What is the structure of electron??
Him
What is the structure of electron??
thanks!
Adrian Cable
Him wrote:
>
> What is the structure of electron??
> thanks!
The electron is presently believed to be fundamental, i.e. a point mass
- it does not have any discernible radius.
Thanks, cheers,
Adrian Cable.
Agustín Sánchez
Adrian Cable wrote:
> Him wrote:
> >
> > What is the structure of electron??
> > thanks!
>
> The electron is presently believed to be fundamental, i.e. a point mass
> - it does not have any discernible radius.
What do you mean by "discernible radius"? Something we can't calculate or
measure?The sole idea of something to be strictly "a point" is
unacceptable, because it leads to a lot of divergences: infinite density,
infinite electric energy, ...
There is a well known estimation of the "classic" radius for an electron
(H. Semat 1966): Consider it as a sphere of radius R, calculate its
electric energy, about q^2/R, and then:
q^2/R ~ m c^2
R ~ q^2 /(m c^2) ~ 10^-15 m
Kaplan (1962) made this calculus from the cross section of electrons in the
X rays scattering, and obtained a similar result.
I know, I know, these are very classical reasoning. But from the quantum
point of view is also impossible to imagine the electron as a point,
because of the Heisenberg UP, or because of its wave properties.
--
=========================================
Agustín Sánchez
asmamb...@SPAMusa.net
(Remove the words "NO" and "SPAM" to mail)
==========================================
Uncle Al
Him wrote:
>
> What is the structure of electron??
> thanks!
An electron is a fundamental point (zero-dimensional) particle. Its
properties arise from a cloud of Feynman diagrams obscuring/illuminating
the singularity.
--
Uncle Al Schwartz
Uncl...@ix.netcom.com ("zero" before @)
http://uncleal.within.net/
http://pw2.netcom.com/~uncleal0/uncleal.htm
http://www.ultra.net.au/~wisby/uncleal.htm
http://www.guyy.demon.co.uk/uncleal/uncleal.htm
(Toxic URLs! Unsafe for children, Democrats, and most mammals)
"Quis custodiet ipsos custodes?" The Net!
Jon Bell
None, as far as anyone knows. That is, electromagnetic and
weak-interaction theory consider the electron as a mathematical point, and
there have so far been no experimental observations that indicate anything
to the contrary.
--
Jon Bell <jtb...@presby.edu> Presbyterian College
Dept. of Physics and Computer Science Clinton, South Carolina USA
Smart1234
><HTML><PRE> Him <cc...@hkstar.com> wrote:
>>What is the structure of electron??
>
>None, as far as anyone knows. That is, electromagnetic and
>weak-interaction theory consider the electron as a mathematical point, and
>there have so far been no experimental observations that indicate anything
>to the contrary.
>
>
I show an alternative view of the internal structure of the atom and the
electron at :
http://members.aol.com/smart1234
A very interesting discovery I have made about the electron structure is
that, it is analogous to the structure of the atom as a whole.
jo...@petcom.com
In article <6k0v0j$3q...@venus.hkstar.com>,> thanks!
>
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John
-----== Posted via Deja News, The Leader in Internet Discussion ==-----
http://www.dejanews.com/ Now offering spam-free web-based newsreading
Bryan W. Reed
In article <3564426A...@SPAMusa.net>,
Agustín Sánchez <asmamb...@SPAMusa.net> wrote:
>
>What do you mean by "discernible radius"? Something we can't calculate or
>measure?The sole idea of something to be strictly "a point" is
>unacceptable, because it leads to a lot of divergences: infinite density,
>infinite electric energy, ...
The problem is not so obvious to me, since, because of quantum mechanics,
the probability of finding the electron absolutely precisely at some
particular position is zero. Unless you have a singularity in the wave
function itself, which is something else altogether.
