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lightarrow
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Is it possible to define in some way, theoretically or experimentally, a size for an electron?
lightarrow said:Is it possible to define in some way, theoretically or experimentally, a size for an electron?
At which energies are those experiment performed? Very high. From De Broglie relation it comes that their associated wavelenghts are extremely small, so it's not such a surprise to me that they behave as point-like. Having said this doesn't correspond to have said that electron's size = wavelenght; I'm wondering about a possible relation between the two things.jtbell said:The predictions of QED for the results of electron-electron and electron-positron scattering, assuming pointlike particles, have been verified up to the highest achievable energies, corresponding to tiny approach distances (in a classical sense). Believe me, it would be big news if any discrepancies appeared!
Got any other ideas?
Not exactly,but there is thing in physics called "classical electron radius".lightarrow said:Is it possible to define in some way, theoretically or experimentally, a size for an electron?
Done. It was a disappointment, however, because I thought to find something more than what I studied at university 20 years ago; instead, it's still the same.tehno said:Not exactly,but there is thing in physics called "classical electron radius".
Do a Google for it to see what it means and how it is derived.
lightarrow said:Done. It was a disappointment, however, because I thought to find something more than what I studied at university 20 years ago; instead, it's still the same.
In about 80 years, physicists has never been able to make a better model of the electron than to think of a little ball? My compliments for the fantasy!
lightarrow said:In about 80 years, physicists has never been able to make a better model of the electron than to think of a little ball? My compliments for the fantasy!
Here:ZapperZ said:Can you show me where physicists think an electron is a little ball?
I thought it was obvious I was answering to the this post; I will make it more clear, then: In about 80 years, physicist have never been able to find a better classical model for the electron than that related to the classical radius? I can't believe it.Originally Posted by tehno
Not exactly,but there is thing in physics called "classical electron radius".
Do a Google for it to see what it means and how it is derived.
lightarrow said:Here: I thought it was obvious I was answering to the this post; I will make it more clear, then: In about 80 years, physicist have never been able to find a better classical model for the electron than that related to the classical radius? I can't believe it.
lightarrow said:I wonder why, talking about an atom behaviour, it's always said that this is one example of Classical Physics failure, since the only electron's classical model used to show this is the point-like electron. I mean, knowing now that an electron cannot be point-like, at least because it also has wave-like properties and because of the problems with infinite electrostatic energies and so on, it doesn't seem so strange to me that such a model of the atom couldn't work!
lightarrow said:Here: I thought it was obvious I was answering to the this post; I will make it more clear, then: In about 80 years, physicist have never been able to find a better classical model for the electron than that related to the classical radius? I can't believe it.
Yes, ok. What about a model in which the electron is, e.g., a wave packet spread around the nucleus, and that reabsorbs the same radiation it emits?dicerandom said:In Physics, "Classical" usually means "wrong" Nobody is saying that we should be modeling the electron as a rotating sphere. Every professor in every quantum mechanics course I've ever taken has made sure to explicitly state that is not the case, as a matter of fact. What they're saying is that if you want a simple model of an electron then a rotating sphere with this particular radius will get you a few of the right answers for the wrong reasons.
The classical model of the atom doesn't fail because the electron is approximated as a point particle, it fails because the radial states are not quantized. In the classical model of an atom you have an electron which orbits the nucleus in much the same way that planets orbit the sun. The problem here is that the electron is charged and accelerating due to the circular motion, so it should radiate. If it radiates it loses energy so it should lose speed and spiral in towards the center. If you work it out this whole process ends up taking about a nanosecond, so with that model we really shouldn't have any atoms at all.
http://en.wikipedia.org/wiki/Classical_electron_radiusZapperZ said:2. What EXACTLY did you understand by the term "electron classical radius"? Hint: it is connected to an ATOM. This doesn't even come close to being the electron's SIZE! So why are you hung up on this?
The classical electron radius...r_e = ...
