Are We Alone?

NASA scientists, those champions of global warming, now have predicted that within 20 years we will have established that there is alien life on some distant planet in the universe … see: CBS Story. Actually this prediction is limited to our galaxy, the Milky Way, where NASA estimates that there are “100 million worlds within the Milky Way galaxy [that] are able to sustain complex life forms.” Who am I to argue with such considered logic? But notice NASA does not use the term “intelligent life forms” nor do they suggest that we might communicate with them … nor visit them … nor even have them visit us. I have in the past done some rudimentary analysis on this very subject (see: Cosmic Silence ) which I would like to apply to NASA’s newer speculations.

Let us start with some facts about the Milky Way … it has about 200 billion stars, is about 13.6 billion years old and is 120,000 light years across.  Our solar system is about 26,000 light years from its center … or roughly half way out from its center … see: Universe Today.  I would now like to slice this prediction two ways … by time and space.

First let’s look at time horizons: The Milky Way is about 13.6 billion years old and our earth is about 1/10 of that age ... all back-end loaded.  I would imagine that many of these other NASA theorized exo-planets are either yet to be ... or have been burnt to a crisp when their suns became red giants. So, if NASA did not account for these life-limiting events, automatically these 100 million of stars with habitable exo-planets is reduced by some large factor.  But, you know what, I’ll here give NASA the benefit of the doubt and keep their number at 100 million.

From my previous analysis I opine that “sapient life on our earth has existed for perhaps only a million years ... or 1/13,000 of this earth's existence and scientific advancement sufficient to understand our time and place in the universe has existed for, at most, 100 years ... or 1/130,000,000 of this planets existence.  Let us (optimistically) imagine that this enlightenment age on earth will last for another 13,000 years.  This would result in a sapient window for our planet to be about 1/1,000,000 (one-millionth) of its total existence ... which fraction I suggest should then apply to other exo-planets.”  So this logic would reduce NASA’s estimate to only 100 exo-planets in the Milky Way with current intelligent life forms (within their sapient windows) … out of NASA’s 100 million estimated exo-planets with any form of complex life. But still encouraging … no?

But next we still have to deal with immense distances. Simple geometry says that the average distance to any other exo-planet in our Milky Way (our sun’s nearest star, Proxima Centauri, a red dwarf, being 4.22 light years and the furthest, being about 94,000 light years) is almost 47,000 light years … clearly such distances preclude much intra-galactic travel … even if one could travel at the speed of light (which, according to Einstein is impossible.)  It also eliminates much possible contemporary communications … even with electro-magnetic waves traveling at near to the speed of light … unless such distant exo-planet’s sapient window is within the last 47,000 years. And, even at that, the turn-around time to acknowledge a “hello” would not reach them until the year 49,014 AD … at which point they might have forgotten that they sent the message to begin with.

So, let us make things easier and estimate that we will only hope for intelligent life on those exo-planets that lie within 100 light years of our solar system (assumedly all within our Milky Way). It is estimated that the number of stars that are within this arc is some 15,000 (see: Imagine) ... but lets make it simpler by upping it to 20,000.  This is 1/10,000,000 (one ten millionth) of the stars in the Milky Way … which proportion needs then to be applied to that 100 exo-planets estimate in the whole Milky Way with possible intelligent life (from paragraph four above).  This says to me that the chances that there is an exo-planet within 100 light years of Earth with intelligent life at 1 in 100,000 (=100/10,000,000).

Clearly not very possible … yet we are spending billions of dollars to get these ETs to phone home. We Earthlings (and NASA) clearly are romantic souls ...

Afterward: This analysis (like my other blog referenced above) does not show that there is not any life nor intelligent life anywhere in the Milky Way. In fact, if one's vista was to include the entire universe, I do believe that it is quite likely that there is such life ... and even intelligent life ... out there. But what is does conclude is that it is very, very unlikely for us ever to have any conclusive evidence that intelligent life exists or did exist elsewhere.  The time and space constraints are just too vast.