>There is a well known estimation of the "classic" radius for an electron
>(H. Semat 1966): Consider it as a sphere of radius R, calculate its
>electric energy, about q^2/R, and then:
>
> q^2/R ~ m c^2
>
> R ~ q^2 /(m c^2) ~ 10^-15 m
>
>Kaplan (1962) made this calculus from the cross section of electrons in the
>X rays scattering, and obtained a similar result.
>
>I know, I know, these are very classical reasoning. But from the quantum
>point of view is also impossible to imagine the electron as a point,
>because of the Heisenberg UP, or because of its wave properties.
You're confusing the particle with its probability field. The quantum
mechanical wave function tells you the probability per unit volume of
finding the point particle at a given point. This has nothing to do
with whether the particle itself has zero radius.
Anyway, if the elementary particles have finite radii, it introduces
some problems in relativistic quantum field theory. If you think of
an electron as a perfectly rigid sphere of finite size, you get nonlocal
effects and potential causality violations. Fun stuff.
Have fun,
breed
Agustín Sánchez
Bryan W. Reed wrote:
> Agustín Sánchez <asmamb...@SPAMusa.net> wrote:
> >
> >What do you mean by "discernible radius"? Something we can't calculate or
> >measure?The sole idea of something to be strictly "a point" is
> >unacceptable, because it leads to a lot of divergences: infinite density,
> >infinite electric energy, ...
>
> The problem is not so obvious to me, since, because of quantum mechanics,
> the probability of finding the electron absolutely precisely at some
> particular position is zero. Unless you have a singularity in the wave
> function itself, which is something else altogether.
>
First of all, I'm not saying that the electron (nor a nucleus) have a
definite
radius. The question is whether accepting or not that it could have no
radius at
all, and be a geometric point with all its mass concentrated in a null
volume.
> You're confusing the particle with its probability field. The quantum
> mechanical wave function tells you the probability per unit volume of
> finding the point particle at a given point. This has nothing to do
> with whether the particle itself has zero radius.
>
Right! But, obviously, it does not sustain the assert of a null radius.
You can describe also the movement of a proton, or a nucleus, with
evident non null -although undefined- radius, by a wave function, and
the same
uncertainty will arise. There is a possible interpretation of the
Uncertainty
Principle and of the wave function that tell us about an intrinsic
uncertainty
(not only for the observers and their ability to measuring), and a true
spreading
of the particle as it moves (propagates).
> Anyway, if the elementary particles have finite radii, it introduces
> some problems in relativistic quantum field theory. If you think of
> an electron as a perfectly rigid sphere of finite size, you get nonlocal
> effects and potential causality violations. Fun stuff.
Very fun, indeed. Quantum Field Theory has a lot of problems, I guess,
as the
Standard Model has also. It is not my fault as I've made -unfortunately-
no
contributions to them. And theorists probably are right trying to
simplify the models
speaking of "points", or, more exactly, disregarding any consideration
about the
radius. But a point is something meaningless, because density would
become infinite. How
many problems would arise if we had to consider an electron as a black
hole or a naked singularity?
Let's take a last glance of the electron. It is very little, fuzzy,
mobile, we
can't see it, but it creates a very strong EM field. There is a great
energy's
density around it. There is some mass' density also, in agreement with
the well known Einstein's formula. This density decreases as the
distance from the "electron", whatever
it could be, increases. But strictly speaking, it is spread all over the
whole universe.
Glad to meet you.
Gregory Loren Hansen
In article <3565D91F...@SPAMusa.net>,
Agustín Sánchez <asmamb...@SPAMusa.net> wrote:
>Bryan W. Reed wrote:
>> You're confusing the particle with its probability field. The quantum
>> mechanical wave function tells you the probability per unit volume of
>> finding the point particle at a given point. This has nothing to do
>> with whether the particle itself has zero radius.
>>
>
>Right! But, obviously, it does not sustain the assert of a null radius.
>You can describe also the movement of a proton, or a nucleus, with
>evident non null -although undefined- radius, by a wave function, and
I think the conclusion that the electron has zero radius comes from
scattering experiments. You can smash electrons into each other and
measure the angles at which they emerge. And you can try to guess its
internal structure by just assuming it has a certain type of structure and
working out theoretically how it should scatter. Then compare your theory
to experiment. If it had a radius, it would scatter differently than if
it was point-like.
