There is a moment in this story that I
would like you to imagine.
A sheet of paper, covered in the output of
a machine.
Most of it means very little to anyone who
hasn't learned how to read
it. Numbers. Letters. The patient record
of something that has been
working while people have been doing other
things.
Somewhere on that page, a small sequence
is waiting to be noticed.
The setting we're imagining is a
reconstruction.
The page, and what happened to it, belong
to the historical record.
On August fifteenth, nineteen seventy-
seven, the Big Ear radio telescope
in Ohio detected an unusual signal.
Jerry Ehman noticed it while examining the
printout several days later.
He circled the sequence and wrote the word
that would become its name.
WOW.
By the time someone recognized that
something remarkable had happened,
the observation was already in the past.
No room full of people had risen to its
feet.
There was no voice introducing itself
through a loudspeaker.
There was a measurement, and then there
was a human being who understood
why that measurement deserved attention.
I keep coming back to the possibility that
a discovery like this could
arrive quietly. Someone checks a page.
Something catches their attention.
And suddenly an ordinary task opens onto a
question much larger than
the room. That's where I want to begin.
Because we tend to picture contact as
something impossible to miss.
The sky changes. A craft arrives.
Every screen carries the same
announcement.
Whatever life looked like the day before,
it cannot look that way again.
We would know which side of the dividing
line we were standing on.
Before contact. After contact.
But imagine something less cooperative.
An event that provides just enough
information to make you take it
seriously, and too little to tell you what
it is.
You can keep the record. You can invite
other people to examine it.
You can return to the place where you
think it happened.
What you cannot do is require the universe
to perform it again.
That is an uncomfortable kind of mystery.
The evidence has edges. Your curiosity
doesn't.
It reaches past the final measurement and
begins filling the space
with possibilities. An instrument problem.
Something on Earth. Something natural in
space.
Something made. Each possibility changes
the meaning of the same few
marks.
Tonight, we are going to begin with the
Wow!
signal. Then we're going to follow a
different kind of message, one
people on Earth deliberately designed and
sent from a spacecraft near
Mars. And eventually we are going to turn
the telescope around, in
a sense, and look at what humanity has
chosen to say about itself.
There is a question connecting all three
stories.
If another intelligence wanted to be
noticed, would noticing it be
the easy part?
I'm Bill, and this is Unknown Origin.
What If We Only Hear Them Once?
For this journey, I'd like you to hold on
to a distinction.
A signal is something you detect.
A message is something you think has been
made to convey meaning.
An invitation is something else again.
We are capable of moving between those
ideas very quickly, especially
when we desperately want the last one to
be true.
You hear a knock at a door, and your
experience supplies a person on
the other side. You don't begin by
wondering whether doors sometimes
make deliberate knocking patterns by
themselves.
The sound belongs to a world you
understand.
You know what a door is for. You know
people use it.
You know that someone who knocks usually
expects somebody inside to
respond.
Carry that confidence into space, and
suddenly most of its support
disappears. We haven't shared a
neighborhood with the possible sender.
We haven't watched it learn to
communicate.
We don't know whether it has anything
resembling a door, a visitor,
or a reason to announce itself.
Even the phrase, hear them once, contains
an assumption.
It gives the unknown a plural pronoun
before we have established that
anyone is there. The title is a
possibility we are exploring.
It isn't a conclusion about the event in
Ohio.
And yet the possibility is worth
exploring.
A single observation could matter
enormously.
A fleeting event can be real even when
nobody gets a second look.
The difficulty is deciding which
explanations the available evidence
can support, and how much uncertainty we
can honestly carry with us.
Think about the difference between finding
a footprint and meeting
the person who made it. The footprint can
be measured.
Its depth, shape, and position might tell
you something.
But a footprint alone cannot tell you
whether the person was coming
toward you, passing through, or leaving a
place for the last time.
You need context. You need a trail.
Now imagine there is only one impression,
and even the nature of the
thing that made it is uncertain.
That is closer to the emotional terrain
we're entering.
There is enough to keep returning.
There is no promise that returning will
give us what we want.
To understand why those marks on paper had
such an effect, we need
to meet the instrument behind them.
And before we meet the instrument, we need
to understand the decision
that put it there, listening.
Imagine deciding to spend part of your
working life looking for something
whose existence has never been
established.
You need equipment, people, power, and
time.
Someone will reasonably ask what success
looks like.
You can describe it. Then they'll ask when
you expect it.
That is a harder question.
