What forces are at work when neutrons are ejected?

[Chris Bradley]

I've kicked this question over from a 'FAQ' thread-drift, because I think it is quite an interesting question and have discussed it with other forum members before, off-line....


Steven Sesselmann wrote:
> why would a neutron be kicked out of a stable nucleus?
> There is no Coulomb repulsion between the neutron and the other nucleons, so what if anything would kick it out and why?

In classic terms, the neutron will be ejected by magnetic forces. The neutron is charge-neutral, but has a magnetic moment because it is composed of charged quarks...

.... yeah, I find that somewhat unsatisfactory too. From what I have read, I get the impression that the field within an atom is around 1T, and 1T isn't enough to deflect a neutron in macroscopic experiments. There again, what is the magnetic field within a momentarily fused nucleus itself? Could be PetaTeslas for all I know....

I suppose one might suggest there is some sort of quark-soup stage of nuclear fusion, and at that point the charged quarks have some sort of repulsive behaviour.

However, further to the discussion in another thread, I think there is a fundamental 'temporal' behaviour to quantum effects, and having the neutron ejected is energetically preferential. The question 'what is the force involved' may be a fundamentally flawed question: I'll posit that what we describe as 'forces' are actually the macroscopic manifestation of these thermodynamic [energetically preferential] effects, rather than the other way around!

[Dennis P Brown]

Neutrons are subject to the strong nuclear force and as a result, are under extreme confinement - read localized. This is the 'binding energy of the neutron in the nucleus.

When they are no longer bound, the previous energy of confinement is huge and once free of the strong nuclear force, will have this kinetic energy (In the MeV range.)

Using the size of the nucleus, Planck's constant, and the neutron mass, the kinetic energy of a free neutron can be obtained (roughly) by using the Heisenberg uncertainty principle. That is h/2Pi must be greater than or equal to delta (x) delta (p); where delta x is 5*10^-15m; so just solve for p.

A rough calculation I did puts it at about 0.1 MeV; this is not corrected for relativistic velocity effects (big effect at these energies) so this value is too low - just as it appears to be - so the real answer would be more like a few MeV. Still, this simple approach shows that the energy of confinement is huge so a neutron (no longer bound by the strong force (read gluon force)) would have a huge KE outside the nucleus.

A few words on the meaning of some of this: While it appears to an observer that the neutron has a huge KE of ‘ejection’ - this is not meant to be literal - nothing 'ejects' the neutron from the nucleous - rather it is no longer bound. So the neutron appears suddenly free (no longer confined!) and has this KE due to having been confined. Sometimes physicists write things out and are sloppy in the words they use. Don't read into this real meaning like a force 'ejected' the neutron - that is NOT what happened. What happened is that the neutron no longer 'feels' the strong nuclear force (and charge and magnetic forces mean nothing here) and since it was confined but is now free, all that 'stored' energy is now converted into KE.

An aside: a neutron, like all particles, has a finite chance to 'tunnel' out of the nucleus. Hence, under extremely rare instances, a neutron could leave a stable nucleus. Of course, as most know, neutrons are really only released by unstable nuclei where these lifetimes can be as short as 10^-15 sec and for a few elements, to many millions of years.

[Steven Sesselmann]

Dennis,

Our general understanding of confinement is to hold someone or something against its will, so how do you explain the neutrons unwillingness to be in the nucleus, and if it wants to be somewhere else then where and why?

Steven

[Chris Bradley]

Dennis P Brown wrote:
> When they are no longer bound, the previous energy of confinement is huge and once free of the strong nuclear force, will have this kinetic energy (In the MeV range.)

This makes little sense. When I apply the parking brake on my car, the 'confinement' provided by the brake may be up to several thousand Newtons (depending on how hard I pull it!!). When I release the brake, my car will only begin to accelerate if it were already on a slope - that is to say, there is the force of gravity just waiting to pull my car down closer to the centre of the earth.

My car would not accelerate 'just because' the brake is released. There has to be [in classic physics] a latent force waiting to do something to that mass that is no longer restrained.

The question is - what is the latent force waiting to accelerate the neutron 'downhill' from the nucleus. The strong force works only 'towards' the nucleus. It is like gravity in that regard - one directional.

