48,345 reputation
230101
bio website
location Greece
age 74
visits member for 3 years, 7 months
seen 1 hour ago

Retired experimental particle physicist.

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


17h
comment Does this count as moving faster than light?
@babou well, read this en.wikipedia.org/wiki/Four-vector
1d
answered Does this count as moving faster than light?
1d
answered Entropy and the uncertainty principle
2d
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.
Aug
16
answered What experiment would prove string theory?
Aug
16
comment Entropy and dark matter structure
we would not be there to measure it :) or even guess at it. probably a negative exponential multiplying 1 kelvin
Aug
16
comment Entropy and dark matter structure
It will depend on what dark matter is. no? fermions? bosons already?
Aug
16
comment Entropy and dark matter structure
I accept that the time taken may be much longer but your argument then would mean that no gravitational collapse of dark matter will exist either. If we assume, as the question assumes that there will be a gravitational collapse of dark matter, then gravitons will take the role of photons. as long as there exists a gravitational force, gravitons are there by construction
Aug
16
answered Entropy and dark matter structure
Aug
16
comment Entropy and dark matter structure
we are talking of dark "matter", no? it has gravitational interactions. At the moment an effective quantization of gravity is accepted otherwise no BB model. Gravitons will take the place of photons in an eventual collapse in the counting of microstates and angular momenta. Photons beat them by far due to the small coupling constant of gravity in the normal collapse/entropy argument. imo
Aug
15
answered Is our universe an emulation?
Aug
14
comment For what wavelength is wave nature observable?
so you should think on the lines above: can you have a double slit experiment of that order of magnitude for lamda? I see xray double slit journals.aps.org/prl/abstract/10.1103/PhysRevLett.105.173901 .look at this hyperphysics.phy-astr.gsu.edu/hbase/phyopt/slits.html
Aug
14
comment For what wavelength is wave nature observable?
Generally wave effects appear when the detecting/observing apparatus has apertures of the same order of magnitude as the wavelength.
Aug
14
comment For what wavelength is wave nature observable?
How did they define "observable" in the problem?