The history of Big Ear includes an answer
made through persistence.
A twenty twenty-six account coauthored by
former observatory personnel
describes its transition to a dedicated
search for extraterrestrial
intelligence in nineteen seventy-three.
Robert Dixon and observatory director John
Kraus helped shape that
change. Later, volunteers and supporters
helped sustain the work through
financial and development pressures.
The telescope was eventually dismantled in
nineteen ninety-eight.
Its records survived.
There is something moving about an
instrument outliving its own physical
existence through what people bothered to
preserve.
We can no longer ask that particular
telescope to listen again.
We can still ask questions of information
it left behind.
It is easy to admire the instant of
discovery.
The less cinematic part is maintaining the
possibility of discovery.
Repairing something. Checking an output.
Making sure a record is kept in a form
somebody else can understand.
Showing up on a day when nothing
extraordinary happens, and doing the
work properly anyway.
A long search asks people to invest in a
future they might never personally
get to celebrate. That doesn't make them
certain of the answer.
It means they think the question deserves
an opportunity to be answered.
And the physical form of Big Ear is worth
getting right.
It wasn't the familiar great bowl that
turns toward a selected star.
Its reflector arrangement was different,
and Earth's rotation helped
carry parts of the sky through its view.
For our purposes, picture a listening
window through which the sky
passes. That picture is simplified, but it
gets us closer to the actual
observing problem than a dish chasing a
mysterious object across the
heavens.
A window has limits. You can see what
crosses it while you are looking.
You don't automatically know what happened
outside its frame.
If something appears briefly, you must
separate the behavior of the
thing from the behavior of your view of
it.
Let's bring that down to a human scale.
Imagine standing inside a dark room and
watching a road through a narrow
gap in the curtains. A vehicle's lights
grow brighter, pass across
the opening, and disappear. You have
observed a rise and fall in brightness.
That does not mean the driver increased
the headlights, dimmed them,
and switched them off. The changing view
produced much of what you
saw.
If you open the curtains later and the
vehicle isn't there, you have
learned something. But you haven't
established that the car ceased
to exist. Nor have you established who was
driving it.
There are observations you can make from
that room, and questions the
room cannot answer.
The analogy only goes so far. A radio
telescope is not a person behind
curtains, and a signal in space need not
behave like a vehicle.
What matters is the separation between an
event and the way an instrument
samples it. That separation will follow us
through the entire episode.
There's another limitation that is easy to
overlook.
Listening to the universe isn't the same
as having every possible conversation
open at once. You must decide where to
look, which frequencies to examine,
what timescales matter, and what should
count as interesting.
An instrument can be extraordinarily
capable and still leave enormous
parts of the possible search untouched.
Imagine being told that somewhere on
Earth, at some time today, a person
will say something important. You aren't
told the language, location,
volume, or duration. You are allowed to
place microphones, but not
everywhere. You are allowed to record, but
not indefinitely.
Before you hear a word, your choices have
already shaped what you can
discover.
Now suppose the speaker doesn't know you
exist.
They may be addressing somebody else.
Or the sound may be a by-product of
something they are doing.
An engine can tell you that someone built
an engine, even though it
isn't trying to introduce its maker.
A possible sign of intelligence and a
deliberate attempt at contact
are different prospects.
That opens a much larger landscape than
the image of an alien patiently
repeating hello. It also makes the task
more demanding.
We might recognize an unfamiliar
technology through its effects before
understanding what it is doing.
Or we might fail to recognize it precisely
because we are expecting
communication to look like communication
we already know.
This is why the human work around an
observatory matters.
Instruments embody expectations.
People can revisit those expectations.
A preserved record allows a later
generation, equipped with different
questions, to find significance that
wasn't accessible to the first.
There is no need to imagine a hidden
message buried in every archive
to find that compelling. The ordinary
possibility is extraordinary
enough: our ability to understand an
observation can change long after
the observation itself is over.
So return to Ohio. A system has been built
to pay attention to a particular
part of the radio sky. It turns incoming
measurements into something
that can be inspected. Most of the output
belongs to the regular business
of observing. Then a short sequence stands
out.
Before we ask what made it, let's
understand what those characters
actually say. Because they say much less
than an alien greeting, and
considerably more than nothing.
The famous sequence is six, E, Q, U, J,
five.
Those characters are often displayed as
though they might be a code
waiting to be translated. In this case,
they are a compact way of recording
signal strength. The changing symbols
describe changing measurements.