[Dennis P Brown]

If you are asking for the 'why' of quantum mechanics (the uncertainty principle), that is far beyond my pay grade!!! (LOL)

[Dennis P Brown]

OK, I think I see the issue here and I hope this helps clear up the issue some - the uncertainty principle is not something that exists in our daily lives - there is no example of this in the macro world. I cannot point at a macro object and show this. This is all due to purely quantum effects and seen by experiment. One creates an unstable nucleus and "see's" a neutron appears with a few MeV of KE. We say it was 'ejected' from the nucleus but in reality, it is just no longer confined by the strong force. Since the force is no longer holding the neutron in place, it is free and has the energy of its confinement. These are experimental observations and these are placed in a context of the best mathematical framework – it is dangerous to use literal interpretations about these concepts.

[Chris Bradley]

Dennis P Brown wrote:
> These are experimental observations and these are place in context of the best mathematical framework – it is dangerous to use literal interpretations on these concepts.

So, what *is* the theoretical/mathematical framework you mention? Your reply looks like a simple 'I give up, no idea, why question it?' answer, which gets us nowhere.

The neutron is definitely a material part of the two deuterons that come together. None of those parts is travelling as fast as the neutron that may come out of their fusion. In the inertial frame of that collision, and in conventional mechanics, some force *must* have been applied over a given distance for the neutron to have gained KE in that frame.

Accepted science says there are 4 forces. Ex-nucleus neutron acceleration isn't down to weak or gravity. That leaves electro-magnetic or strong. 'Strong' works towards the nucleus, so that's not it.

That leaves electro-magnetic. Is it EM, or something we don't understand. Either way, the *next* question, 'how does this act on the neutron?', could be a very telling question in ways to elevate fusion probability. It is known that magnetic spin polarisation of B-11 accelerates fusion rate, but this has not been observed in DD, to my knowledge.

If fusion rates in Steven's device are also augmented, maybe there is a way to usefully electrically polarise DD reactions? Others have also proposed this. Maybe it is already happening in a fusor?

But if that's the case, that electrical forces are at work, why does the neutron accelerate away from the nucleus?

[Dennis P Brown]

Steve, the reason neutrons are confined is that they 'lower' their energy by being with a proton. This is why neutrons decay when not in a nucleus; interestingly, a neutron-neutron pair is almost stable enough to exist and might for very short times - people are looking for this.

The strong force holds neutrons just like it does protons - so electric forces are not the issue. rather, the neutron has a stored energy caused by the bounding force between the neutron and proton. When this force is lost (for what ever reason - often the weak force has a role here) the neutron acts like a ball that has compressed a spring but the 'string' that was holding the system together is broken (The strong force no longer holds the neutron) and all that stored energy in the spring allows the ball to fly away.

I hope this helps to clarify the issue. I am no expert in nuclear physics!

[Dennis P Brown]

Chris, the uncertainty principle is what causes the KE - the strong force (really the leakage of the gluon force) is, as you correctly point out, only a binding force. In fusion, the weak force is critical - it changes favor of one of the nucleons (neutron to proton or a proton into a neutron; notice charge is not conserved here.) The reason the now free particle has KE (and the other particles have opposite recoil energy) is solely due to the uncertainty principle. That is a very real law of physics that explains ALL of quantum mechanics. It is, in fact, when quantum was invented - when the black body radiation paradox was solved by Planck.

Modern physics textbooks cover all this and would do a better (far) job than I can. Get one at the library and check out the binding energy issue.

(Sorry about late edits but I am typing fast. When I say "neutron to proton or a proton into a neutron; notice charge is not conserved here." I mis-spoke: An electron is created or absorbed so there is no net electric field change but that the conversion is after the fact; the weak force takes a neutral particle and creates a pair of charged particles. The correct statement is that quark favor is not conserved.)

[Dennis P Brown]

You have asked a lot of questions – some are answered by my previous answers (the uncertainty principle) and a few of may 'answers' need further clarification.

I did not give up – the uncertainty principle is more fundamental than the strong force (which really does not exist – it is viewed as leakage of the gluon force between nucleons) and really answers the ‘why’ of quantum. This why cannot be explained - it is not derived from math (but many other concepts have been) but rather is what nature forces us to accept in order to explain experimental observation. It is, of course, given a mathematical framework – the famous relation that I gave in my first answer on the relationship of momentum and position of any ‘bound’ system to Planks constant.

