Are we alone in the universe? Are there alien civilizations scattered throughout our
From a scientific point of view, these questions fall under the purview of SETI (the Search for
Extraterrestrial Intelligence). And for the most part, SETI's approach has focused on
searching for radio and optical signals intentionally
broadcast by alien civilizations. But should their strategy include searching for artifacts
from these civilizations?
In his recent book Extraterrestrial, Harvard astronomer Avi Loeb argues that searching
exclusively for radio and optical signals stacks the odds against success for SETI.1 If
human history is any indicator, alien
civilizations will only possess the technology to communicate their presence for a fraction of
the time they exist. These broadcasts won’t begin until these civilizations become highly
advanced. And the duration of the broadcasts
will be cut short if the civilizations collapse or disappear altogether.
Instead, Loeb argues that SETI investigators need to expand their search to include long-lasting
evidence for alien life, such as biosignatures (e.g., oxygen and methane in the atmosphere) and
technosignatures (i.e., pollutants).
As Loeb also points out, humans have been generating radio emissions at the meter-wave radio
spectrum for decades. These emissions are a type of radio pollution. If we are generating that type
of electromagnetic pollution, then why
wouldn’t alien civilizations do so, too? Loeb believes SETI should direct some of
its resources to search for these types of signatures.
Finally, Loeb proposes a different strategy for SETI altogether—an approach he calls
astro-archaeology. In this vein, Loeb argues that SETI should search for the relics of alien
civilizations. He points out that we have deliberately
sent five spacecraft (Voyager 1, Voyager 2, Pioneer 1, Pioneer
2, and New
Horizons) out of our solar system into interstellar space. Why wouldn’t alien
civilizations do the same? Additionally, Earth’s orbit is now littered with space debris from
derelict spacecraft and rocket launches. Again, Loeb expects
alien civilizations to leave behind the junk from their activities in space, too. In fact, Loeb
believes that SETI may have better success by expanding its search to include spacecraft and space
debris generated by alien civilizations
than by focusing its attention on broadcast radio and optical signals. Once these
artifacts are produced, they will last far beyond the alien civilization itself.
Loeb believes that astronomers unwittingly discovered an alien
artifact in the fall of 2017. Over the span of 11 days (beginning October 19, 2017), the Panoramic
Survey Telescope and Rapid Response System
(Pan-STARRS)—a network of telescopes and high-definition cameras positioned on top
of Maui's dormant volcano Haleakala—recorded observations of an unusual interstellar
object, 1I/2017 U1 (nicknamed Oumuamua),
that fills the bill of alien technology—at least in Loeb’s opinion. If so, this
object would stand as the first evidence for the existence of an alien civilization beyond our solar
Oumuamua came from the Vega star system (which is about 25 light-years away), moving through our
solar system with a hyperbolic trajectory at 58,900 miles per hour. It spent about a month in our
solar system before exiting towards the
constellation Pegasus. Pan-STARRS observed Oumuamua during its final days in our solar
Most astronomers don’t agree with Loeb. Instead, they interpret Oumuamua as an asteroid or
comet of interstellar origin—albeit one with some unusual and unexpected properties. Yet, for
Loeb, it is these unusual properties that
lead him to conclude that this object is alien technology.
In the face of the widespread skepticism confronting Loeb's proposal, he uses
Extraterrestrial as the vehicle to present a systematic, multi-pronged case that
Oumuamua is, indeed, an extraterrestrial spacecraft.
Is Oumuamua Alien Technology?
First, Loeb notes that Oumuamua has an anomalous
shape, at least 5 to 10 times longer than wide. The aspect ratio of Oumuamua would be the most
extreme ever observed for an asteroid or
comet. Loeb maintains that this aspect ratio would fit an object that is either shaped like a cigar
or pancake. In fact, Loeb claims that astronomers know of no natural process mechanism that could
generate these shapes for comets
Loeb also calls attention to the reflectivity of Oumuamua. It is about 10 times more luminous than
any known asteroid or comet.
As Oumuamua’s orbit took it past the Sun, its trajectory changed. This
change is expected because of the influence of the Sun’s gravity. But the change in the
trajectory far exceeded what the Sun’s gravity alone could
have achieved. Something generated a propulsive force as Oumuamua moved past the Sun. But, as Loeb
points out, no natural process mechanism can account for Oumuamua’s acceleration. If Oumuamua
experienced outgassing as the Sun
warmed volatiles associated with it, then this could change its trajectory. But astronomical
measurements failed to detect any water, carbon-based gases, and dust coming off Oumuamua’s
surface. If Oumuamua disintegrated,
this process could accelerate it as well. But, once again, astronomers failed to detect the expected
change in spin that should accompany disintegration. Also, they noted that the change in
acceleration was unexpectedly smooth and
continuous, not jerky, as expected if Oumuamua disintegrated.
