Wednesday, January 30, 2013

Color in the Eye of the Beholder

When you look at a traffic light, what colors can you name? Most people will say that the lights are red, yellow, and green. However, Japanese people often will refer to the light as being blue in color, not green. This has its roots in the history of the Japanese language, as their word ao—until the modern period—covered both green and blue. Ao in Japanese comes from the dye plant, ai, which as a dyestuff covers the whole of the blue-green portion of the spectrum.  Some cultures have what might at first seem to be peculiarly chosen "basic" color names until you learn their associations with the culture's central food sources or dye plants, or precious commodities.

The color name that covers both blue and green in many native languages of the American Southwest is also the name for the stone, turquoise. You can be certain that, in cultures where a staple food is poisonous when green and edible when red, there are separate names for green and red. In our own history, we have a very similar example to the "blue" traffic lights of Japan: "orange" didn't enter English as a color name until the 16th century, after the fruit itself was first brought to England, quite late in the evolution of our color vocabulary, which is why we still refer to "red" hair.

Berlin & Kay—early theorists of the order of evolution of color names—had to, at some point, translate the names their subjects gave to colors into English in order to assign them a place in their evolutionary chart. Often they did this using bilingual subjects, which is of course problematic, since they would already think or operate in two different linguistic color spaces. When they used dictionaries, how had the dictionary writer decided on the English equivalent of the color name?

Finally, most male English speakers can come up with eleven independent color names, but female speakers are far more likely to come up with dozens of color names without straining. Girls are culturally conditioned to be familiar with this terminology from an early age.

 If you want to participate in a color naming experiment, visit, as the folks over there are trying to determine an online color naming model.

Saturday, January 5, 2013

Density of the Universe

The density of the universe seems to be about 10-30 grams per cubic centimeter (source). With a proton having a mass of about 1.67 * 10-24 grams, we have about one proton per million cubic centimeters, i.e. one proton per cubic meter. Since electrons are much less massive than protons, this is also approximately equal to about one hydrogen atom per cubic meter.

So if the mass of the universe were spread evenly throughout space, how much could a container fit? A ten-liter container would thus hold about one-hundredth of a hydrogen atom. Not a lot!
Imagine all the mass of the universe was the size of marbles--how far apart would they be? Assuming all matter is divided up into pebbles, and assuming a pebble has a mass of about 4 grams, this means that we would need 4 * 1030 cubic centimeters (4 * 1015 cubic km) of volume for every pebble to get the right matter density for the universe. This is a lot; assuming equally spaced pebbles, this means that the average distance of one pebble to its closest neighbor is about 1.6 * 1010 cm, or 160,000 kilometers. To put this into perspective, if one pebble is the earth, and another the moon, there would only be one pebble sized distance between them.