A new Journal of Cosmology article says that sealed deep in the water-clay-full sort of (CI1 carbonaceous) meteorites that likely come from comets, one consistently finds forms that look visually and chemically like ancient bacteria fossils. Typical reactions:
This effort clearly falls into the category of “extraordinary claims” that require extraordinary evidence. (more)
Dr David Marais, an astrobiologist with NASA’s AMES Research Centre, said he was very cautious about jumping on the bandwagon. These kinds of claims have been made before, he noted and found to be false. “It’s an extraordinary claim, and thus I’ll need extraordinary evidence,” he said. (more)
Those are odd and intriguing formations, to be sure. … Contamination, no matter how unlikely, is a more mundane explanation than extraterrestrial life, and Occam’s Razor will always shave very closely here. We have to be very, very clear that contamination was impossible before seriously entertaining the idea that these structures are space-borne life. I’ll be honest: my own reaction is one of extreme skepticism. As it should be! All things being equal, I would take news like this with a very large grain of salt, and want a whole lot of outside expert analysis. (more)
The last one links to this explanation:
Extraordinary claims require extraordinary evidence because they usually contradict claims that are backed by extraordinary evidence. The evidence for the extraordinary claim must support the new claim as well as explain why the old claims that are now being abandoned, previously appeared to be correct.
Alas, these attitudes make far more sense in status terms than in information terms.
In status terms, it would of course be big news to hear that academia had declared its consensus that alien life had most likely been found. Academia’s public and patrons would take heed, and the academics associated with inducing that event would gain high status. So academics want to ensure that only folks with quite impressive academic abilities could gain such a prestigious honor. Thus they naturally want to that this honor goes to folks with extremely impressive data, methods, etc. And this paper, published in a low prestige journal by a low prestige academic, using solid but not especially difficult techniques, seems below that bar.
But in information terms, this new result does seem in the ballpark of tipping us over the threshold of thinking it likely than alien life has been found.
First, our prior estimate that alien life would be found in comet-based meteorites should have been pretty high. The idea that life came here from out there is a standard reasonable view:
Panspermia is no longer a marginalized view. It may not yet be the majority opinion, but it shows up often in journal articles and conference proceedings.
Counting by volume, comets seem the most likely place to find such life, and so meteorites from comets would be the most likely place to find alien fossils. We also seem to see alien fossils from Mars. Furthermore, the only known betting market on this topic has for 15 years consistently said we’d find evidence of alien life by 2050:
Not only should our prior on finding alien life in comets be high, the likelihood of this new data seems much higher if alien comet life were common than if it didn’t exist. This new data was was careful to examine only opened surfaces in a sterile vacuum:
The study was confined to investigations of uncoated, freshly fractured, interior surfaces of the meteorites. All tools, sample holders and stubs were flame sterilized. Lunar dust samples and silicon wafers were used as negative controls. … The meteorites were stored in sealed vials at -80 oC and after preparation, electron microscopy stubs were kept in sealed containers in dessicator cabinets or in the freezer. The fusion crust and old cracks in the stones were carefully avoided. The meteorite samples were placed in the instrument chamber (with the fresh fracture surface up) a pumped down immediately after the stones were fractured. All solvents, acids or other liquids were strictly avoided. … Only one seriously Murchison sample was found to be contaminated with fungal filaments (in old cracks in the fusion crust) and not a single pollen grain has been encountered during extensive studies of carbonaceous meteorites carried out since 1996 at the NASA/Marshall Space Flight Center.
Furthermore, the chemical signatures found match ancient fossils far better than recent life. And how could meteorites that fell to Earth a century ago get contaminated with ancient Earth fossils? Yes these forms might have non-biological explanations, but the point is the likelihood ratio – that such forms that look much like known life are much more likely given life than given not.
Informationally, a nearly neutral prior together with a strong new likelihood ratio should have us now accepting the claim as more likely than not. But academia will not publicly admit that fact until they can find a status holder to credit who they consider worthy of the honor. The journal says:
Members of the Scientific community were invited to analyze the results and to write critical commentaries or to speculate about the implications. These commentaries will be published on March 7 through March 10, 2011.
I’d bet these commentaries will mostly say this is interesting but doubts remain, that this evidence is too ordinary to support its “extraordinary” conclusion, and yet they’ll refuse to bet on the subject. How sad is that?
Added 2:30p: This claims Ladbrokes offers 1000 to one odds against finding alien life, but I can’t find more details online. This says William Hill offers 100 to one odds against “proof of the existence of intelligent extra-terrestrial life will be provided within a year”, but there’s no word on longer time scales. PaddyPower‘s odds estimate a <20% chance “The sitting President of the USA making a statement confirming without doubt the existence of alternative life beings from another planet” after 2020, and a <30% chance for before 2020 (including a 2.5% chance for 2011). An Intrade offer of 5% for a NASA announcement by 2013 also implies ~2.5%/year.