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232116
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location Greece
age 74
visits member for 3 years, 9 months
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Retired experimental particle physicist.

The picture is a fayum . It looks like aunts and cousins of mine :).


Oct
5
comment Why do electrons in an atom occupy only the stationary states?
@ACuriousMind Nuclei are stable, atoms are stable, ( unless energetically disturbed) the limit on lifetime of a proton is a tiny experimental number. In a specific potential well, the electron will occupy the lowest empty level, maybe radiating a characteristic photon. It will not be dithering ( have a probability to be in another higher energy level) between energy levels, because we would be seeing several photons coming out and energy would not be conserved also.
Oct
5
comment Why do electrons in an atom occupy only the stationary states?
@garyp and danielSank too, do you have a link for this state? I am always willing to learn . I am talking for something like the hydrogen atom, or the shell model of nuclear physics
Oct
5
answered Why do electrons in an atom occupy only the stationary states?
Oct
5
comment Why does the speed of light $c$ have the value it does?
@DanielSank as for equations? Operators operating on the wave function give numbers in appropriately defined units for energy, mometnum ets. So equations must have units in order to relate to physical measurements.
Oct
5
comment Why does the speed of light $c$ have the value it does?
@DanielSank Think a bit. What is a unit definition? Take length. The unit is "meter", we divide everything connected with length by "meter" to get a number. It is a choice of unit. When we put c=1 , we divide everything relevant to velocity by c in meters/second and change the number to units of c.
Oct
5
comment Odd experiment results (electromagnetics)
What material is the plate made of? metal is not enough, its magnetic properties are important. Easy to check with a small permanent magnet.
Oct
4
comment Parity of baryons. Why it is hard to find the parity determination of baryons?
@Rob you are correct. The convention is for protons and neutrons
Oct
4
comment Why is it said that the Heisenberg model is a hard-core boson model?
until you get a theorist's answer have a look at this search books.google.gr/… . It seems that in this case the model ends up with a U(1) symmetry instead of SU(2)
Oct
4
comment If stars are ionized, where are the electrons?
An electron in a star plasma may meet a rare positron and annihilate, but the bulk of electrons that are separated from the nuclei ( hydrogen , helium nuclei) will not find a positron to annihilate into because the creation of e+e- pairs is rare.
Oct
4
comment If stars are ionized, where are the electrons?
You must have heard of energy conservation and charge conservation? The positrons in our universe can only appear with charge conservation, for every positron there exists a negative charge to balance it, in our universe, concurrent with the generation of the positron, or it is just a product from a nuclear decay and the balance is given by the charges of the nuclei. There are very few positrons even in a very high energy plasma, and in any case for every created positron an electron is created concurrently.
Oct
4
comment If stars are ionized, where are the electrons?
Electrons and nuclei form a "soup" called plasma . en.wikipedia.org/wiki/Plasma_%28physics%29. Curiousone answer is correct . The electrons are there in the soup. Over all the star is neutral
Oct
3
comment How does an electron undergoing uniform circular motion exactly lose energy?
Please have a look at this link where the energy losses in a magnetic field are shown google.gr/…
Oct
3
comment Electromagnetic interaction physical interpretation
Try these cmm.cit.nih.gov/intro_simulation/node1.html ,physics.ucdavis.edu/physics7/Physics7/7C200807/lectures/… . also this might help, keeping in mind that wavelength and energy of photon are connected with E=hc/lamda
Oct
3
revised Electromagnetic interaction physical interpretation
edit after comment
Oct
3
comment Electromagnetic interaction physical interpretation
OK, I will edit. Radiation is not just waves and you must not have reached that part in your studies.
Oct
2
comment Electromagnetic interaction physical interpretation
It will have to be a direct scatter with the outer electrons, the x ray will lose a bit of energy ( attenuation) and the fall back electron will be in the visible. The probaility for direct scatters is lower than matching energy levels. Small wavelength is like passing through the holes of a fishing net if you are a fly
Oct
2
comment What is the future of complexity theory in black-hole physics and string theory?
Let us continue this discussion in chat.
Oct
2
revised Electromagnetic interaction physical interpretation
added 82 characters in body
Oct
2
answered Electromagnetic interaction physical interpretation
Oct
2
awarded  Nice Answer