# The Naked Scientists Forum

### Author Topic: What is spin and :) Why do we need color charge  (Read 18484 times)

#### yor_on

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##### What is spin and :) Why do we need color charge
« on: 28/01/2009 19:18:03 »
Well two then:)

#### DoctorBeaver

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##### What is spin and :) Why do we need color charge
« Reply #1 on: 28/01/2009 19:25:06 »
Spin is a quantum property of particles.

Colour charge is to gluons what EM is to photons. I think

#### yor_on

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##### What is spin and :) Why do we need color charge
« Reply #2 on: 28/01/2009 19:43:41 »
Ok let's throw the idea of only two sentences to the winds:)

Spin is a property of particles but can you tell me what it does?
the name suggest something 'twisting' but?
And Colour charge, why do we use colours?

#### DoctorBeaver

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##### What is spin and :) Why do we need color charge
« Reply #3 on: 28/01/2009 20:07:50 »
Colour is used in Quantum Chromodynamics. In the same way as you add red light to green light to blue light you get white (neutral) so the 3 colours of QCD add together to make neutral charge.

Spin is a bit more complex. Quantum spin has some prperties that set it apart from classical angular momentum although mathematically it is treated the same. Electron spin is the foundation of the Pauli Exclusion Principle. The quantum state of a particle is given by 4 parameters: the principal quantum number, the azimuthal quantum number, the magnetic quantum number, and the spin quantum number.

#### yor_on

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##### What is spin and :) Why do we need color charge
« Reply #4 on: 28/01/2009 20:28:14 »
Thank you DB
That was a nice description but still I want more:)
Just quoting different sources here.

---

The spin of a particle is the 'angular momentum' that the particle has when it is not moving, and in quantum mechanics, it gives the change in 'wavefunction phase' when you do certain rotations.

A. So the wavefunction phase is the magnitude (relative strength?) of the wave function?

And "a wave function phase carries no physical information, it just describe that the wave function is a wave.
the magnitude of the wave function carries information about the probability finding the particle in some points in space.
The magnitude of the wave function in a point in space is proportional to the probability of finding the particle in that point"

B. what kind of 'rotations' are we doing on a particle?

And the angular momentum of a particle about an origin is a vector quantity (speed and direction) related to rotation, equal to the mass of the particle multiplied by the 'cross product' of the 'position vector' of the particle with its 'velocity vector'.

Don't you just love that:)
1. cross product (do they mean the 'combination of')?
2. what differs the position vector from the 'velocity vector'

It may be a very precise description but it just gives me more questions:)

So do they have a real physical :) spin..
Or is it a mathematical quality it describes.

------------
Unlike in more complicated quantum mechanical systems, the spin of a spin-½ particle can be expressed as a linear combination of just two eigenstates, or eigenspinors.

(A eigenstate is a quantum state that is left unchanged after an observation corresponding to a particular operator ...
But as Heisenberg's uncertainty principle should come into play when observing particles?
That definition of 'eigenstates' throws me off a little too?)

These are traditionally labeled spin up and spin down. Because of this the quantum mechanical spin operators can be represented as simple 2 × 2 matrices, as opposed to the infinite dimensional matrices commonly needed to represent operators like energy or position. These matrices are called the Pauli matrices.

----

And color charge?

Ok DB:)
We use it in Quantum Chromodynamics.
But how come we find the concept of colour's a better description?
What does that say about our mathematical definitions?

« Last Edit: 28/01/2009 20:49:01 by yor_on »

#### DoctorBeaver

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##### What is spin and :) Why do we need color charge
« Reply #5 on: 28/01/2009 20:40:57 »
I'm just a dumb psychologist

#### yor_on

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##### What is spin and :) Why do we need color charge
« Reply #6 on: 28/01/2009 20:49:50 »
Nope DB, none that reads you would give you that description.

Ah, psychologist that is ::))

Awh...
You left that one wide open DB, don't blame me::::))))

But no, you're cool.
« Last Edit: 28/01/2009 20:51:25 by yor_on »

#### DoctorBeaver

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##### What is spin and :) Why do we need color charge
« Reply #7 on: 28/01/2009 20:51:07 »
Nope DB, none that reads you would give you that description.

They don't know me well enough

#### yor_on

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##### What is spin and :) Why do we need color charge
« Reply #8 on: 28/01/2009 20:52:36 »
Awh I really have to stop editing my answers.

Mine is a slooow mind, only working bit wise:)

#### DoctorBeaver

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##### What is spin and :) Why do we need color charge
« Reply #9 on: 28/01/2009 20:54:43 »
Mine is a slooow mind, only working bit wise:)

Obviously. You don't seem to have realised yet that you're trying to discuss quantum physics with a beaver!

