# reperiendi

## Making of Wolverine’s claws

Posted in Fun links by Mike Stay on 2011 July 11

## Axiom of fun choice

Posted in Fun links, Math by Mike Stay on 2011 April 14

A fun choice function is a function $f$ defined on a collection $J$ of jobs that must be done such that for every job $j \in J, f(j)$ is an element of fun. The axiom of fun choice states,

For any set $\displaystyle J$ of jobs that must be done, there exists a fun choice function defined on $\displaystyle J.$

This axiom asserts that one can always find the fun in any job that must be done; a theorem of Poppins deduces from this that all such jobs are games.

## Bioluminescence

Posted in Evolution, Fun links by Mike Stay on 2011 January 31

Australia’s massive forest fires in 2006 were followed by 10cm of rain, which washed all the nutrient-rich ash into the lakes, which caused a bioluminescent algae bloom in 2008.

## Regular tilings of three-dimensional spaces

Posted in Astronomy, Fun links, General physics, Math by Mike Stay on 2011 January 31

If you start at the north pole and make an equilateral triangle 6000 miles on a side, the bottom will lie on the equator, each of the angles will be 90 degrees, and only four of them will fit around the pole.

In a similar way, large enough tetrahedra would tile the surface of a hypersphere. This paper identifies the eleven regular tilings of three-dimensional spaces and whether they’re spherical, Euclidean, or hyperbolic tilings, and then looks at the geometry of spacetime to see how it might be tiled.

The “cubic” tilings (where eight polyhedra meet around a vertex like cubes do in Euclidean space) are amenable to taking cross-sections; this tiling of hyperbolic space with dodecahedra

has a cross section with a tiling of the hyperbolic plane with pentagons:

## Lazulinos

Posted in Borges, Fun links, General physics, Perception, Quantum by Mike Stay on 2010 April 27

Lazulinos are quasiparticles in a naturally occurring Bose-Einstein condensate first described in 1977 by the Scottish physicist Alexander Craigie while at the University of Lahore [3]. The quasiparticles are weakly bound by an interaction for which neither the position nor number operator commutes with the Hamiltonian. A measurement of a lazulino’s position will cause the condensate to go into a superposition of number states, and a subsequent measurement of the population will return a random number; also, counting the lazulinos at two different times will likely give different results.

Their name derives from the stone lapis lazuli and means, roughly, “little blue stone”. Lazulinos are so named because even though the crystals in which they arise absorb visible light, and would otherwise be jet black, they lose energy through surface plasmons in the form of near-ultraviolet photons, with visible peaks at 380, 402, and 417nm. Optical interference imparts a “laser speckle” quality to the emitted light; Craigie described the effect in a famously poetic way: “Their colour is the blue that we are permitted to see only in our dreams”. What makes lazulinos particularly interesting is that they are massive and macroscopic. Since the number operator does not commute with the Hamiltonian, lazulinos themselves do not have a well-defined mass; if the population is N, then the mass of any particular lazulino is m/N, where m is the total mass of the condensate.

In a recent follow-up to the “quantum mirage” experiment [2], Don Eigler’s group at IBM used a scanning tunneling microscope to implement “quantum mancala”—picking up the lazulino ‘stones’ in a particular location usually changes the number of stones, so the strategy for winning becomes much more complicated. In order to pick up a fixed number of stones, you must choose a superposition of locations [1].

1. C.P. Lutz and D.M. Eigler, “Quantum Mancala: Manipulating Lazulino Condensates,” Nature 465, 132 (2010).
2. H.C. Manoharan, C.P. Lutz and D.M. Eigler, “Quantum Mirages: The Coherent Projection of Electronic Structure,” Nature 403, 512 (2000). Images available at http://www.almaden.ibm.com/almaden/media/image_mirage.html
3. A. Craigie, “Surface plasmons in cobalt-doped Y3Al5O12,” Phys. Rev. D 15 (1977). Also available at http://tinyurl.com/35oyrnd.

## The best of the worst

Posted in Fun links by Mike Stay on 2008 August 13

## Hou tu pranownse Inglish

Posted in Fun links by Mike Stay on 2008 June 17

There are rules for pronouncing American English given the spelling; there are just a lot of them, and they’re ugly.  No one’s going to get educated people to change how they spell–they’ve invested too much in learning it, and there’s too much legacy.  But the way people speak, their dialect, varies widely with geography.  So why not introduce a new one that pronounces words as they’re written?