No force accelerated the neutron that leaves after the fusion (i.e. when the extremely short ranged electro-weak force converts one of the nucleons.) The neutron is left unbounded so it now is free of the gluon force and has all its confinement energy available. We call this KE and observe the neutron with a very high velocity. Just like tunneling, there is no macro world way to explain the ‘speed’. It was not accelerated nor was it acted upon by a force at all. Viewing it as a force that accelerates the neutron is an incorrect interpretation of the experimental results of fusion.

Relative to magnetic spin, maybe this has some small effect (maybe more?) but until someone can use this force to explain the KE (and do away with the uncertainty principle) that will not be a good model to use since it does not explain current thinking or experimental results (currently.)

I do not know what a polarized D-D looks like or even what that means so I could use some explanation on that topic.

The electro-magnetic force DOES factor into nuclear issues in the nucleus but cannot affect a neutron directly. However, when the weak force converts a neutron into a proton, the electro-magnetic force would come into play but so would the gluon leakage force or what is called the strong force.

However, it is not clear to me on how this effects D-D fusion or the nucleus.

[Frank Sanns]

Before this thread rambles much deeper into conjecture, it might be helpful to look at the situation of the neutron itself. A neutron is not stable outside of an atom and it decays into a proton, electron and an anti-electron neutrino. None of which can exist as themselves inside of the neutron. Banter about forces and uncertainties but even the fundamentals of the fundamentals are poorly understood by mainstream science.

Frank Sanns

[Dennis P Brown]

Frank, I very much used well-understood and clear physics - I did not once use "conjecture". I am somewhat lost at what you are getting at? Please point out where I did not offer clear and exact physics in my answers. Also, I did in fact point out that the neutron is unstable outside a bound system. I have answered the first question Steve and Chris were wondering about and most certainly did not extend this thread in a non-useful manner - I did clarify and expand my answers in response to questions that were asked. Thanks.

[Richard Hull]

Let's face it.....

It is all made up as we go along. (Vector force bosons?, gauge particles?, flavors?, color?) It is all dreamed up to explain the unknowable into an acceptable fabric that certain powers have found to explain, to their own and their associates satisfaction. Each new observation that doesn't fit the ever expanding fabric sends the powers scrambling to expand the fabric with new assertions.

It helps that uncertainty is a virtually accepted tenat for within it, what is, in effect, "the hand of God" can make things happen as if by magic or more acceptably the probablistic roll of some nuclear dice that contain an infinite number of sides.

The casting of the bones are read for us by the powers that be, based on their solid,yet, ever expanding logical framework.

Science, for me, ends at the easily demonstrable and perpetually perdictable outcomes. The moment I am told that there is some uncertainty in why something occurs or a possibility of various things will occur due to a single physical setup, Science fades from view and I stop weighing and considering that which is told to me.

In short, I accept the unknowable and find contentment in that which can be expalined fully. I have tried to stop musing over the unknowable, mysterious uncertainies within the nucleus. For at the level of proclaimed uncertainty, the powers that be are, themselves, powerless of persuasion.

Richard Hull

[Jeff Robertson]

I'm not sure how I feel about the uncertainty principle being used in this context. The uncertainty principle, as the name implies, is intended to explain the fundamental uncertainty in measuring both position and momentum of a particle. The "delta x" and "delta p" are really just standard deviations of their respective variables - it is sloppy notation by many generations of authors that has led people to think they're anything else. So in the rough calculation you did, you solved for the uncertainty in the momentum of the neutron, rather than the momentum itself. I dunno, maybe I'm completely wrong and this is in fact a valid analysis of the nucleus, but this is just my understanding of quantum mechanics. Tunneling and all those fun quantum effects, however, are still in play though (as you mentioned).

I think the ejection of a neutron can be explained with barely, if any, quantum physics. Classically, the energy of a system is defined as the kinetic and thermal energy of a particle, as well as the binding energy holding it. For example, in a proton-electron (hydrogen, if you will) system, the electron is in a stable orbit around the proton. The reason for this is that the total energy of the electron is negative, which is one of the main characteristics of a bound system. The reason for this is that the electron's kinetic/thermal energy is less than the magnitude of the potential binding energy (the potential energy is in fact negative) due to the coulomb force. So E = (KE) + (PE), where PE is a negative number whose magnitude is greater than KE.

It's not that the electron doesn't have kinetic energy, it's just that its kinetic energy isn't enough to overcome the binding force. Kinetic energy can manifest itself in the form of linear motion, rotational motion, and vibration. In the electron-proton system, the electron orbits around the proton in addition to having an intrinsic amount of angular momentum (known as spin), so the kinetic energy reveals itself in this way.

