Physics Discussion Forum

As I understand it, a free neutron takes a few minutes to decay after being ejected from a radioactive material. What is it that keeps the neutron intact outside a nucleus for so long? I assume electrostatic attraction between the compressed proton and the electron has something to do with it, but why would that bond hold for a few minutes outside the nucleus and give up then and only then? If there was something about the force/energy environment of the nucleus that keeps the two compressed, you would expect a neutron to be ejected not as a neutron at all but as a proton and electron. If the electrostatic attraction is strong enough to prevent immediate decay outside the nucleus, why doesn't it hold them together permanently? Does it take a (few) collision(s) with other particles to loosen it up? Or is there maybe something more fundamental going on where charge actually disappears during neutron-formation and spontaneously emerges in lower-gravity/higher-energy situations? Is a neutron an inverted hydrogen atom where the electron has been relegated to some sub-ground energy level (orbital) or does charge only exist in lower-pressure systems, and if so why would that be the case?

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!

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!

I don't understand the general dynamics of quarks the way I do protons and electrons as charged particles with mass, so if you know of a good link that explains them clearly and concisely, that would be a big help. If the electron isn't compressed to some inverted orbital, what happens to it during compression when gravity is overcoming electron degeneracy pressure? Likewise, what causes the proton and electron to suddenly emerge with charge when the neutron is decaying? If quark-mechanics explains neutron formation and decay, it must also explain charge-formation, no?

Ok, I've been reading about quarks on wiki and it seems that neutrons are charge-neutral because they have two up quarks with -1/3 charge and one down quark with +2/3 charge. Then, somehow one of the up quarks changes into a down quark during decay, which shifts the charge to 4/3 - 1/3 = +1. I guess the electron just appears on the scene once it's attracted by the newfound positive charge of the fresh proton. The problem is wiki gives no real explanation of what quarks are or why they exhibit charge in -1/3 and +2/3. It is very strange that charge doesn't exhibit original symmetry. E.g. is it just pure coincidence that the charge of the electron is perfectly balanced against that of the proton? 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? Would quarks and electrons form in tandem with each other in some way and that explain the charge symmetry between protons and electrons? And what happens when the up quark changes into a down quark? How can something with -1/3 charge suddenly have +2/3 charge? Do quarks have any potential to explain the relationship between electron pressure and neutron formation and decay?

Hi inertron. You raise a lot of good questions, so here is an answer to one of them:

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?

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!

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!

Hello BA,

I wish I had an intuitive sense of what level of gravity/temperature/pressure such a particle would have to occupy to be able to interact prior to decay. Otherwise I don't know what to make of those kinds of particles. If the Delta baryons decay into nucleons, I take it the decay is exothermic, in which case I don't see how they can be a stepping stone in the process of energy converting into matter. 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.

Hi Inertron and Bill Angel,

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.

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.

In a way it is like trying to "tease" your reflection out of a mirror.... You can convince yourself that the image in the mirror is real but it does not have an existence outside of the one viewing it. Symmetry-wise an image in the "mirror" completes a "simple" picture of our idea of a Universe composed of parts but these separate parts cannot be actually separated from the "host". What this "host" to these phenomena are is very elusive to define... it kind of telling us something about the indivisibility of our spacetime. The search for the Higgs Boson is an attempt to "split a tiny bit off spacetime".

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.... ultimately spontaneously creating it's own Universe along the way in this process that I have just mentioned by suddenly disintegrating from this single particle high symmetry object into lower energy particles with much lower symmetry which occupy more and more space until we have a Universe like this one (a universe with almost no discernible gross symmetry to the naked eye).... a Universe with a vast amount of space and lots of lower energy physically large particles occupying it.

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. In fact spacetime remains intact but in some way the energy remains dispersed into this spacetime which appears localized into an energy packet... meaning that the energy cannot just simply flow away being trapped in an infinite hall of mirrors with their corresponding "self reflections" which behave every bit as real as the core originating particle we think we are searching for. In fact there is probably no such thing as the "bare particle" without all these ancillary reflections (these "reflections" are virtual particles). Actually quantum theory tells us that there are non-local aspects of particles that are not accounted for in this view of matter. You can say it does not make sense and everything must be composed of parts but that is simply a prejudice we all have from living in the world of apparently composite objects. Our intuition does not operate that well in the quantum realm.

Hi Good Elf, you raise many thought-provoking ideas. There are just a few points I want to respond to, though the rest is certainly something to keep in mind as a check against going beyond tentative in one's appropriation of these theories of unobservables.

Good Elf wrote:If there really were actual entities like quarks they could exist outside the nucleus and stand alone.

I've avoided even thinking about quarks until now out of a similar feeling, but I wonder if the reason these particles "can't exist outside the nucleus and stand alone" is just because they require certain force-field dynamics to maintain the energy-levels and speeds that sustain them. I mean, if you were a particle-accelerator jockey living on a neutron star, you would have a hard time believing that carbon atoms could stabilize permanently instead of collapsing immediately into neutron-mush, right?