They are not six characters received as an
extraterrestrial sentence.
In Ehman's account, the observation is
conventionally described as
lasting about seventy-two seconds.
The rise and fall drew attention because
it resembled what the telescope
could record as a compact source passed
through its sensitive region.
The signal appeared in one of the
instrument's two observing beams,
without the corresponding detection
expected in the other.
That combination helped make the event
difficult to explain.
The point isn't to turn you into a radio
astronomer.
It is to make the page legible enough that
we can stop asking it for
information it doesn't contain.
Consider a very simple instrument.
It measures how bright a room is once
every ten seconds.
You switch on a lamp, wave a flashlight,
or open a door onto a sunlit
hallway. Different events might produce
similar values.
If all we keep is one brightness number
for each interval, much of
the original scene is gone. The numbers
can still be useful.
They cannot become a video simply because
we want to see what happened.
The same principle applies to timing.
Suppose those readings show elevated
brightness over several intervals.
That gives us information about what the
sensor received.
It does not automatically reveal the
complete lifetime of the light
source. Perhaps the light existed before
it entered the sensor's view.
Perhaps it continued after leaving.
Perhaps it changed. We need more than the
outline of the recording
window to choose among those
possibilities.
This matters because a precise number can
give us a false sense of
completeness. Seventy-two seconds sounds
like a neatly bounded event.
We imagine a beginning, a transmission,
and an ending.
We may even imagine someone pressing a
button at one end and releasing
it at the other. None of those imagined
actions is contained in the
number.
A twenty twenty-five archival reanalysis
revised several estimates,
including the signal's location,
frequency, strength, and timing.
Its duration estimate is around seventy-
three seconds as a lower bound.
That refinement is scientifically useful.
It still does not supply a transmitter, a
purpose, or an exact duration
for everything the source was doing.
The most useful change in our
understanding is therefore not the extra
second. It is learning to ask what a
reported duration describes.
A measurement interval. An inferred
transit.
A limit. A complete event. Those can be
different things, even when
an illustrated video turns them into the
same flashing dot.
Let's do a small exercise. Imagine I show
you six measurements rising
and falling. You are free to describe the
shape.
You can compare it with the expected
response of the instrument.
You can test whether an ordinary source
crossing its view could produce
something similar. But if I ask you
whether the source was friendly,
the measurements provide no answer.
That leap sounds absurd when stated
directly.
It becomes much easier to make when the
measurement arrives inside
a story. A dark sky. A lonely observatory.
A suggestive musical note. An image of a
distant world.
Now the same data can begin to feel like a
gesture.
We haven't added evidence. We've added a
situation in which our minds
know how to imagine a sender.
There is nothing wrong with imagination.
We are going to use it throughout this
episode.
I just want us to notice when it starts
carrying a conclusion the observation
hasn't established.
Another part of the appeal is the
frequency region.
Hydrogen has a characteristic radio
transition that has long interested
people thinking about interstellar
communication.
A naturally recognizable feature of the
universe seems like a possible
meeting place: something two technological
civilizations might independently
know about. But hydrogen is also part of
nature.
A frequency associated with it cannot, by
itself, serve as an address
label from an intelligence.
Think of two people trying to meet in an
unfamiliar city without being
able to communicate beforehand.
They might independently choose a
prominent landmark.
That would be a reasonable strategy.
Finding someone near that landmark would
still not prove they had come
to meet you. The location is shared by all
kinds of activity.
The attractive idea is common ground.
If biology, history, and language differ
radically, perhaps some properties
of the universe could provide a starting
point.
The limitation is that recognizing common
ground doesn't tell you why
something happened there.
The second beam adds another unfinished
part to the picture.
A continuing source in the right place
should ordinarily have offered
another opportunity for detection as the
observing geometry changed.
That expected counterpart wasn't recorded.
There are different ways of trying to
account for that.
The event does not come with a label
telling us which one applies.
So we are left with an observation that is
interesting in several connected
ways, rather than one magic feature that
certifies its origin.
Its appearance, its narrow frequency
range, its strength, the observing
geometry, and the absence of the expected
counterpart all become parts
of the investigation.
I find that more compelling than the
simplified version in which scientists
heard something obviously alien and then
inexplicably gave up.
The real problem is harder. People had a
limited record of a striking
event. They tried to learn more.
The sky did not provide an easy
continuation.
And this is where the word once becomes
especially slippery.
Once in a record is not necessarily once
in the universe.
An event could recur when you aren't
observing.
