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04-11-12, 12:11 PM #741Valued Senior Member
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04-11-12, 01:58 PM #742
As I explained, it's not the case that positron+electron = 2 photons every time. The likelihood of
can be computed using quantum electrodynamic scattering processes, specifically calculating lots of Feynman diagrams.
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04-11-12, 02:34 PM #743Valued Senior Member
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04-11-12, 02:41 PM #744Valued Senior Member
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QED is pretty much Greek to me but you could try this PAGE 6 shows a Feynman diagram of what I think Alpha was talking about.
It showed up on the following Google search, "positron electron annihilation qed".
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04-11-12, 03:24 PM #745Valued Senior Member
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There is the case of an electron interacting with a positron resulting in two gamma rays, but positrons are rare being an antimatter particle.
In the usual situation an electron is associated with a group of neutrons and protons and as it settles in with these it gives off photons of very specific wavelengths. It seldom falls into the nucleus giving up all of it energy.
Even when it does the proton that turns to a neutron would have gained mass. (I don't know too much about this but will look it up soon.)
I have never heard of unravelling an electron all the way down to nothing.
For that is what your equation seems to be suggesting to me. To keep on stripping the electron of its mass you would need to keep putting it nearer the largest possible nucleus. What is the heaviest atom possible? Do they draw the electron into the nucleus and become unstable?
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04-11-12, 03:45 PM #746Valued Senior Member
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Has the heaviest element been found?
http://www.newscientist.com/article/...een-found.html
Amnon Marinov of the Hebrew University of Jerusalem led a team that analysed a purified solution of thorium (element 90) by running it through a mass spectrometer, which can measure the mass of individual atoms. The thorium should have an atomic mass close to 232 (including neutrons), but the team saw a handful of counts with a much greater mass - just over 292.
That's heavier than any known atom. Molecules can easily be that heavy, and Marinov considered the possibility that hydrocarbon molecules from oil used in the experimental apparatus might have caused the signal. But he says tests found no contamination.
"Every molecule that can be found [in the lab] has slightly lower mass," Marinov told New Scientist.
Instead, he says that mass could fit element 122, in a variety, or isotope, containing 170 neutrons; or possibly element 124, in an isotope with 168 neutrons.
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04-11-12, 06:53 PM #747Valued Senior Member
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Electron capture.
http://en.wikipedia.org/wiki/Electron_capture
Electron capture is a process in which a proton-rich nuclide absorbs an inner atomic electron (changing a nuclear proton to a neutron) and simultaneously emits a neutrino. Various photon emissions follow, in order to allow the energy of the atom to fall to the ground state of the new nuclide.
Electron capture is the primary decay mode for isotopes with a relative superabundance of protons in the nucleus, but with insufficient energy difference between the isotope and its prospective daughter (with one less positive charge) for the nuclide to decay by emitting a positron. Electron capture also exists as a viable decay mode for radioactive isotopes with sufficient energy to decay by positron emission, where it competes with positron emission. It is sometimes called inverse beta decay, though this term can also refer to the capture of a neutrino through a similar process.
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04-12-12, 11:32 AM #748Valued Senior Member
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Suppose in an interaction of particles some amount of mass (m) generates many types of photons . Then from Einstein's Equation it can be said that ,
E(m) = n1*E(p1) + n2*E(p2) + n3*E(p3) + ..... ; where p1 , p2 , p3 are different types of photons with energy E(p1),E(p2),E(p3) and n1, n2, n3 are there respective numbers . E(m) is the energy of the mass m .
Thus energy of mass(or inertia) can be conserved with energy of different types of photons .Last edited by hansda; 04-12-12 at 12:05 PM.
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04-16-12, 11:17 AM #749Valued Senior Member
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What you want to conclude from your above two postings ?
Why you are interested with heaviest element or electron-capture ?
For any interaction of particles , energy will be conserved . Einstein's Equation is very useful for conservation of energy , specially for mass(or inertia) to energy(or photon particle) conversion .
I think perhaps quantum-gravity also can be calculated from Einstein's Equation .
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04-16-12, 11:40 AM #750Valued Senior Member
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04-16-12, 11:47 AM #751Valued Senior Member
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04-16-12, 02:37 PM #752
Whoa there partner, that ain't even close!
Electrons don't crash into the nucleus (at least not 99.999999999999999% of the time). One reason is that if the orbital starts to become compressed then the position will become more definite which will make the momentum becomes less definite (uncertainty principle). Overall the KE increase more which tends to move the electron farther from the nucleus, until it reaches a happy medium. This makes sense because the electron can only have certain orbitals it can occupy.
For me a simplistic way to look at the maximum size of the nucleus is to realize that the strong force is short range and the electical repulsion is long range. The (long range) electrical repulsion of the protons adds together and overcomes the attraction of the (short range) strong force. The more protons the larger the repulsion inside the nucleus. That is sufficient for the big picture, it will not however explain things like the difference in the half-life between different isotopes of Plutonium.
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04-16-12, 02:46 PM #753Valued Senior Member
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04-16-12, 03:58 PM #754
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04-16-12, 10:36 PM #755Valued Senior Member
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04-17-12, 12:57 PM #756Valued Senior Member
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From Wiki
In quantum mechanics, the Heisenberg uncertainty principle states a fundamental limit on the accuracy with which certain pairs of physical properties of a particle, such as position and momentum, can be simultaneously known. In layman's terms, the more precisely one property is measured, the less precisely the other can be controlled, determined, or known.
Sounds a lot like a measurement issue, to me.
It would be arrogant for "us" to assume that any limitation(s) we experience in understanding and/or measuring the world, let alone properties of subatomic particles, are the fault of the world or particle, rather than the product of "our" own limitation(s).
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04-17-12, 06:46 PM #757
No refinement of measuring devices can overcome the uncertainty relation. Measurement issues reside in the measuring device, not the phenomenon measured. The precision cannot be improved because the limit is inherent to the phenomena, not the tools.
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04-17-12, 07:47 PM #758Valued Senior Member
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04-17-12, 10:13 PM #759
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04-17-12, 11:39 PM #760Valued Senior Member
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Syne, there is no way to separate, the limitations of observation and measurement, from any conclusion about the world we make.
Our best theories, remain theories — based on those very limitations. Even then they are no more than our best attempts to describe what we observe and how we have come to understand those observations.
As I said earlier, to attempt to project our limitations on the world is arrogant.
The fact that we cannot know simultaneously everything about a particle, with certainty, does not mean that there is no simutaneous certainty, just beyond the limits of our ability....
What we know of the world, the universe and the fundamental quantum nature of matter, is not what defines the world, the universe and matter. It is what defines the limits of our understanding.
The uncertainty principle is a definition of the limits of what we can know, simultaneously with certainty, not a final description of that which we seek to describe. The limits — our limitations change over and with time... They always have and I am fairly certain that will not change soon. There remains too much we cannot yet explain, to believe we know most of what we think we know, with any real certainty.
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