Our search for E.T. hasn't covered much space

摘要

With no luck so far in our six-decade search for alien signals, you'd be forgiven for wondering, "Where is everyone?" A new calculation shows that the volume of observable space combed for E.T. is equivalent to searching a large hot tub's orth of, water for evidence of fish in Earth's oceans, Penn State astronomer Jason Wright and colleagues write in a paper posted online September 19 at arXiv.org. In a "hot tub's worth of water in the ocean, you wouldn't always expect a fish." Wright says.