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230103
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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
22
answered Speed greater than light in circular motion
Aug
22
answered Why doesn't the light from galaxies appear stretched?
Aug
21
answered What is the electromagnetic field and what is the Higgs field?
Aug
21
comment Entropy and dark matter structure
It is my opinion, after all. As gravity is quantized ad hoc at the moment maybe we should wait for the definitive work to decide whether only quadrupoles, which after all are a classical construct and should be emergent behavior in a full quantized gravity, are the only source of graviton radiation. It is probable that a dark matter particle interacting gravitationally with another dark particle will radiate as interaction is change . arxiv.org/abs/hep-th/9909012 . There might be a type of black body radiation of bulk matter from an ensemble of quadrupole elementary particles
Aug
20
comment Entropy and dark matter structure
Well, I do not think that the gravitational field disappears even in very small time scales. It is weak but it is there, otherwise there would be no accumulation of this dark matter. gravitons must be exchanged and radiated analogously to the photons always, no?
Aug
20
revised What makes us move in time?
edited body
Aug
20
answered What makes us move in time?
Aug
20
awarded  Nice Answer
Aug
20
comment How literally should you take “The Higgs boson gives other particles mass”?
I do not think that the distinction between a field and its excitations is a quibble. A field is defined in all space time, a higgs boson is an excitation of the field, and in our reality it needs 125 GeV to manifest. The mass of the electron is ~o.5MeV, and it is due to the higgs field. "Particles don't acquire masses until the point at which the Higgs boson appears," is wrong.
Aug
20
answered Lattice QCD and attempt to prove that the universe is a simulation
Aug
19
comment Does this count as moving faster than light?
@babou well, read this en.wikipedia.org/wiki/Four-vector
Aug
19
answered Does this count as moving faster than light?
Aug
18
answered Entropy and the uncertainty principle
Aug
18
comment How to understand “accelerating charge radiate” using intuition?
@NikosM. well, physics is modeling observations using mathematical tools with their axioms and physics postulates that relate the mathematics to observations. Unless one follows a sort of platonic world view, "there exist mathematics and nature is molded into it", which I do not.
Aug
17
answered What to do when you are sitting in a closed room without any fan or AC
Aug
17
comment Which electromagnetic radiation is faster in water, microwaves or light?
You have a contradiction here "So, higher frequency waves generally go faster. So, as they have a much lower frequency than visible light, microwaves are supposed to travel faster. "
Aug
17
answered Single Photon emission from positronium in strong magnetic fields; how is momentum conserved?
Aug
16
comment Photon striking a molecule and getting reflected
@jkej There exists total reflection from the water given by the index of refraction and angle of incidence. This is backwards elastic scattering of photons . As the index of refraction is constant in the water, there will be angles where the light will be totally reflected but it will depend on the local geometries of light and water motions. The reflection happens on water molecules.
Aug
16
answered Photon striking a molecule and getting reflected
Aug
16
comment Photon striking a molecule and getting reflected
well there are reflections after a certain angle with respect to the index of refraction, and those reflections are composed of photons. There do exist elastic photon electron scattering at all angles. In this case it will be photon electric-field-from-collective-eletrons scattering in the volume . Some back scattering in the volume will also occur because we can see inside the liquid. Now if it is from solvent or solute is moot, imo. probably from both.