In my
favorite spot for finding unwarranted claims by scientists (the
Nautilus web site), there is a recent post by astronomer Seth Shostak
entitled “Why We’ll Have Evidence of Aliens—If They Exist—By
2035.” Shostak tries to argue that the great big pie-in-the-sky of
“signals from extraterrestrials” will be delivered within a
decade or two. But his argument is very unconvincing.
Shostak's
argument essentially boils down to merely saying something kind of
along the lines of we're
looking real hard, in more ways, in more places, and with more
frequencies, and that will do the trick. Shostak
mentions optical SETI, the search for optical pulses from
extraterrestrials
(a bit like getting a flashlight signal across the stars). The way
he describes things, you might think that this type of search was in
its infancy. But, to the contrary, a
scientific paper
not mentioned by Shostak reported on a search for optical signals
coming from sun-like stars. Almost 5,000 such stars were searched over the
course of two years, but no such signal was found.
Shostak also tells us,
“There is a completely different approach that has yet to be
explored in much detail: to look for artifacts—engineering projects
of an advanced society.” From the way he writes, you'd think that
no one had done such a search. But Shostak fails to mention a search
of 100,000 nearby galaxies looking for signs of extraterrestrial
engineering, a search that came up empty.
The
main way of searching for extraterrestrial civilizations is to
attempt to pick up radio signals from other planets. Shostak tells
us, “Within two decades, SETI experiments will be able to
complete a reconnaissance of 1 million star systems, which is
hundreds of times more than have been carefully examined so far.”
Hundreds of times more?
That would only be true if fewer than 5000 stars had been searched so
far. But this paper alone discusses 9293 stars that were
unsuccessfully searched for extraterrestrial signals. Were we to add
up the total number of stars searched for radio signals by
astronomers, in 50 years of SETI efforts, it would be a number much
greater than 9293.
Shostak
talks about two approaches to searching for extraterrestrial signals:
“One is to scan as much of the sky as possible; the other is
to zero in on nearby star systems.”
He suggests the second approach is better, saying that if
extraterrestrials live on planets, “It’s better to devote
precious telescope time to examining nearby star systems.” But a
2006 article says, “Recent work confirms long-standing suspicions
that star-by-star targeting should be abandoned in favor of scanning
the richest star fields to encompass very large numbers of stars,
even if most of them are very far away.” That's the approach that
has already been taken by projects such as the SERENDIP project. But
they came up empty.
Shostak
then states the following:
SETI
practitioners from Frank Drake to Carl Sagan have estimated that the
galaxy currently houses somewhere between 10,000 and a few million
broadcasting societies. If these estimates are right, then examining
1 million star systems could well lead to a discovery. So, if the
premise of SETI has merit, we should find a broadcast from E.T.
within a generation.
Such
estimates are just examples of picking numbers out of a hat, and both
of the people Shostak sites were astronomers, not people with
degrees in biology. There are very strong reasons for believing that
unless there is something special going on in terms of cosmic
teleology, something to better the long odds, the chance of
extraterrestrial civilizations arising anywhere else in our galaxy
are very low.
Lets
consider some of the things that need to go right in order for a
communicating civilization to arise on another planet:
- Life has to begin, consisting of cells that would have to be very complex for even the simplest life.
- At about the same time, a genetic code has to somehow arise.
- Life has to progress from the simplest cells (prokaryotes) to the vastly more complicated cells called eukaryotes.
- Life has to progress to macroscopic life with complicated organ systems.
- Macroscopic life has to evolve into intelligent life.
- Intelligent life has to develop both language and limbs sufficient to make tools, as well as the advanced consciousness and abstract thinking needed for a species to have an interest in communicating with other species on other planets.
The
first of these things is something that seems so unlikely to occur by
chance that we should not assume it has accidentally occurred even
one other time on billions of other planets in our galaxy.
Darwinian ideas are of no value in explaining life's origin, since
natural selection can only occur when life exists. 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).
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. Homochirality is the fact that in a
laboratory the components of sugars and amino acids are chemicals
that are “left-handed” or “right-handed” in equal numbers,
but in living things essentially all sugars are made of “right-handed”
components and all proteins made of “left-handed” components –
a situation that seems fantastically unlikely to have occurred by
chance.
If by
some miracle life were to arise on a planet, from a naturalistic
perspective it seems extremely likely that cells would simply stay
stuck in a prokaryotic state, rather than making the leap to the much
more complicated eukaryotic cells. The prevailing theory (or perhaps
one should say “fairy tale”) on how such a leap occurred is not
even a Darwinian explanation, but a very far-fetched endosymbiosis
story involving “incorporation by ingestion” that tries to kind
of say, “Cells got vastly more complicated by eating other cells.”
We are asked to think that a biological organism could become vastly
more complex just by gobbling up other things. In the recent book
Aliens, biologist Matthew Cobb gives a description of current thinking on this topic, emphasizing the
improbability of it:
What
happened on Earth – known as eukaryogenesis – was not the product
of random mutation and the subsequent sifting of acquired characters
that have differential fitness (the essence of natural selection).
Instead there appears to have been a single event of mind-boggling
improbability, for it involved two life forms interacting in a most
novel way....Prior to that moment, all life had consisted of small
microbes with no cell nucleus and no mitochondria. Everything changed
when one unicellular life form, known as an archaebacterium, ended up
inside another, called a eubacterium.
