What is spin and :) Why do we need color charge

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Offline yor_on

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In one sentence each, please.
Well two then:)
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Offline 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  [???]
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Offline 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?
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Offline DoctorBeaver

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« 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.
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Offline 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 »
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Offline 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
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Offline yor_on

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« 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 »
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Offline DoctorBeaver

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« 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  [;D]
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Offline yor_on

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« 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:)
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Offline DoctorBeaver

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« 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!  [:D]
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Offline yor_on

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« Reply #10 on: 28/01/2009 21:09:10 »
Eh?
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Offline yor_on

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« 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 »
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Offline DoctorBeaver

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« Reply #12 on: 28/01/2009 21:14:22 »
Me ->
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Offline yor_on

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« 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?
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Offline DoctorBeaver

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« Reply #14 on: 28/01/2009 21:20:10 »
I'm a friendly little critter  [:D]
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Offline yor_on

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« 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...




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Offline DoctorBeaver

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« 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!  [:(!]
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Offline yor_on

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« 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 »
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Offline DoctorBeaver

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« Reply #18 on: 28/01/2009 21:43:43 »
Threads here have a habit of wandering off the subject  [:D]
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Offline yor_on

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« 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 »
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Offline 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.

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Offline yor_on

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« Reply #21 on: 28/01/2009 23:52:29 »
I can see that you might:)
I just would like to understand how it works?
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Offline yor_on

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« 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 »
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Offline Vern

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« 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 »

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Offline yor_on

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« 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 »
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Offline Vern

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« Reply #25 on: 30/01/2009 20:54:12 »
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, I hope:)?

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




I like that [:)] Good observation!

Give me about an hour and I'll have the Photonics Theory thread going in the New Theories Forum.
« Last Edit: 30/01/2009 20:55:54 by Vern »

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Offline yor_on

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« Reply #26 on: 30/01/2009 20:55:11 »
Should  I be grateful or insulted Vern?
:)
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Offline Vern

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« Reply #27 on: 30/01/2009 20:56:47 »
Should  I be grateful or insulted Vern?
:)
I was trying a complement. I meant it as one anyway.

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Offline yor_on

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« Reply #28 on: 30/01/2009 21:05:25 »
Awh:)

It's like throwing water on a goose Vern.
Expecting me to be able to be serious for any longer timespan:)

Let's call it by its right name.
'Short attendance syndrome'

My middle name.

---
But I knew you liked it.
Otherwise you wouldn't have bothered to write:)

----

I'll blame it on insufficient understanding of nuances.
And hope that you do the same.
« Last Edit: 30/01/2009 21:12:50 by yor_on »
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Offline Vern

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« Reply #29 on: 30/01/2009 21:11:53 »
Ok; Photonics Theory is now a thread in the New Theories Forum. I just need to put one more graphic which I will add as a reply. I didn't talk about relativity phenomena in the first post of the thread but relativity phenomena develops naturally by assuming flat space-time and the construct of matter which has as its primary constituent fields that must move at the invariant speed of light.
« Last Edit: 30/01/2009 21:17:21 by Vern »

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Offline yor_on

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« Reply #30 on: 30/01/2009 21:14:43 »
So I will learn something new then.
Good.
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Offline Vern

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« Reply #31 on: 30/01/2009 21:32:01 »
So I will learn something new then.
Good.
I was hoping you could teach me by finding a fatal flaw in the scheme.

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Offline yor_on

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« Reply #32 on: 30/01/2009 22:37:53 »
Your math have a sounder ground than mine Vern.
When you try to create a mathematical foundation for your ideas you are definitely outside mine competence:)

Then it is people like, ah, none mentioned, none forgotten, (You know which ones I mean anyway:) that I would trust.
I'm pretty sure that one and one makes two (mostly) but otherwise?


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Offline Vern

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« Reply #33 on: 30/01/2009 22:47:54 »
But I see you are well versed in physics. I have to confess that there is one flaw that I know about that could be fatal to the Photonic Theory. It is impossible to make a neutrino particle within that scheme. I have been waiting to see what is the final come down on the neutrino. I am not 100 percent certain that it exists but I know many are certain.

