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network profile
| bio | website | nathanielvirgo.com |
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| location | ||
| age | ||
| visits | member for | 1 year, 7 months |
| seen | 4 hours ago | |
| stats | profile views | 824 |
I'm a post-doctoral researcher with a wide range of interests. My career is in complex systems science (or maybe cybernetics) and the origins of life, but I also have research interests in
- the foundations of statistical mechanics and its relationship to information theory
- Earth systems science
- non-equilibrium thermodynamics in general
I'm also generally interested in the foundations of quantum mechanics and in black holes, though I wouldn't say I'm an expert on those things.
It's probably worth noting that despite the fact that my research is in physics-related areas, all my degrees are in other subjects. If I occasionally seem to start talking in an alien language, this is probably why.
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May 15 |
comment |
From where (in space-time) does Hawking radiation originate? But the issues to do with the in falling matter were the entire point of the question! |
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May 14 |
comment |
Definition of entropy Shannon entropy and thermodynamic entropy have an awful lot to do with each other actually. See bayes.wustl.edu/etj/articles/stand.on.entropy.pdf , for example. |
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May 14 |
comment |
Can one get clear ice crystals from a dirty suspension? Another relevant thought: if the solid particles act as nucleation sites then each will start out embedded in its own ice crystal and they won't get separated at all. |
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May 14 |
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Our Universe Can't be Looped? @Qmechanic ok, fair enough, I didn't follow the link in the answer to the other question. |
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May 14 |
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From where (in space-time) does Hawking radiation originate? I'm aware of the issue to do with simultaneity. When I said "moment of collapse" I should have said "the top-most point of the line representing the horizon", and when I said "before" I should have said "in the past light cone of". |
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May 14 |
comment |
From where (in space-time) does Hawking radiation originate? It was my understanding that Hawking's original model was for a collapsing star black hole, but perhaps I am wrong about this. The Penrose diagrams in my post and your answer are for a black hole that forms from a collapsing star and then evaporates - the Penrose diagram for a Schwarzchild black hole looks rather different. |
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May 14 |
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From where (in space-time) does Hawking radiation originate? I didn't mean to imply that the radiation is caused by interactions with the infalling matter. I'm just saying that if there is any infalling matter then most or all of it be will further away from the event horizon than the region where the Hawking photons appear, and consequently they must interact with it. |
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May 14 |
answered | What is our estimated running speed on Moon's surface? |
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May 14 |
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What is our estimated running speed on Moon's surface? There are a few videos of astronauts running on the moon, e.g. youtube.com/watch?v=wo3-fuYKWB4 and youtube.com/watch?v=HKdwcLytloU . Note that they have to adopt quite different gaits from on Earth. However, they were encumbered by space suits that were heavy and stiff, and they were probably moving fairly carefully in order to avoid the danger of a puncture. It's difficult to say how much faster a human could run in a more optimal suit, but it's almost certainly slower than Earth. |
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May 14 |
revised |
Bleaching groundstate link to source |
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May 14 |
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Bleaching groundstate In general, on this site and anywhere else, please always, always, always cite your source when giving a quotation. |
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May 14 |
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From where (in space-time) does Hawking radiation originate? There's also an interesting issue about the conservation of energy. In your diagram, all of the matter-energy that ever falls in escapes in the form of radiation before the moment of collapse. This seems as if it should be correct. But that seems to imply that none of that matter-energy can ever pass the horizon. I used to think nothing could pass the horizon, but after learning about Penrose diagrams I thought I had been mistaken - now I'm unsure again. |
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May 14 |
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From where (in space-time) does Hawking radiation originate? Thanks, this looks promising. It would seem to imply that from the distant observer's point of view, the photons would appear to come from the practically-infinitely-hot extended horizon, and thus should appear to have interacted very strongly with the infalling matter. |
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May 14 |
revised |
What are the limitations of performing music in space? might need to re-tune a piano |
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May 14 |
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Bunsen Burners and the Sun It's worth clarifying the answer to part 2 of the original question: yes, they are two different phenomena. The sun's yellow light is the result of black-body radiation, whereas the blue of a bunsen flame is due to spectral lines. To see the difference, compare the spectrum in this post to a black body one. |
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May 14 |
answered | What are the limitations of performing music in space? |
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May 14 |
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What are the limitations of performing music in space? The bellows of a pipe organ would be quite difficult to operate, although they're typically electric these days. |
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May 14 |
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What are the limitations of performing music in space? It might be quite difficult to play a double bass, just in terms of the logistics of holding on to it without gravity to brace it against the floor. |
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May 14 |
revised |
From where (in space-time) does Hawking radiation originate? explained why pjcamp's answer is not a complete one. (It's getting a lot of upvotes.) |
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May 14 |
revised |
From where (in space-time) does Hawking radiation originate? does the energy-time uncertainty play a role? |
