# Kinetic energy of a nucleus

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We are dealing with field excitations. Ie confined wavefunctions its pointlike not point as per a corpuscular bullet.

Here read this in regards to the pointlike nature

Edited by Mordred

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If you mean there is a difference between something being pointlike and being a point in reality, fair enough, but there should be some things made clear about objects that act like they are point like interactions. Just because something tends to act like a pointlike object, does not tend to mean in physics it is. Classical physics already predicted early on that particle interactions would be pointlike in nature. I forget the mathematical details now, but this is true.

String theory of course, is about extended objects in space but are rescaled to interact like pointlike objects. ... Ok I just took a look at your link, what is it you mean Mordred about this point? The main question was actually about a nucleus and whether it has a rotational kinetic energy. I explained it can and will have if the nucleus is not perfectly spherical.

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The pointlike characteristic is often poorly understood the term particle is a misnomer itself that we are stuck with for historical reasons. So one must switch their understanding of what is defined as a particle.

This is something I wanted to make sure you are aware of as it is and immense help in understanding the creation annihilation operators via constructive destructive interference patterns.

This will also apply to the nucleus. With that understanding look again at your principle quantum numbers and their corresponding wavefunctions

Edited by Mordred
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Yes. Ok.

Maybe we should create a thread on this topic, gather as much evidence as we can for this argument. It's a good topic, I just wish it had started on better terms.

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That would be a good idea to cover in greater detail.

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It may take some time, but I'll write something up.

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Sounds good I was about to recommend some pre study. The easiest way to grasp it is to look at how the hydrogen atom is modelled prior to more complex atoms

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Whereas I think the issue is problematic for pointlike systems. Our models can't seem to handle them as they natural create divergence problems.

One solution was to suggest field theory provided an answer by electron shielding of the particle, but study of the electron shape casts some doubt on this.

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2 hours ago, Dubbelosix said:

Previous experts?

Name them.

Myself and Mordred.

2 hours ago, Dubbelosix said:

No one here is an expert in my opinion.

That an \$5 will get you a cup of coffee.

2 hours ago, Dubbelosix said:

And I think you will find the evidence I provided is overwhelmingly in my favour, I find your behaviour, strange concerning this.

Nope.

2 hours ago, Dubbelosix said:

Your question was ''show me how the electron had a spin.'' I explained this was a red herring. You then went on to talk about protons, and other objects which are not pointlike.

I've asked the question multiple times: How do you account for the angular momentum that must accompany the alleged rotational KE of a nucleus?

2 hours ago, Dubbelosix said:

Intrinsic spin was suggested to be required because a point cannot rotate classically. The electron is the only pointlike particle in existence, as far as we can tell. Atoms do rotate classically, and the nucleus rotates classically - there is no need for intrinsic processes, that's just woo woo.

And you have provided none of the evidence I have asked for.

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I haven't provided you a direct example, simply because I haven't found the right kind of material yet. But by the Poincare space translations,  there is no need for a system with a radius to possess such a thing as an ''intrinsic spin.'' This seems to be something that is being completely ignored, intrinsic spin was a property given to the electron because attempts to measure a radius have failed.

A poster in the link I gave you however, could give an example, albeit, it was verbal.

Let me find it, we'll go through it.

So he says

''If you're talking about a single particle, the rest mass is defined to be the total energy when the particle is at rest - there is no way to separately discuss contributions to this energy. Furthermore, "spin" does not represent a degree of freedom - there is no motion associated with it, and hence no kinetic energy.

Some compound particles on the other hand have genuine rotational degrees of freedom. A deformed (non-spherical) nucleus can rotate, and may therefore possess rotational bands: excited states with increasing angular momentum, and associated rotational kinetic energy.''

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3 minutes ago, Dubbelosix said:

I haven't provided you a direct example, simply because I haven't found the right kind of material yet. But by the Poincare space translations,  there is no need for a system with a radius to possess such a thing as an ''intrinsic spin.'' This seems to be something that is being completely ignored, intrinsic spin was a property given to the electron because attempts to measure a radius have failed.

A poster in the link I gave you however, could give an example, albeit, it was verbal.

Let me find it, we'll go through it.

I am certainly far from anything close to expert on this, but it was my understanding that quantum spins were intrinsic. You seem to be saying that anything that is capable of having classic spin cannot have intrinsic (quantum to me, interchangeably) spin. Is that what you are saying or claiming? Is it accepted as correct?

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"Any  `kinetic’  energy  associated  with  S2 is  absorbed  into  the  rest  mass"

I think maybe the confusion here maybe nuclear spin  $\mathbb{I}$ which is different than intrinsic spin of the electron. Don't confuse the two nor isospin for the strong force.

