48,922 reputation
230103
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location Greece
age 74
visits member for 3 years, 7 months
seen 5 hours ago

Retired experimental particle physicist.

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


5h
comment Does dark energy annihilate energy?
There are no antiphotons or antigluons, they are themselves their own antiparticle. Photon photon interactions have very small probability and gluon-gluon will create more gluons or other particles. Energy is kinetic and mass energy ( E=mc**2) for all particles .
5h
comment Dark matter a medium for light propagation
@user1247 I was talking of classical fields which is the background of the question. Not of the QFT vacuum, which respects Lorenz invariance of course .
10h
comment Dark matter a medium for light propagation
@user1247 the electromagnetic field is actually a varying electric and magnetic field with energy and momentum, not permeating all space either.
10h
comment Dark matter a medium for light propagation
Dark matter may propagate sound, i.e. pressure waves of some type. In general it has been hypothesized to fit the gravitational orbits of galactic clusters, so dark matter is not something permeating all space uniformly.
10h
comment Dark matter a medium for light propagation
no. the michelson morley experiment shows that there exists nothing with the attributes of ether and special relativity has made everything consistent. what void?
19h
comment Can an experiment be designed to distinguish between actual wave interference and probability or pilot wave results?
the single particle double slit experiments show that the wave structure appears in the space probability distribution, so no two actual waves interfering. en.wikipedia.org/wiki/…
21h
comment What experiment would prove string theory?
He is active in physicsoverflow.org
1d
comment What experiment would prove string theory?
@TerryBollinger It has been done, have a look at my question and Ron Maimon's reply here physics.stackexchange.com/questions/27671/…
1d
comment If we could build a neutrino telescope, what would we see?
I think the BB model is already tested better with the gravitons, (if the BICEP2 results are confirmed by other setups). In any case, this link scienceblogs.com/startswithabang/2013/07/17/… says the task is impossible "If you want to know what you can do to win a Nobel Prize, come up with a way to detect them, and the Nobel Prize in physics will surely be yours!"
1d
comment If we could build a neutrino telescope, what would we see?
After BICEP2 the CMB date has been surpassed, as gravitational waves have given a snapshot of the inflationary period, at 10^-32 sec, while CMB is at 380000 years.en.wikipedia.org/wiki/BICEP_and_Keck_Array . Why should one go to the incredibly difficult task of detecting such cold neutrinos?
1d
comment Questions about electromagnetism
@DavidZ I had already translated it while you were cogitating on holding. I edited , so maybe you can open it?
2d
comment Does a high energy photon experience deceleration or direction-change when it impinge into water or something due to the change of refraction index?
since this came up to front again, I have to note that the photons are not absorbed and re-emitted. Absorption is a quantum effect for a photon. It either gives up all its energy and disappears, and if a photon is re emitted it will have a 2 pi angle to decay into, so the phases will be lost, or it scatters with the various ways photons can scatter elastically or inelastically.
Aug
29
comment How Exactly Does Linear Regge Trajectories Imply Stability?
thanks . you mean it is a second level string theory validation, validation by embedding more limited theories that themselves are validated by data. i.e. no direct line string theory which has not already been predicted by the minor ones. :(
Aug
28
comment How Exactly Does Linear Regge Trajectories Imply Stability?
Ron, I was looking up strings and regge trajectories an this old question of yours came up.There have been some discussions of validation of string theory and I have been wondering whether you have unearthed any "predictions", checkable with the plethora of resonance data, that a string theory could give.
Aug
28
comment What experiment would prove string theory?
I have been thinking if we could look at HEP data again in the framework of Regge trajectory exchanges we could get another handle on checking strings. It was fairly successful in describing resonances and the data arising from them. This would be another test then.
Aug
28
comment Is the Big Bang defined as before or after Inflation?
classical BB. It will still emerge and apply at its region of validity . The various definitions you state are due to this confusion of trying to keep both the classical and QM frame at once .
Aug
28
comment Is the Big Bang defined as before or after Inflation?
We actually live our everyday lives in a classical physics framework. That it is emergent and the underlying framework is quantum mechanical does not invalidate the theoretical models that describe so successfully our classical experience. It just limits their region of validity. The Big Bang model is successful in its region of validity and it is modeled as if there is a singularity at the very beginning. When the limits of the validity of classical GR are reached then QM has to be invoked and the data modeled with it, which is what the inflationary model does. That does not invalidate the
Aug
28
comment Is the Big Bang defined as before or after Inflation?
@innisfree I am not talking about mysteries of quantum gravity. I am talking of mixing two frameworks that have different postulates and axioms and expect consistency. Generally in quantum mechanics singularities disappear. The classical frame is an emergent frame. When one is actually "handwaving" , mixing two frames, confusions will arise.
Aug
27
comment How do you add temperatures?
I am curious, why do you want to add temperatures? To get an average temperature for a location?
Aug
27
comment How can blackbody radition be explained by quantization?
Funny. The black body spectrum IS electromagnetic radiation. Those oscillators ARE charged. What you are saying is a parallel projection of similar solutions for non existent matter. Mathematics that is.