4,928 reputation
11523
bio website vyznev.net
location Helsinki, Finland
age
visits member for 3 years, 4 months
seen 7 hours ago

I'm a PhD student in biomathematics, working on stochastic individual-based models of evolution in spatially structured populations. My other interests include cryptography, programming games and puzzles, photography and graphic design.

I started programming (in AmigaBASIC) when I was 10 years old. Nowadays, I'm most comfortable using Perl, C and JavaScript. I know Java and PHP too, but I can't really say I like them. I also know some Python, but not as much as I'd like.


CC-Zero Please consider any (original) code I post to Stack Overflow and other Stack Exchange sites to be released under CC-Zero unless stated otherwise. You may do whatever you want with it and don't have to credit me in any way, although of course that would be nice.


I'm the main author and maintainer of the Stack Overflow Unofficial Patch (SOUP), a user script for browsers with GreaseMonkey-compatible user script support (Firefox, Chrome, Opera, possibly Safari) that fixes or works around a number of outstanding issues with the Stack Exchange user interface.

I tend to answer a lot more questions than I ask. Some answers I'm rather proud of:


Nov
13
comment Why does an atom remain uncharged after emission of an alpha particle?
@ratchetfreak: In fact, that is where most of the helium on Earth comes from. That party balloon you bought is filled with the decay products of unstable nuclei.
Nov
13
comment Have we proven that higher dimensions exist?
Hmm, I can think of plenty of meaningful and non-trivial physics theories of the form "X exists", where X is, say, any hypothesized object, particle, interaction or state, and these are, in fact, frequently confirmed by observations (to a varying degree, depending on the reliability and unambiguity of the observations). For instance, the existence of atomic nuclei was pretty directly confirmed by the Rutherford gold foil experiment. Going a bit further afield, there are plenty of examples in, say, chemistry or astronomy (which, if not considered physics as such, are at least very close).
Nov
13
comment Have we proven that higher dimensions exist?
While trying not to get all epistemological here, I should note that theories of the form "an X exists" can, in fact, be experimentally proven true by directly observing an X. In fact, such existential statements can never be experimentally proven false, since it's always possible that an X exists but we just haven't found it yet. (Of course, technically, we can never be 100% sure that our observations of an X are correct, either, but sometimes the evidence can be fairly overwhelming. For example, I'm pretty sure that computers exist, because I'm typing this comment on one.)
Nov
13
comment Solving Optics problem with and without differentiation result in different results
Completely unrelated, but I just noticed that the lens outline in your image is just slightly wobbly. Was this maybe scanned and vector-traced from a printed version, or did someone actually draw that lens by hand? o_O
Nov
10
comment Why does correlation length diverge at the percolation threshold?
Related: physics.stackexchange.com/questions/59678/…
Nov
10
comment Does Newton's third law apply to momentum or to forces?
By now, with all the edits and updates, this question and its answers have turned into an all but unreadable mess. In hindsight, this question would've been better suited for a threaded discussion forum (or perhaps for chat) than for Stack Exchange.
Nov
5
comment Do the probability density and the probability current density have a unit
By "(probability) current density", I assume the OP was referring to (probability) flux, which would have units of base quantity per "area" (= surface of a "volume") per time. Of course, $A/m^2 = C/m^2/s$ is a unit of (electric charge) flux, the 1/time part is just hidden inside the definition of the ampere.
Oct
27
comment Why does intramolecular hydrogen bonding cause molecules to separate?
Anyway, I do think that this is a pretty pure chemistry question -- it's not really even "physical chemistry", as the term is conventionally understood -- and, given that it already has a good answer, it might in fact be worth migrating. Yes, I know it could be argued to be on topic here too, but IMO the only real argument to be made for that is that "chemistry is a subset of physics, and so all chemistry questions are on topic", a view which I don't really consider very productive in practice.
Oct
27
comment Why does intramolecular hydrogen bonding cause molecules to separate?
