The Twilight Zone, Part II: Is there life out there in space?

This is the second in our 3-part series on the idea of ETI (extra-terrestrial intelligence), and the theories and ideas that astronomers and cosmologists have typically advanced.  We're specifically triggered to do this by an article we referred to yesterday, by Howard Smith in the latest American Scientist.  See Part I for more on the source, and for background.

Within his area of expertise, Smith makes many valuable points about why he believes that either there is no intelligent life 'out there', or why even if there is it's moot to talk about because we'll never detect it.  However, we think he is typical of astronomers who seem to feel no restraint in leaving their own field, which they know about, to speculate very naively about evolution,  for reasons we'll discuss below.  But let's briefly consider his more robust points about ETI first.

First, he's only talking about 'intelligent beings'.  Micro-organisms that can't communicate with us are irrelevant.  If there's only 'primitive life' out there, for all intents and purposes we're still alone -- the life he's interested in has to have something equivalent to a radio technology with which to send signals.

That life has to be close enough to Earth to allow a signal to get here, or for ours to get there, before the universe ends.  It has to be within the 'cosmic horizon', the constraint being how far light can travel within the age of the universe.  Since the universe is expanding and distances are getting larger, this further restricts the possible planets from which signals can reach us.  And distant signals of course represent not life as it exists now, but life as it existed perhaps eons ago when the signals were sent, so we may never catch up with ETI in anything like real time.  But this means that that distant life would have evolved a lot sooner than life on Earth.

And that distant planet has to be stable, that is its host star must be a stable size, with stable enough radiative output to have given life time to evolve, and of the right age -- not too young that life didn't have time to evolve, and not too old that the star's luminosity, which increases with time, isn't too great to have overwhelmed and destroyed the planet (many of these criteria might in fact be called the Goldilocks criteria).

The planet's orbit must be just right vis à vis its star, planetary mass must be "massive enough to hold an atmosphere, but not so massive that plate tectonics are inhibited, because that would reduce geological processing and its crucial consequences for life."

And the planet must "contain elements needed for complex molecules (carbon, for example), but it also needs elements that are perhaps not necessary for making life itself but that are essential for the environment that can host intelligent life: silicon and iron, for example, to enable plate tectonics, and a magnetic field to shield the planet's surface from lethal charged winds from its star."

But now, Smith works out some--indeed many--of his calculations from what seems to be an evolutionary point of view.  Life has to start and then evolve to become intelligent.  Here, let's take for granted that we know what 'intelligent' means.

In a nutshell, Smith asks how many planets have liquid water.  How many have ample carbon.  How many would be in systems where gravitational and other forces tilt the planet at an angle so it has seasonality of climate.  How many have physical and gravitational properties that will lead to an atmosphere.  How many have radioactive cores or other means by which they have plate tectonics to shift around the hardened crust and renew or recycle needed elements for life.  How many would have the billions of years needed for intelligence to evolve, which has to do with the age of their solar systems.  How many would circle around only one star rather than two, so their gravitational status was stable and so they did not have long cycles of being too hot or too cold.  In how many could DNA evolve and function, leading to intelligent beings.  And so on.

It all sounds sensible and of course the questions are relevant.  But what they ask in essence is: how many planets are just like earth and their life like earth-life? But that is far off the central question--are we alone in the universe?

The criteria he uses are post hoc--they say this is how earth-life evolved, and so this must be how other life has to evolve, so let's see how likely it is that just the same conditions exist elsewhere.

Playing the infinity game we discussed in Part I, one could say that if the universe is infinite, then the same conditions must exist (infinitely many times!) in the universe.  But if the universe is finite--even no matter how big and how numerous its stars--then things become different.  That's because if you multiply guesstimates of the probabilities of all the just-like-earth conditions, the net probability of all of them being true will become infinitesimally small.  Then, even if there is a planet that's just-like-earth, the likelihood of being contemporaneous (in the galactic communication sense) with us would be so small as to lead to the conclusion--his conclusion--that we better take care here because we're the only here there is.

Of course there is no way to know how different among these earthy planets conditions could be and still be compatible with life, and again the issue is probabiltity of earthy viability times the number of existing space-objects that could in principle, host life. If the product is greater than one, then the statistical expectation is that there is at least one such planet somewhere.

On the other hand, this is exceedingly naive evolutionary thinking.  Astronomers should stick to their telescopes.  The core facts of evolution as a process are divergence from shared origin and adaptive change.  There are also some other basic aspects of earthly life that Smith doesn't mention, but that are the main points in our book The Mermaid's Tale, such as the sequestering of interacting but semi-independent units, combinatorial information transfer (signaling), and so on.

