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| bio | website | lightandmatter.com |
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| age | ||
| visits | member for | 1 year, 11 months |
| seen | 13 mins ago | |
| stats | profile views | 1,194 |
I teach physics at Fullerton College, a community college in Southern California. I have an undergrad degree in math and physics from Berkeley and a PhD in physics from Yale. Back when I was doing research, my field was experimental low-energy nuclear physics.
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Balmer absorption lines #2 was asking about absorption, not emission, so the answer would involve what frequencies (visible) are available already, i.e., what frequencies are making their way through the outer layers of the sun. |
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Magnetostatic energy density — derivation without introducing induchance? @LarryHarson: I could be mistaken, but I think it's pretty common that when you have something that's not a full answer, but may be helpful, you post it as a comment. |
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answered | Why does no physical energy-momentum tensor exist for the gravitational field? |
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Why does no physical energy-momentum tensor exist for the gravitational field? As with your previous answer, there is a basic problem, which is that you're not distinguishing between local and nonlocal. Since, e.g., gravitational waves do carry energy and momentum, your conclusion can't be correct. Your logic also doesn't make sense because the energy-momentum tensor is the source of the gravitational field, so it's irrelevant that "The gravitational field is unique in not being the source of any other physical field." |
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Magnetostatic energy density — derivation without introducing induchance? Try taking two parallel sheets of current, finding their force on each other, and calculating the mechanical work required to move them farther or closer. |
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Have general relativistic effects of all of the components of the stress-energy tensor been measured? added 246 characters in body |
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answered | Have general relativistic effects of all of the components of the stress-energy tensor been measured? |
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Please Give me the Correct Answer with Explanation. Thanks in advance If this is homework (or other assigned school work), please use the homework tag. Questions are expected to show research effort -- what are your own thoughts? It's up to you to present the question in a way that shows some motivation and explains why it might be of interest to someone besides you. You haven't done that, so I'm voting to close as too localized. |
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Can the photoelectric effect be explained without photons? The question is specifically about the photoelectric effect, so the material about Compton scattering and black-body radiation is off topic. However, a semi-classical picture of Compton scattering can't explain (1) a change in wavelength in the limit of low-intensity incident radiation, or (2) the results of the 1924 Bothe-Geiger electron-x-ray coincidence experiment. |
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Can the photoelectric effect be explained without photons? Nobody disputes that semi-classical theories such as Bohr-Kramers-Slater (or rehashes of it by Lamb or you) can explain some aspects of these phenomena. A viable theory needs to explain all of the observations. Whatever difficulties the wave theory may or may not have with modern anti-correlation experiments [...] "Modern" is misleading. BKS was proposed in 1924, then disproved in 1924-1925 in a series of experiments by Bothe and Geiger, one of which observed exactly the anticorrelations predicted by the photon theory. |
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Conservation of Energy and Quantum Fluctuations Long before virtual particles were imagined, the Bohr-Kramers-Slater theory proposed that energy and momentum were only conserved statistically, on the average. This was disproved in 1925 in a series of experiments by Bothe and Geiger. This is the kind of experimental evidence that the first WP quote refers to, and that quote is correct. The second WP quote is of a qualitatively different nature. The word "appear" refers to an optional philsophical interpretation of a mathematical construct -- not to the results of actual experiments. |
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Can you speed up radioactive decay of plutonium? The Shnoll paper is wrong. This is the same kind of kook material as Jenkins and Fischbach, debunked by Lindstrom arxiv.org/abs/1006.5071 . |
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Why is the anode (+) in a device that consumes power & (-) in one that provides power? "Consumes power" and "provides power" should be "consumes electrons" and "provides electrons." What provides power is the chemicals inside the battery. What consumes power is the load. It's charge that flows in a circle, not power. |
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awarded | Pundit |
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Why can't some light ever reach earth? possible duplicate of What is the theoretical limit for farthest we can see back in time and distance? |
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Why can't some light ever reach earth? You're repeating a common misconception. See Davis and Lineweaver, arxiv.org/abs/astro-ph/0310808 |
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awarded | Generalist |
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Is faster than light travel possible using nothing but ordinary matter and special relativity? This is basically a question about fictional physics, which is not within the scope of physics.SE. Physics.SE is for "accepted and/or actively researched theories" posed by "active researchers, academics and students of physics and astronomy." Voting to close as off topic. |
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answered | Does the uncertainty principle apply to photons? |
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Does the uncertainty principle apply to photons? related: physics.stackexchange.com/questions/66977/… |
