Many reasons to hide exist. In the animal kingdom, concealment—crypsis—is the ability to avoid detection using visual, olefactory (smell), or auditory techniques. While the tactics vary greatly, the strategic purpose is generally either an antipredator adaptation (what animal wants to be eaten?) or a predation strategy (what predator wants its hunting to be detected?).
Camouflage—the visual form of crypsis—is accomplished in several ways: a creature can modify its appearance to resemble its surroundings; it can use disruptive coloration (employing strongly contrasting patterns or colors to hide edges or distinguishing characteristics); it can eliminate shadows by fitting and flattening to its… Read the rest
People have always prized “the real thing” over copies. This is why there is only one Mona Lisa. Extremely accurate copies can be made, but they are not prized nearly as highly as the priceless original. The idea that the copy is inferior to the original goes back at least as far as Plato’s “Republic”, where the ideas of “imitation” and “copy” are discussed in philosophical terms.
Other commonplace expressions convey this similar concept: we say “It’s the real McCoy” and “It’s the genuine article”.
But favoritism for originals is not an absolute rule: sometimes the copy is good enough.… Read the rest
Aluminum is one of today’s most commonly-used metals, but its use is relatively new. Unlike some metals, for instance gold, aluminum does not naturally occur in metallic form. Moreover, aluminum didn’t exist at all in metallic form 200 years ago.
Most of today’s aluminum is either refined from bauxite, its primary ore, or it is recycled aluminum. Recycling aluminum is increasingly common, as aluminum is infinitely recyclable and the recycling of aluminum products and alloys is very energy efficient when compared to refining bauxite.
Refining bauxite into metallic aluminum happens in two stages. Bauxite is first mined, often from shallow… Read the rest