It could recur somewhere your instrument
isn't looking.
It could change frequency or fall below
your sensitivity.
It could also fail to recur because your
original explanation of it
was wrong.
Every additional possibility carries a
cost.
We cannot keep inventing conditions that
protect a favorite explanation
from every unsuccessful search.
At some point, an explanation must tell us
what we could observe that
would make it stronger or weaker.
Otherwise we are keeping a story alive by
making it impossible to test.
The people who returned to the wow
question understood that problem.
They needed to do more than look wistfully
at the famous printout.
They needed to decide how another
observation could change what was
known.
That meant making a practical bet about
what the source might do next,
and arranging to be there if it did.
Imagine a light sweeping across a dark
coastline.
You see one flash. Then nothing.
If the light comes from a rotating beacon,
waiting in the same place
could eventually give you another flash.
But how long should you wait? A minute?
An hour? Until morning? Your answer
depends on what you think is turning,
and how often it points toward you.
That is an analogy, not an explanation of
the Wow!
signal. It does, however, capture a real
question behind later observations.
Robert Gray and Simon Ellingsen
investigated the possibility of an
intermittent or repeating source.
Their two thousand two paper describes
observations using a twenty-six-meter
telescope in Tasmania, tracking the
apparent source regions for nearly
fourteen hours at a time on multiple days.
They did not recover a signal resembling
Wow!
Their findings constrained the kinds of
repeating source their observations
could have detected, while leaving other
schedules and possibilities
open.
Fourteen hours is a different kind of
commitment from a quick glance
back at a famous location. It is a
deliberate attempt to give a possible
recurrence time to happen. And an
unsuccessful result still carries
information. If a sufficiently strong
beacon should have crossed your
view every hour, and you observe for
fourteen hours without it, that
particular picture becomes harder to
sustain.
But consider a different fictional beacon.
It flashes once every few days.
Or it does not follow a regular schedule.
Or it is active only during a particular
kind of operation.
Those possibilities change what your
waiting period can tell you.
They also require assumptions.
A useful search makes those assumptions
explicit rather than treating
every period of silence as equally
mysterious.
In twenty twenty-two, David Kipping and
Gray examined an irregularly
repeating-source hypothesis using the
historical observations.
Their analysis found tension between that
model and the available follow-up
data, but did not exclude it outright.
That is a statement about a model tested
against observations.
It is not a calculated probability that
the signal came from aliens.
Numbers in a paper can acquire a very
different meaning when they enter
a headline. A statistical result about a
proposed repetition schedule
can become, in casual retelling, a
percentage attached to extraterrestrial
life. The question being calculated
matters as much as the answer.
Otherwise a careful piece of work can end
up supporting a claim its
authors never made.
For the person following this mystery, the
waiting can be almost more
unsettling than the original event.
You have a location, or possible
locations.
You have a record of something striking.
You have increasingly capable ways to
listen.
What you lack is the cooperation of
whatever produced the first observation.
There is a temptation to turn that lack of
cooperation into intention.
It went quiet because it noticed us.
It stopped because we weren't ready.
It transmitted only once because one
message was all it wanted to send.
Those can be premises for fascinating
stories.
They aren't observations of motive.
The instrument did not measure a decision.
And the range of possible explanations
includes a universe that is
stranger than our current catalog of
natural phenomena.
In twenty twenty-four, Abel Méndez and
colleagues proposed a mechanism
involving cold hydrogen clouds briefly
brightened by a powerful transient
event. They drew on weaker narrowband
emissions in archival Arecibo
observations. The proposed connection to
Wow!
was a hypothesis, not a recording of the
original cause.
Their paper explicitly left alternative
origins open.
That possibility deserves to be understood
on its own terms.
A rare natural radio event would be an
interesting discovery.
It would change how searches recognize
potential false positives.
The fact that a finding doesn't give us
another civilization doesn't
make the universe less remarkable.
Equally, the existence of a proposed
physical mechanism doesn't mean
that the historical case is closed.
We should be able to distinguish a
mechanism that might fit an observation
from an identification supported by enough
evidence to settle its origin.
Curiosity benefits from that distinction.
It keeps us interested in what further
work could reveal.
The twenty twenty-five reanalysis returned
to the surviving records
themselves. Among its revisions was a
change to the estimated sky position.
That sounds like the beginning of a
dramatic revelation: perhaps everyone
had simply been looking in the wrong
place.
But the authors noted that previous
searches generally covered the
revised positions, with different
sensitivities.