So, back to the main discussion, a neutron bound to the nucleus has kinetic energy (mostly in the form of vibrational I'm assuming), but the strong interaction overwhelms the neutron and forces it to remain confined. If this balance is disturbed, say by the collision of another subatomic particle, the potential energy of the neutron due to the nucleus will be changed. For example, in nuclear fission a neutron collides with a large, barely stable nucleus. The short range of the strong nuclear force cannot hold together such a nucleus anymore, and the neutrons on the outskirts of the nucleus lose a bit of the binding energy they had before. This drop in binding energy is enough for their internal kinetic energy to overcome the energy confining them to the nucleus, so the system becomes unstable and they are free to leave the atom.

I'm not sure if this is a satisfactory explanation, but this is just how I interpret what's going on. Now as to why a neutron is ejected as opposed to a proton, that is an interesting question. I think Frank put it nicely though - the neutron by itself is less stable than a proton, so if one of the two had to go it sort of makes sense that the neutron would be kicked out first.

I don't really see how the magnetic force plays a major role in this. While a neutron does have a small magnetic moment, the other forces at play (coloumb and strong nuclear) are likely much more powerful than any magnetic effects, at least on the atomic scale.

Jeff

[Steven Sesselmann]

Could we explain the neutron ejection as an extreme case Boyles law?

Steven

[Jeff Robertson]

Steve,

I'm not sure what you mean, could you go into more detail? Boyle's Law, if I remember correctly, is basically the ideal gas law for a constant temperature. The ideal gas law is derived from the basic assumption that a gas is made up of independent moving particles, and the "pressure" in both the ideal gas law and Boyle's Law is due to molecular impacts from gas molecules on the walls of a container. This seems like an entirely different phenomena (and a macroscopic one, compared to the size of the nucleus) than what's responsible for the neutron's behavior.

Jeff

[Dennis P Brown]

Richard, I see you can wax poetic!

[Dennis P Brown]

Jeff, I think you miss understand the uncertainty principle and what it is saying - it is not a series of uncertainties in measurements like someone in the lab weighing a tiny bit of chemicals - it is an absolute statement to the limit of knowledge that the universe imposes and says deep things about what atoms and particles can and can not due - it is what keeps electrons from spiraling down into the nucleus.

Remember the electro-static attraction between an electron and proton? Well, have you considered that there are NO significant forces that prevent the electron from reaching the proton? The fact that it does not IS due to the uncertainty principle in action combined with selection rules (take about something pulled out of thin air.)

Calculate the energy an electron would have if bound with a proton on the dimensions of a nucleus and the energy is huge! Far beyond normal nuclear binding energies. And why the electron can not be bound by the electro-magnetic force so close to a proton (the gluon force does not 'see' electrons.

Yes, this principle has no bases in our normal world and appears as a fix but quantum does not ask us to believe anything except experimental results. Until a better theory is developed that explains experimental results better, that is the reality. My calculation is SOP (also, I used the momentum formula to relate KE besides the uncertainty formula) for modern physic courses.

People have spent many decades working on these problems and do you really think they missed something so simple as what you are saying? Maybe but they calculate nuclear constants and predict effects using standard models and this works well - yes, there is a lot not understood but it is pointless to believe they are all wrong and you have a better insight. That is, unless you have experimental data proving that you get better energies? Try calculating the KE of the neutron and see using your idea if it gives a better answer than mine. If so, you are on to something, otherwise, you are not.

Isn't predicting possible results as accurately as possible what we all want a theory to do? Just because we don't like it does not invalidate it.

[Dan Tibbets]

Neutron binding is dependent on forces, but it is also dependent on position. I think nuclear chemistry is similar to regular (electron) chemistry. The protons and neutrons are occupying defined orbits (round / elliptical or possibly hyperbolic (if escaping) . And these orbits can be changed- think of fluorescence in regular chemistry, and isomers in nuclear chemistry. If a neutron is near the maximum extent of it's orbit, it will take a relatively small perturbation to escape- or errors of position and or momentum.
Ihave a wak knowledge of the weak force in the picture, except that it is the major consideration in the binding of unlimited neutrons. The competing interactions mediated by the strong force, electromagnetic force and their relative ranges do a good job of predicting proton and electron numbers in a nucleus. But since this interaction is absent with neutrons* so the weak force dominates.