Using classical electrostatics, the amount of energy required to assemble a sphere of constant charge density, of radius r_e and charge e is: E = (3/5)*e^2/4*(pi)*epsilon_0*r_e
Ignoring the factor of 3/5, if this is equated to the relativistic energy of the electron (E = mc^2) and solved for r_e, the above result is obtained.
lightarrow said:
Wikipedia already said it...Wikipedia said:Such a radius does not exist as a physical entity but it is sometimes useful in theoretical calculations.
I'm not hung up on this at all, I intended to answer to tehno in an ironical way, sorry, it was not a good idea. I know very well how concepts of "classical electron radius" are nothing more than simbols. Indeed it's for these reasons I started this post. Anyway, if you wish, you can terminate it here. However, reading to every post helped me understand that it's impossible, for today physics to define a size for the electron.ZapperZ said:And my question was, why are you so hung up on this?
lightarrow said:I'm not hung up on this at all, I intended to answer to tehno in an ironical way, sorry, it was not a good idea. I know very well how concepts of "classical electron radius" are nothing more than simbols. Indeed it's for these reasons I started this post...
Ok. Very well. So, having taken note of this, what does your answer:tehno said:1.)I don't have any special idea of the electron except that it is fundamental particle ,a source of Coloumb field,without subdivsion property.
2.)Classical model definitely not. For the other part of the question I don't have idea which is the "best model" of the electron outside Standard Model(that one doesn't model bloody damn particle)
3.)I don't have a vision of the model of electron ,I have never seen a one in person.Electron wavelenght ,is not related to the electron size ,but it is related to circumstances of electron mass and velocity in the framework of known relations of quauntuum physics.
has to do with my question:Not exactly,but there is thing in physics called "classical electron radius".
Do a Google for it to see what it means and how it is derived.
?Is it possible to define in some way, theoretically or experimentally, a size for an electron?
It has to do a lot.It gave you a scale range of upper bound of the "size" of the free particle:Somewhere between Plank length and ~[tex]10^{-15}[/tex]m.And extrapolating from modern high energy experimental work of researching electromagnetic force between two directly interacting electrons,you can even conclude that actual "size" is even below [tex]10^{-16}[/tex] m (Coulomb force holds well up to that scale down).That's pretty damn small if compared with an Atom scale "size" or "size" of a typical nucleus.And this is my final answer I'll give you.You'll not hear from me any story of HUP, wavefunctions ,and dual nature of a small world behaviour where the entity called electron lives in.lightarrow said:Ok. Very well. So, having taken note of this, what does your answer:"Not exactly,but there is thing in physics called "classical electron radius".Do a Google for it to see what it means and how it is derived"
has to do with my question:"Is it possible to define in some way, theoretically or experimentally, a size for an electron?"
.
lightarrow said:Is it possible to define in some way, theoretically or experimentally, a size for an electron?
lightarrow said:Locrian, is this clear or do you need me to explain it better?
The size of an electron is infinitesimally small and is typically described in terms of its charge and mass. The charge of an electron is approximately 1.602 x 10^-19 coulombs and its mass is approximately 9.109 x 10^-31 kilograms.
Scientists use a variety of experimental techniques, such as scattering experiments and spectroscopy, to indirectly measure the size of an electron. Theoretical approaches, such as quantum mechanical calculations, are also used to estimate the size of an electron.
No, the size of an electron is still a topic of ongoing research and debate in the scientific community. While there have been many experimental and theoretical measurements, there is no universally accepted value for the size of an electron.
According to the Standard Model of particle physics, the size of an electron is considered to be a fundamental constant and does not change. However, some theories propose that the size of an electron may vary in certain extreme conditions, such as in the presence of a strong magnetic field.
The size of an electron is a fundamental property of matter and plays a crucial role in understanding and predicting the behavior of atoms and molecules. Additionally, the size of an electron is closely linked to other physical constants and can provide insight into the nature of the universe at a fundamental level.