Anonym said:
We already discussed that in “Particle-Wave duality and Hamilton-Jacobi equation“. Sorry, that I repeat:
Lightarrow:”I still don't know if and how would be possible to create a definition for an electron's size.”
You refuse to follow the standard rules of the scientific development. The notion of size was introduced by Egyptians, perhaps 7000 years ago. You take two points and stretch a cord. Then you ask what an angle is (firstly what is 90deg angle. It leads to the phenomenological result: 3^2+4^2=5^2 and to the corresponding theoretical generalization). It provides foundation for Euclidian geometry. That provides foundation for the mathematical formalism of metric spaces.
That provides foundation for Newtonian formalism. Later you introduce the communication problems. That provides the foundation of special and general relativity based on non-Euclidian geometry. And so on. In the non-relativistic QM it is well defined notion: the eigenvalues of the self-adjoint operator called dispersion of a position are measurable quantities. The mathematical formalism of relativistic QM is still open problem. You can discuss, but can’t require giving you definition of the size there. For sure, the answer to a question what is the size of an electron, quark or gluon a posteriori will be consistent with the Egyptians.
I consider anyone who deny that Don Kishot.
Regards, Dany.
I have no idea how this is even relevant here, and why something consistent with the Egyptians would even matter. I can think of many things that aren't consistent with the Egyptians.
And this issue isn't about the measurement of position, nor the spread of the position. This has nothing to do with the determination of a size. Each time an electron strikes a CCD, it makes a mark. Yet, no one in their right mind would use that mark to determine the 'size" of an electron, no matter how "accurate" the detector is.
Or do you think there is an operator that specifically measures the "size" of a particle?
This thread was going in every different directions and people seem to be pushing things in and out. I wanted to at least try to establish something based on what is known and what has been accepted. By my standard, something listed inside a well-known and well-accepted
reference standard is a very good starting point. If experts who use such reference books use them, then I would say that is a very unambiguous
endorsement. CODATA, PDG handbook, and even the CRC handbook are what I listed. Anyone dealing with the tons of data that have to be analyzed out of any particle collider WILL use the values listed out of the PDG book as part of the analysis. These are the most accepted definitions and values for any and all elementary particles. So if something is listed there, it is the BEST that we know of at this moment. So I wanted to first of all established, once and for all, whether at the level of the best of our knowledge, is there such a thing as the "size of a photon".
There isn't, and this is despite the barrage of responses. These standard references do not list a set of "values" for the size of a photon, or even make any attempt to lay down a definition for determining the size of a photon.
Now, take note that *I* did not say anything about the size of a photon. I could believe in anything about it, and it will still NOT change the FACT that these standard references say NOTHING about it, whether you and I like it or not! This is some simply, straightforward fact that I wish to establish once and for all.
When this fact is recognized, then at the very least, we can then proceed with the understanding that the issue of the "size of a photon" isn't well-established and isn't widely accepted, and certainly not something physicists either use, or need! One can then start looking for publications that that may hint, or even give methodology on the determining of such a concept. Doing this clarifies several important points, especially to those who are not well-versed in such a topic: (i) the size of a photon isn't part of standard physics and (ii) we are now looking for any indication of the possibility of defining one, and maybe actually extracting some rough values. This is certainly a clearer (and I believe, more ethical) way to proceed with this question, that has continuously pop up every so often. To throw around the concept of the size of a photon as if it is something obvious and well-accepted does not convey the true scenario as being practiced today.
It is why I asked for the PDG etc. sources as the starting point ("ground state"). I never insisted that any of you cannot establish (with appropriate references) in this thread the concept of the size of a photon. There are many areas of physics that are still being studied that are not well-established and well-accepted. I have talked about various candidate theories for high-Tc superconductors. None of these are part of the "standard references" for superconductivity. I always made sure that people who read my posts are aware that these are still NOT generally accepted or well-established. Yet, these have been published in respected peer-reviewed journals and thus, these theories are well-defined and CAN be discussed on here. For students and people who are not familiar with it, it puts the whole discussion into the
proper perspective. Not doing that simply creates a whole lot of confusion, especially when there are several different versions of theories that can explain the phenomenon. This is exactly what is going on with this thread, where there are more than one way already that have been mentioned to define the size of a photon.
So unless someone disagrees with my assertion that the size of a photon isn't covered in standard reference sources, I will assume that this issue is done. From now on, all discussion on the size of a photon will proceed with that understanding.
Zz.
I really feel for you, after reading through this thread!