I recall a gravity / planet orbit program ("Newton" I believe) that would calculate the orbits and show a graphic of the orbits of planets around a star, another planet, etc.. If a too long of a time slice was used (speeds up the program) the errors build up and planets will start escaping from their orbits and even the solar system. The problem is that the precision of the calculations suffers. If the time slices are short enough, the orbits are well behaved, and the program is boring as the updates are slow. The uncertainty principle may be considered in the same way, except the highest precision is set by the universe, not by the whim of the computer user. I wonder if time is quantized and if this plays a role. Or, stated another way, the precision is set by God, not by humans. And, a computers precision is based on the number of bits it can handle, A 64 bit processor is better than a 32 bit. The uncertainity of the calculations are always present. Even if the uncertainty principle is ignored, the precision of any calculation is limited by the number of particles (or wave packets if you prefer) in the universe. The numbers are not infinite, so any calculation cannot be absolutely accurate, nor can the calculations always come up with the same answer (perfect precision).

The question becomes not why there is a an Uncertainty Principle, but why it is set at a level that leads to the statistical effects that underlies known quantum physics.

Whether we can understand why is not really relevant. That we can develop a theory that successfully makes predictions is. The standard model does this (so far), and I suspect it does so through multiple levels of assumptions and squirming. It may have little to do with reality, except that it predicts things accurately. String theory derivatives try to answer the question of why, but without testable predictions they are mathematical flights of fantasy that might be elegant and consistent, but are otherwise useless. And, of course they do not answer the question of reality, but only shifts the assumptions to a 'finer' level. If physics is based on strings, what are strings based on?

Sorry, I waxed philosophical.

*The strong force still plays a role with the neutron binding verses the weak force due to the limited range of the strong force in comparison to the volume/ radius of the nucleus. When a neutron is transiting the core of the nucleus it experiences the maximum strong force interaction. But when it is in a more distant portion of it's orbit the strong force interaction has weakened considerably, but the weak force has lessened to a smaller degree (1/r^3 vs 1/r^2?). At some radius the neutron will experience a net repulsive force. The same happens with the protons (?), but since the electromagnetic force is so much stronger than the weak force, it occurs much closer to the nucleus center and the weak repulsion is essentially irrelevant. I have no idea at what radius the weak force becomes stronger than the attractive strong force and what the orbital maximum radius of the neutron may be, or what magnitude of the Uncertainity Principle applies. but the assumption is that as neutrons accumulate, the orbits reach dimensions where there is significant chance of escape. A hint may come from the uncertainty effects on the D-D fusion cross section data (it is very significant).

Dan Tibbets

[Frank Sanns]

Dennis,

The conjecture is is from the particle zoo model and other inconsistent explanations. Leaking gluons doesn't really float my boat like many of the other pet theories that are floating around in mainstream science. Actually, the theory for the sake of theory isn't as important than results. Take all the theories that you want and it will be tough to get me interested but give me one experiment with a result and you have my attention.

Frank Sanns

[Frank Sanns]

The Uncertainty Principle is not something mystical or magical. It is not even unique to quantum mechanics. It is applicable to all forms of waves including those in the ocean and sound waves too. It simply is a relationship between trade offs. Usually is it measuring time and precision.

If there is a sound wave with 2 meter wavelength and you only measure for one tenth of the time that the wave goes by, they you will not have a very good estimate on the wavelength or the energy of the wave. If however, you measure for a long time for multiple waves to go by, then you will have a good estimate of the wavelength but it will have taken much more time. Nothing magical here. Just basic wave physics.

Frank Sanns

[Dennis P Brown]

No one has said the uncertainty principle is magical and please don't add such nonsense.

Also, the quantum uncertainty principle is not the same as what is used for uncertainty in measurement related to ocean waves - the quantum uncertainty principle puts absolute limits on what can ever be achieved with measurements, and relates this to Planck's constant.

Time does not enter into the measurement equation I gave for the uncertainty principle for position/momentum - what you are using is an invalid analogy. Of course if you limit a time dependent measurement in time, you introduce a finite and well determined error relative to wave position - this has no relevancy to the topic of the neutron energy when it is no longer bound within a nucleus - only quantum principles apply to this situation. Macro measurements based on Newtonian mechanics does not apply - this has been proven by experiment.

When one uses the uncertainty principle, and the standard Newtonian momentum/energy relation corrected for relativistic effects, the exact answer for the neutron KE is obtained for the now free neutron.

