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Zeynel
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In this CERN video quarks are represented as spheres. Is this how quarks look like. I thought they were fluctuations in the quantum field.
Zeynel said:In this CERN video quarks are represented as spheres. Is this how quarks look like. I thought they were fluctuations in the quantum field.
In this case that's a good thing. It's all imagination and all we have is the observed behaviour of the 'things' that allows us to make sensible predictions.Zeynel said:I'm just confused
Zeynel said:This is confusing. You say subatomic *particles* but then you say these are not *particles* (not objects).
Then you say "think of a free electron." So how do I think about it, visually? Because it is not a particle or an object. But it sounds as if you suppose that a free electron is a particle because then you ascribe to it a "field strength." Maybe you considered to be a "point particle". But to me this sounds like a particle in name only because a mathematical point is not a particle.
And then, if I understand correctly, you consider the spherical field to be the electron. What is this sphere made of? It's not made of particles. Just an imaginary sphere. Sorry, I'm not trying to prove anything I'm just confused.
BvU said:the contents of the constituents of the nucleus
Zeynel said:So we know that there is a nucleus and this nucleus has parts. But we have no idea what these parts inside the nucleus look like. Did I understand correctly?
At this scale, that is the atomic/subatomic scale, scientists detemine the properties and behaviors of particles from experiments (like scattering experiments) and the physical models describe and predict these behaviors. We can say a number of things about the particles and their behaviors, but we can not say what they look like, if we mean looking with our eyes, because we can not see these particles with our own eyes. We can say how they appear to behave with respect to the scientific instruments we use.Zeynel said:So we know that there is a nucleus and this nucleus has parts. But we have no idea what these parts inside the nucleus look like. Did I understand correctly?(my bolding)
DennisN said:Since you are interested in quarks, I have a couple of links about this, so I'll be back.
ZapperZ said:The problem here is that you attached too big of a significance to the English words that we used to describe things in physics. You should never do such a thing. There are many terminologies that we use that, taken literally, will get into into the wrong rabbit hole. The word "spin" is one clear example as used to designate the magnetic moment of electrons and other quantum "particles". The same thing with the use of the words "wave" and "particles" in QM.
It is why the first and foremost way to understand physics is to understand the mathematical description, because there is often no ambiguity in that description. Our interpretation of it may differ, but there is usually no similar ambiguity on what we are dealing with.
Zz.
To make this simpler: Physics is about making quantitative predictions about nature. Everything necessary for that goal is physics, the rest is not.Zeynel said:This must be so because the fundamental unit of study of physics is the "physical quantity" which is defined as a number with a unit. Physics cares nothing about the name of a physical quantity or even if it exists at all. Investigations of the form or essence of this physical quantity falls outside of the realm of physics.
Well, quark is not what I would call a well-known English word with clear and simple meaning.Zeynel said:Ok, so, physicists take well-known English words with clear and simple meanings and redefine them in physics. They make them physics jargon. I may criticize this practice of taking perfectly good English words and changing their meanings but this is standard practice in physics and must be accepted.
You are using words here which tend to be very slippery when discussing science, like essence, real, nature of, but I'd like to say that I am of the opinion that the science branches, including physics, are the best branches of human knowledge for describing and understanding the physical world.Zeynel said:If our goal is to understand the essence or the real shape and nature of things, physics will not help us because physics is the science of measuring quantities.
Kilogram is the standard SI unit for mass, while eV (electronvolt) is a unit of energy commonly used in atomic and particle physics. 1 eV is about 1.6 x 10−19 joules, where joule is the SI unit of energy. Switching between joules and eV is easy, it's just a unit conversion just like switching between kilometers and miles.Zeynel said:But there is ambiguity here too because physicists defined two units of mass. One is the old definition of mass as kilogram the other is the definition of mass as multiples of electron volt (if I understand correctly).
"Nothing" is an exaggeration. It has developed like that over the centuries: in the old days 'charge' and 'mass' were designated with names taken/derived from everyday experience. By the time mankind dug deeper such parallels were no longer available. I would venture the turning point was around the first signs of strange behaviour that led to the naming of the strange quark. After that, charm, top and bottom (they tried 'beauty' for a while) clearly distantiate from meaningful naming. Let alone the 'color' of quarks -- a term that seduces normal people to ask 'what do they look like ?' or even: 'what paint is used for that ?' (*)Zeynel said:Physics cares nothing about the name of a physical quantity
Zeynel said:Ok, thanks for this explanation. Let me write what I understood from it. Correct me if I’m wrong.
“...English words that we used to describe things in physics.”
So,
1. There are “things”. This is a given.
2. In order to refer to these things we need to name them.
3. As far as physics is concerned, these names are not important. We can call a thing “quark” or any word whatsoever and in terms of physics the name of the thing has no significance.
These names should not be taken literally. For instance, the word “spin” has a clear description outside of physics but in physics it has a different technical meaning. (But this meaning should be irrelevant too, no? Only its meaning in an equation should be relevant.)
