What is the physical makeup of an electron?

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The discussion centers on the nature and physical makeup of electrons, questioning whether they are composed of smaller entities or if they are fundamental particles. It is established that electrons are considered point-like in modern Quantum Field Theory, with no internal structure, and their properties are defined by mass, charge, and spin. The concept of enlarging an electron to observe its structure is challenged, as quantum properties would vanish at macroscopic scales. The charge radius of an electron is debated, with current experimental limits suggesting it is less than 10^-18 meters, but no definitive prediction exists. Ultimately, electrons are described as excitations of an electron field, emphasizing their role as fundamental particles in the framework of quantum physics.
  • #51
Even in classical electrodynamics one can describe the electron as an orbiting massless charge embedded in its synchrotron radiation and obtains the fundamental properties, also the mass and the de Broglie wave.
The /size/ of the mass needs quantum mechanic considerations
 
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  • #52
In post # 47, a minimum electron radius value, (3Gm/c^2) was noted. From this radius, a fundamental mass value is defined, using a ring shape with the angular momentum (h/4pi). The charge spins at light velocity so that the effective mass times velocity times radius will equal angular momentum.
m c (3Gm/c^2) = h/4pi
(m)^2 = (h/4pi) (c/3G)
m = (hc/12pi G)^1/2
m = (1/2) (2/3)^1/2 (Planck mass)
I suggest this mass value is the fundamental value that has a specific relationship to the electron mass, the muon mass and the tau mass.
The photon wavelength that has energy to produce two particles with each particle mass value equal to (hc/12pi G)^1/2 is (3pi hG/c^3)^1/2 meter. This wavelength is:
wavelength = 2pi (3/2)^1/2 (Planck length)
The ratio of this fundamental wavelength to the wavelength (h/2mc) is approximately 1.025x10^-22 to one. I will suggest that this is also equal to [h/(2pi)^2] divided by (2mc^2) where the m value is the electron mass. This ratio is 1.025028393x10^-22. If these ratio values are precisely correct then the true G value must be very close to 6.671745197x10^-11. Improved experiments will determine if this is correct.
 
  • #53
First off I'm no physicist but an EE. So my question might seem odd, but in light of everything that was said until now, why has nobody (except for one guy I believe) proposed string theory to try to explain what elementary particles are (electron included)? Is this because it is still an "unproven" (untested) theory?

String theory seems to be acknowledged by many recognized scientists, so perhaps it is a valid one at answering the initial question: what is an electron?

Btw, what a great forum this is. Just recently found it. Since then I just can't help but try to read every single posts. Waaa, I'm going crazy :)
 
  • #54
Hi kended, String Theory and Quantum Gravity are well covered in the book by Lee Smolin, titled Three Roads To Quantum Gravity. Much work is needed if string theory is to accomplish its objective. A quote from the book follows:
"Modern physicists try -- to explain particles in terms of fields. But this does not eliminate all problems. Some of the most serious of these problems have to do with the fact that theory of fields is full of infinite quantities. They arize because the strength of the electric field around a charged particle increases as one gets closer to the particle. But a particle has no size, so one can get as close as one likes to it. The result is that the field approaches infinity as one appraches the particle. This is responsible for many of the infinite expressions that arize in the equations of modern physics."
He suggests, we may deny that space is continuous and so it is impossible to get arbitrarily close to a particle. We may also replace particles by little loops or strings. String theory is interesting but it is not yet mature enough to explain specifics such as electron mass.
 
  • #55
DonJStevens said:
Hi kended, String Theory and Quantum Gravity are well covered in the book by Lee Smolin, titled Three Roads To Quantum Gravity. Much work is needed if string theory is to accomplish its objective. A quote from the book follows:
"Modern physicists try -- to explain particles in terms of fields. But this does not eliminate all problems. Some of the most serious of these problems have to do with the fact that theory of fields is full of infinite quantities. They arize because the strength of the electric field around a charged particle increases as one gets closer to the particle. But a particle has no size, so one can get as close as one likes to it. The result is that the field approaches infinity as one appraches the particle. This is responsible for many of the infinite expressions that arize in the equations of modern physics."
He suggests, we may deny that space is continuous and so it is impossible to get arbitrarily close to a particle. We may also replace particles by little loops or strings. String theory is interesting but it is not yet mature enough to explain specifics such as electron mass.
Thanks for your reply DonJStevens.

