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22476
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location Greece
age 74
visits member for 3 years, 2 months
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Retired experimental particle physicist.

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


Apr
12
comment What if photons are not the fastest particles?
Well , with all those extra dimensions shortcuts might be the first thought to come to mind because the experimental evidence up to now validates special relativity to very great accuracy. It would have to be something rare enough so why not shortcuts.
Apr
12
comment About blackholes
when approaching close to the singularity en.wikipedia.org/wiki/Black_hole#Singularity I would expect so . But as the temperature is inversly proportional to mass the average particle within the horizon of a black hole has very small kinetic energy. search for "temperature" in the link.
Apr
12
comment Radio waves and frequency of photon
Photons are neutral but in bulk, if they are coherent ( in step) they built up electromagnetic waves which do have electric and magnetic fields. The way the build up happens is illustrated here motls.blogspot.com/2011/11/… . In a hand waving sense the potentials entering the maxwell equations enter the equations for photons, so they have the rudiments for the build up.
Apr
11
comment Why is the black body radiation so important?
Have a look at this hyperphysics.phy-astr.gsu.edu/hbase/mod6.html . Preferred frequencies come from quantization of light. Most everyday sources are in thermal equilibrium, mostly : temperatures equilibrate after a while, unless there are energy sources.
Apr
11
comment In calculating work done by a constant force over a constant distance, why doesn't the subject's initial velocity matter?
It is good that you emphasize definition. A mathematical model becomes a physics model by imposing laws/postulates definitions that connect the mathematics to measurements.
Apr
10
comment Why doesn't dark matter affect planetary motion?
better read the article in wikipedia en.wikipedia.org/wiki/Dark_matter . Today dark matter is 26% dark energy 68% and 5% normal matter . Dark matter was postulated while using Newtons equations, because galaxies would not be stable without it. Dark energy is hypothetical permeating everything en.wikipedia.org/wiki/Dark_energy
Apr
10
comment Has the collapse of wave function due to observation been recorded?
They have done the experiments with shutters at the slots en.wikipedia.org/wiki/User:Jordgette/… . see also from a book books.google.gr/… .
Apr
10
comment Has the collapse of wave function due to observation been recorded?
yes, the single slit is such a pattern and what you get if you put detectors at the slit it is two such single slit patterns.
Apr
10
comment Has the collapse of wave function due to observation been recorded?
We are talking visible light here so I do not understand what you mean
Apr
10
revised Would electromagnetic radiation impart a pressure on a surface of neutrons?
deleted 3 characters in body
Apr
10
answered Would electromagnetic radiation impart a pressure on a surface of neutrons?
Apr
10
comment Batteries and fields?
The field inside the conducting container of the batteries is non zero because there exist charges inside, from the charge separation. It is only an outside shell that is metal. doitpoms.ac.uk/tlplib/batteries/printall.php , look at the zink acid battery drawing. The two poles that come out of the metal shell create a field around them because of the charges inside the battery. Batteries are usually stacked in parallel and any stray fields will be parallel.
Apr
10
comment what is QCD Background?
@DamianDulkawie Yes, "background is a blanket term that covers the non-signal". We used to say "this year's signal next year's background" :). 30 years ago QCD was the sought for signal and the parton model provided the background.
Apr
10
comment Batteries and fields?
close is a relative notion. Their centers are at least a few centimeters apart. 1/25 is already a small number . Metals are conductors. Electric field lines do not cross conductors en.wikipedia.org/wiki/Electric_fields
Apr
10
answered Probability and the many-worlds interpretation
Apr
10
comment Light emanating from finger tips?
There is no way light emanates from a body , unless by an optical trick, as far as physics is concerned. It could be optical illusion from an afterimage: en.wikipedia.org/wiki/Afterimage . In metaphysics there exist what are called "auras" and some people claim to be able to see them. Even physicists !! amazon.com/Hands-Light-Healing-Through-Energy/dp/0553345397
Apr
10
comment Batteries and fields?
Usually batteries have metallic covers and electric fields do not pass through metal. The field coming out of the two poles comes from spatially separated charge distributions within the battery, the geometry is not uniform. Even if the covers are not metallic the 1/r^2 drop of the field from the source giving it off will ensure that the interference from close by batteries will be small.
Apr
9
answered Spherical Waves-Strength at close distances
Apr
9
answered Why don't X-rays/Gamma rays ionize all the atoms at the surface of a material?
Apr
9
comment How many gas centrifuges are needed to build two small nuke within a year?
@user44218 if he has helped you for your novel you should give him a +1 . Here is a link en.wikipedia.org/wiki/Isotope_separation . and another link princeton.edu/~rskemp/… . It seems that time can be shortened with this cascade method.This second link shows it is not easily done within a year or two because Iran would have done it.