Nathaniel

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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.

	6,259 reputation	bio	website	nathanielvirgo.com	visits	member for	1 year, 7 months
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May 7	answered	Calculating the mechanical power of a water pump
May 7	comment	Calculating the mechanical power of a water pump Does "fountain pump" mean "pump used in a fountain", or does it have some other technical meaning? I ask because your average fountain probably gets through quite a bit more than 10 litres per hour.
May 7	comment	How can I understand a Vortex Tube and its efficiency? This is a very interesting question - I hadn't heard of these things before.
May 7	revised	How can I understand a Vortex Tube and its efficiency? spelling
May 7	revised	Calculate how hot PLA will become edited in OP's image
May 7	comment	Ideal gas concentration under temperature gradient I think your argument about chemical potential breaks down because you're considering equilibrium between systems at different temperatures. In this case, I believe, you should have $\mu(z)/T(z) = \mu(0)/T(0)$ instead of $\mu(z) = \mu(0)$, as in general it's the entropy change that has to be zero at equilibrium, rather than the energy change. (The two being proportional to one another in an isothermal system.) I haven't worked through all the details, but I suspect this should lead to the same answer as assuming the pressure is constant.
May 7	comment	Can Increasing the Turbulence Inside a Pipeline Economically Increase Flow? It's not entirely clear from that article whether riblets work by generating turbulence, or just by organising vortices that would have been present anyway into a pattern that causes less dissipation. Do you have any extra information about that? (I'm just curious.)
May 6	answered	General relativity and the microscopic/macroscopic distinction
May 5	comment	Pendulum in an elevator Energy isn't conserved, but momentum in the $x$ direction is, since the external force acts only in the $y$ direction. Maybe that's enough to work out the answer?
May 5	comment	Calculate how hot PLA will become You're probably right that "it should stop getting a hotter once the rate at which it recieves heat and rate rate at which it can dissipate that heat to the air match", but the problem is that calculating convective dissipation tends to require specialised modelling software, so you'll probably have to resort to measurement.
May 5	comment	Calculate how hot PLA will become Is there any chance you could post a quick sketch of a diagram? It's hard to work out the geometry from what you've written. (Just post a link to an image and someone else can edit it into your question.)
May 5	answered	Temperature of a small system
May 5	answered	Does the scientific community consider the Loschmidt paradox resolved? If so what is the resolution?
May 5	comment	Why Quantum Mechanics as a non-fundamental effective theory? I'm hoping I can get away with cross-posting this answer, because the other version is on a different Stack Exchange site.
May 5	answered	Why Quantum Mechanics as a non-fundamental effective theory?
May 5	comment	Why isn't temperature measured in units of energy? Oh, sorry, I just realised this question is older than that one.
May 5	comment	Why isn't temperature measured in units of energy? Possible duplicate: physics.stackexchange.com/questions/60830/… (Even if it's not a duplicate, you might find the answers helpful.)
May 4	comment	Independent systems and Lagrangians The question I linked to is indeed quite different from yours, but nevertheless I think it's relevant because both questions are about the relationship between probabilities and Lagrangians. In the classical world this relationship occurs because of statistical mechanics, which is the subject of the question I linked to. In the quantum world it's more straightforward because of the path integral formalism, as levitopher points out.
May 4	revised	What's the physical difference between the quantities $\langle v_{i}v_{j}\rangle$ and $\langle v_{i}\rangle\langle v_{j}\rangle$? fixed markup in title
May 4	comment	Why Quantum Mechanics as a non-fundamental effective theory? Although this is quite a different question from philosophy.stackexchange.com/questions/6670/… , my answer to it would be pretty much the same.