The real improvement was more careful
characterization, not a clean
excuse for every unsuccessful observation.
I like that aspect of the story.
It refuses to become as tidy as either
side might want.
The famous mystery isn't automatically an
alien message.
A natural explanation isn't automatically
a confirmed solution.
Better information can narrow uncertainty
without making it disappear.
There is also a lesson in the survival of
the records.
We often think the future will answer old
questions by building a bigger
instrument. Sometimes it begins by taking
better care of what was already
measured. A page that seemed finished can
become useful again when
someone asks a different question of it.
Imagine inheriting a photograph of a place
you cannot visit anymore.
You might initially notice the people in
the foreground.
Years later, a detail in a window helps
establish the date.
Another person recognizes a building.
The photograph hasn't changed.
The community of people able to interpret
it has.
That doesn't justify inventing details too
small to see.
It gives you a reason to preserve the
original and distinguish it from
the annotations added later. A mystery
needs room for new understanding,
but it also needs an anchor that doesn't
drift every time the story
is retold.
For Wow!, that anchor remains a
remarkable, limited observation.
We do not have an established
extraterrestrial sender.
We do have a long human effort to
understand what happened.
It would be a mistake to confuse those two
statements.
It would also be a mistake to think the
second has no emotional weight.
Still, I want to take us one step beyond
this particular uncertainty.
Suppose the problem of origin had already
been solved.
Suppose everyone involved agreed that the
transmission was artificial,
deliberate, and constructed to contain
something.
Would the rest be straightforward?
We have a real example that lets us
explore that question.
Its makers were human. They told the world
what kind of experiment
they were attempting. There was no need to
guess whether a mind was
behind it. Even with those advantages,
receiving the transmission and
understanding what it carried turned out
to be separate adventures.
In May of twenty twenty-three, an
experiment called A Sign in Space
used the European Space Agency's Trace Gas
Orbiter near Mars to transmit
a human-designed message toward Earth.
Media artist Daniela de Paulis developed
the project with scientific
collaborators. It was a public exercise in
reception, decoding, and
interpretation, using a real spacecraft as
part of the performance.
Nobody needed to pretend the message had
actually been composed by
extraterrestrials.
That openness is what makes the exercise
useful.
We can set aside the dispute over whether
someone made it.
Someone did. The challenge begins with
what a recipient has to do next.
Picture a collection of unfamiliar data
arriving on your computer.
Before you can interpret a message, you
must identify which part of
the incoming material is the thing you are
supposed to interpret.
Then you need a way to arrange it.
Then you need to recognize what the
arrangement represents.
Even after all of that, you may still need
to ask why anyone chose
to send it.
ESA's account says an online community
extracted the message from the
signal data within ten days. The later
decoding milestone came in June
of twenty twenty-four, when a father and
daughter, Ken and Keli Chaffin,
recovered an image depicting five amino
acids.
That is a tremendous change in what you
can see.
It does not automatically turn the image
into a sentence with an agreed
meaning.
I want to pause at that difference,
because it is easy to lose the
achievement by rushing toward the next
mystery.
People took an unfamiliar structure and
found a method that revealed
something recognizable. That mattered.
Interpretation remained open, but the work
had advanced.
Uncertainty hadn't swallowed every answer.
The project's account of the solution
describes a cellular automaton:
a system that repeatedly applies a rule to
small groups of cells.
In this case, a reversible transformation
moved the pattern through
thousands of steps until the molecular
diagrams emerged.
We do not need to reproduce the entire
procedure here.
The striking idea is that a pattern which
initially appeared one way
could contain a different organization,
accessible through a particular
process.
Let me offer a much simpler illustration
of my own.
Imagine a square divided into small cells.
Some are dark, some are light.
You and I agree on a rule for moving the
dark cells.
We apply it once, then again, then again.
If I show you only a later state, the
image you expect may be hidden
by the transformation. Finding the rule
could be as important as recognizing
the eventual picture.
That illustration is not the actual
message or its decoding algorithm.
It is a way of feeling the difference
between staring harder at an
image and discovering that it needs to be
processed differently.
A pair of eyes can keep searching for a
face in the same marks while
a different method reveals chemistry.
Now consider what our expectations do to
that search.
Show a person a scattered pattern against
black, and a star map may
come to mind. Show them repeated shapes,
and they may look for a language.
Give them a sound, and they may try to
hear speech.
Those instincts are useful starting
points.
They can also become traps if the first
plausible interpretation becomes
the only one we can see.
