron (2002) Zephir is the heart and soul of pseudoscientist. Dripping with confidence and answers for everything, which never a caution for the unwary that his ideas are (at best) poorly tested.
The fact, the water tetramers weren't detected in water vapor by reliable way doesn't mean, the concept of water droplets, confined by only their surface tensions is terribly wrong. In fact, the formation of polymers in vapor phase is the very weak evidence of the formation of such droplets, until these droplets will not become quite large. It's rather difficult to create the droplet in mildly saturated vapor, but once its created, the further growth of it can become undeniable. Once such droplet will appear during LHC experiment, it will start to grow by avalanche mechanism in contact with ordinary matter. And this is the whole problem of neutron clusters confirmation. I've no problem to confirm their existence in free cosmic space - but the experimental refusal of such stuff in CERN underground can become the very last success of dumb mainstream science, which is sufficiently ignoring even the most trivial and apparent analogies of inertial reality over last hundred years.
To Zephir: The H2O molecule is intrinsically polar as the two hydrogen ions (essentially positive protons) are both near each other on one side. (With 105 degrees angular separation due the electronic “orbital configuration” of the molecule.) Thus water is increasingly polymerized as the temperature drops. Why ice floats is that the these long xH2O chains are sort of like radomly crossed spaghetti stings and have increasingly more void space between them as the temperature drops below 4C. Above 4C, the molecules of a drop of water have strong Coulomb forces acting between them. Those force acting on the H2Os inside the drop have a long term average force of zero applied, but this is not true of the H2Os on the “skin of the drop.” Those outer molecules have a strong long term average electrical or Coulomb force attracting them towards the interior. There is no such thing as a “surfaced tension” force. Stop with your nonsense about it. THERE ARE ONLY FOUR FORCES.* If you insist on speaking about a non-existent force, let’s talk about the much stronger “unicorn force.” Those suckers can really pull! Please Register or Log in to view the hidden image! -------------- *According to the "dumb mainstream science," Please Register or Log in to view the hidden image! which lacks your special knowledge and insite about the fifth "surface tension" force. Please Register or Log in to view the hidden image! P.S. If you want to write a article about the surface tension force, for my journal: Collection Relating All Claims, Karma, Propositions Or Theories, I can guarantee speedy global circulation. (I am the owner and editor.) Just send the low $10 page charge to address I will PM to you after I receive the article.
From post 4: Are you sure about this? I thought the smallest "neutron droplet" was N8, a little cube with 6 flat sides. Please Register or Log in to view the hidden image! That brings me to the suggestion that N8, with each of the neutrons having three "contacting neighbors" bound by the strong force may be more stable than N4, but how could it form? The most stable configuration of N4 of course also has "three contacting neighbors" for each of the neutrons, but in N8 each neutron has the additional binding from four other neutrons as they are all still separated from it inside the attractive force range.
If it's so trivial, why are you wrong? We didn't conclusively detect neutrinos, which are stable, till around the 1970s. Something being elusive doesn't mean it's unstable. This is a very trivial conclusion.
