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230112
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location Greece
age 74
visits member for 3 years, 8 months
seen 42 mins ago

Retired experimental particle physicist.

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


Apr
28
comment How to understand the thermal radiation?
the energy reaching the ice will be E*A. have a look nsidc.org/cryosphere/seaice/processes/thermodynamic_melt.html . i think it should be .5, the reflectivity not the emissivity. so the factor should be 0 .5 not 0.05 . emissivity is not the same as absorptivity. of that 50% energy not reflected, look at ice solarmirror.com/fom/fom-serve/cache/43.html .
Apr
28
comment How to understand the thermal radiation?
you have a spelling mistake and i do not understand your "what's the energy from run and reach an ice (with emissivity about 0.050) on earth". generally the impinging radiation energy falls as 1/r^2 with distance from the source, as all incoherent radiation. Once you have the energy per meter square falling on some substance to find how much of this enerhy can be absorbed you need the reflectivity: a perfect mirror would absorb nothing . emissivity is the coefficient for the black body radiation at the temperature reached.
Apr
28
revised How to understand the thermal radiation?
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Apr
28
answered How to understand the thermal radiation?
Apr
25
revised Transfer of electron energy to atoms (heating up of matter by absorption of photons)
added 237 characters in body
Apr
25
answered Transfer of electron energy to atoms (heating up of matter by absorption of photons)
Apr
25
comment What is the process that gives mass to free relativitic particles?
I think Luke you should read @Siva 's comment and go to the link provided. It is the Higgs field not the Higgs boson that gives the mass to elementary particles and the link explains it simply. Higgs bosons arise because of the quantization of the Higgs field and have a definite mass again acquired by the interaction with the field. Also GR has very little to do with elementary particle sizes and measures ( well unless you take into account string theories).
Apr
25
comment Space time a function of itself, objects in it, or both?
Well, it is OK to ask someone else, it is the method of transferring knowledge accumulated over centuries. I should have added in the concluding paragraph that: that is how the SR framework blends with the GR, as the very weak gravitational sources become more important with size and location. It is the weakness of the gravitational constant that allows the SR framework to be very good for studying particle physics, as an example; with only SR, as if they are in a vacuum as far as GR is concerned.
Apr
24
revised Space time a function of itself, objects in it, or both?
concluded
Apr
24
answered Space time a function of itself, objects in it, or both?
Apr
23
comment Why the water remains on the surface of the Earth?
@Nathaniel It would not be negligible, but it probably would not empty the oceans. The asteroid rain is supposed to be continuing . As I was looking around I found that the crust tends to "cement" , I suppose it is because most of it comes from cooled lava. Cement can even become like porcelain. The link I gave from a book gives very small permeabilities, but that does not cover large holes and breaks of course what with tectonic movement and volcanoes.
Apr
23
comment Why doesn't a stationary electron lose energy by radiating electric field (as per coulomb's law)?
There is no dissipation . The field just is there . It is similar to the potential energy of a lake in a mountain. It just sits there. If a channel down hill appears the water will run and change the potential energy to kinetic energy which then is expended.
Apr
23
answered Why doesn't a stationary electron lose energy by radiating electric field (as per coulomb's law)?
Apr
23
comment Why the water remains on the surface of the Earth?
@Nathaniel Well, I have been impressed with the water from asteroids theory forbes.com/sites/jaynejung/2011/10/06/… . In any case the accepted theory now is that the earth started as rocks "Based on current theory, the Earth began as hot waterless rock formation. "
Apr
23
answered Why the water remains on the surface of the Earth?
Apr
23
reviewed Approve suggested edit on What is the difference between Radiation and Electromagnetic Radiation
Apr
23
answered Composition of solar spectrum
Apr
23
answered What is the difference between Radiation and Electromagnetic Radiation
Apr
21
revised Is it only the spin of a particle that can be entangled with another particles spin?
emphasised "position"
Apr
21
revised Why are alpha particles such a prominent form of radiation and not other types of nucleon arrangement?
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