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234123
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location Greece
age 74
visits member for 3 years, 10 months
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Retired experimental particle physicist.

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


Aug
22
comment Hawking Radiation - Why it causes black holes to die?
@eJunior . Negative energy is negative versus a hypothetical zero. For example there exists potential energy below zero and kinetic energy above zero. It has no esoteric meaning further than algebraic. It means you have to subtract, as you do subtract energy when a particle leaves the ergosphere with E and the anti drops in the hole at a level -E with respect to a zero at the surface.
Aug
22
comment What if the strong force gave up?
@Dimension10 Sorry, an inconvenient time for me, as I am waiting for my son and family to come from the swim to have lunch ( which I have prepared) . It is 2:32 pm here and I am hungry :(
Aug
22
comment What if the strong force gave up?
@Dimension10 Of course. Hbar and c values depend on the mks or whatever system of units one assumes, but they are crucial in defining the way nature developed. That is why we can work with an hbar=c=1 units base
Aug
21
comment What if the strong force gave up?
@Dimension10 yes, but if in these units we were of dimensions comensurate to hbar reality would be quite different.
Aug
21
comment What if the strong force gave up?
@Dimension10 Can you elaborate? In our given system they have a given value. It is not an arbitrary one.
Aug
21
comment Single photon and double-slit experiment
@BenCrowell Photons are elementary particles and behave as other elementary particles. THeY HAVE TRAJECTORIES or they have probability distributions according to their squared wave function as do all other elementary particles. Single gamma rays in elementary particle interactions have a straight trajectory from the interaction point to the calorimeter where they are detected. Their wave nature appears in their indeterminancy within lamda, by the HUP .
Aug
21
comment Do nuclear reaction cross sections depend on the angle between incident beam and target-crystal?
@BenCrowell Well, the crossection depends on the crystal axis : if the particle goes through undisturbed on the axis then the crossection is different than if it is off axis, both strong and electromagnetic.
Aug
21
comment Do nuclear reaction cross sections depend on the angle between incident beam and target-crystal?
@BenCrowell He is NOT specifying nuclear or electromagnetic, crossection tables contain both; the muon channeling shows that as far as charge goes the crystal axis does play a role. If you google you will find also other charge particles affected.jetp.ac.ru/cgi-bin/dn/e_042_04_0641.pdf . sdu.dk/media/bibpdf/Bind%2030-39/Bind/mfm-34-14.pdf . etc
Aug
21
answered Do nuclear reaction cross sections depend on the angle between incident beam and target-crystal?
Aug
20
answered How to distinguish high-energetic muons and electrons in the CMS and ATLAS muon detectors?
Aug
20
comment What is it called when two particles are associated so that what happens to one happens to the other?
you might mean entanglement. A particle cannot be split in two.
Aug
20
comment X-ray imaging and diamond
You are misinformed. The structure of diamond was found by x-ray crystallography . here is an image too: allposters.com/-sp/… . airport machines catch them : independenttraveler.com/travel-tips/air-travel/…
Aug
19
comment How long until we fall into the Sun?
What about tides of the earth on the sun? shouldn't that work in the opposite direction, increasing the distance as the moon is receding from earth due to the tides?
Aug
19
comment Electromagnetic radiation and quanta
@Michael The wave like properties of all elementary particles are held in the probability function which is the square of the wavefunction of the particle. The photon is an "elementary particle". In the case of the photon the synergy between the quantum level and the classical maxwell equation level that gives the amplitude of the classical wave in the varying electric and magnetic fields is such that the same frequency appears in both cases. An individual photon is defined just by the spin and energy and mass=0. The link to Motl's blog derives how the synergy works mathematically.
Aug
18
answered What does one need to learn to become a experimental particles physicist?
Aug
18
comment Electromagnetic radiation and quanta
Are you not confusing mathematical representations with the reality they represent? When I have an event with one gamma measured what is the meaning of the plane wave representation except mathematical complexity? Nature has already solved the problem of the emergence of coherent states from the quantum world, in that sense it is inevitable , imo ofcourse. It is a philosophical decision, is it mathematics that exists and nature fulfills it, or is it nature that exists and mathematics describes it. As an experimentalist I am of the second school.
Aug
18
comment Electromagnetic radiation and quanta
I think it is misleading to say that the free wave is a one photon state. In my opinion it goes against a basic quantization concept, that at the microlevel energy appears in quanta. That continuous classical solutions emerge from the quantum substrate should be inevitable, if the quantum theory is right. The photon is an elementary "particle" , one at a time, whether it manifests as a probability wave or as a classical type particle. In the sense you use the "one" then there is "one hydrogen state" etc.
Aug
17
comment Electromagnetic radiation and quanta
From Ben's link I see that optical trapping is of dimensions suitable to use the classical electromagnetic form, since the particles are in dimensions of microns. My answer is suitable to the creation of the laser light, but that is an other story, and for atomic trapping as in prl.aps.org/files/RevModPhys.70.721.pdf . Once atomic dimensions are reached quantum mechanical entities have to be considered,the photon in this case.
Aug
17
comment Electromagnetic radiation and quanta
Because an atomic transition is an individual photon interacting with an individual atom. The classical wave does not know about photons. The photons though do build up an emergent classical wave , as shown in the link I supplied.
Aug
17
revised Predicting the mass of the Higgs particle
clarified concepts