A friend of mine asked me today what I thought about UFOs and ETs. I hold two seemingly inconsistent thoughts on the subject. One is encapsulated in a typically Feynman comment (primarily regarding religion). I forget the lead up, but the punch line was: ‘And he came to Earth, he came to planet EARTH, mind you … I mean, look what’s out there!’

Richard Feynman was referring to the huge number (over 10,000,000,000,000,000,000,000) of stars and planetary systems ‘out there’, some much older than our own, some much younger, but all made up from the same 92 constituent chemical elements, all behaving in identical ways to those here on Earth. The implications are overwhelming; not only are there ETs ‘out there’, there are multitudes of them.

To which the traditional anthropocentric response is “Well, where are they then?” implying any alien worth their salt would want as a first priority to inform humans of their existence. I have two thoughts on this.

(1) Radio communication has only been possible here on Earth for the last 100 years or so, and is only likely to be used for perhaps another 100 years before we find something more effective (think of smoke signals, posting a letter, or the telegraph). This gives us a maximum radio window of say 200 years, and therefore a 200 light year range in the nearest stars with which to potentially communicate by radio. This amounts to about 20,000 stars in our solar vicinity.

Given similar evolution rates to those of life here on Earth, this limits us to a time window of some 200 years out of the 4,000,000,000 years of evolution here on Earth. Or just a 1 in 20,000,000 chance of any one of those 20,000 stars being at the right distance and at the right stage of evolutionary development to make radio contact. In other words, a 1000 to 1 chance against of ever making radio contact with anyone.

(2) The second consideration is mundanely human: if you were an advanced alien life form, and had closely observed and monitored human society for thousands of years, would you wish to make contact? As a human being (on a good day) I’m pretty damn sure I wouldn’t!