Science > Physics > why do spin 1/2 particles obey Pauli Excl. Principle?
| Topic: |
Science > Physics |
| User: |
"Bishop" |
| Date: |
27 Feb 2006 07:05:43 PM |
| Object: |
why do spin 1/2 particles obey Pauli Excl. Principle? |
Hi,
Is there a physical reason why spin 1/2 fermions such as electrons,
quarks can't occupy the same space (obeying pauli exclusion
principle) and spin 1 or bosons can (occupy same space)? It's like
is it possible that in spin 1 particle... somehow something
is cancelled that's is why there is no stopping it from occupying
the same space (for example. combining fermions to produce integer
can turn them into bosons). What is the general conceptual
consensus about this.
Bishop
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| User: "QCD Apprentice" |
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| Title: Re: why do spin 1/2 particles obey Pauli Excl. Principle? |
27 Feb 2006 07:55:33 PM |
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Bishop wrote:
Hi,
Is there a physical reason why spin 1/2 fermions such as electrons,
quarks can't occupy the same space (obeying pauli exclusion
principle) and spin 1 or bosons can (occupy same space)? It's like
is it possible that in spin 1 particle... somehow something
is cancelled that's is why there is no stopping it from occupying
the same space (for example. combining fermions to produce integer
can turn them into bosons). What is the general conceptual
consensus about this.
Well, from the point of view of quantum field theory, you
can't quantize a system of half-integer spin particles
(1/2,3/2,etc.) using commutation relations. You have to use
anti-commutation relations, which means that the whole mess
is going to be anti-symmetric under interchange of identical
particles.
If it's antisymmetric under interchange of identical
particles, then there can be at most one particle in any
particular state.
Think of it in terms of functions.
If f(x1,x2) = - f(x2,x1)
then if x1=x2
f(x1,x1) = -f(x1,x1) = -f(x1,x1)
=>
2*f(x1,x1) = 0
f(x1,x1) = 0
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| User: "ma1ibu" |
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| Title: Re: why do spin 1/2 particles obey Pauli Excl. Principle? |
28 Feb 2006 07:57:05 AM |
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I like how the poster
asks, "Is there s physical reason......",
and some adherent of QM jumps in.
QM doesn't have a model which can
be physically modelled.
QM HAS NO PHYSICAL MODEL.
Do you people not understand that?
John
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| User: "Gregory L. Hansen" |
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| Title: Re: why do spin 1/2 particles obey Pauli Excl. Principle? |
01 Mar 2006 09:39:24 AM |
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In article <1141135024.934238.265540@t39g2000cwt.googlegroups.com>,
ma1ibu <vegan16@accesscomm.ca> wrote:
I like how the poster
asks, "Is there s physical reason......",
and some adherent of QM jumps in.
Spin 1/2 particles and the Pauli exclusion principle are quantum
mechanical concepts. How else to discuss them, except in the context of
QM?
QM doesn't have a model which can
be physically modelled.
QM HAS NO PHYSICAL MODEL.
Do you people not understand that?
I understand that you're trying to tell Nature what to do, rather than
asking her questions by experiment and then devising theories based on her
answers.
--
"Work hard, be curious and persistent, and you will prevail." -- Howard
Schilit, "Financial Shenanigans" 2nd ed.
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| User: "Sam Wormley" |
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| Title: Re: why do spin 1/2 particles obey Pauli Excl. Principle? |
28 Feb 2006 08:26:28 AM |
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ma1ibu wrote:
I like how the poster
asks, "Is there s physical reason......",
and some adherent of QM jumps in.
QM doesn't have a model which can
be physically modelled.
QM HAS NO PHYSICAL MODEL.
Do you people not understand that?
John
Your problem John is that "PHYSICAL MODEL" to you means
"Newtonian Model" which is totally inapropriate for
understanding the quantum world.
Read Feynman's QED
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| User: "ma1ibu" |
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| Title: Re: why do spin 1/2 particles obey Pauli Excl. Principle? |
28 Feb 2006 09:59:53 AM |
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And a 'physical model' in the quantum
(read: 'imaginary') world is.........................
fill in the blank- YOU CAN'T.
You have an IMAGINARY MODEL, Sam.