## Cool robot

Posted in Fun links by Mike Stay on 2008 March 18

Posted in Fun links, History, Theocosmology by Mike Stay on 2008 March 8

http://farms.byu.edu/display.php?table=jbms&id=112

Some excerpts:

“Also worth noting is the relative strength of comparative linguistic evidence. The nature of comparative linguistic evidence provides large bodies of data—several thousand words per language—that is nonforgeable. Ruins and buildings yield some facts, though who built them is not always one of the facts revealed. Words of a translation can be debated endlessly, and written records can feasibly be forged, but no one can fabricate a language family of several Native American tribes speaking a variety of related languages…

“In addition to numerous lexical similarities, some features of Northwest Semitic morphology are still productive in UA, i.e., are still functionally active, such as the masculine plural suffix and niqtal prefix, while much more is fossilized, i.e., nonfunctional “frozen” patterns are detectable such as the feminine plural, qittel forms, hiqtîl and huqtal forms, etc. With that in mind, consider a few of some 1,000 identified similarities between Hebrew and Uto-Aztecan…

“Among Latter-day Saint scholars are a few Semitists, to whom queries regarding the validity of the Semitic data can be directed. As for Latter-day Saint Uto-Aztecanists, I know of no others besides myself. Therefore, because it may be difficult for nonspecialists to assess the merit of proposed linguistic connections, it may be well to mention that I have privately shared this material with five Uto-Aztecanists (linguists who have studied and published in UA linguistics) and four of the five were quite overwhelmed at the quantity and quality of the evidence—two spoke very highly of it; two, in surprise, could hardly speak at all after seeing it; and the fifth did not like the proposal generally, but offered no substantive refutations.”

## Computer-aided Origami

Posted in Design, Fun links, Math by Mike Stay on 2008 February 26

With really cool bugs!

http://www.langorigami.com/index.php4

## Touch-sensitive plant

Posted in Fun links by Mike Stay on 2008 February 26

Mimosa pudica – this stuff was all over the place in Guatemala.  The tender leaves fold up, drop down, and expose lots of thorns.

## A most excellent gentleman

Posted in Fun links, Time by Mike Stay on 2008 February 26

## Seriously silly

Posted in Fun links by Mike Stay on 2007 August 2

## Giger’s Alien in Lego

Posted in Fun links by Mike Stay on 2007 June 20

## Exponential growth

Posted in Fun links, Math by Mike Stay on 2007 June 1

## Totally. Awesome.

Posted in Fun links by Mike Stay on 2007 May 30

## The metallurgy of utensils

Posted in Fun links by Mike Stay on 2007 May 1

## Cellular automaton for land combat

Posted in Fun links, Programming by Mike Stay on 2007 April 27

This CA was developed to simulate land combat and presented in a Smithsonian lecture. Really cool pictures.

## Universality of nonlinear media

Posted in Fun links, Math, Programming by Mike Stay on 2007 April 27

Here’s a neat paper comparing cellular automata and solitons in several different nonlinear media.

## What’s in a name?

Posted in Fun links by Mike Stay on 2007 April 23

## Try to see things my way…

Posted in Fun links, Perception by Mike Stay on 2007 April 19

Mice adapt to becoming trichromats pretty easily.

## Time

Posted in Fun links, Time by Mike Stay on 2007 March 10

## Diatoms as nanomachines

Posted in Fun links by Mike Stay on 2007 March 9

## Turning photo albums into 3d-walk-throughs

Posted in Fun links, Perception by Mike Stay on 2007 March 3

## Powers of 10 toward the black hole in the center of the galaxy

Posted in Astronomy, Fun links, Math by Mike Stay on 2007 January 30

http://www.cs.indiana.edu/%7Ehanson/Movies/blackhole.mov

Also see Hanson’s other visualizations here:
http://www.cs.indiana.edu/~hanson/
and this 3-d projection of the 5-d Calabi-Yau manifold:
http://www.bathsheba.com/crystal/calabiyau/

## Great site on the inner complexities of a piano

Posted in Fun links by Mike Stay on 2007 January 26

## Potion +5 against Sandman

Posted in Fun links, Perception, Time by Mike Stay on 2006 December 4

## Coolest crossover idea I’ve ever heard

Posted in Fun links by Mike Stay on 2006 December 2

Terminator, The Matrix, and Battlestar Galatica:
http://randytayler.livejournal.com/21122.html

## "I looked out the window and what did I see…"

Posted in Chemistry, Fun links by Mike Stay on 2006 December 2

Salting your popcorn with liquid sodium and chlorine gas!

## A pool of oobleck

Posted in Fun links by Mike Stay on 2006 December 1

## Star Wars Kid remixes

Posted in Fun links by Mike Stay on 2006 December 1

## White and nerdy

Posted in Fun links by Mike Stay on 2006 December 1

Coming from one who speaks Javascript and Klingon, Weird Al’s White and Nerdy is brilliant.

## Go for a swim

Posted in Design, Fun links by Mike Stay on 2006 October 26

## A critical analysis of Vernor Vinge’s Singularity

Posted in Fun links, Theocosmology by Mike Stay on 2006 October 4

## Dinosaur blood

Posted in Evolution, Fun links, History by Mike Stay on 2006 October 3