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233119
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location Greece
age 74
visits member for 3 years, 9 months
seen 1 hour ago

Retired experimental particle physicist.

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


12h
comment Modeling a collision phenomenon
I think this is a physics set up and a legitimate request. I do not see an opinion expressed ! so I voted to reopen
13h
comment What's inside a quark?
elementary particles are point particles by all indications of our experiments and the theoretical models that fit and predict their behavior. en.wikipedia.org/wiki/Standard_Model
23h
comment Do electrons in absorption spectra absorb photons with enough energy to release them from their parent atoms?
What is wrong is in assuming that the bound electrons are absorbing energy or emitting it. It is the atom that does that
1d
comment Why does not electron cloud collapse over Nucleus?
This has answers here physics.stackexchange.com/questions/44949/… , and further physics.stackexchange.com/questions/135222/… and here
1d
comment Can Half Lives (hypothetically) be Measured by Wave-functions?
say that the lifetime is "contigent" to the exponential in any existential way. Wave functions are much more complicated mathematical models that have been arrived at by inspiration while fitting experimental data, and wavefunctions squared will give the lifetime (i.e. exponential functions) but as I say in my answer there does not exist a complete mathematical model from which all observations can be predicted. Suppose it existed , it is there that philosophy comes in : mathematics creates reality ( platonic ideas) or is a useful tool to model reality?
1d
comment Can Half Lives (hypothetically) be Measured by Wave-functions?
this becomes philosophy. Physics is the process of gathering observations on one hand and creating mathematical models which and some postulates which prescribe how the solutions will relate to the data. Half lives have been observed experimentally by fitting the decay distributions with simple exponential functions and calculating how much time it will take to lose half of the sample. One does not have to wait for hours or days or years, a high statistics curve will give an accurate lifetime even with small time interval. The exponential is the simplest mathematical model, and nobody would
1d
comment Is $E^2=(mc^2)^2+(pc)^2$ correct, or is $E=mc^2$ the correct one?
are you maybe confused by the E=m*c^2 formula of relativistic mass fame ? In the formulas you are quoting m is the rest mass, usually denoted by m_0. The relation between the two is m=m_0*gamma, en.wikipedia.org/wiki/Mass_in_special_relativity
1d
comment Can the strings in string theory be thought of as troughs in a field?
@JohnRennie there do exist corresponding diagrams to the Feynman diagrams of QFT though.benjaminjurke.net/show/string-theory
1d
comment Why free electron has orbital magnetic moment?
"free" is in contrast to "bound in an atom". In the link they are talking electron beans in magnetic fields, and there the electron has a curvature (Bqv=mv**2/r for the perpendicular case )which will give rise to a magnetic moment.
2d
comment Is it true that gravitational lensing only occurs for objects made of plasma?
@honeste_vivere to get to the phase of matter that is plasma one needs very high temperatures. Temperatures at a distance from active stars are of the order of 3Kelvin. there is a phase diagram plot here opencourse.info/astronomy/introduction/08.matter_phases . A lot of energy has to be supplied to keep the charges separate.
2d
comment How is a photon measured?
@garyp maybe it is my greek-english. display polarization by induction ? If you line up dipoles, there exists an overall electric field directiion. Anyhow this is irrelevant to the main question
2d
comment How is a photon measured?
@garyp and what are polarizable media except media with a polarization of the electric field? I think we are talking at cross purposes here. Light collectively consists of a great number of photons . That the reflection is coherent enough to transmit an image means that the photons keep their phase relations to each other. classical studies are useful but one could go through the song and dance of photons in an ensemble . In metallic surfaces (behind mirrors), where electrons form bands it is easier to see that it is a collective interaction with many electrons shared by the lattice.
2d
comment How is a photon measured?
@Ruslan Thanks. I will delete and resend.
2d
comment How is a photon measured?
@Ruslan atoms are of order of angstrom, red light is about 7000 angstrom.
2d
comment How is a photon measured?
@Ruslan it is the combined spill over electric field, the same that gives the Van der Waals forces.
2d
comment How is a photon measured?
@Ruslan If the electrons are free yes. If they are in an atom or a solid state, as a wall is, there is a collective field to which the photon interact. Optical frequencies have a much larger wavelength than atomic distances.
2d
comment Should the answer to Einstein & Quantum gravity be found in conditions of our local observable universe?
can you please give a link for what this IGM/IPM means?
2d
comment Does a ball spin more from left to right than it does from right to left?
Well, maybe for right handed people the spin imparted would have a left bias and for left handed a right bias? or vice verso
2d
comment How is a photon measured?
Yes, yes, stories but written in beautiful mathematical language with predictive power. Yes, models all the way up, to fit "turtles all the way down",( a primitive model of the earth).
Oct
27
comment What is the experimental support behind taking electrons as a revolving particles in E.Rutherford model?
He knew the charge, positive against positive (alpha positive, repulsion in scatter) , and that the atoms are neutral, and that electrons come out of atoms