You can't draw it. You can't
build a working mobile.
You can't do f***-all with it.
It sucks.
You're wrong.
Sam, Sam, Sam, your problem
is you think yourself to be made up
of totally non-physical, random fluctuations
of energy.
Fortunately- for you- actually you are
made up of a very, very large number
of atoms which are identical in every
way with galaxies, including being populated
with life-forms like you and me and, yes,
some of those life-forms ARE actually smarter
than you and me.
Now, what is nice for us is these life-forms
are at a rate where the speed of light is
about 30 times faster, so information travelling to
us from them is MUCH FASTER than information travel
in this matrix.
So, let's say you have an emergency; all your
options can be programmed and got back to you
essentially instantaneously, enabling you to make
your very best move at the very best instant
IF you listen to your 'inner self'..
It's called being 'in touch'.
John
Galaxy Model for the Atom
http:users.accesscomm.ca/john
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| User: "Sam Wormley" |
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| Title: Re: why do spin 1/2 particles obey Pauli Excl. Principle? |
28 Feb 2006 10:06:20 AM |
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ma1ibu wrote:
Fortunately- for you- actually you are
made up of a very, very large number
of atoms which are identical in every
way with galaxies, including being populated
with life-forms like you and me and, yes,
some of those life-forms ARE actually smarter
than you and me.
Is that why you registered at crank dot not, John?
http://www.google.com/search?q=%22GALAXY+MODEL+For+The+ATOM%22+site%3Awww.crank.net
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| User: "Bishop" |
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| Title: Re: why do spin 1/2 particles obey Pauli Excl. Principle? |
28 Feb 2006 08:15:43 AM |
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ma1ibu wrote:
I like how the poster
asks, "Is there s physical reason......",
and some adherent of QM jumps in.
QM doesn't have a model which can
be physically modelled.
QM HAS NO PHYSICAL MODEL.
Do you people not understand that?
John
I've been analyzing this matter today. Internal symmetry space,
isospin, spin... these are supposed to be just mathematical
entities, but they have real effects on this world. Either we
have to suffice with mathematical models only or there may
be higher spaces involved. I'm trying to visualize 4 dimensional
shape. Imagine there is a point in the center of a cube. Try
to move the point to a new dimension without changing
the length of any of the 4 equal distance to the corner of
the cube. Maybe isopin, spin has higher correlates in
a higher dimensional space. what do you think QCD
Apprentice? I know you'd say isospin is just an mathematical
abstraction.. but what if there is a higher dimensional
correlate or something. Can you prove the internal symmetry
space is categorically just a mathematical abstraction or
device with zero possibility of being connected to a higher
dimensional space?
To John, you can't model physics using discrete continuous
mechanistic 3D models. Thousands of physicists since Planck
have tried it. No one succeed. QM is the end result. QM
is just tip of the iceberg.
Bishop
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| User: "ma1ibu" |
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| Title: Re: why do spin 1/2 particles obey Pauli Excl. Principle? |
28 Feb 2006 10:08:01 AM |
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http://users.accesscomm.ca/john/Methane1.GIF
will prove you wrong.
Look at the coins: they rotate once every time
they precess twice.
This allows one or two but no more to ride each of
the colored pathways.
I am in the process of moving eight members
in such a way that they move repeatedly through
a system of four linked orbitals at the points of
a tetrahedron.
Just because it's never been done doesn't
mean it can't be done.
Here's the basic orbital, which contains
one or two members depending on if there
is another on the other side of the disc.
http://users.accesscomm.ca/john/He.GIF
John
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| User: "Sam Wormley" |
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| Title: Re: why do spin 1/2 particles obey Pauli Excl. Principle? |
28 Feb 2006 10:11:11 AM |
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ma1ibu wrote:
http://users.accesscomm.ca/john/Methane1.GIF
will prove you wrong.
Look at the coins: they rotate once every time
they precess twice.
This allows one or two but no more to ride each of
the colored pathways.
I am in the process of moving eight members
in such a way that they move repeatedly through
a system of four linked orbitals at the points of
a tetrahedron.
Just because it's never been done doesn't
mean it can't be done.
