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Our future, our universe, and other weighty topics


Thursday, March 9, 2017

Do the “Easy Life” Guys Want 8 Billion Bucks for Metaphysical Reassurance?

On the Ars Technica website, there is a very detailed and lucid explanation of NASA plans to search for life on Europa, a moon of the planet Jupiter. The mission described is fascinating, but it may be a case of people who want to spend 8 billion dollars to reassure themselves that their dubious philosophical assumptions are correct. The mission seems to be all about proving an “easy life” hypothesis, one which seems to be very unlikely to be true from a purely scientific standpoint.

Europa is believed to be covered with a thick layer of ice, but it is believed that deep below that ice is a watery ocean. The plan is to land a robot probe on the icy surface of Europa. The probe will then drill down into the ice, looking for signs of life. Advanced plans for searching for life on Europa have always looked like the plan shown in the NASA visual below. Under such plans a probe would release something that drills down through the ice, and makes contact with the ocean below.

Europa mission
The best way to search for life on Europa (credit: NASA)

When I read the Ars Technica article, I was expecting to hear about a mission such as this, one that would somehow make contact with Europa's ocean underneath its ice. But the article did not describe such a mission. It merely described a mission that would drill down a little into the ice, and look for signs of life inside the ice.

There are two reasons why such a mission seems like a gigantic boondoggle that will almost certainly fail. The first and lesser reason is that even if life had evolved in an ocean underneath Europa's thick icy layer, it is unlikely that signs of such life would pass up all the way through such a layer of ice. That ice is believed to be between 15 and 25 kilometers thick (10 to 15 miles thick). It seems unlikely that any type of organism could survive a journey through such a thick layer of ice.

The second and better reason why such a mission seems very unlikely to succeed is that the chance of life appearing in an ocean of Europa seems extremely low. To calculate this chance, we must consider all of the insanely improbable things that seemed to be required for life to originate from non-life. It seems that to have even the most primitive life originate, you need to have an “information explosion.” Even the most primitive microorganism known to us seems to need a minimum of more than 200,000 base pairs in its DNA (as discussed here).

Scientists have been knocking their heads on the origin-of-life problem for decades, and have made little progress. The origin of even the simplest life seems to require fantastically improbable events. Protein molecules have to be just-right to be functional. It has been calculated that something like 1070 random trials would be needed for a functional protein molecule to appear, and many such protein molecules are needed for life to get started. And so much more is also needed: cells, self-replicating molecules, a genetic code that is an elaborate system of symbolic representations, and also some fantastically improbable luck in regard to homochirality.

Facts such as these are troubling to those who believe in a random, purposeless universe. To such people, it would be embarrassing to have to concede that our planet seems to have been blessed by an astonishingly improbable set of lucky events that got life started. So such people often advance a kind of counter-thesis: what we may call the idea of “easy life.” The “easy life” hypothesis maintains that we didn't get lucky, because given the right ingredients and chemicals, life will inevitably appear. Such thinking is perhaps rather like the daughter's thinking in this conversation:

Mother: Why are you leaving us and heading 2000 miles to Hollywood? The chance of you becoming a star is one in a million.
Daughter: No, it is inevitable that I will become the world's greatest starlet.

When you are faced with a mathematical reality that something that you want to happen is very unlikely to happen, it is very effective psychologically to “cross out” this troubling improbability by maintaining that the thing is not unlikely at all, but instead has a probability of 100%.

In the case of the proposed Europa mission, we have a mission that we might describe as “Desperately Seeking Easy Life.” Some people pitching such a mission want very much for their “easy life” hypothesis to be proven, and they are asking for 8 billion dollars of taxpayer funds so that they can achieve this metaphysical reassurance, and say to themselves, “I'm so relieved – Earth wasn't so lucky!” It's basically the kind of “give me lots of money so I can be reassured about my assumptions” thing that would go on if a fundamentalist group were to ask for millions of taxpayer dollars to fund projects digging underground looking for Noah's ark.

Looking at the probability of life arising by pure chance in Europa's ocean, a purely chemical and biological assessment must rate the probability as being extremely low. Now it is true that there may have been some additional factor involved in the origin of life on Earth. Perhaps life got started here through the action of some divine being or the action of extraterrestrial visitors. But while such a higher power may have acted to spur the start of life on many planets in our galaxy, the chance of such a higher power working to create life in some buried ocean underneath 20 kilometers of ice seems much smaller. So even if we throw in the possibility of some additional power helping life appear in our galaxy, it still seems unlikely that life would exist in Europa's ice-buried ocean, given all of the fantastically improbable things that have to happen for life to appear from non-life.

The proposed Europa mission seems like a fantastically expensive “shot in the dark” that is very unlikely to succeed. Even if some hint of life were to appear, it might well be some ambiguous signal like the one produced by the 1976 Viking mission to Mars. A mission putting cameras down into Europa's ocean might conceivably yield fascinating footage of swimming creatures. But a mission drilling only a little into the ice (like the currently proposed mission) would merely yield some numerical data that might be of interest only to scientists. Such data probably would still be subject to debate, and would be unlikely to give a final decisive answer as to whether life exists on Europa.

We don't need the Europa mission because there are other ongoing scientific research programs that can be used to test the “easy life” hypothesis. One such program is the search for radio signals from extraterrestrial civilizations, with a price tag a tiny fraction of the proposed Europa mission. If the “easy life” hypothesis is true, we would expect such searches to be successful before long. (Their failure so far despite thousands of hours of searching time may be a strong indication that the “easy life” hypothesis is not correct.)

Another such program is the search for atmospheric signs of life from planets revolving around distant stars. If the origin of life is easy, and life is all over the galaxy, we can expect that soon our space instruments will start showing up by-products of life (such as abundant oxygen) in the atmospheres of extrasolar planets.

So an advocate of the “easy life” hypothesis cannot claim that the Europa mission is essential to test such a hypothesis, as the hypothesis will be tested by other programs searching outside of our solar system. 

Postscript:  The selling point constantly made for SETI outside of our solar system is: there are so many planets where life might have appeared, so eventually we'll find something. But that argument cannot be used whenever you are talking about searching for life on one particular moon or planet. Think of it this way. Investing in some telescopic search of many stars (or a radio search of many stars) is like buying two big stacks of lottery tickets. But sending a robot mission to look for life on one moon or planet is like buying a single lottery ticket, and just as unlikely to pay off.  8 billion dollars is way too high to pay for a lottery ticket.