#### yor_on

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##### What is spin and :) Why do we need color charge
« Reply #10 on: 28/01/2009 21:09:10 »
Eh?

#### yor_on

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##### What is spin and :) Why do we need color charge
« Reply #11 on: 28/01/2009 21:12:28 »
Was that an insult??

Nah, that would go against your grain my dear Beaver.
I'm sure I've heard about you in some book

Ah yes, now I remember:)
The Wind in the Willows right!!!

I've always loved that one:)

So that must be a compliment?
I insist:)

Or was it a friend??
Nah, it was most definitely a book.
« Last Edit: 28/01/2009 21:14:41 by yor_on »

#### DoctorBeaver

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##### What is spin and :) Why do we need color charge
« Reply #12 on: 28/01/2009 21:14:22 »
Me ->

#### yor_on

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##### What is spin and :) Why do we need color charge
« Reply #13 on: 28/01/2009 21:17:21 »
Jesus weeps.
Are you an attack beaver...

Those are known to be a most dangerous species.
How will I ever be able to go to sleep knowing that you live in my laptop?
Are you reproducing?

#### DoctorBeaver

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##### What is spin and :) Why do we need color charge
« Reply #14 on: 28/01/2009 21:20:10 »
I'm a friendly little critter

#### yor_on

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##### What is spin and :) Why do we need color charge
« Reply #15 on: 28/01/2009 21:26:06 »
Ok, I'll take your word for it.
But I warn you, the least trouble and your whole habitat will be gone...

Directly to the scrapyard, ya'hear.
Ugh, white man has spoken...

#### DoctorBeaver

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##### What is spin and :) Why do we need color charge
« Reply #16 on: 28/01/2009 21:36:16 »
Be careful who you threaten. I have lots of relatives in the north of your country!  [:(!]

#### yor_on

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##### What is spin and :) Why do we need color charge
« Reply #17 on: 28/01/2009 21:41:43 »
Awh, A conspiracy is it?
Starting in My LapTop is it!!!

Look here Mr King Beaver.
I've always been especcially nice to beavers.

And I will never ever turn your habitat off.

---
Thinking again.

Seems like we took a slight detour here?
But my questions remains.

No, not those.
What is spin and color charge?
« Last Edit: 28/01/2009 21:43:30 by yor_on »

#### DoctorBeaver

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##### What is spin and :) Why do we need color charge
« Reply #18 on: 28/01/2009 21:43:43 »
Threads here have a habit of wandering off the subject

#### yor_on

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##### What is spin and :) Why do we need color charge
« Reply #19 on: 28/01/2009 21:56:53 »
No, I can't say that I agree.

As I see it you have given me new, valuable, and possibly dangerous information about what happens inside my laptop.
I just hope that your little friends don't brand you as a traitor because of this.

But if so, I want you to know that we do have some protected environments in the north of Sweden called Sarek, where beavers still live a life of beauty and freedom in the wild.

Possibly they are happy too?

Without hot shower's?
Nah:)

---

Any which way:)

What is colour and does it spin?
Or something to that matter.
« Last Edit: 28/01/2009 22:07:29 by yor_on »

#### Vern

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##### What is spin and :) Why do we need color charge
« Reply #20 on: 28/01/2009 22:26:05 »
I couldn't contribute much to a discussion of spin. I rather liked the idea of an actual spin.

#### yor_on

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##### What is spin and :) Why do we need color charge
« Reply #21 on: 28/01/2009 23:52:29 »
I can see that you might:)
I just would like to understand how it works?

#### yor_on

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##### What is spin and :) Why do we need color charge
« Reply #22 on: 30/01/2009 20:05:47 »
Let us take a look at colour charge then:)

There will be a lot of condensed information here.
You probably have it sorted already, ah, I hope too, when finished :)
It's the charge associated with the 'strong interaction'.

By that we mean any interaction by two particles associated with color charge.
Those are gluons, quarks and antiquarks.

Gluons and quarks is what makes up what we call the nucleus inside an atom.
And it is gluons that we see as the 'carrier' of this force, knitting them together into 'hadrons', bound by their 'strong interactions'.

There are two classes of hadrons, 'baryons' and 'mesons'.

-----

'Mesons' are color-neutral consisting of one quark and one antiquark, and they have a 'spin' of a 'whole' number, like one or zero.
That makes them into what we call 'bosons' like kaons and pions (and photons).

"Photons according to quantum chromodynamics interacts both as a point-like particle, as a collection of quarks and gluons, like a hadron.
The photon is determined not by the traditional valence quark distributions as a proton, but by fluctuations of the pointlike photon into a collection of partons."

Bosons may be 'superimposed' on each other.
That states that you can 'stack' how many you want upon each other, without them taking any space what so ever.