There is no reason that life elsewhere has to 'evolve' in the way we understand from what happened here on earth, but let's not quibble about that.  Even then, there is no prior reason to think life must be based on water, or carbon (some have suggested that life, even earth like life, could be based on silicon, for example), or be restricted to particular temperatures (after all, we have Inuit and Saharan nomads, even under our own conditions), or that evolution would have a DNA or any other information-inheritance basis--lamarckian inheritance of some form might evolve on some planet somewhere, for example.  There is no reason evolution would take 4 billion years to become 'intelligent', nor that our kind of intelligence or ideas about communication would evolve.

Even if we accept the two core premises, there is simply no way to work out how or how long intelligence would take.  In a sense the whole point of evolution is that it works under the conditions it finds, and would work in its own way under what to us here would be harsher conditions, or more variable conditions, than Smith considers to preclude life.  We can't rule out non-earthlike chemical bases for life, other than for earthlike 'life'.  Natural selection can work in ways we may not know if, if inheritance is different, for example.  It's not that hard to think of other ways.

If  life does exist elsewhere does it have to be 'intelligent' in our sense to count?  Is the ETI question really about earth replicate life--that would and would want to communicate with the likes of us in the way we (currently) do it?

We think his article is very interesting and useful, but we also think it reveals the cardboard caricature  of life and evolution that (as we repeatedly harp in MT) is so widely prevalent outside of a rather limited range even of biologists.

In addition to these ideas, there is the possibility that even if ETI exists, it is so aggressively acquisitive of resources and so on that it destroys itself quickly, reducing the likelihood that two such sources would exist at similar enough times and stages to be able to detect each other.

There are many reasons that ETI may not exist at all, or if it does that we'll never detect it.  The conclusion that we're all alone--for all practical purposes--seems rather sound.  Even if one were to suppose that English-speaking life existed, say, a thousand light-years away (that is, nearby in space terms), it would take more than 2000 years to exchange a single message by electromagnetic means (actually more, because of the delay in reading and responding, and the rapid expansion of the universe), assuming neither our nor their life did not destroy itself in the interim (or theirs had not ended before their message got here).  2000 years is the time since the Roman Empire.  How long would it take even to find out, to within a reasonable accuracy, just where the ETs were (and they us) so that travel could be planned or messages accurately directed. So even if somebody does claim to have discovered ETI in their telescopic data, don't let NASA talk you into voting for a big budget increase.  Indeed, why allow NASA even the expensive sport of SETI, when lots of us here in the US don't even have health care?

So, we're with Smith in saying:  let's take care of what we have, instead of yearning for companionship we can't provide for each other!

There are a couple of other fascinating sides to this story that we'll pursue in Part III.

The Twilight Zone, Part I: Is there life elsewhere in the universe?

Figure 1 from the article.

MT is about biology, genetics, evolution, and the anthropology of science (besides digressions, ramblings, rants, and other miscellany).  But sometimes these subjects can get rather far afield.  A case in point in the current (July-August) issue of American Scientist,  a very nice article by Howard Smith, entitled "Alone in the Universe" (the abstract, or if you subscribe, the entire article, is here).  Read it if you have a chance, but here we'll present just some thoughts of our own, partly overlapping with his.  In Part I, here, we will lay out some of the basic case. In our next post, Part II, we'll go over why this is relevant to evolution and the nature of life here and (maybe) elsewhere--and we'll show how even in cosmology, naive views about evolution are rife.  In Part III, we talk about the multiverse theory, which posits infinitely many universes right here on earth.

A favorite subject of Science Fiction is how we would deal (and be dealt) with by ET's, aliens from outer space.  The idea that ETs are real and have, could, or are trying to contact earth, is irresistable.  NASA panders to it widely to justify spending (wasting?) gobs of money on sending people to find life on Mars.  Even they are at least restrained enough not to claim that there are Little Green Men there.  Still, so distinguished a scientist as DNA co-discoverer Francis Crick suggested that life here was seeded, perhaps by trash if not intent, by alien spacecraft passing by earth (yes, he did!).

Nobody expects to be able to spot a SpaceBus with our usual visual telescopes, but with the advent of radio and other non-optical telescopes the idea that 'intelligent' life may--or must--exist out there has been taken seriously, including that the ETs would know about elecromagnetic means of information transfer (radio, for example).  This doesn't mean they know about us or want to communicate specifically with us (why would they, if they knew about what kind of beasts we are?).  If so, and if we can intercept signals by al Qaeda, why not from ETs as well?

