Rare Earth hypothesis

The Rare Earth hypothesis suggests that life on Earth needed an improbable combination of astrophysical and geological circumstances. It is proposed by Peter Ward and Donald Brownlee. If it is true, then the chances of extraterrestrial life elsewhere is close to none.

The idea has nothing to do with the chemicals known as rare earths. The proposed idea suggests that the Earth itself is rare. Certainly, we do not know how rare it is or is not. At present we cannot see planets as small as Earth orbiting their stars. Presumably that could be decided if our powers of magnification were great enough.