On
another page Cobb says this:
We could in principle
calculate the probability of the appearance of eukaryotes, but we
would soon run out of zeros...That weird hybrid was our ancestor, and
its existence – and therefore ours – was incredibly improbable.
As far as we are aware, no such event happened before or since.
It
also seems extremely likely that life would just stay in a
microscopic state rather than making the leap to multi-cellular life
forms consisting of multiple layers of organization such as cells,
tissues, organs and organ systems. On Earth this seems to have
happened in a sudden burst, at about the Cambrian Explosion about 540
million years ago. Scientists have never adequately explained this
sudden blossoming, in which most major phyla of animals suddenly
appeared.
To
plausibly explain the appearance of large, multi-cellular,
macroscopic life consisting of cells, tissues, limbs, organs, and organ
systems, we would need a theory explaining gigantic amounts of biological organization. But we
don't have that – merely something vastly less, the theory of
accumulation that is Darwinism (a theory of the accumulation of
favorable random mutations).
To clarify the difference between the two (organization and accumulation), below we see a depiction of organization, the metabolic pathways in the human body:
Credit: US Department of Energy
Then
there are the difficulties of explaining the appearance of
intelligent life, the type of life that might be interested and
capable of interstellar communication. In the case of humanity, we
have a species with about 10 fundamental mental characteristics that
separate us from the animals: things such as abstract thinking,
language ability, mathematical ability, philosophical ability,
spirituality, ethics, altruism, self-consciousness, and intellectual
curiosity. As argued here, none of these things increased the ability of humans to
survive in the wild, so we cannot explain such things as being due to
natural selection.
In moments of candor, some evolution experts such as George Gaylord Simpson and Ernst Mayr argued that the appearance of humanity was such a fluke that we should not at all expect it to happen on any other planet in the galaxy. In the recent book Aliens, biologist Matthew Cobb states that “a study of the key points in life's history” leads us to the pessimistic conclusion that “there are no alien civilizations.”
In moments of candor, some evolution experts such as George Gaylord Simpson and Ernst Mayr argued that the appearance of humanity was such a fluke that we should not at all expect it to happen on any other planet in the galaxy. In the recent book Aliens, biologist Matthew Cobb states that “a study of the key points in life's history” leads us to the pessimistic conclusion that “there are no alien civilizations.”
You
can summarize the situation as follows: based only on what we
currently know for sure, if an extraterrestrial planet existed the
right distance from its sun, with overwhelming likelihood no life
would arise on the planet; and if life did by great luck appear on
the planet, it would with overwhelming likelihood stay in the simple
prokaryotic microscopic state; and if the vastly more complex
eukaryotic microscopic state did by great luck arise, with
overwhelming likelihood the planet would never see multi-cellular
life with limbs and tissues and organ systems; and if by great luck
very organized multi-cellular life arose, it would with overwhelming
likelihood not reach anything like the consciousness, linguistic
fluency and manual dexterity needed for interstellar communication.
Given
such a reality, there is no basis for the estimates Shostak cites for
the number of communicating civilizations in our galaxy (between
10,000 and a million). If we realistically consider things based
purely on known biology and chemistry, without assuming anything
special helps life along, our best guess should be that there is no
other civilization in our galaxy. There are billions of other
galaxies, so such an estimate would not preclude there being many
other civilizations scattered across the universe's galaxies. But the
chance of communicating with a civilization in another galaxy is
remote. The fact that SETI has been searching for extraterrestrial
civilizations for decades without finding anything is consistent with
an estimate that we are the only civilization in our galaxy, and is
rather inconsistent with claims that there are 10,000 or more
extraterrestrial civilizations in our galaxy.
But
there is one reason for thinking that there might be many
civilizations in our galaxy. Given the seemingly terrible odds of
intelligent life appearing even once in a galaxy, it may be best to
assume that there must have been some special “X factor” that
helped intelligent life appear. We can use the vague term “cosmic
teleology” to describe such a thing. A kind of “big umbrella”
term that can cover many possibilities, the term “cosmic teleology”
covers everything from the possibility of deliberate supernatural
assistance to the possibility that there is some kind of cosmic
life-force that causes biological life to become progressively more
organized. The fact that many a biologist has declared such a
concept to be taboo and forbidden is no reason at all why we
should avoid it.
A
believer in cosmic teleology can be a believable optimist when it
comes to the search for extraterrestrial intelligence (SETI). For
example, such a person might maintain that we will succeed in finding
extraterrestrials within 50 years, because there is some cosmic
life-force that acts throughout the galaxy, causing life to appear on
every habitable planet, and also causing life to become
ever-more organized. But someone who has not articulated any
doctrine of cosmic teleology is not a believable short-term optimist about SETI.
Similarly, if you have for some reason a compelling theory you can
count cards or read minds or influence the rolls of dice with
mind-over-matter, you might have a good basis for optimism about
going to Las Vegas and coming back with $100,000 in winnings; but if
you have no such theory, you have no business being optimistic about
such an outcome.
As for
Shostak's claim that we will make contact with intelligent
extraterrestrials within 20 years (because the search technology is
getting better and better), it seems no more convincing than the
claim that we will be able to telephone the dead within 20 years,
because smartphones are getting better and better. 50 years of SETI
failure suggests that if extraterrestrial civilizations exist, they
are very hard to find, and that it is unlikely that we will find any
extraterrestrial civilizations within the next 20 years.
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