--
Stay alert! Trust no one! Keep your laser handy! The Computer is
your Friend!
Jim Carr
Adrian Cable wrote:
}
} Him wrote:
} > What is the structure of electron??
}
} - it does not have any discernible radius.
"Agustín Sánchez" <asmamb...@SPAMusa.net> writes:
>
>What do you mean by "discernible radius"? Something we can't calculate or
>measure?
I would say that if the electron has a radius, it is too small to
be seen with present experiments. All data are consistent with
the predictions of QED assuming a point "form factor" for the
electron. Similarly for the quarks, although the limits are
tighter for the electron.
>The sole idea of something to be strictly "a point" is
>unacceptable, because it leads to a lot of divergences: infinite density,
>infinite electric energy, ...
Those divergences lead, through renormalization, to predicted effects
that are seen in experiment. The Lamb shift is the most famous.
>There is a well known estimation of the "classic" radius for an electron
>(H. Semat 1966): Consider it as a sphere of radius R, calculate its
>electric energy, about q^2/R, and then:
>
> q^2/R ~ m c^2
>
> R ~ q^2 /(m c^2) ~ 10^-15 m
>
>Kaplan (1962) made this calculus from the cross section of electrons in the
>X rays scattering, and obtained a similar result.
And Compton invented the idea a few decades earlier. Anyway, that
"radius" is constructed from the coupling constant and the recoil
mass and has nothing to do with a physical size. Simple comparison
to the proton will establish that.
>I know, I know, these are very classical reasoning. But from the quantum
>point of view is also impossible to imagine the electron as a point,
>because of the Heisenberg UP, or because of its wave properties.
This is not true. Non-relativistic QM does not care, and QED is
based on the idea of structurless electron.
--
James A. Carr <j...@scri.fsu.edu> | Commercial e-mail is _NOT_
http://www.scri.fsu.edu/~jac/ | desired to this or any address
Supercomputer Computations Res. Inst. | that resolves to my account
Florida State, Tallahassee FL 32306 | for any reason at any time.
Agustín Sánchez
On 1 Jun 1998 22:05:39 GMT, j...@ibms48.scri.fsu.edu (Jim Carr) wrote:
>
>"Agustín Sánchez" <asmamb...@SPAMusa.net> writes:
>>
>>What do you mean by "discernible radius"? Something we can't calculate or
>>measure?
>
> I would say that if the electron has a radius, it is too small to
> be seen with present experiments. All data are consistent with
> the predictions of QED assuming a point "form factor" for the
> electron. Similarly for the quarks, although the limits are
> tighter for the electron.
>
>>The sole idea of something to be strictly "a point" is
>>unacceptable, because it leads to a lot of divergences: infinite density,
>>infinite electric energy, ...
>
> Those divergences lead, through renormalization, to predicted effects
> that are seen in experiment. The Lamb shift is the most famous.
>
>
(snip)
>
>>I know, I know, these are very classical reasoning. But from the quantum
>>point of view is also impossible to imagine the electron as a point,
>>because of the Heisenberg UP, or because of its wave properties.
>
> This is not true. Non-relativistic QM does not care, and QED is
> based on the idea of structurless electron.
Maybe you're right. Nevertheless, I've checked the Schweber's
_Relativistic_Quantum_Field_Theory and I was not able to find the need
of a null radius for the electron. In spite of this, in the section
15b (Mass Renormalization and the Nonrelativistic Lamb Shift) (p.
524), we can read the need of consider the free electron to have a
spread-off charge, and some kind of function is postulated to the
charge distribution, and a radius (!!!) given by:
a ~ h/(2 pi m c)
I am not specialist in these questions, and perhaps the Scheweber's
book is out of date. Will you point me to better references?