Here's the basic orbital, which contains
one or two members depending on if there
is another on the other side of the disc.
http://users.accesscomm.ca/john/He.GIF
John
Is that why you registered at crank dot not, John?
http://www.google.com/search?q=%22GALAXY+MODEL+For+The+ATOM%22+site%3Awww.crank.net
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| User: "Puppet_Sock" |
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| Title: Re: why do spin 1/2 particles obey Pauli Excl. Principle? |
28 Feb 2006 10:11:44 AM |
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ma1ibu wrote:
I like how the poster
asks, "Is there s physical reason......",
and some adherent of QM jumps in.
QM doesn't have a model which can
be physically modelled.
QM HAS NO PHYSICAL MODEL.
Do you people not understand that?
Um. I understand it so far as it is capable of being understood.
It's not even wrong. QM has a perfectly good physical model.
You just don't comprehend it.
For example, the question was about spin 1/2 particles. Spin 1/2
particles do not exist outside of quantum mechanics, as classical
particles must be integer spin. But then, you don't think that has
a physical model either.
Socks
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| User: "Daniel Pitts" |
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| Title: Re: why do spin 1/2 particles obey Pauli Excl. Principle? |
01 Mar 2006 09:49:29 AM |
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Puppet_Sock wrote:
ma1ibu wrote:
I like how the poster
asks, "Is there s physical reason......",
and some adherent of QM jumps in.
QM doesn't have a model which can
be physically modelled.
QM HAS NO PHYSICAL MODEL.
Do you people not understand that?
Um. I understand it so far as it is capable of being understood.
It's not even wrong. QM has a perfectly good physical model.
You just don't comprehend it.
For example, the question was about spin 1/2 particles. Spin 1/2
particles do not exist outside of quantum mechanics, as classical
particles must be integer spin. But then, you don't think that has
a physical model either.
Socks
Hmm.. I'm pretty sure electrons exist outside of quantum mechanics, and
I do beleave that they are Spin 1/2.
I think a better way to phrase the OPs message is:
According to the Pauli Exclusion Princible, there is a "pressure" which
keeps electrons (and other 1/2 spin particles) from existing in the
same space (state). This is an observable physical phenomena.
Does anyone know what causes this pressure? Is it a type of force? Are
there "virtual bosons" pushing against the fermions?
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| User: "Gregory L. Hansen" |
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| Title: Re: why do spin 1/2 particles obey Pauli Excl. Principle? |
01 Mar 2006 10:07:50 AM |
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In article <1141228169.416651.209200@t39g2000cwt.googlegroups.com>,
Daniel Pitts <googlegroupie@coloraura.com> wrote:
Puppet_Sock wrote:
ma1ibu wrote:
I like how the poster
asks, "Is there s physical reason......",
and some adherent of QM jumps in.
QM doesn't have a model which can
be physically modelled.
QM HAS NO PHYSICAL MODEL.
Do you people not understand that?
Um. I understand it so far as it is capable of being understood.
It's not even wrong. QM has a perfectly good physical model.
You just don't comprehend it.
For example, the question was about spin 1/2 particles. Spin 1/2
particles do not exist outside of quantum mechanics, as classical
particles must be integer spin. But then, you don't think that has
a physical model either.
Socks
Hmm.. I'm pretty sure electrons exist outside of quantum mechanics, and
I do beleave that they are Spin 1/2.
I think a better way to phrase the OPs message is:
According to the Pauli Exclusion Princible, there is a "pressure" which
keeps electrons (and other 1/2 spin particles) from existing in the
same space (state). This is an observable physical phenomena.
Does anyone know what causes this pressure? Is it a type of force? Are
there "virtual bosons" pushing against the fermions?
There actually isn't a pressure related to that. You can see that by
finding two-particle wavefunctions in the infinite potential well for
non-interacting fermions, bosons, and non-identical particles. Put one of
the particles in the ground state and the other in the first excited
state, and find the energy of the system. Find how the energy changes
when the width of the well changes-- that is the work done on (or by) the
system. Force is dW/dx. It is the same for all three possibilities.
What is different is that it's possible for the bosons and the
non-identical particles to release energy as a photon or some such--
condensation is possible so that both particles are in the ground state.