@Chris: IME, mods on most sites don't much like being bothered to migrate questions that could've been "self-migrated" (i.e. deleted and reposted on the other site) by the OP. But, yes, cross-posting as such (i.e. having the same question active on two sites) is generally somewhat disliked. In those rare cases where it may be justified, e.g. to get answers from two very different communities (like, say, Christianity vs. Role-playing Games), it's best to explicitly note it in the respective posts.
Jul
30
comment Why aren't units with powers, like cm³, surrounded by parentheses?
@supercat: The IEC binary prefixes exist precisely for that purpose. If you mean $16 \times 2^{20}$ bytes, write 16 MiB; if you mean $16 \times 10^{6}$ bytes, write 16 MB without the "i".
Jul
29
comment Why aren't units with powers, like cm³, surrounded by parentheses?
@supercat: According to the current ISO/IEC standard, $4\,{\rm kB/s}$ $=$ $4{,}000\,{\rm B/s} $ $\ne$ $4{,}096\,{\rm B/s}$ $=$ $4\,{\rm KiB/s}$.
Jun
6
comment Of all the electrical energy used in a home, is there any portion that won't eventually become thermal energy in the home?
@Klik: It goes outside. Usually mostly into the air, although some setups might also transfer heat into the ground.
Jun
2
comment Why don't two musical instruments sometimes generate destructive interference?
@user6972: Wait, what? How do you get "fundamental tone" from "first five harmonics bins"? Looking at the paper (e.g. Figure 2), it seems pretty clear that they're saying that most of the signal power is in the first five harmonic frequencies, i.e. from the fundamental to the fourth overtone; that's not the same as saying that the signal power would be concentrated in the fundamental frequency alone.
May
30
comment Power fit to some experimental data
NLLS is only (strictly) appropriate if your measurements have additive normally distributed errors. If the errors are mostly multiplicative and log-normal, you do want to use LLS in log space; if they're something more complicated, you either need more advanced methods, or you just pretend your errors are nice and normal / log-normal, even if they really aren't, and hope that your data is clean enough to still give you a decent fit. The real problem isn't so much finding the right fitting method, but that the right method depends on the error distribution, and you usually don't know that.
May
21
comment In the case of riding a bicycle, why can the system of the bicycle and rider be accelerated if no external net force?
@tpg2114: Trust me, a cyclist on a really smooth sheet of ice does accelerate. On average, downwards. Briefly. BTDT.
May
19
comment What will I see in this scenario? Will this be faster than the speed of light?
I'm going to have to give this a -1 as it stands. The answer in your last paragraph is correct, but you seem to have taken a pretty strange and convoluted route to get there.
May
18
comment How does light bend around my finger tip?
@Samuel: Depends on exactly what you mean by a "parallax effect"; even after reading your answer, that's still not 100% clear to me. The bending effect arises because the light from each point in the background arrives at the lens through multiple paths, some of which can be occluded by the foreground object, and because, with the lens not in focus, each of those paths generates a different part of the blurred image. That's a kind of a parallax effect, or at least something related, but not quite what I'd typically think of when speaking of parallax e.g. in photography.
May
8
comment How does light bend around my finger tip?
@MattWilko: Actually, that does not appear to be the case; the observed effect can be fully explained and reproduced by ray optics, with no need for diffraction or other wave effects.
May
8
comment How does light bend around my finger tip?
@BrianFunt: This does not actually seem all that surprising: the human eye has some chromatic aberration, which causes different colors to be in slightly different focus, and thus to experience the bending effect in different amounts. I suspect that photographing this effect would be easiest with a really low-quality camera lens with significant chromatic aberration; a good achromatic lens will defeat your efforts here.
May
7
comment Could a hard drive actually have been erased as described in Cryptonomicon?
@BrandonEnright: I thought so too, at first, but I rather doubt it. The thing is, even an alternating magnetic field still attracts ferromagnetic materials, since the ferromagnet's polarity simply tracks the external field. At least, this holds up to the point where the frequency gets too high for the magnetic domains in the ferromagnet to follow, but at that point the field also becomes an inefficient degausser (since flipping the magnetization in the disks is what you want to do).