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237151
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location Greece
age 75
visits member for 4 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
7
comment How does energy get transfered from destructive interference point to constructive one?
physics.stackexchange.com/q/23930
Apr
6
comment 5 sigma result proof for particle discovery
@RobJeffries Right, not "anywhere". It is a measure of the the reproducibility of the result at the same energy by another experiment.
Apr
6
comment 5 sigma result proof for particle discovery
In the case of the Higgs the noise in the background is insignificant due to the large number of monte carlo events. The significance is the number of sigma ( square root of n of the real events) from the background considered constant. It is probably a semantic miss-atribution, as in particle physics we call the sigmas "significance" implying the probability value. A bin has N events, the backround is G events, N-G is the signal. The square root(N)/N gives the error, and (N-G)/error is what we call two or three or five sigma significance.
Apr
6
revised 5 sigma result proof for particle discovery
added 474 characters in body
Apr
6
comment 5 sigma result proof for particle discovery
@RobJeffries have a look at this brazil plot when differences from calculated background were searched to find a signal for a possible Higgs. atlas.ch/news/images/stories/3-plot.jpg the caption can be found atlas.ch/news/2012/latest-results-from-higgs-search.html
Apr
6
comment 5 sigma result proof for particle discovery
@RobJeffries OK, if you delete I will delete the answers also. I am editing my answer
Apr
6
answered Is a single photon also a Maxwellian wave?
Apr
5
comment 5 sigma result proof for particle discovery
@RobJeffries . There are a lot of events in the plots. Poisson is not useful in particle physics currently. Please read my comment to Major above. The whole signal is treated as one bin and the probability of 5 sigma over the background event number is 0.000027% probability. In particle physics we know the background curves(see plot above) from monte carlo calculations and look for the new and unexpected as statistical deviations from the background, bin by bin.
Apr
5
comment 5 sigma result proof for particle discovery
@Major_Tom It should not be less than five. Think of the whole signal in one bin. the square root of the number is the error to the number.The normal distribution is the probability distribution for the statistical variations of that one bin. The statistical error on each bin is described by a normal distribution (turtles all the way down)
Apr
5
revised 5 sigma result proof for particle discovery
addressed the five sigma statement
Apr
5
revised 5 sigma result proof for particle discovery
added 388 characters in body
Apr
5
answered 5 sigma result proof for particle discovery
Apr
5
comment How can anti-matter annihilate matter?
when the nucleons are different (a proton and a neutron, for example). " google.gr/… Antiparticles have the exact opposite in quantum numbers and are not identical to particles.
Apr
5
comment How can anti-matter annihilate matter?
There is no repulsive component of the strong force. You might be thinking of the nuclear force "The nuclear force is only felt among hadrons. At small separations between nucleons (less than ~ 0.7 fm between their centers, depending upon spin alignment) the force becomes repulsive, which keeps the nucleons at a certain average separation, even if they are of different types. This repulsion is to be understood in terms of the Pauli exclusion force for identical nucleons (such as two neutrons or two protons), and also a Pauli exclusion between quarks of the same type within nucleons,
Apr
4
comment We Don't NEED Quantum Gravity because Gravity isn't Even A Force!
you state " I honestly want to work on a theory myself." A word from an old grandmother physicist: If you look how the successful theories of physics develop they develop because the authors know very well the previous theories, see discrepancies, they think out of the box and get a better mathematical model for the data, with greater predictive power. First get well grounded in the run of the mill theories with their mathematics, i.e. learn the box, and then look where new mathematical models are needed to describe experimental discrepancies, where a new theory would be useful.
Apr
4
revised Show that a photon cannot transmit its total energy to a free electron. Contradiction with Photoelectric effect?
clarification
Apr
4
comment Show that a photon cannot transmit its total energy to a free electron. Contradiction with Photoelectric effect?
As the other answers states and the feynman diagram above shows, the photoelectric effect kicks out one electron and the energy and momentum balance is kept by the left over Z atom and the outgoing electron. The incoming e- is the outer electron tied to the Z shown here as independent for clarity. The original Z has that electron in an outer shell.
Apr
4
answered Show that a photon cannot transmit its total energy to a free electron. Contradiction with Photoelectric effect?
Apr
4
comment Mass without Matter?
@jjack yes. example electron positron annihilation en.wikipedia.org/wiki/Electron%E2%80%93positron_annihilation
Apr
3
answered How is extremely low frequency (ELF) radiation collected by a submarine antenna?