And then, all else being equal, you would expect the system with less
energy to exert less pressure.
--
"We don't grow up hearing stories around the camp fire anymore about
cultural figures. Instead we get them from books, TV or movies, so the
characters that today provide us a common language are corporate
creatures" -- Rebecca Tushnet
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| User: "PD" |
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| Title: Re: why do spin 1/2 particles obey Pauli Excl. Principle? |
28 Feb 2006 12:30:49 PM |
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ma1ibu wrote:
I like how the poster
asks, "Is there s physical reason......",
and some adherent of QM jumps in.
QM doesn't have a model which can
be physically modelled.
QM HAS NO PHYSICAL MODEL.
Describe your criteria for "physical".
I take it you assume that it must include properties like
-size
-shape
-mass
-color
-texture
-taste
-stiffness
Do you people not understand that?
John
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| User: "Bishop" |
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| Title: Re: why do spin 1/2 particles obey Pauli Excl. Principle? |
28 Feb 2006 04:21:43 PM |
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Right now. There are only two possibilites about physics.
Either the mathematical models alone can suffice (meaning
the universe may be a program) or we are dealing with
higher dimensions not curled up but infinite as in Randall
concept. These are few possibilites powerful enough to explain
QM, SR, GR. Note almost all the 20+ crackpot models
are based on mechanistic newtonian models. This is
where they are wrong because they are not compatible
with 100% of experimental data (most don't even reach 50%
of it). They are not aware of them and somehow sticking
their heads in the sands thinking that the universe would
magically conform to their world. This is why I mostly ignore
those crackpots thing now. They are a waste of time.
Bishop
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| User: "FrediFizzx" |
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| Title: Re: why do spin 1/2 particles obey Pauli Excl. Principle? |
28 Feb 2006 06:04:03 PM |
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"Bishop" <BishopSemanticsGroup@yahoo.com> wrote in message
news:1141165303.898041.287280@v46g2000cwv.googlegroups.com...
|
| Right now. There are only two possibilites about physics.
| Either the mathematical models alone can suffice (meaning
| the universe may be a program) or we are dealing with
| higher dimensions not curled up but infinite as in Randall
| concept. These are few possibilites powerful enough to explain
| QM, SR, GR.
I'll vote for the Randall-Sundrum type models; especially RS-1.
However, let's make the two 3-branes intersecting somewhat and also
allow virtual fermion pairs in the "bulk" which is now the intersection
part. And allow "less than virtual" fermion pairs in the "gravity"
brane. This could basically be a modified Dirac-like Sea.
| Note almost all the 20+ crackpot models
| are based on mechanistic newtonian models. This is
| where they are wrong because they are not compatible
| with 100% of experimental data (most don't even reach 50%
| of it). They are not aware of them and somehow sticking
| their heads in the sands thinking that the universe would
| magically conform to their world. This is why I mostly ignore
| those crackpots thing now. They are a waste of time.
What cracks me up is that a lot of these "aether" people want to have
photons that have mass even if just a tiny bit of mass. If there is a
medium, it has to be relativistic over an extremely wide range of
energies and then gauge bosons are just collective motion of the medium.
Photons would have to be defined to be massless in this type of
scenario. The medium also has to be consistent with quantum fields most
likely.
FrediFizzx
http://www.vacuum-physics.com
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| User: "Gregory L. Hansen" |
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| Title: Re: why do spin 1/2 particles obey Pauli Excl. Principle? |
01 Mar 2006 09:36:28 AM |
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In article <1141088743.168562.302710@p10g2000cwp.googlegroups.com>,
Bishop <BishopSemanticsGroup@yahoo.com> wrote:
Hi,
Is there a physical reason why spin 1/2 fermions such as electrons,
quarks can't occupy the same space (obeying pauli exclusion
principle) and spin 1 or bosons can (occupy same space)? It's like
is it possible that in spin 1 particle... somehow something
is cancelled that's is why there is no stopping it from occupying
the same space (for example. combining fermions to produce integer
can turn them into bosons). What is the general conceptual
consensus about this.
Bishop
If spin 1/2 particles commuted they would violate causality.
--
"Beer is living proof that God loves us and wants us to be happy."
-- Benjamin Franklin
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