I think I may have to read some more on this subject. It seems though that the book was written in 2002. So perhaps has the subject evolved a bit since then.

Now with the very recent "supposed" discovery (measurement) of the Higgs-Boson, I read that string theorists are even more excited as this would somehow fit their theory in relation to particle mass.

Anyhow I just thought that instead of saying that we "don't really know what an electron is", I would rather try to explain it using string theory that many great minds do believe in and where the mathematical constructs apparently make sense that is, until proven right.

Btw, your former job sounded very cool :)
 
  • #56
The charge radius of an elementary particle has nothing to do with the spatial distribution of its charge. The charge radius is a length scale characterizing a scattering cross-section.

In Quantum Field Theory, elementary particles are thought as excitations of the corresponding matter field that propagate carrying energy-momentum. These excitations may be created and destroyed by the action of sources. Consequently, the energy of the field's excitation due to two sources differs from the sum of the energy of the field's excitation due to the separate presence of each source. This is interpreted as a potential energy of interaction of two sources due to the exchang of virtual particles.

The sources of some kinds of particles become quantum operators themselves corresponding to a (conserved) Noether current density corresponding to a continuous symmetry of the theory. For example, the free-electron Lagrangian has a global U(1) symmetry, corresponding to the invariance of the Lagrangian with respect to an arbitrary change in phase of the "electron field". The corresponding noether current is the electric current density, that acts as a source term for the "photon field". The photon "listens" to the electric charge in its vicinity and mediates the electromagnetic interaction. Since the range of the interaction is infinite, the photons are massless, and there is only a kinetic term for the photon field. This effectively describes Quantum Electrodynamics (QED), the simplest (Abelian) gauge theory of the Standard model.
 
  • #57
So a photon that undergoes pair production does so because of because it is a perturbation energetic enough to inititiate the pair's own standing waves. But why at one point, not another? Why don't we just see a pair and the lower energy photon from, for instance, Co60, but instead see a high energy photon and the pair production photons later? Is that because this "Noether" field has to be in the correct configuration locally for the pair production to occur, or because the virtual particle must form, which isn't a given, but a statistical process?
 
  • #58
I just want to point out to the OP. You're getting down to the basic building blocks of matter. When ever you describe something, call it E, you break it down or you reduce it to it's parts or its properties, X Y and Z. I think Vanhees said it perfectly:

vanhees71 said:
To conclude: To the best of our knowledge today (i.e., in this case the standard model of particle physics) the electron is an elementary spin-1/2 Dirac particle with one negative elementary charge and a mass of about 511 \; \mathrm{keV}/c^2. It's a lepton, i.e., participates only in the electroweak interaction (let alone gravitation, which acts universally on anything that has energy and momentum).

It is so difficult to describe an electron because you're running up against the basic building blocks of the universe which cannot in principle be described. Notice that Vorhees described an electrong in terms of charge, mass, spin, and the forces with which it participates. So we have some reduction. But charge, mass, spin we cannot reduce those entities to anything else, at least not now, and they remain in principle undescribable.
 
  • #59
Despite of the great success of mathematics one should reconsider the building blocks from time to time.

Dirac invented his equation to describe the properties of spin 1/2 particles. The interaction of electrons are perfectly described by this equation.

Especially D. Hestenes investigated this equation in detail and found a description of the electron: The electron is circulating with speed of light which is described by the Zitter-Bewegung, generates an angular momentum - the spin, and with E = h x nu the Compton wavelength defines the circumference of the circulation.

But why the charge should circulate is still open.

All models in the past ignore the synchrotron radiation of the charge.
Even in classical physics a circulating charge embedded in its synchrotron radiation yields the angular momentum of the particle, the Compton wavelength as the wavelength of the radiation and the classical electron radius is the result of quantum mechanic interaction with the singularity. Circulation with v = c yields mass = field energy.

The spherical solution of the radiation just guides the charge onto a circular orbit and is thus the reason for the circulating charge.