We bring a great deal of the world with us
when we look at a picture.
We know that an outline can stand for an
object.
We know a diagram can show relationships
rather than literal appearance.
We know the same line can represent a
road, a connection, a boundary,
or the edge of a cup. Context tells us
which kind of line we are seeing.
Take the context away, and familiarity
becomes less reliable.
A drawing of a hand could be an anatomical
description.
It could be a counting aid. It could
identify the maker.
It could be a warning about touching
something.
Recovering the shape is an achievement.
Recovering its role requires more.
Imagine receiving a perfectly clear
picture of a staircase.
You understand the geometry. You might
infer that it was built to permit
movement between levels. But you don't
know whether the sender is showing
you a home, a sacred place, an obstacle, a
historical artifact, or
a joke. The picture is legible while the
intention remains obscure.
Now imagine the sender has no body
remotely like yours.
The steps may not be steps at all.
You have recognized an arrangement by
matching it to something in your
life. That match could be useful.
It could also be the first serious error
in the conversation.
This is where I find the human-made
exercise especially interesting.
Its participants had enormous advantages
that a real encounter with
another intelligence might not provide.
They knew the project existed.
They knew humans had designed it.
They could discuss methods with other
people and compare work.
Those conditions do not tell us how long
decoding an actual extraterrestrial
message would take. They show us some of
the different tasks hidden
inside the single word, understand.
There is no sensible conversion in which a
year spent on one artistic
puzzle equals a certain number of
centuries needed to understand aliens.
A real message might be easier, especially
if its makers deliberately
taught us how to read it. It might be
incomparably harder.
It might not be addressed to us at all.
The exercise gives us questions and
experience, not a universal timetable.
What it does give us is a human story with
a satisfying turn.
A father and daughter found a way into a
structure that had resisted
interpretation. We don't need to invent
their dialogue or place them
in an imagined room to appreciate that.
Their relationship alone makes the
achievement feel different from
the phrase, data successfully processed.
Someone persisted. Someone tried a method.
A pattern became visible. The result could
be shared so that other
people could examine it. Those are
ordinary human actions carrying
an unusual amount of wonder.
And then came the next stage. Suppose a
message presents components
associated with life. What is it doing?
Describing the sender? Pointing to
something we share?
Offering a lesson? Inviting a question?
An image can support several imaginative
readings before there is enough
context to choose among them.
That openness was part of an artistic
project.
It shouldn't be mistaken for proof that
science cannot establish meaning,
or that every interpretation is equally
good.
Some readings fit a structure better than
others.
Some require details that are not present.
Some may be interesting as art while
failing as descriptions of the
intended encoding.
In a real exchange, additional messages
could help.
A sender might repeat examples, vary one
element at a time, or respond
to something we send. Meaning could become
more stable through interaction.
The problem in our title is what happens
when there is no interaction
to work with. Only one encounter with the
information, and no certainty
of a second.
Let's imagine you discover a box
containing one unfamiliar tool.
If its maker is beside you, a gesture may
solve the problem.
If the maker is gone, you have the object,
its marks, and whatever
surroundings survived. You can experiment.
You can infer. You can make mistakes that
nobody is available to correct.
A message received once could have that
quality.
Not meaningless. Not necessarily
undecipherable.
But separated from the person, culture, or
process that would have
made its significance easier to establish.
This is the point where the mystery turns
toward us.
We have wondered whether another
intelligence might make itself understood.
We have also sent things outward in the
hope that someone unfamiliar
might recognize what we were trying to
express.
If our message reached such a recipient,
would we be as easy to understand
as we like to imagine? Would the part we
considered obvious be the
part they found most confusing?
And would they recognize that, somewhere
behind the diagrams and measurements,
there were people hoping to be known?
Before we decide what we would say in
reply, let's look at what we
have already chosen to send.
In nineteen seventy-four, the Arecibo
telescope in Puerto Rico transmitted
a deliberately constructed radio message
toward the star cluster known
as M thirteen. It was part of a ceremony
marking an upgrade to the
observatory. The message offered a compact
pictorial representation
of aspects of humanity and our world.
It was a demonstration of what we could
send, rather than the beginning
of a conversation with a known recipient.
The transmission contained one thousand,
six hundred and seventy-nine
binary digits. That number can be factored
into twenty-three and seventy-three,
both prime numbers. Arrange the
information with the intended dimensions,
and a picture begins to emerge.
The arithmetic offers a clue about
organization.