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« Reply #34 on: 30/01/2009 22:52:48 »
In which way do they break your ideas?
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Offline Vern

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« Reply #35 on: 31/01/2009 00:02:34 »
In which way do they break your ideas?
The neutrino is a neutral Lepton. In my scheme any time the path of a photon is bent the result is electric charge. So you can't make a neutral particle with a photon bent into a circle. It would have to exhibit electric charge.

Since the major premise of the whole scheme is: The final irreducible constituent of all physical reality is the electromagnetic field, and you can't reduce a neutrino to an electromagnetic field, the scheme breaks down.

However, the neutrino is alone in this. All other constituents of physical reality in this universe do reduce down to an electromagnetic field.
« Last Edit: 31/01/2009 00:05:43 by Vern »

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« Reply #36 on: 31/01/2009 01:30:23 »
But there seems to be 'exchange currents' which carry no electric charge and mediate certain types of electroweak interactions?

"The electromagnetic interaction is mediated by an exchanged photon γ. Since the photon carries no electric charge, there is no change in charge between the incoming and the outgoing particles.

The charged-current weak interaction is mediated by the exchange of a charged intermediate boson, the W+, and thus, for example, an incoming neutral lepton such as the νμ is changed into a charged lepton, the μ−.

In the neutral-current weak interactions, the exchanged intermediate boson, the Z0, carries no electric charge (hence the name neutral-current interaction), and thus for example, an incident neutral lepton, such as the νμ, remains an outgoing neutral νμ. "

And this might interest you?
http://arxiv.org/abs/cond-mat/0105357

---- ------ Quotes ---- ------

In particle physics, flavour is a quantum number of elementary particles related to their weak interactions.
In the electroweak theory this symmetry is gauged, and flavour changing processes exist.
In quantum chromodynamics, on the other hand, flavour is a global symmetry.

http://en.wikipedia.org/wiki/Flavour_(particle_physics)

And in theoretical physics, flavour changing neutral currents (FCNCs) are expressions that change the flavour of a fermion current without altering its electric charge.

If they occur in the Lagrangian, they may induce processes that have not been observed in experiment.
Flavour changing neutral currents may occur in the Standard Model beyond the tree level, but they are highly suppressed (the GIM mechanism).

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But I will have to read up on this:)
And looking it up some more, I get this sinking feeling that it may take some time.
Years?


 
« Last Edit: 31/01/2009 02:04:30 by yor_on »
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Offline Vern

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« Reply #37 on: 31/01/2009 01:56:29 »
But there seems to be 'exchange currents' which carry no electric charge and mediate certain types of electroweak interactions?

"The electromagnetic interaction is mediated by an exchanged photon γ. Since the photon carries no electric charge, there is no change in charge between the incoming and the outgoing particles.

The charged-current weak interaction is mediated by the exchange of a charged intermediate boson, the W+, and thus, for example, an incoming neutral lepton such as the νμ is changed into a charged lepton, the μ−.

In the neutral-current weak interactions, the exchanged intermediate boson, the Z0, carries no electric charge (hence the name neutral-current interaction), and thus for example, an incident neutral lepton, such as the νμ, remains an outgoing neutral νμ. "

And this might interest you?
http://arxiv.org/abs/cond-mat/0105357
 
Yes, but this is all theory; there's no observation there. It is arrived at by manipulating the concepts via arithmetic to predict observable outcomes. I will admit that the predictions are very good but a developed alternative scheme might make predictions that are just as good.

Quantum Theory does not predict relativity phenomena at its fundamental core. And when you analyze it via the Lagrangian maths, it can only predict the existence of mass by postulating the Higgs boson. So theories have limits that take time and much mind muscle to solve.
« Last Edit: 31/01/2009 02:02:57 by Vern »

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« Reply #38 on: 31/01/2009 02:08:25 »
Well yes, most probably so.
But this thing about flavours interest me´.
Just from a 'philosophical' point of view, sort of:)

First I was wondering about colours, and now I found flavours?
Where will I end???