---------

And Quantum chromodynamics (QCD) is the theory describing all interactions by those quarks and gluons found inside hadrons, namely 'Colour force'.

---

Then we have the 'Baryons' consisting of three quarks, like protons and neutrons
Their spin is broken down into half quantum units of angular momentum (spin) and are called 'fermions'.
That means that those have no 'even' integers like one or zero.

They also obey the Pauli Exclusion Principle.
That states that no two identical 'fermions' ever can occupy the same quantum state simultaneously.

That means that they have to have an amount of 'space' between each one fermion.
Thinking about it you will fast understand that this must be one of the definitions we have for 'matter' or 'particles' creating it.

-----------

The mathematics describing color charge belongs to a special unitary group, SU(3).
The (3) in SU(3) stands for the three color-charges that those quarks may have.
SU stands for "Unitary Symmetry, based on a fundamental multiplet of three equivalent particles.

In particular the approximate symmetry based on the up, down, and strange quarks.
(And those names of quarks I will defiantly blame on 'physicist humor':)
And the exact symmetry based on the three differently colored quarks of a given flavor.

The idea behind using colours is that when you have those three quarks together, in a so called colour-singlet or colour neutral state.
They, as when mixing primary colors of paint, will give us a 'white' which here then is understood as a 'neutral charge'.

So the math behind this differ rather strongly compared to the math used to describing electric charges.
And are very specific to this colour analogy.
There are three (different) anti-colors for antiquarks, which, when combined also is colour neutral and then called a 'antibayron'.

A 'Meson' is created by a quark and a antiquark, and is also colour neutral.
'Gluons' is described as massless particles that, like photons, travel at lightspeed.
They mediates, or carries, the strong, or nuclear, force by their colour force.

Gluons have one color and one anti-color, and one that is a combination of both and therefore color neutral.
That gives you three times three possibilities = Nine possibilities, all in all, but one of them as stated
will then be color neutral.
So there are, as I understands it, only eight 'functioning' types.
And they are thought to 'glue' quarks together.

-------

"Unlike other forces, the force between quarks increases as the distance between the quarks increases.
Up to distances about the diameter of a proton, quarks behave as if they were free of one another, a condition called asymptotic freedom.

As the quarks move farther apart, the gluons that move between them utilize the energy that they draw from the quark's motion to create more gluons—the larger the number of gluons exchanged among quarks, the stronger the binding force. The gluons thus appear to lock the quarks inside the elementary particles, a condition called confinement. Gluons can also bind with one another to form composite particles called glueballs.

According to QCD, only colorless objects may exist in isolation.
Therefore, individual gluons and individual quarks cannot exist in nature, and only indirect evidence of their existence can be detected.
In 1979, compelling evidence was found when quarks were shown to emit gluons during studies of particle collisions at the German national high-energy physics laboratory in Hamburg."

--------

That's as far as I've come to understand them.
Even though we live in a universe that is non linear, with few, none or 'infinite' solutions (?:) and that we use chaos theory to describe it, it seems to me that this colour analogy is another 'thing'?
Or maybe I'm putting to much importance to something rather simple?
« Last Edit: 30/01/2009 20:40:19 by yor_on »

#### Vern

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##### What is spin and :) Why do we need color charge
« Reply #23 on: 30/01/2009 20:39:44 »
That is a very good summary and is much like I remember when I studied QCD as part of my Nuclear Instrumentation classes at DeVry Tech. However, I never did like that Quark theory. So I developed an alternative. My own speculative nuclear model that I won't dwell upon here since it is speculative. I'll just show a graphic of the model so you can see how the strong force dynamics fit into it.

The rings are electromagnetic shells; notice that like charges face each other from the smaller to the larger rings. When the nucleons separate, they must overcome a force that increases with distance for a short distance because opposing forces must move closer together.

I'll write a condensed version of my speculative theory and put it in the New Theories forum if you care to see it. I'm looking for ideas about why it can't possibly represent reality. I'll call it Photonic Theory.
« Last Edit: 30/01/2009 20:45:41 by Vern »

#### yor_on

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##### What is spin and :) Why do we need color charge
« Reply #24 on: 30/01/2009 20:47:37 »
Vern, you better explain that one?
(It's suspiciously like two gauchos frying eggs under their sombreros:)

And while doing it, assume that my name is Nob.
Not that it is (..well maybe?) when you're finished, not I hope:)?

----
Not even I know what I mean here?
Ah well:)

I've tried to clarify my reasoning now, and yes,  it seems very clear to me:::)))
?
« Last Edit: 30/01/2009 20:54:12 by yor_on »

#### The Naked Scientists Forum

##### What is spin and :) Why do we need color charge
« Reply #24 on: 30/01/2009 20:47:37 »