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….

The thing that keeps me from launching off into the potentially infinite diversity of particles is that I keep trying to focus on the conditions of their formation/fragmentation and existence, along with whether their formation and decay processes consume or release energy. In that way, I feel like I can at least look for relationships between disparate force-energy states, such as the gravitational compression of a neutron star and the gravitationally-weak but nuclearly-strong conditions of an isolated atomic nucleus. Likewise, if I start looking at the proton-electron system as a variation on a neutron, it seems like there could be quarks or other mechanics at work with the nucleons that could logically explain their transformations as well as interactions. "15 minutes of stability" for a free neutron seems like it could be a big clue into the internal mechanics since a lot changes for the neutron in those 15 minutes, right?

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.

This makes sense to me. It's as if there are always fissures within 'particles' that allow them to be fragmented into what are thought of as independent components, but it may just be in the nature of energy to generate space/volume in whatever it is added to by virtue of the fact that it has to do something until it can figure out a route to escape/transfer to its next sink.

edit: speaking of fragmentation, it just occurred to me that the entire solar system in which we exist may well be a highly fragmented and expanded glob of neutrons spit out of a supernova. Once the glob cleared a certain gravitational horizon of its mother star, its neutronium began decaying into various elements within the different objects that formed from the cooling torus (sorry if too much of this is wild speculation deviating from current theories about solar system formation). Anyway, the point is that gravity and motion at the macro level create the space/gravity conditions that allow neutrons to decay into protons and form different elements with various stabilities and nuclear potentials. Yet the system is ultimately a set of entangled components of a unified nascent neutron mass, right?

Hi Inertron,

Just a couple of comments. You speak as if Gravity is what everything is being held together by? Gravity is most probably a by product of the stronger forces.... it is infinitesimally weak and plays virtually no role in particle formation or their destruction (as far as we know). The forces involved are (to the best of our understanding) electromagnetism and variants of electromagnetism on different scales. Gravity is a kind of left over process like Van der Waals forces in molecules. Einstein realized that Gravity is a pseudo-force the result of spacetime curvature on mass. As John Wheeler put it... Mass curves spacetime and spacetime tells mass how to move.... like a skateboard in a skateboard park.... there is no "force" attracting the skateboard to the other side of the park it is the curvature (slope) under the wheels of the board and nothing else (aside from the "pushes" the skateboard rider gives it).

If you consider this Universe's space and time as I have stated then all space and time have come from an object of high symmetry, almost infinite mass and almost no volume (no space). This mass shows up when the particle disintegrates... and not before. When this primary unstable (but highly symmetric) object disintegrated (in the same way an atomic particle disintegrates).... all current space, time and matter flowed out from it in the "Big Bang". Space is still being created today... we call it dark energy. It is still filling the spaces between the points of matter in our Universe. Consider an atom... it is almost all empty space... I said "almost all". The bit that is not empty space is "solid matter"... it is a very tiny fraction of this whole. In an atom if the electron shells (the bit where the speeding electron are found) were the size of the biggest football stadium in the world then the nucleus would be the size of a small bowel of cherries in the middle. Unfortunately that solid matter is likewise also almost all empty space (it's internal components are also spinning at relativistic speeds... as noted recently by tests at Jefferson Labs) ... there will be something "solid" inside each component too.... and then we look at that object .... it will also be almost all empty space... inside of it there will be more components an even more rapidly moving energy source with a hard core.... the story goes on and on and we know not where it ends.

We already know that there are at least three orders of matter at higher and higher energies... there may be an infinite progression. They relate strongly to the primary particles in matter just more and more heavier versions of them with more symmetry of a smaller size when you try and separate them out. Leave these heavier versions "inside" they have less mass and the overall particle is less symmetric. Being heavier they are smaller and are more and more internally symmetric. Leave them alone inside the primary "causative" particles and they have almost no extra contributory mass. Electrons, protons and neutrons are the most stable... but neutrons are less stable if you pull it out of it's "causative" particle (the nucleus) and it will disintegrate usually into a simple proton and an electron --- the pair have lowered symmetry compared with the neutron and occupy more space.... if you don't believe me try putting the electron back into the proton. Protons and electrons are ultimately what the Universe is composed of... simple hydrogen.... the rest is fusion and fission in supernova since the big bang. What we know is in this process a lot of empty space is formed and it is all around us right now. I hope you are seeing this pattern? An extended version of this is called the Holographic Theory but believe only as much as you need to reconcile the model in your mind.

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

Hi "Good Elf"

Good Elf wrote:If there really were actual entities like quarks they could exist outside the nucleus and stand alone

I would draw your attention to the wiki article titled Deep Inelastic Scattering

To quote from the conclusion at the end of this article

"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."

The idea in the experiments was that high energy electrons were were fired at protons and neutrons in atomic nuclei. The analysis of the results from inelastic scattering experiments confirmed that in baryons [i.e protons and neutons] , there are three points of deflection (i.e. baryons consist of three quarks).