Most Life On Earth Is Microbes. We've

We Might Expect Intelligent Life And Technological Communities To Have Emerged In The Universe Billions Of Years Ago. Given That Human Society Is Only A Few Thousand Years Old, And That Human Technological Society Is Mere Centuries Old, The Nature Of A Community With Millions Or Even Billions Of Years Of Technological And Social Progress Cannot Even Be Imagined. ... What Would We Make Of A Billion-year-old Technological Community?

"are We Alone In The Universe?" This Is A Question Which Goes Back To The Dawn Of History, But For Most Of Human History It Has Been In The Province Of Religion And Philosophy. Fifty Or Something Years Ago, However, It Became Part Of Science.

So How Can We Test The Idea That The Transition From Nonlife To Life Is Simple Enough To Happen Repeatedly? The Most Obvious And Straightforward Way Is To Search For A Second Form Of Life On Earth. No Planet Is More Earth-like Than Earth Itself, So If The Path To Life Is Easy, Then Life Should Have Started Up Many Times Over Right Here.

In 1911 The Little Town Of Nakhla In Egypt Was The Scene Of One Of The Most Remarkable Events In Historym When A Chunk Of Rock Fell From The Sky And Killed A Dog. This Is The Only Known Canine Fatality Caused By A Cosmic Object. Improbably Though This Encounter Was Already, Its Truly Extraordinary Nature Was Revealed Only Decades Later When Scientists Found That The Culprit Was Not A Common-or-garden Meteorite, But A Piece Of The Planet Mars.

Scientists Have No Agreed Theory Of The Origin Of Life - Plenty Of Scenarios, Conjectures And Just-so Stories, But Nothing With Solid Experimental Support.