According
to Hollywood, Earth is surely one of the galaxy's "top places to visit
before you die." Cinema aliens come here often enough that the State
Department should probably set up passport control.
Of course,
that's fiction. But in the last hundred years, Homo sapiens has been
flamboyantly belching clues into space that could alert technically savvy
extraterrestrials of our presence. Radar
and television, odd chemical compounds in the atmosphere, and even the
occasional spacecraft sent beyond the heliopause are all messages in bottles
that could conceivably wash up on the shores of ET's planet.
When I
point this out in talks, a frequent reaction is "Won't they come here and
kill us?" I offer this response as proof of the general optimism of 21st
century humankind.
Nonetheless,
maybe this dystopian view is worth considering. Would the extraterrestrials
come here — if not to kill us — then to take our resources or compromise our
virtue?
The answer,
of course, falls within the discipline of alien sociology — a field in which
the data are, shall we say, sparse. Indeed, since we have no idea what the
mores or motivations of extraterrestrials might be, you might conclude that,
really, there's nothing we can say about whether the aliens would come here or
not.
But there's
an alternative to this "know-nothing" approach. Let's consider what
might conceivably encourage visits by those who've learned that humans are
strutting and fretting upon Earth's stage. After all, we've unraveled a few
things about astronomy and physics, if not much about alien comportment.
Taking our
cue from Tinseltown, I note that most cineplex
sentients come to Earth either to solve some sort of ugly reproductive
crisis or simply to take over the planet. The former doesn't make any sense
whatsoever. You can't breed with creatures at the zoo, despite the fact that
most of the base pairs in the inmates' DNA are identical to yours (note that
this is a biological incompatibility, and not just zoo regulations). The
aliens, needless to say, will have a different biochemistry, and probably no
DNA at all. Forget, if you can, the breeding experiments.
Taking over
the planet would only make sense if there were something really special about
our world. The best guess of the exoplanet specialists is that the number of
Earth-size planets in our galaxy exceeds tens of billions. That doesn't sound
like our hunk of real estate is terribly privileged.
They won't
come here to mine our minerals, either. The entire universe is built of the
same stuff, and while the solar system has a higher percentage of heavy
elements than found in many stellar realms, it turns out that this is precisely
the condition that seems to foster planet formation. In other words, ET's own
solar system will be similarly blessed with these useful materials. So why
would they come here and incur multi-light-year transport charges?
Colonization?
A hunt for additional living space? If the former is something aliens do, then
they won't wait to hear from us before doing it. The British, after all, didn't
begin their colonization of Australia because they had intercepted some
aboriginal communications.
As for
getting a bit of lebensraum, well, planets are not great new habitat,
because they're spheres. They're cursed with the minimum surface area for their
mass. As pointed out three decades ago by Gerry O'Neill, it's both more
efficient and enormously cheaper to build artificial habitats in your home star
system.
OK, you
argue, but Earth is more than just a handy source of gold or molybdenum, more
than merely random cosmic acreage aching to be invaded and subdued. It's an
exceptional habitat for life. Water, oceans ... it's so gosh-darn good, it's
positively rare. The aliens will find our world lovable because it's livable.
Well, that
doesn't pass the smell test, either. If the type of world that can support life
is rare, then you don't have to worry about nearby extraterrestrials. There
won't be any.
Other
suggestions about why they might visit include forestalling competition in the
Milky Way marketplace, proselytizing, or just learning more about us. It's not
clear that any of these goals requires "killing us," of course, but
the logic is wobbly anyway. Any beings that actually could come here
will be far beyond us in technological accomplishment. Imagine if you could
visit the Neanderthals. Would you worry about commercial competition? Would you
give them bibles? Remember: these are (nearly) the same species as you are. The
aliens won't be. I dare say you wouldn't try convincing porpoises to join your
church.
Then again,
there's that last point: they just want to learn more about us. Well, perhaps
so. Maybe that's really what's interesting about Homo sapiens. Not
grabbing our habitat, saving our souls (or our environment), or subverting our
industrial output — but assaying our culture. I'm willing to consider that even
very advanced beings might find our culture mildly worthy of study.
Keep in
mind that if they're near enough to find us, that implies that there are many,
many galactic societies (otherwise the distances between any two of them will be
enormous). If there are lots of them, then we're just another entry in a
big book. Once again, not all that special. Kind of like another weird fish
found in the Atlantic. I don't expect mammoth expeditions to be sent our way.
But in any
case, if they do pick up our TV signals — or even bother to get in touch — then
they can study our society from home. It's a lot cheaper and a lot faster than
bridging the light-years.
I guess the
State Department doesn't need to set up that passport control.
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