For all we know, that could be a vast overestimate.
So then let's just agree on a likely percentage. That should be pretty easy, right? How small of a percentage are we willing to accept when discussing the
possibility of life arising on other planets.
In our own Solar System, life is known to exist on 1 of the 8 planets. We are still awaiting confirmation of Mars having life in the distant past, but all the signs are there - we just need confirmation. However, for fairness, I will not assume that life ever existed on Mars and we'll just stick with the 1-in-8 chance for now. But I wouldn't dare use a 1-in-8 ratio for the rest of the Universe, because there are simply too many variables involved. Will we accept 1-in-100,000? 1-in-1Million? 1-in-1Billion?
Seriously, let's just come to an agreement on the percentage point and then use some known data to determine the likelihood of life arising elsewhere in the Universe.
.00000000001% ?
.000000000000000000001% ?
**** it. Let's use the smallest number. That's one-one hundred quadrillionth % chance
800 Octillion stars x .000000000000000000001% = 800 Million Solar Systems
We know from actual observations that anywhere from 6-22% of stars in the Milky Way host terrestrial planets in the habitable zone. (We've discovered more than 1,000 exoplanets to date)
So let's use the smaller number, @ 6%. This assumes that for the 800 Million suggested Solar Systems, only 6% of those have planets that could possibly host life as we know it.
800 Million x .06 = 48 Million.
So there's 48 million possible life hosting planets, right? Do you know how many highly unlikely things happen 1 in 50 Million times?
Split Colored Lobsters...
http://wtop.com/watercooler/2015/07/split-colored-lobster-caught-off-maine-1-in-50-million-find/
Identical Triplets...
http://www.metro.us/new-york/rare-i...e-in-50-million-chance/zsJoir---j065RwuTjz7k/
So things are super ****ing rare, but they happen, don't they? The odds are certainly stacked against them and the variable needed to match up are almost incredibly hopeless if you're just waiting around for it to happen. But, at the end of the day, they do happen, don't they?
If people play the lottery, what are their chances of winning? If it's Powerball, the chances of wining on a single ticket are ridiculously slim - like 1 in 175 Million. But people do win the powerball on a single ticket, don't they? I mean, the largest single Powerball jackpot in history was one on the purchase of a single ticket...
http://www.nbcnews.com/news/us-news...0m-ticket-sold-michigan-shell-station-n436666
So, ridiculously rare things still obviously happen... At what point do we have to admit that it's fairly likely that life exists elsewhere in the Universe? How big of a number do we have to use before we concede that it's impossible? Is it even possible to whittle down the possibility to a number so small as to make it impossible given what we know at this point about Astrobiology?