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I can see myself trying to explain the flavour of a colour in the 'Langaraian field' in a pub.
I will very fast get towed away by burly men in white clothes:)

'Please Sir, just another quark before I go'
« Last Edit: 31/01/2009 02:12:05 by yor_on »
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Offline Vern

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« Reply #39 on: 31/01/2009 02:27:55 »
I have to admit that QCD is a fascinating concept and you can spend hours playing with the Feynman diagrams. I don't have any problem using QCD to predict outcomes if I need them. It has been a long time since I needed to do so however. I don't remember a time since I left school.

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« Reply #40 on: 31/01/2009 03:09:18 »
Well, I don't even know what charge is?
It seems to me as the photon, we know it exist and we have descriptions for it.
We use it on a daily basis.

But I'm still not sure what the descriptions are talking about.
We can speak of electrons missing and entropy, like time, having an arrow wanting to 'equalize' the difference between those electrons missing and that other end where we have more of them.

"a charge is any generator of a continuous symmetry of the physical system under study.
When a physical system has a symmetry of some sort, Noether's theorem implies the existence of a conserved current. The thing that "flows" in the current is the "charge", the charge is the generator of the (local) symmetry group. This charge is sometimes called the Noether charge."

I like this description though as it is at my level:)
http://www.owlnet.rice.edu/~elec201/Book/basic_elec.html

And if one have a burning interest then this one is good too:)
http://searchcio-midmarket.techtarget.com/sDefinition/0,,sid183_gci840676,00.html

And reading those two definitions you will know more than me:)
As my memory is like a sieve.

And I know that you don't need it Vern.
But I'm surprised over how easy it is for me to forget things I thought I knew.
I do it all the time:)

-----'loose'--quotations---

"Noether's theorem (also known as Noether's first theorem) states that any differentiable symmetry of the action of a physical system has a corresponding conservation law.
The action of a physical system is an integral of a so-called Lagrangian function, which is a function of the generalized coordinates and velocities of a dynamical system from which the equations of motion in Lagranges form can be derived.
From there the system's behavior can be determined by the principle of least action.
This seminal theorem was proven by Emmy Noether in 1915 and published in 1918-

And a Langrarian function is just a mathematical 'generalization' that summarizes the dynamics of the system using "any convenient variables" and "generalized coordinates" This makes it easy to incorporate constraints into a theory by defining coordinates which only describe states of the system which satisfy the constraints.

like you can do the same experiment in that jet-plane, as you can on the ground, not having to care that our earth moves at a constant speed of 30 km a second (I think:). So what it seem to state is that as long you are 'stationary' relative a uniformly moving frame of reference you won't notice any difference in your experiment, that is, if I got it right?
« Last Edit: 31/01/2009 03:38:20 by yor_on »
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« Reply #41 on: 31/01/2009 03:38:31 »
What is spin? What spin?

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« Reply #42 on: 31/01/2009 03:45:46 »
A Chevrolet -56 midnight blue with silver stripes.
Out for a spin on the strip.

That would be nice:)

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« Reply #43 on: 31/01/2009 03:46:55 »
Come on, I'm waiting for you to edit something...[:)][:)]

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But seriously? What spin?

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« Reply #44 on: 31/01/2009 03:52:02 »
I tried but i had no 'rights' to your post Sir.
What spin are we spinning now Mr Chem?
*truly suspicious*
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« Reply #45 on: 31/01/2009 03:53:07 »
Are you talking about electron spin?

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Offline yor_on

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« Reply #46 on: 31/01/2009 03:54:38 »
Yep, just wondering what it is:)
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« Reply #47 on: 31/01/2009 03:56:05 »
Have you found the answer?

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« Reply #48 on: 31/01/2009 03:57:53 »
Nope, but I have some practical experiments planned.

Involving a hula hoop and lots and lots of tequila sunrises.
Either one will help, as long as she doesn't hit me:)


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How many do you think I will need Mr Chem?
She recommended http://www.firetoys.co.uk/juggling/hula_hoops.html

And wants me to sing 'I'm on fire' doing it?
What's his name?
Bruce, ah, lee??
« Last Edit: 31/01/2009 04:05:25 by yor_on »
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« Reply #49 on: 31/01/2009 04:01:26 »
How many do you think I will need Mr Chem?
Hola hoops or the other one? I've got no idea [???]

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Btw, are you good with waves?

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Who is 'she'?
« Last Edit: 31/01/2009 04:04:58 by Chemistry4me »