Hacker News: kkylin

New comment by kkylin in "2026 Nobel Prize in Physiology or Medicine: Deisseroth, Hegemann, Nagel"

kkylin — Mon, 05 Oct 2026 17:48:03 +0000

Calcium imaging of neuronal activity (see, e.g., https://alleninstitute.org/education-resources/how-scientist...) is a thing, and has been for a while. It does something like what you said: neurons that have been genetically modified glow briefly, which can be picked up by microscopy. It has many advantages (and some drawbacks) compared to more traditional electrical recording techniques.

New comment by kkylin in "What California is learning from solar panels built over irrigation canals"

kkylin — Wed, 23 Sep 2026 02:07:04 +0000

Happened right here too: thieves opened up man hole covers in city parks and took the wires. The city now has large boulders right over those man hole covers...

New comment by kkylin in "Jean-Pierre Serre turns 100"

kkylin — Wed, 16 Sep 2026 03:10:05 +0000

Euler was a master manipulator of formal expressions; don't think it bothered him very much whether, e.g., an infinite series converged or not. (Unfortunately don't remember a source for this offhand -- maybe a leftover impression from having read ET Bell's book long ago? I also don't know how reliable Bell is.)

Edit: added semi-source

New comment by kkylin in "Necker, 1832: "An optical phænomenon on viewing a figure of a geometrical solid""

kkylin — Mon, 14 Sep 2026 03:51:07 +0000

Just from the title it sounds really cool, but I guess the server got the hug of death (kept getting timeout)

New comment by kkylin in "How an MIT research project became the Julia programming language"

kkylin — Fri, 04 Sep 2026 16:07:22 +0000

There's understandably been a focus on speed, but what I really like about Julia is being able to write clear code: it has a lot of the flexibility and expressiveness that I like in Lisps, but with better numerical libraries than most Lisps/Schemes, and I really like prototyping algorithms in it. To me (an applied mathematician) it is just a nice tool for thinking in. Not having to compromise too much on speed is a big bonus.

New comment by kkylin in "Europe's summer drought is so extreme that desertification is a growing threat"

kkylin — Sun, 30 Aug 2026 16:44:01 +0000

I just came back to CA from the UK, and the two places looked surprisingly alike: yellow fields everywhere

New comment by kkylin in "What's new in Emacs 31.1"

kkylin — Tue, 25 Aug 2026 16:51:47 +0000

Unfortunately the NS/macOS version still needs work as far as I can tell. Even not fully featured it's still useful: I prefer reading PDF in xwidget-webkit than pdf-tools, and it's great to have Jupyter notebooks running inside a browser inside Emacs.

New comment by kkylin in "The lost civic life of movie rental stores"

kkylin — Thu, 30 Jul 2026 15:28:08 +0000

Where I live we still have a locally owned video rental store, though several years ago they put in a bar and now it's more a bar with a video section than a video store where you can get beer and watch movies. We do still rent when there's something we can't stream on one of the services we pay for; I much rather do that than give more $ to Amazon and the like.

New comment by kkylin in "Claude Fable produced a counterexample to the Jacobian Conjecture"

kkylin — Mon, 20 Jul 2026 16:35:58 +0000

New comment by kkylin in "The Boeing 747 begins its final descent"

kkylin — Mon, 29 Jun 2026 00:30:59 +0000

Actually we weren't (& aren't) able to afford this kind of thing. Dad worked for the airline & somehow got this perk, just once.

New comment by kkylin in "The Boeing 747 begins its final descent"

kkylin — Sun, 28 Jun 2026 22:04:20 +0000

We got front lower deck seats once when I was a kid. My sister and I had extra open floor space for playing. It was great.

New comment by kkylin in "The Life and Works of Raoul Bott (2002)"

kkylin — Thu, 11 Jun 2026 15:05:00 +0000

Bott is often quoted as saying "Evrey mathematician has a secret weapon. Mine is Morse theory." Every time I see his name I've tried to look up a source. Finally found one:

https://mathoverflow.net/questions/100316/raoul-botts-quote-...

Anyway if you enjoyed this you might also enjoy

https://www.numdam.org/item/10.1007/BF02698544.pdf

New comment by kkylin in "Lost Images from the 1945 Trinity Nuclear Test Restored"

kkylin — Fri, 22 May 2026 15:27:11 +0000

Slightly off topic (since there's already been so many better answers than I can write), but our knowledge of the dino-slaying asteroid came much later: https://en.wikipedia.org/wiki/Alvarez_hypothesis

New comment by kkylin in "What Do Gödel's Incompleteness Theorems Mean?"

kkylin — Thu, 21 May 2026 17:50:00 +0000

I really do think the incompleteness theorems deserve the attention they get, not just because of what they say about efforts to formalize mathematics and because of the historical context -- remember Gödel numbers came (just) before Turing and the first recognizably modern electronic computers. That numbers can represent things that are not numbers was (IMO) a revolutionary idea.

Having said all that, I'd taken mathematical logic in college to learn about incompletenss, but the most interesting things I got out of it were completeness and compactness. Non-standard models really can be quite interesting.

New comment by kkylin in "The Aperiodic Table"

kkylin — Mon, 18 May 2026 15:33:33 +0000

In addition to the above links on quasicrystals etc, it may help to have a bit of context on periodic tilings, which have very precise mathematical properties: https://en.wikipedia.org/wiki/Lattice_(group).

The structure of the periodic table itself can also be understood, to leading order anyway, in symmetry terms. See for example https://mathstodon.xyz/@johncarlosbaez/112540366778806757 and references there.

New comment by kkylin in "Some Unusual Trees"

kkylin — Sat, 04 Apr 2026 16:30:04 +0000

Of course one reads a (nice) post like this and must add one's favorite not on the list. Here's mine: https://en.wikipedia.org/wiki/Fouquieria_columnaris

New comment by kkylin in "New iPad Air, powered by M4"

kkylin — Mon, 02 Mar 2026 15:14:44 +0000

I had an even older iPad I was happily using for similar use cases. Until one day a family member bricked it and I needed to factory reset. No big deal, I thought -- nothing important on it. Turns out it needed to phone home to do the factory reset, and since the server it wanted to talk to was no longer up (or perhaps the address changed?) I couldn't factory reset the iPad.

If someone has a work-around I'd love to hear it. Until then, or until Apple changes this design, I think I'm done with iPads. I don't want to pay that much to "own" something that Apple can simply make obsolete by reconfiguring or turning off a server somewhere.

Edit: fix typo

New comment by kkylin in "GNU Texmacs"

kkylin — Wed, 25 Feb 2026 19:23:03 +0000

In my couple decades as an academic mathematician I've only ever met one. He was a strong advocate, and got me to install & try it, but I could never convert to using it fulltime.

New comment by kkylin in "In Praise of APL (1977)"

kkylin — Thu, 22 Jan 2026 17:14:00 +0000

I've had the same dream! thanks for the pointer.

New comment by kkylin in "MIT Missing Semester 2026"

kkylin — Tue, 23 Dec 2025 00:55:53 +0000

Yes, 1.00 was popular with Course 6ers who wanted easy units.