Agustín Sánchez
asmamb...@SPAMusa.net
(Remove "NO" and "SPAM" to mail)
Charles W. Shults III
Agustín Sánchez wrote:
>
> On 1 Jun 1998 22:05:39 GMT, j...@ibms48.scri.fsu.edu (Jim Carr) wrote:
>
> >
> >"Agustín Sánchez" <asmamb...@SPAMusa.net> writes:
> >>
> >>What do you mean by "discernible radius"? Something we can't calculate or
> >>measure?
<big snip>
Actually, the electron radius now has a value. It is 2.81794092 x
10^-15 m.
That's pretty small!
Cheers!
Chip Shults
George Bugh
How fast is that electron spinning at the surface?
How fast is it spinning halfway to the center?
me...@cars3.uchicago.edu
In article <35799E...@gdi.net>, "Charles W. Shults III" <aic...@gdi.net> writes:
>Agustín Sánchez wrote:
>>
>> On 1 Jun 1998 22:05:39 GMT, j...@ibms48.scri.fsu.edu (Jim Carr) wrote:
>>
>> >
>> >"Agustín Sánchez" <asmamb...@SPAMusa.net> writes:
>> >>
>> >>What do you mean by "discernible radius"? Something we can't calculate or
>> >>measure?
>
><big snip>
>
> Actually, the electron radius now has a value. It is 2.81794092 x
>10^-15 m.
>
quantity with the dimensions of length which you can define using the
electrons mass, charge, and the speed of light. It is not an actual
"electron radius".
Mati Meron | "When you argue with a fool,
me...@cars.uchicago.edu | chances are he is doing just the same"
Jim Carr
Agustín Sánchez wrote:
}
} "Agustín Sánchez" <asmamb...@SPAMusa.net> writes:
} >
} >What do you mean by "discernible radius"? Something we can't calculate or
} >measure?
aic...@gdi.net writes:
>
> Actually, the electron radius now has a value. It is 2.81794092 x
>10^-15 m.
That has been know to be wrong for what, maybe 40 years? Certainly
since SLAC came on line. The current limit is more like 10^{-18} m
although it is probably less.
Agustín Sánchez
On 16 Jun 1998 19:45:36 GMT, j...@ibms48.scri.fsu.edu (Jim Carr) wrote:
(earlier follow-ups snipped)
>
> The non-relativistic calculation due to Bethe integrates over
> the H-atom using the Bohr radius, so a length like that appears
> naturally in the answer. That book should have the QED treatment
> in another section.
First of all, I thank you (sincerely) for your post.
After several weeks with interrupted discussions, a summary could help. I expect
you to amend it if needed:
1) The subject is whether the electron is strictly a point or it has to be
spread out in some extent (a radius), although it could be fuzzy and extremely
small.
2) You assert (I think) that any calculated radius is only a maximum limit.
About this, some values have been shown in this ng: The classical radius (Abraam
e^2/mc^2 and some 10-{18} among others. I am not sure you to believe the
electron to be strictly a point, but it appears like that to me from some posts
of yours.
3) You denied any contradiction between the postulated point-like character for
the electron and the HUP principle. Contrarily, I think that the strong
interpretation of HUP does contradict a point-like picture for anything.
4) You assert that all the divergence problems are eliminated by
renormalization.
A null-radius-point-lilke-character for anything is not something to be blithely
accepted. There is a strong possibility that this assumption arises rather from
theoretical convenience in the aim to simplify the models.
Renormalization, which basically consists in subtracting an infinite term and
try to justify it, has been a long and complex mathematical process with plenty
of self contradictions (infrared and ultraviolet catastrophes among others)
divergences, at least till the earliest 70's. It rather belongs to "formalistic"
than "realistic" physics. I accept not to be up to date about that question, so
I expect to learn a lot from that discussion. In all cases, this is not a
question to be cleared of as if it were a simplistic problem.
In the paragraphs below I'll try to collect a brief history of the question as
far as I know, and I invite you to complete and/or correct it.
