meta user
network profile
| bio | website | |
|---|---|---|
| location | Greece | |
| age | 73 | |
| visits | member for | 2 years, 3 months |
| seen | 39 mins ago | |
| stats | profile views | 3,303 |
Retired experimental particle physicist
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May 13 |
answered | Light-Particle Wave Duality |
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May 13 |
revised |
Explanation for the notion that physical laws break down at the Big Bang from request in comments |
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May 13 |
comment |
Explanation for the notion that physical laws break down at the Big Bang Physical laws are not made to deal with infinities. I know that there exists many mathematical infinities but I have not seen them to be useful in mathematical physical models. Physical laws are already modified in the region of large masses. As density tends to infinity the distortions of spacetime can no longer be approximated by flat space, where our physical laws are determined so the physical laws become indeterminate too. |
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May 13 |
comment |
Explanation for the notion that physical laws break down at the Big Bang yes, the value tends to infinity |
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May 12 |
answered | Repulsion does not exist; Gravity assist slingshot as a repulsive force |
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May 12 |
revised |
Theoretical physics and education: Does it really matter a great deal about what happens inside a black hole, or about Hawking radiation? eliminated confusing alternative |
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May 12 |
revised |
Theoretical physics and education: Does it really matter a great deal about what happens inside a black hole, or about Hawking radiation? spellings |
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May 12 |
comment |
List of cross sections? PDG has more than branching ratios. It has crossection plots pdg.lbl.gov/2013/reviews/rpp2012-rev-cross-section-plots.pdf from experimental measurements. I do not think it reasonable that there exists a compilation of theoretical values. You would have to search the literature for the specific reaction's theoretical models available. |
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May 12 |
answered | Theoretical physics and education: Does it really matter a great deal about what happens inside a black hole, or about Hawking radiation? |
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May 12 |
comment |
Theoretical physics and education: Does it really matter a great deal about what happens inside a black hole, or about Hawking radiation? continued: True, where more than one model can apply it may be impossible to falsify the other, but one cannot set limits to a researcher's imagination , because that will stifle creativity and any new discoveries. There may be many tentative explorations that will fall on the side of the road even if not falsified because more satisfactory theories overtake them; at least that is the experience from the history of physics. |
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May 12 |
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Theoretical physics and education: Does it really matter a great deal about what happens inside a black hole, or about Hawking radiation? I think that at your stage of studies it is important to create a strong foundation of mathematics and basic physics, if you intend to go towards a PhD. Try to pursue what catches your imagination and curiosity to motivate yourself towards what part of physics you want to research. Cosmology and General Relativity and Quantum Field Theory at the level of Hawking radiation and black holes is for graduate studies . If you are drawn to cosmology you will also be drawn to the various hypotheses that are currently used to explain the data. It took a long time for GR to be established by data. |
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May 12 |
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Is all matter made of virtual particles? In the case of quarks , they are always bound and therefore off mass shell. You can have approximations that are useful but you cannot have a free measurable quark. |
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May 12 |
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Is all matter made of virtual particles? I am saying that real particles are the ones that leave traces in our detectors and we measure their mass with known accuracy. A first order Feynman diagram's out going legs are an approximation to "free" within large error measurements in macroscopic detection. As Arnold says the accurate calculation involves a sum to all orders, but fortunately our measurements are not all that accurate :). BTW I am an experimentalist and view all these from that POV. |
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May 12 |
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Is all matter made of virtual particles? @drake .I agree with Arnold, where do you see a contradiction? I just carry the concept of virtual versus real in the way it is nested until we reach classical physics levels, which are the levels we measure and call real. Whenever a particle is bound, it is off mass shell and strictly virtual by the definition of virtual particle. In the levels I enumerate less and less binding energy is needed and we can sloppily approximate the molecules in a crystal to on mass shell molecules but in truth, if we could calculate the conglomerate we would be using off mass shell mathematics. |
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May 11 |
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The Preference for Low Energy States @nsanger This question is closer to my answer with the apple. When one has two particles, as your electron, one has particle particle interactions and the solutions of the potential problem depend on the boundary conditions, but always energy is conserved. Entropy is a high numbers statistical variable. In the quantum mechanical state the electron can "fall" on the nucleus by releasing energy in the form of a photon, in quantized steps, if there is an empty energy level below. Quantization does not allow it to fall ontop of the nucleus, there is a lowest energy level. |
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May 11 |
comment |
The Preference for Low Energy States @firtree Sure, I was just illustrating with the simplest possible potential problem solution. |
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May 11 |
answered | The Preference for Low Energy States |
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May 11 |
answered | Explanation for the notion that physical laws break down at the Big Bang |
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May 10 |
comment |
What causes the collapse of a Magnetic Field? The variation observed on earth are due to fluid motion changes which change the direction and magnitude of the generated field. Collapse would come if the fluid would solidify. |
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May 10 |
answered | What causes the collapse of a Magnetic Field? |