It doesn't supply every assumption needed
to understand the picture.
Let's imagine an unknown recipient working
through that problem.
They identify repeated units. They try
different arrangements.
One produces something structured enough
to deserve attention.
At that point, they have discovered a
possible way to view the information.
They still have to determine what its
components refer to.
For a human, a simple figure with limbs
can look immediately like a
person. A representation of a telescope
can be recognized by somebody
who already knows the instrument.
A recipient with a different body and a
different technology wouldn't
necessarily share either advantage.
The message is an ingenious attempt to
cross a gap, and the size of
that gap is part of what makes it
interesting.
There is also a distinction between
successfully transmitting a message
and successfully communicating.
We can measure what we sent. We can
describe its intended meaning.
Unless a recipient provides some evidence
of understanding, the far
end of the exchange remains a hope.
Now move from a radio transmission to a
physical object.
The Voyager spacecraft carry records:
objects that would have to be
encountered and examined. They are not
broadcasting their music continuously
into space. That difference changes the
imagined meeting completely.
A radio message can arrive as an event.
A record can be found as an artifact.
NASA describes the Golden Record as a
selection of pictures, natural
sounds, music, and greetings in fifty-five
languages.
A committee led by Carl Sagan helped
choose its contents.
Each record was accompanied by a cartridge
and needle, with symbolic
instructions on its protective cover.
The designers were trying to give an
unfamiliar recipient a way into
what they had made.
I find the inclusion of instructions
almost unbearably human.
We can imagine the magnificence of another
civilization, and then we
still have to deal with a basic problem:
somebody needs to figure out
how to play the damn thing.
It's the same impulse that makes you write
an explanation on a box
before leaving it for someone else.
Here is what this is. Here is where to
begin.
Please don't mistake the packaging for the
gift.
Only in this case, there is no shared
language, no guarantee of similar
senses, and no assurance that the box will
ever reach anyone.
The cover uses a hydrogen transition as a
reference for time.
It also provides instructions for
reconstructing pictures and includes
a test image with a circle, intended to
help a decoder recover the
correct proportions. That is a lovely
example of trying to communicate
through something more basic than a
vocabulary.
Before you can explain a face, you may
need to establish that the face
isn't supposed to be stretched into an
oval.
Think about how much of ordinary
communication rests on these quiet
agreements. The page has a top.
The photograph represents a scene rather
than a flat object of that
exact size. The sequence has an order.
A mark repeated twice can mean two
instances, emphasis, or a correction.
We absorb so many conventions that they
become almost invisible to
us.
Designing a message for an unknown
intelligence asks you to notice
the conventions again. What can be
demonstrated?
What can be inferred? Which assumptions
can be reduced, and which simply
have to be risked? There may be no
completely assumption-free message.
There can still be a thoughtful attempt to
make the first steps easier.
But the part of the Golden Record that
reaches me most isn't a decoding
instruction. It is the decision to include
human voices.
NASA's historical account describes Nick
Sagan recording a greeting
when he was six years old. A child's voice
became part of an object
intended for a possible audience beyond
our world.
The scale of that is difficult to hold in
your mind.
A small person, at the beginning of a
life, contributes to something
whose possible journey extends beyond any
lifetime we can confidently
imagine.
You don't have to assume it will ever be
heard to feel what the choice
expresses. Someone decided that
representing Earth should include more
than the accomplishments of powerful
adults.
There should be a child among the sounds
we offer.
A person who had barely begun to discover
the world was helping introduce
it.
I'm describing the historical choice, not
pretending we can know what
an unknown listener would feel.
The tenderness belongs to our experience
of it.
A recipient might hear an acoustic pattern
and never infer youth, vulnerability,
or hope. That possibility makes the
gesture more poignant to me, not
less.
Imagine sending a photograph to someone
who has never experienced a
family. They might count the figures,
analyze their similarities, and
infer biological relationships.
Would they recognize the reason you kept
that particular picture?
Would they understand why the badly framed
one mattered more to you
than the technically perfect one taken a
minute later?
The information that makes an object
precious is often partly outside
the object. It belongs to a relationship,
a memory, or a history of
shared attention. Our messages can offer
evidence of those things.
They may not be able to deliver the
experience itself.
JPL's archive describes another small
human touch on the Golden Record.
Timothy Ferris wanted something made
directly by a human hand to appear
on it, and an inscription was etched into
its surface.
Amid the engineering and careful
selection, there was room for a mark
whose manner of making mattered to its
makers.
