and Project Seti
R is the average rate of star formation in the galaxy.
This last term is the most ambiguous. I hear them talking on TV about civilizations "blowing themselves up" ... sheeeesh. They go on quite scientifically with the others till they get here. When they realize that the other calculations leave you with a universe teaming with intelligent life, they "feel" that they must "tone it down a bit" to remain respectable (No UFO believers here! Not us! Nosiree. So ... please ... take us seriously ... please).
Fact is, the mean lifetime of a civilization is indeterminate. True, maybe some here & there blow themselves up ... but ... to be scientific ... we shouldn't ascribe to planetary suicide a percentage greater than the percentage to which we have some accurate knowledge ... namely ... the suicide of individuals, i.e. less than one percent. Therefore, for all practical purposes this term falls out of the equation.
Then why has Project Seti failed to find anybody so far?
This is the rub. To proceed with Seti ... the probability must be kept low but not impossible. Understand that many people have their lives invested in this project and they haven't found anything. By their criterion, this means that there must be "few" civilizations out there trying to communicate. Hence, they need funding. Hence, they get some funding. But ... nothing is showing up.
After years of looking at uncountable millions of stellar systems ... nothing. Without the Last term's ... ambiguity, they cannot schlump around for more funding. They would have to give up their life's work ... a horrible prospect.
Well ... what is it?
Every other term leads one to believe that there are hundreds of thousands of planets out there able to communicate ... and ... that includes ONLY indigenous populations (on their home planet). Can't we presume that they gradually colonize the galaxy?
If they could colonize worlds other than their own ... well ... that puts the figure in the billions. They don't dare do the math here. It's overwhelming. A single planet could easily colonize the entire galaxy in 100 million years. In fact, that's why Enrico Fermi did not believe there were other civilizations in our galaxy ... for if there were he said,
So, Project Seti adherents must be absolutely opposed to the possibility of interstellar travel ... or ... just deny the finality of the math. They have to pull the wool over their own eyes to avoid the horrible prospect that they are headed in the wrong direction. They must assert that there are few civilizations out there ... and ... they can't colonize either. Seti-ites are now backed into a corner from which they cannot extricate themselves.
The absence of data is evidence of absence ... just not total absence.
And they are headed in the wrong direction.
The truth is undoubtedly that it's like dodge'em cars out there. They're here already just as Fermi would have expected (and to which multitudes of witnesses have attested). But they don't say anything for the very reasons I've given elsewhere on this site and others have pointed out as well.
The "L" factor should be given a number of about 200 years ... the amount of time that a communicating civilization broadcasts messages of its presence to the galaxy at large. After that amount of time ... they encode their data as a simple act of privacy. If you were sending letters to another individual or to yourself as in a diary ... would you want everyone else to be reading it? Maybe a teenager wants everyone else to notice him (loud car stereo), but no sophisticated, experienced adult drops his pants in public.
This is why Seti has failed. The data stream from any individual planet dries up in a short span. You have to be very lucky indeed to find that needle. Perhaps they might one day turn up an unintelligible "hiss". But, in principle, it will NEVER be decoded. Think we can tackle 1,000,000 bit encryption? Or, something even more difficult?
Seti ain't gonna' fly ... ever. We're not going to get off that cheap.
But keep on looking. Maybe some day they will find an alien
Now, that would be interesting ...