Details are in G. Poelz "On the Wave Character of the Electron"
http://arxiv.org/abs/1206.0620
 
  • #60
This is a very good question to pose, as quoted by many people have tried to make a modle of a electron while its basic formation is known for the most part it would be a good project to go into to try and look inside of the electron
 
  • #61
Atom1 said:
This is a very good question to pose, as quoted by many people have tried to make a modle of a electron while its basic formation is known for the most part it would be a good project to go into to try and look inside of the electron

We've tried. We can't find anything inside it. And by "we" I mean thousands of people using multiple particle colliders and other experiments over the last 50 years.
 
  • #62
Since MacGregor and Rivas have been mentioned perhaps it is worth mentioning a moderately priced collection of papers What is the Electron?, edited by Simulik that includes papers by each of the them as well as others. It's quirky and in print.
 
  • #63
I obtained the book, What is the Electron, yesterday. Thank you xristy for mentioning this. The Einstein question (on back cover of book) is so very significant.

When he was asked what he thought about the large numbers of short lived heavy particles being produced in high-energy accelerators, Einstein pondered the question and replied, "You know, it would be sufficient to really understand the electron."

At the time little attention was paid to his remark. Yet the electron remains as mysterios today as it was in Einstein's time. The electron will be less mysterious if we learn why all electrons are identical. J. A. Wheeler said "That an electron here has the same mass as an electron there is also a triviality or a miracle." (see page 1215 of book Gravitation)
 
  • #64
DonJStevens said:
I obtained the book, What is the Electron, yesterday. Thank you xristy for mentioning this. The Einstein question (on back cover of book) is so very significant.

When he was asked what he thought about the large numbers of short lived heavy particles being produced in high-energy accelerators, Einstein pondered the question and replied, "You know, it would be sufficient to really understand the electron."

At the time little attention was paid to his remark. Yet the electron remains as mysterios today as it was in Einstein's time. The electron will be less mysterious if we learn why all electrons are identical. J. A. Wheeler said "That an electron here has the same mass as an electron there is also a triviality or a miracle." (see page 1215 of book Gravitation)

You could expand your statement to include all fundamental particles, as they are all identical to other particles of the same type.
 
  • #65
Drakkith, you are so correct, all particles of the same type are identical. This implies that nature has a specific set of requirements that must be precisely met for each particle (type). We expect that theorists will determine and define these strictly imposed requirements. The electron requirements will most probably be the first that we will understand.
 
  • #66
Perhaps Don. We'll have to wait and see!
 
  • #67
We can see now what some theorists have recently written about the electron. In post # 59 a paper by G. Polz was referenced. In this paper the electron is analyzed as a toroidal ring. The author (G. Polz) also references other papers that are interesting to all who want to know more. The referenced paper by Williamson and van der Mark analyzes the electron as a photon trapped in a toroidal path. As we come closer to a correct electron model, the desire to understand becomes ever more intense. As Drakkith said: We'll have to wait and see!
 
  • #68
The book, What is the Electron? noted in post #62 is interesting. The Wave Structure of Matter is discussed (page 227 - page 250). From page 240: "Schrodinger and Clifford predicted that charge was due to wave structures in space. - - We observe this process and call it charge. But as Clifford and Schrodinger wrote, there is no charge substnce involved. It is a property of the wave structure at the center."

This book allows us to see some concepts by theorists who want to help us understand the electron. Thank you xristy for noting this book.
 
  • #69
Hey quick question? can't we just say that the electron is simply a particle of energy? What I meen is maybe the electron is like the photon just different. A photon is a carrier of energy because it has no mass therefor it can carry electromagnetic waves (that being energy). Cant we say look an electron maybe has more energy and therefor some of it must be converted too a mass?

Another question. When an electron feels attraction or repulsion it releases a photon. Therefor shouldn't the mass of the electron decrease albeit a very small amount? But that mass will always be conserved as it is absorb somewhere else?
 
  • #70
spuding102 said:
Hey quick question? can't we just say that the electron is simply a particle of energy? What I meen is maybe the electron is like the photon just different. A photon is a carrier of energy because it has no mass therefor it can carry electromagnetic waves (that being energy). Cant we say look an electron maybe has more energy and therefor some of it must be converted too a mass?

You can call it whatever you like. Ultimately it comes down to the specific properties of the electron described by science. Properties such as mass, charge, spin, etc. Whatever you want to label it as, those properties will not change.

