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230102
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location Greece
age 74
visits member for 3 years, 7 months
seen 34 mins ago

Retired experimental particle physicist.

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


May
2
comment Why does the quantum eraser seem to violate energy and momentum conservation?
lets take the one photon at a time double slit experiment en.wikipedia.org/wiki/… . The interference builds up slowly, but the energy of the electron is the same, and conserved if the absorption of the screen is measured. The same energy electrons through only one slit would not show interference, but would deliver the same energy. what has happened is that the boundary conditions are different, no energy is necessary to produce the effect:a different solution for the same energy content is picked for each case by nature.
May
2
comment Why does the quantum eraser seem to violate energy and momentum conservation?
You have a wrong understanding of conservation of energy and of the interference phenomenon. As I say in my answer the distribution of energy on the screen, as long as the input and ouput are equal is irrelevant. Conservation means the energy budget, in-out=0. . spatial distribution just might make difficult integrating the out, but a calorimeter could take care of that. Nothing is moving, in the sense of a horizontal force, when interference appears.
May
2
answered Electric shock from a power line
May
1
comment Current scope of Chaos theory and non-linear dynamics?
have a look at this list from MIT web.mit.edu/redingtn/www/netadv/Xcomplexit.html . Note that chaos is often coupled with complexity
May
1
comment Elementary question on pion-proton scattering cross-section
The pion when it interacts, even with a simple elastic scatter gets off the beam direction . Have a look capone.mtsu.edu/phys3110/Homework/HW/Extra_12_A/… to see how a pion disappears from a beam line . The crossection gives the probability of interaction
May
1
revised Elementary question on pion-proton scattering cross-section
added 356 characters in body
May
1
comment Elementary question on pion-proton scattering cross-section
I will edit for clarity.
May
1
answered Elementary question on pion-proton scattering cross-section
May
1
revised Elementary question on pion-proton scattering cross-section
added 85 characters in body
May
1
comment Why incoherent source of waves have to be passed though a single slit for double slit interference pattern to occur?
@BrandonEnright read the links in my edit. It seems there exists a coherence length for thermodynamically produced photons too. The incandescence manifests in small coherent regions even when the whole is incoherent. a slit lets many wavelengths through, it has to be of the order of the coherence length .
May
1
answered Why does the quantum eraser seem to violate energy and momentum conservation?
May
1
revised Why incoherent source of waves have to be passed though a single slit for double slit interference pattern to occur?
added links
May
1
comment Why incoherent source of waves have to be passed though a single slit for double slit interference pattern to occur?
@BrandonEnright the grating also separates wavelengths. thus your question is back to why a single slit creates coherence
Apr
30
comment Acceleration, velocity and speed
average speed and velocity are not the same. speed is the measure of velocity.this is a comment, not an answer. look at en.wikipedia.org/wiki/Circular_motion
Apr
30
comment Acceleration, velocity and speed
velocity is a vector, the same as position (x,y,z) is a vector. So is acceleration a vector. speed is the square root of the dot product of velocity with itself. You should use the tag "homework"
Apr
30
comment Can an electron interact with itself to create interference?
I think I would add to "you have to consider the electron's position as a wave function. " 'whose square gives the probability of finding the electron at (x,y,z,t) ' . too often people think that the mass of the electron is spread all over the space. When one is given a probability for living to 80years one is not spread out from now to then ;)
Apr
30
answered Rolling sound of thunder
Apr
30
comment Polarization of sound
could it be summed in: in transverse waves the direction of propagation of energy and the direction of the electromagnetic "vibration" carrying that energy are perpendicular to each other, allowing for an extra degree of freedom. Longitudinal waves the direction of vibration and the direction of propagation of energy are the same, and cannot be unscrambled.
Apr
30
comment Why are electrons in one atom attracted to negative electrons in another atom?
this is not really a physics question. physics can only answer "how" questions: based on a few axioms and postulates one explains how atoms which are electrically neutral have stable bonds to other atoms. the answer to "why" these axioms, is "because" the observations can be described; circular.
Apr
29
comment Early time in the Big Bang
en.wikipedia.org/wiki/Crystal_structure look at equation of cubic structures.depending on the variables different crystals are described. A TOE will have complicated symmetry groups and functonal forms but depending on the variables different facets of matter and laws folloed will be described. I think it is time to stop this. it is my bed time