Continued arguments on this point are silly - if you desire to believe nonsense, that is your right. If you wish to try and disprove this scientific fact, I'll do my best to help you with your ideas and experiments but if you just want to continue to make verbal arguments, you are wasting everyone's time.

[Jeff Robertson]

Hey Dennis,

I know the uncertainty principle very well, and like Frank says (although wrong context) it is not limited to just Heisenberg's famous equation. The formal mathematical model of quantum mechanics contains a famous equation which relates the uncertainty between any two observables. The famous uncertainty principle which you used is just one application of this generalized uncertainty equation, when applied to position and momentum. The "delta x" and "delta p" in Heisenberg's uncertainty principle do in fact represent standard deviations. Not deviations in human error or measurement, as you said, but in the fundamental observables of the particle in question.

I do, in fact, remember the electro-static force between an electron and proton (can't tell if that was intended to be condescending or rhetorical, I'll assume rhetorical). What keeps the electron from spiraling into the nucleus, at least the way I learned it, is the quantization of the electron's angular momentum, which is derived from the wave function of the hydrogen atom. The electron can only take on certain values of angular momentum which are multiples of the reduced planck's constant (excluding the 1/2 spin of the electron itself). Without this quantum law, the electron would radiate as it orbited around the nucleus (as it's constantly accelerating), spiraling down until it collides with the proton. I'm not sure how Heisenberg's uncertainty principle applies to the electron's stable orbit, that's something I'll have to think about. I suppose as the electron travels closer to the nucleus it becomes more defined in its position (as it is stuck in a potential well and there is a less broad region in which it is likely to be), implying a greater uncertainty in the momentum, but I see this as merely a consequence of the wave equation rather than the governing law itself. The quantization of angular momentum is what I learned to be the main governing law which keeps the electron and proton from colliding. An electron's wave function must be in compliance with Schrodinger's equation, and it so happens that virtually every possible solution of the Schrodinger equation for the hydrogen atom allow only discrete values for the electron's angular momentum.

And in the last section of your post, you justify your method of analysis by saying "well, my numbers were close enough." Just because your numbers are in the ballpark of what they should be does not mean you conducted a proper analysis, that's the ends justifying the means. They weren't even in the ballpark at that - you made some comment about neglecting relativity to justify bumping it up an order of magnitude. You act like I'm insinuating that every other physicist is wrong and I think I have discovered the new standard model, when really I just didn't agree with what you did. I'll read up on this tomorrow, it's very possible that I'm just flat out wrong. If your analysis was in fact correct then I'll own up to it, but it doesn't make any of my other points any less valid. My only criticism of your analysis was that the momentum term in the uncertainty principle relates to the standard deviation, rather than the momentum of the particle itself.

In response to what Frank said, the uncertainty principle is an entire different phenomena than what goes on in macroscopic waves (as Dennis said). All quantum mechanic uncertainty principles are derived from the fundamental probabilistic nature of the wave function, which has no analogy towards the macroscopic world. Any uncertainty which exists on a macroscopic level is due entirely to experimental limitations or human error. That said, whether on purpose or accident, Frank stumbled upon an additional uncertainty principle. His analogy to measuring energy and time wasn't invalid at all, in fact it is an actual equation which is perfectly analogous to Heisenberg's uncertainty principle. That is, (delta E)*(delta t) must be greater than or equal to one half the reduced planck constant. This comes directly from the generalized uncertainty principle.

I'm not sure why you're getting so unnecessarily defensive and snippy. This forum is intended to be an open discussion board for ideas and to talk about various physics topics. Frank is not "wasting everyone's time" as you said, he's participating in an intellectual discussion about the underlying physics of nuclear decay. You come across as having a sense of elitism, when in fact you are not the only one who has knowledge on this topic. Telling people they are wasting everyone's time by posting, saying what they believe is nonsense, and that disagreeing with what you say is on par with trying to disprove scientific fact. Your past couple responses seem a touch pompous and just downright impolite. Whether or not someone's thoughts are accurate or not does not give you the right to have such a toxic attitude.

That said, there are some interesting things to think about here. I think tomorrow I'm going to dust off a couple textbooks and read up on some applications of the uncertainty principle.