Another question. When an electron feels attraction or repulsion it releases a photon. Therefor shouldn't the mass of the electron decrease albeit a very small amount? But that mass will always be conserved as it is absorb somewhere else?

This is not true. EM radiation is only released when a charged particle accelerates, not when it *feels* a force. The energy used to create this photon comes from the kinetic energy of the electron, not its mass. Electrons in orbitals around a nucleus experience a very strong attraction yet do not radiate.
 
  • #71
Drakkith said:
You can call it whatever you like. Ultimately it comes down to the specific properties of the electron described by science. Properties such as mass, charge, spin, etc. Whatever you want to label it as, those properties will not change.



This is not true. EM radiation is only released when a charged particle accelerates, not when it *feels* a force. The energy used to create this photon comes from the kinetic energy of the electron, not its mass. Electrons in orbitals around a nucleus experience a very strong attraction yet do not radiate.

Ah that makes sense. I have another question for you. If an electron were completely still and a proton was in range also completely still, would there be an attraction and if so why?
 
  • #72
spuding102 said:
Ah that makes sense. I have another question for you. If an electron were completely still and a proton was in range also completely still, would there be an attraction and if so why?

The EM force is infinite in range, so they would always be attracted to each other. The reason is because opposite electric charges attract each other.
 
  • #73
Drakkith said:
The EM force is infinite in range, so they would always be attracted to each other. The reason is because opposite electric charges attract each other.

I say in range to mean where the force would be felt and not negligible. When an electron is attracted to a proton it releases a photon to "carry" the attraction. is this correct?
 
  • #74
spuding102 said:
I say in range to mean where the force would be felt and not negligible. When an electron is attracted to a proton it releases a photon to "carry" the attraction. is this correct?

Ah, you referring to "virtual" photons. That is an entirely different discussion that should be carried out in it's own thread in the Quantum Physics forum.
There are already some posts, so I'd suggest using the search function to find them.
 
  • #75
Yes wouldn't virtual photons be themselves electromagnetic waves without movement?
 
  • #76
spuding102 said:
Yes wouldn't virtual photons be themselves electromagnetic waves without movement?

I cannot answer that, as it is much too complicated for me to explain, as I don't have a firm grasp on the concept.
Like I said above, I recommend searching the rest of the forum or starting a new thread.
 
  • #77
Hi spuding 102 : The concept of electromagnetic waves without movement is complicated because these waves are light velocity waves. These waves have only one velocity allowed and so we can stay with known rules if we work with energy values rather than zero velocity waves. Recall that a single electron linked with a single proton has maximum binding energy when its orbital radius is at its minimum value. The electron can absorb energy from a photon so that energy is added to the (proton electron) system. In this process, the photon is converted to mass because the total mass of the system increases. This is comparable to winding a watch. Energy added to the watch (system) increases its total mass. I will suggest to Drakkith that no theorist that I have heard of, has a grasp of waves without (observable) movement.
 
  • #78
DonJStevens said:
Hi spuding 102 : The concept of electromagnetic waves without movement is complicated because these waves are light velocity waves. These waves have only one velocity allowed and so we can stay with known rules if we work with energy values rather than zero velocity waves. Recall that a single electron linked with a single proton has maximum binding energy when its orbital radius is at its minimum value. The electron can absorb energy from a photon so that energy is added to the (proton electron) system. In this process, the photon is converted to mass because the total mass of the system increases. This is comparable to winding a watch. Energy added to the watch (system) increases its total mass. I will suggest to Drakkith that no theorist that I have heard of, has a grasp of waves without (observable) movement.

When you are winding a watch are you not converting kinetic energy into mechanical energy? not mass?
 
  • #79
It is correct to say, that energy added to a system will increase the mass of the system. Energy equals m c squared and so energy added, divided by c squared will be equal to the mass increase of the system when energy is added. A spring that has energy added has greater mass than a spring that is not stressed. The mass increase of a watch when wound is very small but we can calculate the mass change value.
 
  • #80
DonJStevens said:
It is correct to say, that energy added to a system will increase the mass of the system. Energy equals m c squared and so energy added, divided by c squared will be equal to the mass increase of the system when energy is added. A spring that has energy added has greater mass than a spring that is not stressed. The mass increase of a watch when wound is very small but we can calculate the mass change value.

yes but energy does not always manifest itself into mass? or does it? For instance when throw a ball does the energy attribute completely to the movement of the ball or does some of it make the ball heavier?
 