Ok, so, physicists take well-known English words with clear and simple meanings and redefine them in physics. They make them physics jargon. I may criticize this practice of taking perfectly good English words and changing their meanings but this is standard practice in physics and must be accepted.
“...to understand physics is to understand the mathematical description, because there is often no ambiguity in that description.”
Is this really true that physics equations represent things without ambiguity? This is questionable.
First, only quantities can be represented in an equation. So words such as “particle” or “wave” cannot be represented in an equation because they are names not quantities. ("Strings" in Computer Science jargon.) Only some quantity associated with these “things” such as “mass” for the particle and “frequency” for the wave can be represented in the equation. But there is still ambiguity. Not only waves have frequencies. Every kind of oscillation will have frequency. So physics, reduced to equations and to “mathematical abstractions” cannot tell us the shape and form of the real object.
“Our interpretation of [mathematical description] may differ but there is usually no similar ambiguity on what we are dealing with.“
But if there are many interpretation of an equation then there must be ambiguity.
So the lesson for me, from your explanation, is this: If our goal is to understand the essence or the real shape and nature of things, physics will not help us because physics is the science of measuring quantities. Physics knows nothing about the general properties or forms of things. Physics knows only the quantity which is measured. This must be so because the fundamental unit of study of physics is the "physical quantity" which is defined as a number with a unit. Physics cares nothing about the name of a physical quantity or even if it exists at all. Investigations of the form or essence of this physical quantity falls outside of the realm of physics.
From these, I also conclude that, as you say, in physics the definitions of words are not important. In physics what is important is the definition of units. So the meaning of the word “mass” have no relevance in physics. Anything with the unit of mass is mass. But there is ambiguity here too because physicists defined two units of mass. One is the old definition of mass as kilogram the other is the definition of mass as multiples of electron volt (if I understand correctly). So in this case calling two different quantities with two different units with the same name is also confusing. Are these masses the same or are they different?
I still think that defining words used in physics uniquely and simply will be helpful in understanding these things.
Sorry, this turned out to be a long response but I think it is relevant to my original question. Thanks again.
This.Zeynel said:As far as physics is concerned, these names are not important. We can call a thing “quark” or any word whatsoever and in terms of physics the name of the thing has no significance.
DennisN said:Well, quark is not what I would call a well-known English word with clear and simple meaning.
And the procedure of naming things, and the risk of choosing less wellsuited names, is not unique to physics nor to science in general.
Human language is human, and naming is a human thing.
You are using words here which tend to be very slippery ... like essence
Mechanics is the branch of physics in which the basic physical units are developed. The logical sequence is from the description of motion to the causes of motion (forces and torque) and then to the action of forces and torque. The basic mechanical units are those of Mass, Length and Time. All mechanical quantities can be expressed in terms of these three quantities.
Kilogram is the standard SI unit for mass, while eV (electronvolt) is a unit of energy commonly used in atomic and particle physics... See
It describes how the Kinetic Energy of a charged particle relates to the change in Electrical Potential through which it has 'fallen'. It's just like equating the gravitational potential of a mass on a high shelf to the KE it will have when it's fallen to the floor.Zeynel said:but can you explain how we get from 1/2 m vv to eV
(If we use the page I posted as a reference)Zeynel said:Ok. I understand. But I don't understand the steps to transform or substitutions to make to arrive to eV starting from 1/2 m vv.
Let's drop it.Zeynel said:Sorry, since this subject is not directly related to my original question maybe we can drop it and discuss it in another thread.
Yes, I can agree with that. But luckily, physics is not the only science branch; we've got chemistry for describing e.g. molecular behaviors and chemical reactions, we've got biology describing living things, and we've got e.g. materials science which may describe some things about billiard balls, just to name a few science branches.Zeynel said:but the link you shared about units and dimensions used in physics made me realize that physics has an inherent limitation when “describing and understanding the physical world."
I can agree with you on that. Particularly since the video started with things that optically can be seen, and ended up with a visual representation* of the nucleon and quarks.Zeynel said:I think it is more intellectually honest for CERN to admit that we do not know how quarks look like and put a disclaimer to that effect. Otherwise they are spreading misinformation and falsehoods to the public.
Zeynel said:Ok. I understand. But I don't understand the steps to transform or substitutions to make to arrive to eV starting from 1/2 m vv.
DennisN said:You could send CERN an email about it,
Or the most likely option 3: Scientists at CERN do know that quarks are not spherical balls, but are also used to abstracted representations and didn't think to put a disclaimer on every schematic graphic.Zeynel said: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.
Zeynel said:this is a serious breach of trust.
You a law student ?Zeynel said: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?
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:Zeynel said: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?
Vanadium 50 said: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.
What does "scientifically accurate" mean here? Is a circuit diagram not "scientifically accurate" to you, because it doesn't look like the actual circuit?Zeynel said:I still think that an institution like CERN has the responsibility to publish scientifically accurate videos to the public.
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.A.T. said:What does "scientifically accurate" mean here? Is a circuit diagram not "scientifically accurate" to you, because it doesn't look like the actual circuit?
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A.T. said: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.