Cheers,
Jeff

[Frank Sanns]

Collapse of a wave function because of observation for example is different than the probability statistics and the uncertainty. The wave function in quantum mechanics is not the same as waves in the ocean as it describes a probability whose form is a wavelike function. However, the Hamiltonian operator (potential and kinetic energies) in the Schroedinger is precisely derived from waves in the ocean. William Hamilton back in the mid 1800s envisioned a planet flooded with water. He imagined what a wave would be like when it passed by its point of origin. Soon it was clear to him that only certain allowed energies (wavelengths) were allowed (constructive interference) while others would not be allowed (destructive interference) as they would quickly die out.

Frank Sanns

[Dennis P Brown]

Jeff,

first off I never said (and this is what you wrote that I said)

"deviations in human error or measurement, as you said, but in the fundamental observable of the particle in question."

I, in fact, said the exact opposite of what you are writing here. I most certainly did point out that the uncertainty principle is not a measure of measurement errors, but an absoult limit on a quatum system.

Also, I did not say my answer was close enough - I carefully pointed out that my approach must be corrected for relativistic effects to get the correct answer.

So here is exactly what I said:

"A rough calculation I did puts it at about 0.1 MeV; this is not corrected for relativistic velocity effects (big effect at these energies) so this value is too low - just as it appears to be - so the real answer would be more like a few MeV. Still, this simple approach shows that the energy of confinement is huge so a neutron (no longer bound by the strong force (read gluon force)) would have a huge KE outside the nucleus."

Note the word 'rough calculation'. And I point out it is not corrected for relativistic effects. Further, at no point and no where did I say my answer was good enough nor even implied that.

Gotta read the post to be accurate Jeff.

I also did add that the other quantum numbers for the electron bound within an atom do in fact come into play but realized this would further confuse someone struggling to understand the uncertainty principle. Glad you decided to expand on that topic but don't imply that I didn't consider this or somehow mised it.

I too have calculated the electron orbits in hydrogen and yes, the other quantum numbers are critical. Also, the orbits are the only solutions. That all said, you really think that will explain the question about why Frank's approch was incorrect? The uncertainty principle does have a factor in this and is a clearer way to explain the issue to him. Maybe not but that is a judgement call. Still, a full hydrogen atom solution would not be helpfull at all.

Relative to the issue of a neutron having KE after leaving the nucleus and why an electron cannot be in a space the size of a nucleus, the uncertainty principle does have a major impact on whether an electron can approch/occupy that volume - do the calculation (and more to the point, most people here can do that calculation using very simple math - that is why I used that example, by the way.)

Yes, spin has a major impact but again, if you notice, the people were just trying to understand why a neutron is 'ejected' with such energy. Your current example does not address this point about the KE of a neutron leaving the atom - my use of the uncertainty principle does and is correct. Frank added a rather simple counter example and I was showing him (without a full blown quantum calculation) that his idea does not work and why. Yes, too simple for people whho have done the real solution of a hydrogen atom. Do you think that would have help Frank understand the error of his counter example?

Jeff, I most certainly did not get "unnecessarily defensive and snippy. " I was polite in my repose after being told by Frank "thread rambles much deeper into conjecture". All I did was point out I used accurate physics. What is defensive about stating a fact?

Or are you referring to when Frank said "Certainty Principle is not something mystical or magical."

This statement is very disrespectful to me and my post and all I answered was "No one has said the uncertainty principle is magical and please don't add such nonsense."

Using the statement 'mystical or magical' relative to my post on a topic that is solid and well know physics was in fact very inappropriate and, frankly, disrespectful to me. So please Jeff, explain where I was silly?

Later I did notice that this thread was continuing to have people add rather far-out attempts to explain away a very simple, straight forward physics concept. Yes, the thread was getting silly and that was said more in jest, but this was true. I will not give the exact example of why I said that because if you read some of the posts, it was not an unreasonable statement. I will not point out its cause out of respect for the poster's honest mistake.

Your knowledge on the subject is obviously good, but others are not so well schooled and I used solid, simple answers to a very good question. Further, I was respectful and handled my posts in a professional manner especially after being told that I was somehow implying that a very clear physics concept was magical - please, my answer to that statement was fully appropiate.

As for the forum, I was in fact doing exactly what it is for - answering an excellent scientific question with well known science. I treated the subject in a manner that I hoped was clear. Please refrain from such incorrect and baseless statements relative to my posts.

Thanks

Aside: your last post, except for the points I don't agree with about my posts, is an excellent explaination and I am glad you added that.