Edited by Mordred
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44 minutes ago, J.C.MacSwell said:

I am certainly far from anything close to expert on this, but it was my understanding that quantum spins were intrinsic. You seem to be saying that anything that is capable of having classic spin cannot have intrinsic (quantum to me, interchangeably) spin. Is that what you are saying or claiming? Is it accepted as correct?

What I am saying is that intrinsic spin was a concept that was deemed necessary for point like systems. To think that this idea intrinsic spin should be modelled to all systems, even though they may have internal degree's of freedom, is an unfounded assumption. There is evidence the nucleus rotates from the rotational bands as suggested by that poster and so would possess a rotational kinetic energy, simply from the classical equations that describe this property.

Of course, rotational bands are more complicated objects than your standard definition in classical mechanics, however, in much the same way as classical physics, I expect there to be corrections to the kinetic energy formula for much the same reason.

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1 hour ago, Dubbelosix said:

I haven't provided you a direct example, simply because I haven't found the right kind of material yet. But by the Poincare space translations,  there is no need for a system with a radius to possess such a thing as an ''intrinsic spin.'' This seems to be something that is being completely ignored, intrinsic spin was a property given to the electron because attempts to measure a radius have failed.

A poster in the link I gave you however, could give an example, albeit, it was verbal.

Let me find it, we'll go through it.

So he says

''If you're talking about a single particle, the rest mass is defined to be the total energy when the particle is at rest - there is no way to separately discuss contributions to this energy. Furthermore, "spin" does not represent a degree of freedom - there is no motion associated with it, and hence no kinetic energy.

Some compound particles on the other hand have genuine rotational degrees of freedom. A deformed (non-spherical) nucleus can rotate, and may therefore possess rotational bands: excited states with increasing angular momentum, and associated rotational kinetic energy.''

Saying it can rotate is not the same as saying the spin is associated with rotational KE.

16 minutes ago, Dubbelosix said:

There is evidence the nucleus rotates from the rotational bands as suggested by that poster and so would possess a rotational kinetic energy, simply from the classical equations that describe this property.

Then let's see the evidence.

Because you neglected to include the part that says "excited states with increasing angular momentum, and associated rotational kinetic energy"

Which means he's not talking about the spin.

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5 minutes ago, swansont said:

Saying it can rotate is not the same as saying the spin is associated with rotational KE.

It sure does.

Anything that classical rotates, requires energy.

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1 minute ago, Dubbelosix said:

It sure does.

Anything that classical rotates, requires energy.

Spin is not classical.

How many times are we going to go around on this?

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7 minutes ago, swansont said:

Spin is not classical.

How many times are we going to go around on this?

There are two types of spin, classical and intrinsic. It's you who isn't getting it, the electron is the only pointlike particle because we cannot measure internal degree's of freedom and so of course, has an intrinsic spin. But this cannot be haphazardly applied to all particle systems, like you are doing.

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5 minutes ago, Dubbelosix said:

the electron is the only pointlike particle

All elementary particles are point like. And they all have (intrinsic) spin.

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A top quark is certainly not pointlike, mind you they consist of composite systems anyway (you never find a free quark) and so can have a centre of mass. I am of course excluding massless radiation in this. What particles did you have in mind?

Edited by Dubbelosix
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size isn't a particle property

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In fact, I'll just leave you to give me a list, because I think quarks can be ruled out (they always form composite systems). Not sure really about the treatment of other fundamental particles, the Neutrino for instance is a strange object.

Just now, Mordred said:

size isn't a particle property

Then how come strings are allowed to exist? Why do we make these assumptions and hold on to them concerning particles?

And why is it ignored in this discussion, that pointlike particles are directly related to the divergence problems, why doesn't that upset people like it troubles me?

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A string is akin to a wavefunction harmonic.

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But it is still spatially extended. It is not a pointlike particle.

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Quote

The quarks, leptons and bosons of the Standard Model are point-like particles.

so that’s all the elementary particles (including quarks, neutrinos and photons)

2 minutes ago, Dubbelosix said:

But it is still spatially extended. It is not a pointlike particle.

Different theory. And there is no evidence strings exist.

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4 minutes ago, Strange said:

so that’s all the elementary particles (including quarks, neutrinos and photons)

Different theory. And there is no evidence strings exist.

I am not a stringy person anyway, that wasn't my point. And whether or not its a different theory, it still matters, because it uses a rescaling principle to explain why point like interactions occur.

Yes I know people say this. But isn't this going off topic a bit. the question in this thread really should be about whether a nucleus rotates. No one disputes here a nucleus is composite and has real internal dynamics. My opinions about fundamental particles are pointless here.

Though, clearly the matter of real rotations for the nucleus has been pertinent to history since the literature indicates that a non-spherical nucleus can only do this. Which occurs frequently in nature as well.

Edited by Dubbelosix

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