I What is a realistic image of quarks?

Vanadium 50

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this is a serious breach of trust.
If this is going to be your reaction to anyone who tries to help you understand something but does not fully incorporate everything without a single simplification, I think the appropriate response is for everyone - including PF - to cease helping you altogether. That's probably not what you want.
 
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BvU

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There are two possibilities. 1. Either scientists at CERN do not know that quarks are not spherical balls, 2. Or, you know that quarks are not spherical balls but you are representing them as such to mislead the public in believing that you discovered a "particle" that looks like a spherical ball.

I am positive that scientists at CERN know that quarks are not spherical balls, then your goal must be to mislead the public.

May I ask why you are aiming to mislead the public?
You a law student ? :rolleyes:
 
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Thanks for your replies and this suggestions. I indeed drafted a letter to CERN. May I ask you to take a look and make any suggestions. I don't want the letter to sound to harsh, what do you think?
I would not be so harsh if I were to write an email to CERN about this thing. I would write it as a friendly suggestion; when you just friendly suggest things to people, the likelihood of a getting a good result (or a result at all) is going up. I would write something like this:

"Hi! I noticed that in this video, which is a nice video about the scale of things, the video goes quite seamlessly from things that can be seen with our eyes to things that are not directly visible and ends up with a visual respresentation of the nucleon and quarks. This may mislead some people to think that the quarks inside a nucleon actually looks like how they are shown in the video. Maybe it would be a good idea to put in a small disclaimer about this at this point in the video, or at the end of it? Maybe something like "This is a visual representation."?
My regards,
(name)"
 
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If this is going to be your reaction to anyone who tries to help you understand something but does not fully incorporate everything without a single simplification, I think the appropriate response is for everyone - including PF - to cease helping you altogether. That's probably not what you want.
I'm sorry but I think there's been a misunderstanding. I appreciate and thank everyone here who tried to help me understand with my question. What you quoted was aimed at CERN. And I also accept @DennisN's toned down letter and probably I will send that. It seems I took this issue more seriously than anyone else here and I apologize if I offended anybody. On the other hand I still think that an institution like CERN has the responsibility to publish scientifically accurate videos to the public.
 

BvU

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You have your work cut out for you. All the institutions that carry atom images, thousands of text book writers, etc. etc. :rolleyes:
 
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How do you know they aren't spherical balls ? Why aren't you enraged that protons are represented by red blobs and neutrons by white ?

Hey, don't get me wrong : you're not alone in wanting to understand a subject, without actually learning the math(s). (okay, maybe I'm projecting a bit)

I'd make the letter even milder than DennisN 's take,

Dear CERN,

Great video ; enjoyed the representation of electron orbitals (I understand they're replacing the archaic figures in schoolbooks), being a more realistic interpretation of what subatomic entities "look" like.

In that regard, I was wondering if the representation of nucleons - as being three spherical objects(quarks), inside an unidentified shell(gluons?) - is realistic in any manner.

Keep up the good work,

A.Fan
 
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A.T.

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I still think that an institution like CERN has the responsibility to publish scientifically accurate videos to the public.
What does "scientifically accurate" mean here? Is a circuit diagram not "scientifically accurate" to you, because it doesn't look like the actual circuit?

slide_6.jpg
 

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What does "scientifically accurate" mean here? Is a circuit diagram not "scientifically accurate" to you, because it doesn't look like the actual circuit?

View attachment 239277
But I'm not objecting to a diagrammatic representation of real images as in your illustration. In the CERN video they are not representing quarks schematically but realistically. I think the correct analogy would be to replace the realistic image of the battery in your illustration, for instance, with a truck. That would be misrepresentation of a battery because a battery is not a truck. Similarly, a quark is not a spherical ball and it would be a misrepresentation to draw a quark as a spherical ball. That's all I'm saying.
 
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Or the most likely option 3: Scientists at CERN do know that quarks are not spherical balls [and] didn't think to put a disclaimer on every schematic graphic.
But the representation of quarks in the video are not schematic representations. They are realistic representations.
 

BvU

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You write to movie companies too ? "These droids are unrealistic ? " "Dragons don't behave like that ?"
 
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How do you know they aren't spherical balls ?
From the responses here:

So by the time you are down another six orders of magnitude to the contents of the constituents of the nucleus it's really an appeal to your imagination
We don't need to know what things visually look like. We know the content of a nucleus, and the content of nucleons. We don't need to know what they visually look like, because this isn't always necessary.
3: Scientists at CERN do know that quarks are not spherical balls...
And also from the fact that in the "Standard Model particles are replaced by quantum fields." Since quarks live in the Standard Model they must be fields not spherical particles.

I also found this question in Physics Stack Exchange: https://physics.stackexchange.com/questions/161146/what-do-quarks-look-like Interestingly the answer includes this sentence:
"Please note that for clarity the standard model particles are shown as little balls, even though they are points at that level of magnification.
What I see as misrepresentation, they consider it clarity. So I think this is simply a matter of opinion.
 

BvU

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And also from the fact that in the "Standard Model particles are replaced by quantum fields." Since quarks live in the Standard Model they must be fields not spherical particles.
Your logic is defective and your premise is wrong. I am sure there will be theoreticians objecting that what you call a fact is in fact not a fact at all, and that particles are disturbances of the field, not the field itself.

