Random Ramblings to 8 August 2009

Archivist
A person who maintains the material in an archive. This can involve collecting, organising and assessing the records. Among their skills, they show expertise in preserving the physical media on which information is contained. In WoW, Auriaya is the archivist for the secrets of Ulduar.

Information asymmetry
A concept in economics which suggests that buyers and sellers in a real-world market cannot find each other easily (lacking information about each others' presence). One needs to search for the other before a trade can occur. However, doing extra searching will come at a cost, so these costs should be balanced against the benefits expected in deciding which to do.

Methanol
An alcohol having the chemical formula CH₃OH. Unlike its cousin ethanol (drinking alcohol), it is highly poisonous, where, if it does not kill, it can cause permanent blindness. It is commonly used in methylated spirits and commonly converted into formaldehyde for (among other things) plastics and paint. Not to be mistaken with menthol.

A bottle of ethanol denatured with methanol.

Metric system
A system of measurements originating in France that is based on the unit of length of the metre. It solved the problem of difficult conversion between units in the Imperial system. Namely, conversion simply involves multiplying the quantity by a certain power of 10 (effectively just moving the decimal point). The base unit is prefixed accordingly (e.g. kilo- means "multiply by 1000"). Its units are based on the properties of simple objects such as the Earth and water. For example, the metre was defined as ¹/_10000000 the length of the half-meridian through Paris, and the gram was defined as the mass of one cubic centimetre of water.

The International Prototype Metre, whose length represents one metre. It has since been deprecated in favour of reproducible experiments.

Mutually exclusive events
Events that cannot reasonably happen at the same time (e.g. a person being both male and female). This concept is commonly used in probability, statistics and logic.

RGB colour model
A system of rendering all of the colours of the rainbow using red, green and blue light. It involves additive mixing of colours, since lights of these colours are cast on a black surface, adding brightness to it. Mixing red and green lights gives yellow, while mixing all three lights can create white. Technically, the surface is white, black only because of an absence of light.


Red, green and blue spotlights arranged in a colour wheel.

RhombusA quadrilateral whose sides are of equal length. It is commonly referred to as a diamond. A square is a special rhombus where all sides are at right angles to each other.