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location Greece
age 74
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Retired experimental particle physicist.

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


13h
awarded  Nice Answer
17h
comment How do substances with like charges repel each other?
then you should try and make more coherent statements not left to the imagination of the reader.After all excess electrons do not exist in normal matter, which has as many electrons as protons, unless set up on purpose. I am clarifying how this excess can happen, and then look at the effects.
20h
answered In terms of physics, does the phrase “time slows down” mean the same thing as “things happen more slowly?”
1d
answered Strength of strong nuclear force vs distance?
1d
answered How do substances with like charges repel each other?
1d
comment How do substances with like charges repel each other?
@VolkerSiegel Not to worry, your answer is on a higher level than the question.
2d
comment Differences between wavefunction, probability and probability density?
+1 for addressing the wavefunction connection to probabilities clearly. I think if people can have clear in their head that quantum mechanical probabilities are the same as probabilities for classical or even for economics events, then the famous "collapse" of the wavefunction can be seen as trivial as picking up an "instance" that builds up a probability distribution, the same as with population probability functions, for example.
Jul
19
answered For a planet which has a temperature gradient, hot in the center and cooler on the surface, why do we get absorption lines?
Jul
19
revised For a planet which has a temperature gradient, hot in the center and cooler on the surface, why do we get absorption lines?
spelling in title and body
Jul
19
comment For a planet which has a temperature gradient, hot in the center and cooler on the surface, why do we get absorption lines?
so you really mean planet? I will edit because as is it is very confusing
Jul
19
comment Has the photon both gravitational and inertial mass?
The photon in the standard model has 0 mass, no adjectives attached. en.wikipedia.org/wiki/Standard_Model . This question belongs to science fiction. I reacts to to gravity through its energy, by special and general relativity rules that have been validated over and over. Mass is defined as the length of the four vector describing a particle and it is an invariant. en.wikipedia.org/wiki/Invariant_mass
Jul
18
answered If there were fundamental forces weaker than gravity, would we know about it?
Jul
18
comment What is the frequency of a photon emitted by an accelerated charged particle?
there are spectra for brehmsstrahlung en.wikipedia.org/wiki/Brehmstrahlung ands synchrotron in en.wikipedia.org/wiki/Synchrotron_radiation
Jul
18
answered Could Dark Matter particles that don't couple to quarks or leptons have been produced?
Jul
17
comment How to understand “accelerating charge radiate” using intuition?
OK, the animation is about a single bunch of photons. Maybe after "nudge into the charge" you should put in parenthesis "giving an instantaneous d(v)/dt " or some such, would make this clear. nudge is too general.
Jul
17
comment How to understand “accelerating charge radiate” using intuition?
It is a pretty annimation but at what point does the acceleration enter? it looks unifromly moving.
Jul
17
answered When you measure position of an electron in a energy pure state, what happens to the energy?
Jul
17
answered How to understand “accelerating charge radiate” using intuition?
Jul
17
comment Can an electron spontaneously be emitted/ejected from a hydrogen atom?
In a sense, the probability that the ground state bound electrons can be found very far away allows for the interactions between atoms to form molecules, crystals, and lattices in general. Matter as we found it.
Jul
16
comment If dark energy is accelerating the expansion of the universe, why can't I feel it?
Yes, from each point (x,y,z,t) in every direction. Please note that if it were not for the cohesive forces (gravity, nuclear electromagnetic) we would not be able to measure expansion anyway! It is the fact that our local surroundings do not change that we can see everything else expanding and an accelerated expansion in our time frame.