We cant find the cutoff radius according with the Dirac hole theory:
Rmax = hbar /mc * e^-137
which had to be rejected, due to strong interactions between virtual mesons and
virtual nucleons at this range. A _breakdown_of_quantum_electrodynamics arises
when fields other than the electromagnetic and the electron-positron field play
a role.
Numerous attempts have been made to reformulate the classical Maxwell-Lorentz
theory in the presence of _point_ charges to avoid divergences, mainly the
infinite self-energy. Thus we have Wentzel, Dirac, and Eliezer. All of them have
serious shortcomings, as self accelerated motions for the electron.
Feynmann and Wheeler postulated a split -again- of the electromagentic field
into a self-field (proper) and an external field. The proper field is supposed
as not acting back on the particle which produces it. Thus there is no such
thing as the "self-energy". But there is ever a prize to pay for: The formalism
is developed as an action at a distance theory, contrary to relativistic
postulates.
Another attempt, due to Stükelberg avoids the infinite self-energy by assuming a
short-range attractive (mesic) force between charges. Lacking of a deeper study
by myself (and I won't have the time) that solution appears as an "ad hoc"
argument, and does not guarantee a point-like charge character.
Several other attempts, as Bopp, Landé and Born-Infeld was not definitively
successful.
It is very interesting the point of view of that old unitary theories (Mie),
which stated that PARTICLES ARISES NOT AS SINGULARITIES, BUT AS SMALL VOLUMES IN
WHICH ENERGY AND CHARGE OF THE FIELD ARE CONCENTRATED (Filkestein). This is my
own intuitive belief.
We have an unambiguous method due to Dyson for the separation of a primitively
divergent integral into an infinite an a finite part. Other contributions are
from Källén an Valatin, and also Caianello, but int Schweber's belief, no answer
has yet been given to the central problem of quantum field theory "Do solutions
exist of the renormalized equations?"
Any comments will be welcome. If a definitive solution to the problem is already
developed, I'll be very glad to know it. But as I am too old for drastic changes
in my thought, and I can't easily accept a point-like picture for the electron.
Regards.
Agustín Sánchez
I.B. Ramón Llull
Valencia
asmamb...@Susa.net
Remove capital letters to mail
Jim Carr
... particle physics added with followups there ...
asmamb...@Susa.net (Agustín Sánchez) writes:
>
>After several weeks with interrupted discussions, a summary could help.
>I expect you to amend it if needed:
>
>1) The subject is whether the electron is strictly a point or it has to be
>spread out in some extent (a radius), although it could be fuzzy and extremely
>small.
There is no experimental evidence that it has to be a non-point
object, and there is experimental evidence that its finite size
cannot exceed some small (pm) limits.
>2) You assert (I think) that any calculated radius is only a maximum limit.
No, I am mainly talking about data analyzed within QED.
The only calculation is that of QED corrections vis-a-vis the data.
>About this, some values have been shown in this ng: The classical radius
>(Abraam e^2/mc^2 and some 10-{18} among others. ...
The classical radius is falsified by experiment.
>I am not sure you to believe the
>electron to be strictly a point, but it appears like that to me from some
>posts of yours.
It is consistent with data, so belief has nothing to do with it.
I suspect that there must be underlying structure to explain the
'family' structure, and in the past that has also manifest itself
as finite size effects. We did get lucky with quark structure
being only a few steps below nuclear structure; there is no reason
to be so lucky every time. There is a 10^5 factor between atoms
and nuclei. It is also possible that a theory could put that
internal structure in another dimension.
>3) You denied any contradiction between the postulated point-like character
>for the electron and the HUP principle. Contrarily, I think that the strong
>interpretation of HUP does contradict a point-like picture for anything.
>4) You assert that all the divergence problems are eliminated by
>renormalization.
The answer to both of these lie in an examination of QED. Both
of these were serious problems circa 1950. They are now solved
in a technical sense, though many find the approach unsatisfactory.
>A null-radius-point-lilke-character for anything is not something to
>be blithely accepted. ....
Of course not. That is why there are experiments, and people ask
this question every time they have an opportunity.