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bio website nathanielvirgo.com
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visits member for 3 years
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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.


Sep
4
comment Is there a minimum energy content of information, other than 0 Joules?
Landauer's principle doesn't apply to storing or transmitting bits. In fact it says that in principle neither of these things take any energy. Landauer's principle says the only thing that takes energy is erasing bits, which isn't needed for transmitting them. (The points about the noise floor are quite reasonable though.)
Sep
2
comment $\mathrm{CO_2}$ rate of deposition
That's basically what the paper says that John Rennie linked to - they propose a liquid nitrogen cooling system, which requires energy input, but it's much more efficient than doing it in a warmer climate where you have to cool the air a lot more.
Sep
2
comment $\mathrm{CO_2}$ rate of deposition
The main figure in the Nat Geo article is correct though - they did measure a temperature of $-93^\circ\mathrm{C}$ by remote sensing. But that's just a momentary thing - the average temperature is much higher, so any CO2 formed will sublime again later, especially during the summer. If the temperatures regularly get that low, I suppose it might be possible to store the resulting dry ice in insulated containers, preventing it from turning back to gas. But my intuition says this probably can't be done on a large scale.
Sep
2
comment $\mathrm{CO_2}$ rate of deposition
Hmm, there's something a bit fishy there - the article says "Antarctic regions are always cold, averaging a nippy -127°F (-83°C) and fluctuating only a few degrees up and down", but in fact $-127^\circ\mathrm{F}$ is $-88^\circ\mathrm{C}$, not -83. Sadly, I suspect this figure is just a mistake on the part of the author.
Sep
2
comment $\mathrm{CO_2}$ rate of deposition
Can you give a source for the figure of $-83^\circ\mathrm{C}$ as a mean temperature? From some informal googling, it looks like there are recorded temperatures well below that, but I'm not finding anything that low quoted as an average. The lowest I can see is the daily mean temperature at Vostok Station in August, which is $-68.0^\circ\mathrm{C}$. If there were areas with annual averages lower than $-78.5^\circ\mathrm{C}$, one would probably expect to find deposits of solid $\mathrm{CO_2}$ there already.
Aug
31
comment Why is it so hard to mix spaghetti with meatballs?
@Jim if the question was "what can I add to the sauce to make these items mix" then it would be a cooking question, but it isn't, it's "why don't they mix?". It's an excellent example of an everyday physics question, and what's more, from a physics point of view the answer isn't at all trivial or obvious as far as I can see.
Aug
31
comment Why is it so hard to mix spaghetti with meatballs?
Or another way to tell: before cooking the spaghetti, break it up into small pieces, maybe about an inch long (2cm). If granular convection is the reason this should make no difference - the meatballs will still separate. But this should greatly reduce the entropic effect, so if my hypothesis is right then doing this will make the meatballs and spaghetti mix more easily.
Aug
31
comment Why is it so hard to mix spaghetti with meatballs?
The other possibility is: mix spaghetti and meatballs in a shallow pile on a big plate. If the meatballs always sit on top of the spaghetti, this suggests granular convection is the reason, but if they end up next to the spaghetti it suggests a different explanation, which might be the entropy-driven phase separation I described, or it might be something else.
Aug
31
comment Why is it so hard to mix spaghetti with meatballs?
@fffred they're two different hypotheses, and to me it seems likely that both are at play. It's hard to think of an experimental way to test between the two --- other than the rather expensive method of cooking pasta on the international space station. If the meatballs separate even in zero-g then we know it's not due to granular convection.
Aug
31
accepted “Delayed choice” quantum imaging experiment - why wouldn't it work?
Aug
30
comment Why is it so hard to mix spaghetti with meatballs?
Would down voters care to explain the issue? Is it badly written (probably - if you can say specifically what's confusing I'll fix it) or wrong (maybe - if you can convince me I'll delete it)? Thanks!
Aug
30
answered Why is it so hard to mix spaghetti with meatballs?
Aug
30
comment “Delayed choice” quantum imaging experiment - why wouldn't it work?
@user12262 by the way, if you post your comment as an answer I'll accept it.
Aug
30
comment “Delayed choice” quantum imaging experiment - why wouldn't it work?
@user12262 thanks! Without a subscription I can see the figure, but I can only read the first line or so of its caption. It looks like it doesn't correspond to what I understood from the news article, as there's some interaction between what I called beam A1 and beam B, before it gets split into B1 and B2. (In the figure, beams b and d both enter the crystal NL2, though I can't see that part of the caption that explains what that represents.) So I guess that pretty much answers my question.
Aug
29
comment “Delayed choice” quantum imaging experiment - why wouldn't it work?
@phono creating an entangled pair isn't necessarily a measurement - I don't think there's anything fishy about that part.
Aug
29
asked “Delayed choice” quantum imaging experiment - why wouldn't it work?
Aug
28
awarded  Nice Answer
Aug
28
comment How do you add temperatures?
@AndrewMedico ah yes, now I remember that, good point.
Aug
27
comment How do you add temperatures?
@SeanD thanks, corrected. (For future reference: this is Stack Exchange, you can just edit for little things like that.)
Aug
27
revised How do you add temperatures?
edited body