Whatever, visually representing either pretty quickly leads to drawing little balls :cool: -- as a kind of minimizing potential criticism (but in your case unsuccesfully).
 

A.T.

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But the representation of quarks in the video are not schematic representations. They are realistic representations.
What does "realistic representation" mean for quarks? Nobody has ever seen one for real, so any representation is implicitly schematic.
 

BvU

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This still doesn't change the fact that you are hung up more on the names we give to these things than to understand the physics associated with those names.
But I understand the physics associated with these names. This narrative in Wikipedia gives me enough information about quarks:

Evidence for the existence of quarks comes from deep inelastic scattering: firing electrons at nuclei to determine the distribution of charge within nucleons .... If the charge is uniform, the electric field around the proton should be uniform and the electron should scatter elastically. Low-energy electrons do scatter in this way, but, above a particular energy, the protons deflect some electrons through large angles. The recoiling electron has much less energy and a jet of particles is emitted. This inelastic scattering suggests that the charge in the proton is not uniform but split among smaller charged particles: quarks.
And from this page I learn that "quarks are never directly observed or found in isolation."

And from @BvU I learn that quarks
...are disturbances of the field...
From the above physics, I conclude that quarks are not spherical balls. Then I ask, If quarks are not spherical balls, why is it that they are commonly drawn as spherical balls? Is that a bad question?
 

ZapperZ

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From the above physics, I conclude that quarks are not spherical balls. Then I ask, If quarks are not spherical balls, why is it that they are commonly drawn as spherical balls? Is that a bad question?
Because a cow from a very far distance looks like a sphere.

Zz.
 

A.T.

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If quarks are not spherical balls, why is it that they are commonly drawn as spherical balls?
How would you draw them instead?
 

BvU

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DaveC426913

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From the above physics, I conclude that quarks are not spherical balls. Then I ask, If quarks are not spherical balls, why is it that they are commonly drawn as spherical balls? Is that a bad question?
The spherical shape represents the strength of its properties. Because the properties are symmetrical about a point; they are the same in all directions.

Look at these two representations of the same molecule:
1283150ec8b21efdd53b00233c003cc192e7dc.png

molecule_h2o.png


The top one renders a sphere at the distance of some large value of charge (so the spheres actually intersect).
The top one renders a sphere at the distance of some small value of charge (so the spheres do not intersect).
 

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DaveC426913

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This is what we actually observe when we look a subatomic particle.

We detect the value of a property of interest at a given distance.
It happens that that value is often the same at the same distance from the centre no matter what direction.
quark.png

How might you represent the above particle?
 

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This is what we actually observe when we look a subatomic particle. [...] How might you represent the above particle?
I don’t understand this graphic. When you say “how might you represent the above particle” do you refer to the point particle at the center of the field or do you call the spherical field of charge a “particle”?

Also “quarks are never directly observed or found in isolation”. So, the “point particle” at the center cannot be a quark. Is this correct?

Where can I find more info about this graphic?
 

BvU

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By reading the accompanying text. And a textbook on physics.
 

DaveC426913

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I don’t understand this graphic. When you say “how might you represent the above particle” do you refer to the point particle at the center of the field or do you call the spherical field of charge a “particle”?
It would be impossible to try to represent zero-dimensional particles in a video Since you would not be able to see them, you would have to artificially inflate their size.

So the next best thing to do is to represent what is essentially an "operating radius".

Also “quarks are never directly observed or found in isolation”. So, the “point particle” at the center cannot be a quark. Is this correct?
Well, it was not meant to be a picture of a quark "in the wild".

But you're right - it isn't really mean to be a quark at all; I'm generalizing how to represent the properties of a subatomic particle.

Where can I find more info about this graphic?
Well, you could ask the artist...:wink:
15808.gif
 

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It may be worth noting that is was a very basic visual representation, and there are other things which were not shown in the picture, for instance that quarks exchange gluons with each other, and quarks have fractional charges.
I found this video that shows the gluons too (also as spheres).

There were some comments here that the CERN video was "visual candy" and should not be taking seriously, but the video I linked was more technical and very informative and I think it reflects the current understanding. So it's a puzzle why physicists know that quarks are not spheres (in the same video he describes quarks as ripples in the quark field) but insist on representing quarks as spherical particles. Any insights?
 
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So it's a puzzle why physicists know that quarks are not spheres (in the same video he describes quarks as ripples in the quark field) but insist on representing quarks as spherical particles. Any insights?
Yes. We are venturing into quantum field theory, which is far beyond this subforum we are in which is general physics. :smile:

Quantum field theory is the most modern and advanced theory of these things, and I'm not very familiar with it.
To the best of my knowledge, according to quantum field theory, all elementary particles have an associated field throughout space. And it is these fields that are fundamental, not the particles; particles can be thought of (note I say thought of, not seen as :wink:) as excitations (or "ripples", or "vibrations") in the fields.
Here is a crash course, or rather, a basic introduction to it by professor David Kaplan (the video is actually about the Higgs boson, but he briefly describes the quantum fields too).
 

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