We don't know what kind of signals they might send, but they should be different from the remorselessly mechanical signals of the broiling, expanding universe.  So if we at least listen, perhaps we can filter out the mechanical to detect the intelligent communications buried within it?  A huge project called SETI (Search for ExtraTerrestrial Intelligence) is one such effort, and has involved co-opting thousands of volunteers' computers to screen incoming electromagnetic radiation.  Wikipedia has an informative page about SETI. Perhaps sadly, but not surprisingly, the result so far can be summarized as: [nothing].

Besides having to guess at what kind of signal would be wafting around in space, detecting ETI requires defining what's mechanical, to see what's left.  But there is much in the order and chaos of space, reflecting many different things: the behavior of galaxies, exploding or coalescing stars, black holes, overall expansion, remnant signals from the Big Bang, and more.  This of course doesn't include such things as anti-matter and so on.

These phenomena vary from object to object or quadrant to quadrant because in the splat! of spatial history each star, galaxy, etc. is behaving differently.  The first task is to be able to identify that, from all directions.  Doing that is not easy since we have no prior theory (if, indeed, we have any theory that everybody agrees on) for what is going on.  Much of what we believe we understand comes from interpreting the signals.  There is a danger of interpreting something as ETI that is really another phenomenon we're misunderstanding.

So for the moment we need some prior thinking to decide why or whether we should make the effort.  The basic reasoning, besides just human interest and curiosity is a kind of infinity argument that goes something like this:

1. If there are essentially infinitely many objects in space, and if any non-zero fraction of them contain conditions on which life could exist, there simply must be life 'out there'.  Our existence proves by itself that such conditions can, and do, exist
2. If that is so, there must be all possible kinds of life.  No probability is so small that in an infinite distribution of objects, it will never occur;
3. Indeed, for the same reason, it must occur an infinite number of times, and with every possible variation!
4. If life can exist, and therefore must exist, it must exist in infinitely many places
5. If life can exist, it can evolve--our human existence proves that, too
6. If it can evolve, it can evolve intelligence--ditto here as well
7. If it can evolve intelligence, intelligent life can travel
8. If it can communicate, it can also--indeed must also--communicate
9. If we understand the physics of the world, we know that communication must (at least in some forms) involve electromagnetic means

Electromagnetic communication travels at speeds and takes forms that we understand.  Thus, radio telescopy is a means to detect what must, inevitably by this reasoning, exist in space.  Wherever, and whenever, the signal was sent, it will travel at the speed of light in all directions, and that means in our direction (it need not be directed here specifically). 

If we have sensitive enough instruments, we should be able to detect the emanations.  For them to be intelligent, they must have systematic rather than random structure, and must be different from the other electromagnetic 'noise' in space.  Why?  Because otherwise Spaceship X could not communicate with its home base.

None of this implies when a given level of intelligent life will arise, or where.  But if the universe is effectively infinite, there must be some signals that will reach us at any given time (such as today).  If the signal comes from very far away, all we know is what the ETs were like back at the time the signal was sent--not what they're like now.  So while detection doesn't help direct space travel plans, or booking of exotic vacations, it would at least answer the question:  Are We Alone in the Universe?

There have been many arguments, some of which we've given above, why we must not be alone, and thus must be able to detect the life that does exist elsewhere.  On the other hand, there are various things that must be true for a given planet to have life that can communicate in the way we've discussed.  The planet must be suitable for life and old enough that life there has already originated.  It must have had life long enough for it to evolve intelligence.  The intelligent beings must have been their and their culture evolved to the stage of sending electromagnetic signals.  And long enough ago for the signal to get here.  And these things must be compatible with the age of the universe, and the age of the Earth.

So, for there to be ETI there are issues of habitability, evolution, time, and coincidence.  The latter is perhaps the most vital, because there must be an intersection between the ETI's stage (at the time of signal sending) and our stage today.  Planets alive but only with moss or bacteria won't help.  Planets that have ETI but too recently for their signals to reach Earth won't help either.  Emanations blocked on their way here by other objects or gravitation, or that got sucked into a black hole, will never get here.  Likewise for planets with ET's that haven't discovered radio, or who are isolationists and don't care to venture forth, or who were too far away from us when they got their smarts for the signal to have got here yet.

Still if space is really infinite there must be at least some such coincidences.  Indeed, there must be infinitely many of them!  Emanations we can detect, scanning in any direction, must literally be loaded with their messages.  And that means such messages must be coming at us from all directions right now!

But there are more issues to discuss, that can make you depressed if you're into SETI, or happy if you wish to be left alone.  We'll discuss some of these in our next post.