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bio website nathanielvirgo.com
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visits member for 2 years, 10 months
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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.


Jul
18
comment Do objects gain and lose heat at the same rate?
@alemi that's very dependent on the situation, e.g. the geometry of the object and its surroundings. Sometimes it does make a big difference. In engineering situations where people really care about heat flow rates, people go to a lot of effort to calculate the convective heat flux. Usually you can only do it by numerically simulating the air flow, and software packages to do this are a profitable business. I've used them in the past. In this case I would expect the sign of the temperature difference to have a measurable effect.
Jul
18
comment Do objects gain and lose heat at the same rate?
This is a good answer, but it would also be worth mentioning convection. A warm object in a cold fridge will heat up the air surrounding it, which will rise up to the top and draw in more cold air from the sides. This increases the rate of cooling. However, a cold object in a warm room will cool the air surrounding it. Cold air sinks rather than rising, so it will mostly just hang around the object and stay cold. So the rate constant will actually be different in the two cases as well.
Jul
18
comment Can you explain Fermat's Principle to me?
Please say which text book you are referring to. Always, always, always give your source when quoting, on this site or anywhere else.
Jul
18
revised Can you explain Fermat's Principle to me?
added 10 characters in body
Jul
11
comment Should a radiation-filled Universe be scale invariant?
I'm not 100% sure of my reasoning here, but if the universe is filled with radiation then doesn't that radiation have to have a particular temperature? If so then the Planck formula gives it a characteristic wavelength, which breaks the scale symmetry. I don't know but I would assume the Friedmann equation is based on radiation at equilibrium at some temperature (which is constant over space but not time for an expanding universe).
Jul
11
comment Why do almost all nuclear reactions release energy?
I don't understand how an endothermic process can consist of exothermic steps. Obviously there can be some exothermic steps, but they have to be outweighed by other ones that are endothermic, because energy is a state function. Right? (I don't know anything about nuclear processes, but thermodynamically what you said sounds odd, unless I didn't understand it correctly.)
Jul
9
revised Is there an upper limit to a rocket's size/payload?
added 34 characters in body
Jul
9
comment Is there an upper limit to a rocket's size/payload?
@Jason I've added the missing explanation to my answer.
Jul
9
comment Is there an upper limit to a rocket's size/payload?
@KyleKanos I've fixed the answer so that it explains the issue with gravitational acceleration properly, and also explains why Asad's answer to the linked question is wrong (and yours is right).
Jul
9
revised Is there an upper limit to a rocket's size/payload?
added 1712 characters in body
Jul
7
comment Why is there water coming out of a car’s tail pipe?
@TimS I meant by volume, which is proportional to mole number for gases.
Jul
6
comment Is there an upper limit to a rocket's size/payload?
@KyleKanos thanks, you're right that I should have included the gravitational acceleration in the equation. But unless I misunderstood it on my quick reading, I don't really agree with Asad's answer. He assumes the burn rate remains constant as the rocket size changes, which seems a weird assumption to me. If you let it scale proportionally to the mass you still end up with $m_f$ times a constant, as in my answer.
Jul
6
comment How is the logarithmic correction to the entropy of a non extremal black hole derived?
I wonder what this looks like in non-Planck units. There must be a bunch of constants inside that $\ln$ to make its argument dimensionless, and knowing what they are might give some insight into your question. (I know this is old, but just saying.)
Jul
6
revised Is there an upper limit to a rocket's size/payload?
edited body
Jul
6
answered Is there an upper limit to a rocket's size/payload?
Jul
2
awarded  Inquisitive
Jul
2
awarded  Curious
Jun
29
answered What are some publications which continue Schrödinger's “What is life?” discussion?
Jun
27
comment Why does sand stick to my shoes?
I don't know for sure but I always assumed it's because salt crystallises out as the water evaporates. The test would be to use pure silica sand wetted with pure water, and see if it sticks to clean shoes.
Jun
25
revised Would infinite time elapse relative to an outside observer if an object was completely at rest?
added 435 characters in body