プランクトン(πλαγκτος)

植物プランクトンは光合成によってエネルギーを生産し、有光層と呼ばれる海や湖の水面で生活する。光合成を通じ、植物プランクトンは二酸化炭素を「食べて」、酸素を生成する地球上の酸素の維持に大きな役割を果たし、植物全体の酸素生産量のおよそ半分を担っている。植物プランクトンの固定した二酸化炭素は、海水中や淡水中の食物連鎖の基礎になっている。鎖の数が少ないという意味において、海中で最も注目に値する食物連鎖の1つは、植物プランクトンがオキアミに食べられ、それをヒゲクジラが食べるというものである。

Anthropic principle

In cosmology and philosophy of science, the anthropic principle, also known as the observation selection effect, is the proposition that the range of possible observations that could be made about the universe is limited by the fact that observations are only possible in the type of universe that is capable of developing observers in the first place. Proponents of the anthropic principle argue that it explains why the universe has the age and the fundamental physical constants necessary to accommodate intelligent life. If either had been significantly different, no one would have been around to make observations. Anthropic reasoning has been used to address the question as to why certain measured physical constants take the values that they do, rather than some other arbitrary values, and to explain a perception that the universe appears to be finely tuned for the existence of life.