  • #81
The inertial mass of a ball does increase when its kinetic energy (due to velocity) is increased. When the ball velocity is small compared to light velocity, then the mass increase is very small and so this mass increase is usually ignored. When velocity is significant (compared to light velocity) then the mass increase must be included in any useful computation. For example, at (approximately) 0.866 times light velocity, then the mass is doubled. The mass is twice as great as it would be when at rest. When velocity is small (compared to c ) we usually consider this to be non-relativistic and so mass change is not included in evaluations (computations). The ball does become heavier due to velocity when thrown by a person but this increase is very very small.
r
 
  • #82
DonJStevens said:
The inertial mass of a ball does increase when its kinetic energy (due to velocity) is increased. When the ball velocity is small compared to light velocity, then the mass increase is very small and so this mass increase is usually ignored. When velocity is significant (compared to light velocity) then the mass increase must be included in any useful computation. For example, at (approximately) 0.866 times light velocity, then the mass is doubled. The mass is twice as great as it would be when at rest. When velocity is small (compared to c ) we usually consider this to be non-relativistic and so mass change is not included in evaluations (computations). The ball does become heavier due to velocity when thrown by a person but this increase is very very small.
r

So then why does light not have mass if it moves so fast?
 
  • #83
spuding102 said:
So then why does light not have mass if it moves so fast?

Because kinetic energy does not add to REST MASS, also known as invariant mass. The ball does NOT have any more mass from it's own frame of reference.
 
  • #84
The referenced material in post #84 shows the electron to be a sphere. "- - if the electron were enlarged to the size of the solar system, its shape would diverge from a perfect sphere less than the width of a human hair." The experimental upper limit (maximum) electron radius is found to be 10 exponent -22 meters. Some theorists describe the electron as a zero radius particle, suggesting it may be gravitationally collapsed to infinite density. Alexander Burinskii has said " Recall, that angular momentum J = h bar/2 for parameters of electron is so high that the - - - spinning particle represents a naked singular ring." (From his paper, The Dirac - Kerr - Newman electron, March, 2008) This suggests the electron density is very high but not infinite. The spherical shape (rather than oval) was not expected by some theorists.
 
  • #85
CF.Gauss said:
HI,
Firstly I'd like to open with I know what an electron is and I know all about its charge and the role it plays in electricity, current, free electron model etc etc.
My question is what is an electron 'made' out of? My reasoning is that it can't be made out of anything physical as its charge would distribute evenly throughout its-self and would fly apart as every part of the electron would repel every other part of the electron.
In physics the electron is thought of as a mathematical point particle but in a 3-spacial dimensional universe a 1-d object can't physically exist so that rules that out.
If i could magically enlarge an electron to the size of a car what would i physically see?
or is there even any credence to asking a question like that?

It is incorrect to deduce that an electron's charge would make the internal structure of an electron fly apart. Negative electrons move apart when they interact with each other's electric fields - not necessarily when they touch each other.
 
  • #86
Please allow me to say, that I'm a failure at mathematics, am left handed, but quite capable of conceptualizing all things. As far as I can tell, Man's grasp of what the Universe "is", is too limited to actually define what an electron actually "is", where it goes or doesn't go when energy is utilized, or what role it actually plays in the "concept" of atomic structure. Our understanding of quantum physics also, in my opinion, falls short of the goal of understanding physical existence. Until we all broaden our horizons of understanding of how small can small be, how large can large be, and for instance what actually "is" gravity, we may fail at attempts to actually "understand" what is happening around and in "us". I guess my point is that the definition of an electron can be practically described, giving that description actual usefulness in life and science, but we don't allow ourselves to proceed in the widest definitions of existence. If I can do anything in my life to promote actualization of an expanded viewpoint of physical existence, then I will be a happy person.
 
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  • #87
An excitation of the electron field. But then you'll ask, "What exactly is an electron field?" Such questions are too metaphysical (read "useless") to be of much value to physicists. It's best to stick to the operational and mathematical definitions.
 
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  • #88
It's the smallest piece of electricity you can have. That's how I'd explain it to a dum-dum.
 
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