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Bill Angel wrote:You should not think of a neutron as containing a proton and an electron that are somehow bound together.
The neutron is considered to be composed of two down quarks and one up quark. The decay of the neutron is associated with a quark transformation in which a down quark is converted to an up quark by the weak interaction. Why a free neutron has a relatively long lifetime of 15 minutes is a very good question!
inertron wrote: Why are there particles consisting of two down quarks and one up or two ups and one down but none that are three ups or three downs?
Bill Angel wrote:My reading indicates that there are short lived particles with those combination of quarks.
See the wiki article about the Delta Baryon. According to that article there are Delta baryons comprised of either three up quarks or three down quarks, but these particles decay quickly via the strong force into a nucleon (proton or neutron) and a pion of appropriate charge.
The lifetime of a Delta baryon is given as 5.58 × 10-24 sec. That's a pretty short time!
IMHO (and in these matters "my opinion" is truly "humble") there is something essentially amiss at this level of observation. The interior of a nucleus is not truly made up of "protons" and "neutrons" and in turn the protons and neutrons are composed of "up" and "down" quarks. This is just a deconstructionist view of this process and it depends on our "tools" and the way we measure these things. If we had different tools we would measure something else but we are limited to measurement with very simple though powerful tools. If there really were actual entities like quarks they could exist outside the nucleus and stand alone. As a point of fact this cannot occur. Extracting the quark simply makes more mirror quarks to prevent this event ever actually occurring. Once you have two quarks it will form a certain kind of particle and the show is all over.Inertron wrote:Why would energy spontaneously coalesce into a quark on the way to subsequent levels of fusion? It must have something to do with gravity being strong but more diffuse in earlier phases of the universe. What is it about sub-nucleons that quickly decay into nucleons that are relatively stable until they grow large enough to become unstable again? If heavier nuclei are more stable under higher gravitational conditions, would the sub-nucleons be stable under super-energetic temperatures? . . . or at least would their macro behaviors help explain other aspects of known physics? I'm trying to milk these concepts for meaningful insights but they seem to be eroding into arbitrary-ness.
Good Elf wrote:If there really were actual entities like quarks they could exist outside the nucleus and stand alone.
Speaking about physical size... Paradoxically the tinier the "bit" that is attempted to be split off or "created" --- the more energy it has --- so the smallest objects in the Universe carry the most energy and conversely the largest fundamental particles in the Universe in size have the least energy. Little things are big (in energy) and big things are little. Note also all the "solid" fundamental particles have an upper limit in size but seem to not have a lower limit due to limitless amount of energy needed to create heavier versions of them. There are a host of very light but large photonic particles but these quanta are at the end of some decay cycle where there is very little elsewhere to go... the end of the line are large sized particles with truly minuscule energies. On the other hand at the high energy end... possibly an endless procession of heavier and heavier particles all the way to infinity.... this would also be the smaller and smaller particle heading towards zero volume of space with the greater and greater energy….
As you must realize by now... this "empty space" is not truly empty. All particles ultimately are concentrations of energy but energy separates events from their origins leading to lags in time between where the particles were and where they are now... this mismatch of spatial energy due to these instantaneous tiny displacements traps the energy in some kind of oscillating system called entanglement. We "think" we are splitting something up with this massive energy, sometimes we may create two particles which are spontaneously opposites of each other but really they are just the one thing.
Summary: From a single point in which there is no time and no space and at close to an infinite density we derive, through the Big Bang, all time and all space seamlessly as this primary object disintegrates (like an unstable atomic nuclei) and loses symmetry and mass in the form of invisible energy creating mainly a lot of space with some less massive particles than the primary particles. This process continues till the most stable forms of particle (lowest energy) exist in a space that is in some way closely related to it. These are the electrons and protons. Through Baryogenesis new elements are formed to arrive at something like the universe we have today and after that stars form and coalesce due to gravity and even heavier elements are formed with lower group energy and even lower symmetry. These newer nuclei normally do not "fall apart" because this stability is part of this "break down" process. Some atoms get added energy in Supernova when some inherently unstable atoms are formed... eventually they also break down again. The closer we inspect "matter" we find more and more space and only very tiny amounts of very massive particles. Inside those particles are even more massive particles but only if we try and separate them from their "causative" particle out into the "outer spaces" of the laboratory environment.
Space and Mass form a continuum and you can't separate out the mass from the space... we think mass is made up of some kind of "matter"... a material different from space which itself is thought of as an absence of matter... as a point of fact and as a consequence --- matter is indistinguishable from space and simply represents different energy densities
Good Elf wrote:If there really were actual entities like quarks they could exist outside the nucleus and stand alone
"The [deep inelastic] experiments were important because, not only did they confirm the physical reality of quarks but also proved again that the Standard Model was the correct avenue of research for particle physicists to pursue."
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