Another unusual feature of Oumuamua
is its origin in velocity position. Before it was accelerated by the Sun, Oumuamua occupied the local
standard of rest
(a frame of reference in which the velocities of neighboring stars average out
to zero). This velocity position rarely occurs for astronomical objects.
In other words, the properties and behavior of Oumuamua are difficult to explain if this object was
an interstellar comet or asteroid. But, according to Loeb, all of the data fits his
hypothesis if Oumuamua were a light sail
launched by an alien civilization.
The Light Sail Hypothesis
The basis for this proposal comes from another
project on which Loeb worked, dubbed the Star Shot Initiative. This project was funded
by entrepreneur Yuri Milner, with the objective
of reaching the closest star system—(Alpha Centauri) which consists of three stars located
4.27 light-years from Earth—within Milner’s lifetime, collecting data that should
provide insight into the prospects of alien
life in the star system and sending the data to Earth.
Achieving this objective would require a spacecraft that can travel one-fifth the speed of light.
This would require a lightweight spacecraft with a light payload. Loeb and his collaborators
demonstrated that such a craft could be built
by attaching a small electronic device (comparable to a small smartphone) to a reflecting sail that
would be propelled by the pressure exerted on it by solar radiation.
A light sail would have the extreme aspect ratio displayed by Oumuamua. It would be accelerated by
light coming from the Sun, smoothly changing its trajectory as it moved through the solar system. It
would also be at the local standard
of rest if it was released at the local standard of rest at the outskirts of its star system of
According to Loeb, if we could conceive and design a light sail, then why wouldn’t an alien
civilization do the same? If launched at its local standard of rest, then it is unlikely that
Oumuamua would be space junk, according to
Loeb. It would be much more akin to a buoy intentionally launched in space until our solar system
collided into it.
Oumuamua and the Science of Design Detection
I find Loeb’s argument to be
probative. Yet, I don’t have the expertise to judge the merits of his
case effectively. (I will leave that task to astronomers.)
As an old-earth creationist and a biochemist—who holds the view that life stems directly from
the handiwork of a Creator—I find Loeb’s case to be instructive, serving as a template
that can be used to make the case
that living systems stem from the work of an Intelligent Agent.
Specifically, Loeb uses three criteria to argue that Oumuamua is the work of extraterrestrial
intelligence (i.e., intelligent agency):
- Absence of a compelling explanation for Oumuamua based on natural processes/mechanisms
- Oumuamua's artificial characteristics
- An assessment of what it would take to build a spacecraft with Oumuamua’s capabilities
Loeb also speculates about the purpose of Oumuamua and suggests the possible motivation behind
its launch. In the process, he draws upon our activities and motivations as human beings, using
them as a gage for what alien civilizations
In many respects, the criteria Loeb uses are identical to the criteria archeologists use to
determine if a stone has been shaped by natural forces or by the deliberate action of a hominin
(i.e., an intelligent agent). This similarity
shouldn’t be surprising because Loeb’s work falls under the umbrella of
Loeb’s work affirms a point that I (and others) have repeatedly made. Science has the toolkit
to detect the work of agency in nature. To put it another way, Loeb’s thesis demonstrates that
detection of intelligent design in
nature is legitimately part of the construct of science.
Design Detection in Biochemical Systems
So, why not apply the same criteria to
biochemical systems? Regardless of worldview, no one disputes that biochemical systems have the
appearance of design. The debate centers
around the source of this design. And, based on Loeb's analysis, science has the toolkit to
determine if that design stems from a mechanism or mind.
In fact, I employ Loeb's criteria to make the scientific case that biochemical systems are,
indeed, the work of an intelligent agent.
In Origins of
Life (a work I coauthored with astronomer Hugh Ross) and Creating Life in the
Lab, I (we) demonstrate that natural processes don’t seem to be able to
account for the origin of life and, hence, the origin of biochemical systems. In my book The
I propose the use of an intelligent design pattern to detect design. Toward this end, I point
out that objects, devices, and systems designed by human beings—intelligent
designers—are characterized by certain properties
that are distinct from objects and systems generated by natural processes. The approach I take in
The Cell’s Design follows after William Paley’s work. Paley described designs
created by human beings as contrivances.
In other words, like Loeb, I take the designs and motivations of human designers as a guide to
facilitate design detection in biochemical systems. In Creating Life in the
I demonstrate that attempts to create protocells starting with simple molecules and attempts to
recapitulate the different stages in the origin-of-life pathway depend upon intelligent agency.
In other words, if Loeb’s light sail hypothesis is considered to be a scientific proposal, then
the claim that biochemical systems are the work of a Mind, must also be considered one as well. It
would be disingenuous to do otherwise.
- Avi Loeb, Extraterrestrial:
The First Sign of Intelligent Life beyond Earth (Boston, MA: Houghton Mifflin