This news has gotten remarkably little coverage. So for those who
have not heard:
Project Ozma failed. Project Durin succeeded. It turned out SETI
(the Search for ExtraTerrestrial Intelligence) was looking in the
wrong direction all along. It was looking up when it should have
been looking down.
Evolution works much the same everywhere in the universe. It
selects for different attributes in different environments, but
one commonality is that it never selects for extreme patience.
How long would anyone keep transmitting a few gigawatts at a silent
planet? A decade? A century? A millennium? The one serious human
attempt to send such a message (the Arecibo message) lasted less than
three minutes, and was never repeated.
If the phone doesn't answer, you leave a message.
As Fermi pointed out decades ago, there's nothing special about the
present age. A solar system which is just a little older, or in which
evolution happened just a little more quickly, would result in a race
millions of years ahead of us. If they sent signals to Earth, they'd
get no reply. If they visited Earth, they'd find nothing more
advanced than dinosaurs, or perhaps blue-green algae. And they
certainly could have visited Earth. Even at the speed of our current
spacecraft, it's possible to reach every part of the galaxy on a
geological time scale.
That is why Ayeph Dee, professor of exobiology at Frank Drake University,
had his students come up with a way to leave a message on an Earthlike
planet that would be detectable and readable for hundreds of millions
of years.
They came up with the idea of buried hollow titanium spheres, a few
meters in diameter, containing tuning forks. Over the course of ages
some would come to the surface and be weathered to dust, and others
would be be subducted to depths at which temperature and pressure
would destroy them. But if there were enough of them, and if they
were carefully placed, some would survive for hundreds of millions
of years at relatively shallow depths, embedded in bedrock.
Project Durin, named for the ruler of Tolkien's fictional underground
land of Moria, consists of a grid of ten thousand broad-spectrum
microphones embedded in the bedrock of the Canadian Shield.
Recordings are made available to the SETIunderground@Home distributed
computing project, whose software turns the array into an acoustic
version of a passive phased array radar. It searches the bedrock
for narrow-band point sources of acoustic energy from tuning forks
excited by natural seismic activity.
Such a source was found, approximately 41 kilometers deep, with a
strong high-Q (~100) resonance at about 14 Hz. This is consistent
with a tuning fork inside a hollow sphere, possibly made of titanium
or tungsten, and possibly filled with oil. There were also several
seconds of broad-spectrum noise, which could be from multiple smaller
tuning forks inside the same sphere. Dee conjectured that such a set
of tuning forks could be used to encode a message, based on their
relative frequencies and their relative locations within the sphere.
Unfortunately, we don't yet have the technology to excavate anything
at that depth. (The deepest borehole ever drilled is just 12
kilometers.) This also means that the rock surrounding the sphere
hasn't been analyzed, so we have no idea of its age, except that it's
certainly Precambrian, probably at least a billion years old, and
possibly two or three times that age.
It's believed that it was originally buried at a shallow depth. It's
not known whether this was on land or under an ocean, or whether the
builders were from our solar system or not. (Venus and Mars may have
been much more hospitable to life eons ago.) It's even possible that
it was constructed by an indigenous terrestrial sapient race, though
it's hard to imagine it would have left no signs of its existence that
we would have noticed by now.
The planned next step is to detonate several embedded explosives, one
at a time, in various locations, as a form of active sonar, to more
closely locate the sphere. Once that is done, a large number of
larger explosives (about 100 of approximately one ton each) will be
detonated almost simultaneously, such that their shock waves will
reach the sphere simultaneously from multiple directions, to excite
a strong and sharp resonance of all the tuning forks.
Searches for additional spheres elsewhere on Earth are encouraged.
Project Durin is always open to suggestions.
