systems. Vakoch came across his work and saw a connection
to SETI, Hoffman says. Though Hoffman hadn’t studied SETI
before, Vakoch asked him to write a paper on the implications of
human vision research for SETI communication.
In the paper, which Hoffman presented at a 2002 conference
on interstellar communication, he argued that images are not in
fact the “universal language” that SETI astronomers thought.
Laypeople and scientists who don’t study vision tend
to think that human vision works like a camera, passively
recording scenes. But years of research shows that instead
the human brain actively constructs what we see from the
ambiguous visual data our eyes take in, using rules that have
developed over hundreds of thousands of years of evolution.
And there’s no reason to think that extraterrestrials would have
evolved the same rules that we did, or would be able to interpret
or even “see” our images the way we intended — especially
given that even different species on earth have evolved such
different perceptual systems.
“The actual [visual] content that we try to communicate [to
extraterrestrials] I would say is almost surely not going to be
received in the way we intended it,” Hoffman says. “We don’t
even understand the perceptual world of an ant, and we’ve been
living with them a long time.”
Given that reality, Vakoch says, the key is to think about
how we could “communicate something meaningful, given the
constraints of communication.”
One idea, for example, would be to start with the most basic
math. “Any civilization that can communicate should know that
two plus two equals four.” And then, with that basis, we could
work up to communicating more complex math, including
game theory — which can also transmit something about the
idea of cooperation.
Even as Vakoch’s and others’ work has laid out the challenges of
communicating with life on other planets, the chance that such
life exists seem to be increasing. Less than three decades ago,
astronomers had yet to identify a single planet orbiting a star
other than the sun. Today, we know that most stars have planets,
and that perhaps 20 percent are in a habitable temperature zone.
“Over the last 20 years, the chances have improved
tremendously for life being out there because we know there’s a
lot of real estate where it’s possible,” Vakoch says.
As those chances have improved, a controversy has emerged
in the SETI community: whether or not to engage in “active
SETI,” or broadcast targeted messages to locations more likely
to contain life, rather than just passively “listen” with radio
Vakoch has been a prominent voice in favor of active SETI,
but he has many opponents. Recently, a group of 28 scientists
signed a petition calling for a moratorium on active SETI until
a “global consensus” was reached on whether and how to do
it. Signers included SpaceX and Tesla founder Elon Musk and
astrophysicist and science fiction writer David Brin.
The active SETI opponents invoke what might be thought
of as a “War of the Worlds” argument — basically, do we really
want to let potentially unfriendly and dangerous aliens know
that we’re here?
But Vakoch and other supporters of active SETI say
the “hostile aliens” argument is moot. Any extraterrestrial
intelligence might already be picking up old episodes of “I
Love Lucy” and all of our other radio and television broadcast
signals, so we might as well try to send a more targeted message.
And Vakoch thinks that the time to try active SETI is
overdue. “We’ve always assumed that if the other civilization
has the ability to communicate, they’ll take on the burden of
contacting us,” he says. “That’s not at all obvious to me.”
The debate played out at a panel last spring at the American
Association for the Advancement of Science, where Vakoch and
Shostak debated Brin. The discussion garnered some media
attention (see further reading box) for a topic the general public
doesn’t hear much about. But given the controversy, active SETI
is unlikely to happen any time soon even though the technology
to try it is easily available, Vakoch says.
“The fact that it is contentious means that it’s difficult to
move forward,” he says.
So does all of this leave Vakoch frustrated? The fact that, for
now at least, we can only listen for signs of extraterrestrial life?
And that after decades of listening, we haven’t heard a peep?
And that there’s a good chance that we won’t in his lifetime?
And that even if we did, his and others’ work suggests how
difficult it will be to understand each other?
“SETI is not a field for those who need certainty,” he says.
“You have to be willing to invest your time in a project with no
guarantee. With psychology, you go into a lab and at the end
either have evidence that supports your hypothesis or not. But
we could go on for hundreds or thousands of years, and not get
any signal, and still not be sure that we are alone.” n
• Achenbach, J. (2015, March 1). Earth is all ears for
long-distance calls. Should it try to dial ET too? The
Washington Post, pp. A1.
• Vakoch, D. (Ed.) (2014). Archaeology, anthropology
and interstellar communication. Retrieved from https://
• Vakoch, D. (Ed.) (2011). Communication with
extraterrestrial intelligence. Albany, New York: State
University of New York Press.