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234128
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location Greece
age 74
visits member for 3 years, 11 months
seen 4 hours ago

Retired experimental particle physicist.

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


20h
comment What was the entropy of the universe at the time of the Big Bang?
@MBN en.wikipedia.org/wiki/… " 1>a situation where matter is forced to be compressed to a point (a space-like singularity)"
23h
comment What was the entropy of the universe at the time of the Big Bang?
@MBN hypersurfaces are not part of the microstates defining temperature, one needs "particles" in space and time. As I said it is my comfort blanket in this area.
1d
answered What was the entropy of the universe at the time of the Big Bang?
1d
comment The status of the BICEP2 'discovery' after Planck 2014
@CuriousOne I agree to that last, though I do wonder how irreducible can a background drawn by rough strokes can be.
1d
answered Is there a material that could “convert” near infrared frequency to infrared?
1d
comment Is there a material that could “convert” near infrared frequency to infrared?
You realize of course that any absorptive material will do that through black body radiation but it will be a dispersed spectrum? You want a coherent beam out of this, or at least a beam? rp-photonics.com/frequency_doubling.html for doubling frequency exists, not for halving though .
1d
comment The status of the BICEP2 'discovery' after Planck 2014
@CuriousOne they were sitting on the data for some time. If you look at the Planck analysis it is even worse, it fits polarization on large temperature maps whereas if you look at the experimental setup of BICEP2 it is very elegant measuring tiny temperature differences in small detectors.
1d
answered The status of the BICEP2 'discovery' after Planck 2014
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comment The status of the BICEP2 'discovery' after Planck 2014
I check for news every now and then : bicepkeck.org/#papers
1d
comment The status of the BICEP2 'discovery' after Planck 2014
@CuriousOne I read it up at the time. It is a different experimental method than the Planck. At the time Planck was giving limits with large errors. Their experiment did measure polarization with five sigma from zero, not limits. The lensing they avoided by choosing the a one degree window and dust was corrected by using Planck published data at the time. After the new results they were supposed to come out with a common paper with Planck by the end of November but no sign of it yet. Disagreement?
1d
comment The status of the BICEP2 'discovery' after Planck 2014
In their publication already part of the signal had been subtracted to account for the dust.
1d
comment Is nature quantized?
in fact it is "because" the black bodies studied experimentally were composed of particles(molecules) in rotational and vibrational levels in the lattice that the model of quantized harmonic oscillators works so well.
1d
answered What happens when I place an object of certain temperature in space ? Does it loose its entire heat energy?
2d
comment Can open, unsafe nuclear fusion reaction burn the atmosphere?
in the answer by physicsphyle Bethe is mentioned, and more calculations. Considering the difficulty of getting fusion going for peaceful purposes because of the very high temperatures and confinement needed for fusion plasma to be self sustained, it is not impossible that Bethe calculated that and assured them.
2d
comment Why is every particle a sphere?
@Gowtham Yes, but that is all we can perceive with our instruments, thus the shape, the probability distributions for the loci of charges around the atom.
2d
comment Why is every particle a sphere?
atoms have complicated shapes en.wikipedia.org/wiki/Atomic_orbital
Dec
19
revised Does quantum entanglement arise from quantum theory or is it merely an experimental observation?
corrections
Dec
19
answered Does quantum entanglement arise from quantum theory or is it merely an experimental observation?
Dec
19
answered Is light emitted in zitterbewegung?
Dec
18
comment Elastic scaterring of neutrinos - Why does the electron neutrino dominate this channel
handwaving: extra Feynman diagrams means extra probability of interaction kvi.nl/~loehner/saf_seminar/2010/… figs 5.1.3a