Correction on discovery date: In 1930 Wolfgang Pauli proposed a solution to the missing energy in nuclear beta decays, namely that it was carried by a neutral particle This was in a letter to the Tubingen congress. Enrico Fermi in 1933 named the particle the "neutrino" and formulated a theory for calculating the simultaneous emission of an electron with a neutrino. Pauli received the Nobel Prize in 1945 and Fermi in 1938. The problem in detection was that the neutrinos could penetrate several light years depth of ordinary matter before they would be stopped. In 1951 Fred Reines at Los Alamos thought about doing some real challenging physics problem. In a conversation with Clyde Cowan they decided to work on detecting the neutrino. Their first plans were to detect neutrinos emitted from a nuclear explosion. Realizing that nuclear reactors could provide a neutrino flux of 10^13 neutrinos per square centimeter per second, they instead mounted an experiment at the Hanford nuclear reactor in 1953. The Hanford experiment had a large background due to cosmic rays even when the reactor was off. The detector was then moved to the new Savannah River nuclear reactor in 1955. This had a well shielded location for the experiment, 11 meters from the reactor center and 12 meters underground. The detection of the neutrino was as the initiator of the inverse-beta decay reaction of: anti-neutrino + proton -> neutron + positron. The target was water with CdCl_2 dissolved in it. The positron was detected by its slowing down and annihilating with an electron producing two 0.5 MeV gamma rays in opposite directions. The pair of gamma rays was detected in time coincidence in liquid scintillator above and below the water by photomultiplier tubes detecting the scintillation light. The neutron was also slowed by the water and captured by the cadmium microseconds after the positron capture. In the capture several gamma rays were emitted which were also detected in the scintillator as a delayed coincidence after the positron's annihilation gamma ray detection. The detector contained 200 liters of water in two tanks with up to 40 kg of dissolved CdCl_2. The water tanks were sandwiched between three scintillator layers which contained 110 5" photomultipliers each, and the whole experiment measured only about 2 meters in each direction. At Savannah River, Reines and Cowan carried out a series of measurements to show that (see Reines' personal accounts below): (a) the reactor-associated delayed coincidence was consistent with theoretical expectation; (b) the first pulse of the delayed coincidence signal was due to positron annihilation; (c) the second pulse was due to neutron capture; (d) the signal was a function of the number of target protons; and (e) the reactor-associated signal was not caused by gamma rays or neutrons from the reactor. The rarity of neutrino capture is shown in their signal rate, which was about three events per hour in the entire detector. The signal to background ratio was about four to one. Thus in 1956 was born the rich and continually exciting field of experimental neutrino physics, as discussed in other articles in this newsletter. This discovery was recognized by honoring Frederick Reines with the Nobel Prize in 1995. Original papers are: "Detection of the Free Neutrino: A Confirmation", C.L. Cowan, Jr., F. Reines, F.B. Harrison, H.W. Kruse and A.D. McGuire, Science 124, 103 (1956). "The Neutrino", Frederick Reines and Clyde L. Cowan, Jr., Nature 178, 446 (1956). "Neutrino Physics", Frederick Reines and Clyde L. Cowan, Jr., Physics Today 10, no. 8, p.12 (1957). The history is detailed in the following accounts by Fred Reines which were the sources for this article: "The Early Days of Experimental Neutrino Physics", Frederick Reines, Science 203, 11 (1979). "40 Years of Neutrino Physics", Frederick Reines, Progress of Particle and Nuclear Physics, Vol. 32, 1 (1994). "The Detection of Pauli's Neutrino", F. Reines, NATO ASI series, ARW94/066, Eds. H.B. Newman and T. Ypsilantis. The history is also in the collected papers: "Neutrinos and Other Matters, Selected Works of Frederick Reines", Eds. W. Kropp, M. Moe, L. Price, J. Schultz, and H. Sobel, World Scientific, 1991. There is also an historical book: "Spaceship neutrino", Christine Sutton, Cambridge University Press 1992. The most easily accessible material may be that linked to by our Physics and Astronomy Department World-Wide-Web site. The links include the excellent writeup by the Royal Swedish Academy of Sciences, historical photos, and current research projects in neutrino physics by the neutrino group. The above is copied from the web page below: http://www.ps.uci.edu/physics/news/nuexpt.html Several light-years depth of ordinary matter to stop a neutrino. In other words, nearly relativistic [travelling at 0.9999999+ c] neutrinos have a VERY low, but non-zero, cross-section for interaction. Likely similar to microblackholes at relativistic speeds being essentially non-reactive, which Mangano is struggling with. See also: http://www.ps.uci.edu/physics/reinestrib.html
I thought that neutrons were not elementary particles. I think I remember reading that a free neutron decays into a proton & an electron. If such is the case, nuclear entities consisting solely of neutrons might be very unstable. BTW: Note that isotopes with too many neutrons tend to be unstable. This seems to be consistent with free neutrons being unstable. neutrons bei
That's true, but inside the neutron stars the neutrons can be stabilized by high gravitational pressure. The same can be valid in small neutron droplets with high surface curvature. After all, the lifetime of free neutron (~15 minutes) makes it sufficiently stable for most catastrophic scenarios. You're not required to have a very stable form of matter if you need to destroy the Earth in milliseconds.
