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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.


2d
comment Why does sand stick to my shoes?
@Ruslan actually your comment makes me question my assumption. When I was a child we had a sand pit in the garden, and we used to make sand castles using fresh water from a hose pipe. They dried just as solid as beach sand, so the phenomenon either requires only tiny amounts of salt, or the sand itself had some salt content, or there's another explanation. (I suppose any of these are possible.)
2d
comment Hourglass on the Moon
@Frédéric the correction due to general relativity will be of the order 0.02 seconds per year of measured time (quoting from Wikipedia because I'm lazy) - far smaller than the error involved in measuring time with an egg timer, so I think this is a perfectly acceptable answer!
2d
comment Hourglass on the Moon
I hope you don't mind that I edited in the derivation of the $\sqrt g$ law from the other answer, since that's what I wanted to know.
Nov
24
comment Hourglass on the Moon
@WetSavannaAnimalakaRodVance interestingly, avalanches on a sand pile are one of the classic examples of self-organised criticality, so in the limit of an infinite pile they follow a power law distribution and don't have a characteristic size. (That's in theory at least; in practice many things can break the scale invariance, including the detailed shape of the grains.) But I'm not sure whether the dynamics of the avalanches are all that relevant to the time taken for all the sand to fall, since they happen far away from the neck where the flow is limited.
Nov
22
comment Hourglass on the Moon
@CarlWitthoft you're right about it probably not being constant - I've changed it to "reproducible".
Nov
18
comment If we traveled at almost light speed with a mirror in hand
I'm also voting to reopen, because the "duplicate" question has been closed as off-topic on the grounds that it's "non-mainstream" physics. As Rod Vance says, this one avoids that by asking about being near rather than at the speed of light.
Nov
17
comment How can anything ever fall into a black hole as seen from an outside observer?
@BenCrowell well thanks for the downvote then. In future when my knowledge is limited and from an unofficial source, would you prefer if I was less honest about it?
Nov
7
comment Is it theoretically possible to have a universe where sound travels faster than light $c$?
@RobJeffries that's very interesting, thank you.
Nov
5
comment Is there a lower bound on energy needed to transfer one bit of information?
in the classical world there's no lower bound. You just transmit the bit by either pushing a mass toward the other station or not. By making the mass arbitrarily small and/or slow-moving, the energy can be as small as you want. In the quantum world it's less obvious though. At a wild guess I'd say the energy-time uncertainty relation might become relevant.
Oct
30
comment A question about Memristors
It's 100% relevant here IMHO. It's a physics question, not an engineering one.
Oct
28
comment Exponentially increasing $\Omega(E)$
Sorry, but this is wrong. The Boltzmann distribution says that the probability of being in a state decreases as its energy increases, but this is not the same as the number of states with a given energy.
Oct
28
comment What mechanism is responsible for the creation of these dunes on Comet 67P/Churyumov-Gerasimenko?
My own wild guess is that they're related to the surface slipping downhill and either wrinkling up or breaking in a series of fractures. It would be very nice to see an authoritative answer!
Oct
27
comment Imaginary time is to inverse temperature what imaginary entropy is to …?
He replaces $\beta$ with $-i/\hbar$, but he also replaces the energy with the action, which at least has units of time times energy, so the $t$ is in there somehow. I have to admit I don't know much about Wick rotations myself, so I'm waving my arms a bit and hoping they'll turn out to be equivalent :)
Oct
23
comment Space elevator: a Earth rotation brake model
(Though I'm not even sure the dissipation thing is that big of a worry anyway - why wouldn't you just transfer the heat to the cable and let it radiate away slowly?)
Oct
23
comment Space elevator: a Earth rotation brake model
Why would it act as a brake? The only friction mentioned in the article is between the elevator and its cable. The article says this will produce enough heat to worry about getting rid of it, but it won't slow down the Earth any more than a normal elevator in a skyscraper does.
Oct
12
comment Is it possible to start fire using moonlight?
Well, the Moon's surface temperature during the day is about 123 celsius, which isn't hot enough to ignite paper or lighter fluid, so if we had to rely on black-body radiation from the Moon and pure optics then it would be impossible. But since as you say moonlight is reflected rather than re-emitted, it might be in-principle possible. I imagine you'd need a ridiculously large collection area though.
Oct
11
comment Why is $d$ generally not used instead of $r$ in Newton's derivation of force of gravitation?
I would guess it's because the most obvious application of Newton's law is to calculate the force on something orbiting a much heavier object in a roughly circular orbit. (E.g. planets around the Sun, or satellites around planets). In this case $r$ is the radius of the orbit.
Oct
10
comment Describe Ising model dynamics in stochastic differential equation or stochastic process
For the stochastic process approach, you might like to look into "Glauber dynamics". As for whether there's a meaningful way to approximate/summarise the dynamics as coupled differential equations, I don't know. It sounds hard.
Oct
7
comment Are all machines linearly scalable?
An even earlier influential discussion was Discourses and Mathematical Demonstrations Relating to Two New Sciences (Galileo, 1638). As I understand it from second-hand accounts, one of the two sciences was the relation between material strength and scaling, and the other was kinematics.
Sep
27
comment Is a chain REALLY only as strong as its weakest link
I've edited my answer - see the last paragraph.