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230102
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location Greece
age 74
visits member for 3 years, 7 months
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Retired experimental particle physicist.

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


Aug
2
comment Electron shells in atoms: What causes them to exist as they do?
Physics does not answer WHY questions, the models physics has answer how from the postulates and equations the observations can be explained. This has been done successfully to start with using the Schrodinger equation and identifying its solutions with the shells very well. Why it is successful? eventually ask the gods.
Aug
2
comment What does the $y$-axis represent in the atomic spectra and what is its significance?
1) error: square root of the number of counts. for 100 it is 10% and too large. 2) reproducibility from other experiments 3) the special interests of the person who took the spectrum. Usually the leading lines are used for identification, from stars for example.
Aug
2
comment What does the $y$-axis represent in the atomic spectra and what is its significance?
No. The strength on each line depends on the probability of that line being excited and the probability of falling back in and emitting a photon of distinct wavelength. For a given atom the strength is calculable for each line from the solutions of the equations that describe the orbitals of the electrons around the helium nucleus. It is different for each line. Though it is characteristic it is not as unaffected by the intervening medium and detector conditions as the location on the wavelength scale is.
Aug
2
comment Can a neutrino act as a virtual particle between two electrons to mediate an electron-electron fermonic interaction?
fine, except that any internal line in a Feynman diagram is by definition virtual, so yes, neutrinos in the final box diagram are virtual
Aug
2
comment What does the $y$-axis represent in the atomic spectra and what is its significance?
The detection can depend on the intervening medium, if it is more absorptive at some parts of the wavelength axis then the detection will change the ratio of intensities from the original emissions
Aug
2
answered What does the $y$-axis represent in the atomic spectra and what is its significance?
Aug
1
comment supersymmetry vs multiverse
I mean that supersummetry and multiverse are not mutually exclusive proposals. Supersymmetry if discovered will become part of the standard model and a multiverse mathematics will have to take care of it too.
Aug
1
comment supersymmetry vs multiverse
I do not think that many physicists take seriously the attractive to science fiction proposal of a multiverse. In any case, if the standard model which was validated with the Higgs is found to have a supersymmetric extension, the multiverse mathematics should take care of that too, it will also be supersymmetric, since the only measurements we can do are in this one universe we live in,
Aug
1
revised If virtual particles have negative mass why do they contribute positive mass to atoms?
clarification
Aug
1
answered If virtual particles have negative mass why do they contribute positive mass to atoms?
Jul
31
revised What does temperature look like at the subatomic level?
additional explanation after comments
Jul
31
comment What does temperature look like at the subatomic level?
continued: for the very small time interval where the ion ion elementary interactions take place.
Jul
31
comment What does temperature look like at the subatomic level?
This is a hypothesis, as is the quark gluon plasma that is being studied now at LHC. One has to hypothesize degrees of freedom for the quarks and gluons so that a temperature can be defined. This is supposed to happen at the early stages of the Big Bang, where the energy of the universe is concentrated in a small volume, and all hypothetical particles are hypothesized free within that volume so a hypothetical temperature can be defined. For quark gluon plasma in the lab the gluons will never be seen but the resulting distributions are expected to be explained by the hypothesis of a plasma
Jul
31
answered What does temperature look like at the subatomic level?
Jul
31
answered How can a detector distinguish between a photon and a gluon
Jul
30
comment Why is fundamental physics taught in terms of particles?
If you want contact with nature and not to remain in the realm of mathematics,i.e. if you want to model the physical reality, then particles are what nature offers for measurement and observation.
Jul
30
answered Is the plasma state always visible?
Jul
30
answered How “unnatural” is the universe?
Jul
30
answered In scattering, how does a particle 'know' which direction it is being illuminated from?
Jul
29
comment About Quantum Mechanics
Well, in my book, they have been ruled out experimentally by the great multiplicity of experiments that validate special relativity. One cannot have a fundamental theory violating special relativity.