We began this episode with a mark on a
printout.
Here is another mark, attached to a very
different hope.
One records a person's response to
something received.
The other accompanies something sent.
Between them lies the wish that
information might eventually connect
minds.
So I want to give you a choice.
This is our own thought experiment, not a
historical description of
how the record was selected. You have room
for one image and one sound.
You cannot include a written explanation
in a language you know the
recipient understands. What do you choose?
A picture of Earth might seem obvious.
But do you choose the planet from far
away, a landscape, or a person
standing in that landscape? Each
communicates a different scale of
belonging. The distant view says there is
a world.
The landscape suggests an environment.
The person introduces a particular form of
life, while leaving almost
everything about that life unstated.
And the sound? Rain on a roof.
A conversation. An instrument.
A crowd. A voice calling someone home.
You might choose something scientifically
representative.
You might choose something you would miss
if you could never hear it
again.
Those are different editorial decisions.
One tries to describe a species.
Another tries to preserve an experience.
A third might try to show the best of what
we could become.
None can include everything. Every
selection creates an absence around
it.
Would you include evidence of our cruelty?
If you leave it out, have you created a
dishonest introduction?
If you include it without the history
needed to understand it, have
you made us seem more frightening than the
whole truth would justify?
A message intended to express peace could
still come from a world that
has struggled terribly to practice it.
I don't think the problem has a simple
answer.
It has a recognizable human weight.
We want to be seen clearly. We also want
to be seen generously.
When the audience is unknown and the
explanation may travel for an
enormous time, those wishes can pull in
different directions.
Even a declaration of peaceful intent
leaves questions.
Does it speak for everyone? For the people
who built the transmitter?
For a particular moment in their history?
Could later generations feel differently?
A message can be sincere without becoming
an eternal guarantee of a
civilization's behavior.
The same would be true of something we
received.
A single transmission might represent a
whole society, a small group,
a machine following old instructions, or
an individual acting alone.
We would need evidence before deciding
which.
The ability to reach us would not
automatically establish the authority
to speak for an entire world.
For me, the beauty of our outward messages
survives all of those complications.
We made an effort. We imagined someone
unfamiliar and tried to offer
them a way in. We put thought into the
possibility that another intelligence
might someday want to know what kind of
place this was.
There is hope in that act, even without a
destination confirmed.
But it also prepares us for a more
difficult question.
Once you have felt the desire to send
something, the idea of refusing
to answer can begin to feel like shutting
a door.
And perhaps it would be. Or perhaps
waiting would be the most responsible
first step. To think about that honestly,
we need to leave the historical
messages where they are and imagine a new
situation, clearly labeled
as our own.
Let's suppose independent observatories
have confirmed an artificial
signal from beyond Earth. This is a
hypothetical.
We are not describing the Wow!
signal, a secret discovery, or an
announcement that has actually happened.
We are constructing a situation in which
the origin question has been
resolved well enough for people to face
the next decision.
The information is available for others to
examine.
The signal is real. It appears to have
been made.
Its purpose is unclear. We do not know
whether it was intended for
us. We do not know whether the sender is
still active.
And we have no reliable basis for
describing its intentions as friendly
or hostile.
Now imagine hearing that news at home.
The room doesn't physically change.
The cup on the table is still where you
left it.
Somewhere, a washing machine completes its
cycle.
Yet a fact about existence has changed
around those ordinary things.
You look through the window, and the same
darkness has acquired a different
possibility.
I suspect that contrast would be one of
the strangest parts.
History can change while your life still
contains errands.
You could feel awe, fear, skepticism about
the announcement, and concern
about tomorrow's responsibilities within
the same hour.
There would be no requirement for humanity
to react as a single character
in a film.
Some people would want to respond
immediately.
Others would want more time. Some would
argue that a discovery belongs
to everyone. Others would worry about what
happens when everyone with
a transmitter decides that speaking for
Earth is a personal opportunity.
The problem of understanding another
intelligence would immediately
intersect with the problem of living
alongside our own.
Consider the first choice: keep listening.
Gather more observations, look for
structure, and make the record easier
to verify. This offers the possibility of
learning before acting.
It may feel frustrating to people who see
silence as fear.
It may feel essential to people who think
an irreversible action deserves
more than the excitement of its first
announcement.
But listening longer doesn't guarantee
that the missing piece will
arrive. In our imagined situation, there
may be no second transmission.
Waiting could mean letting a rare
opportunity pass.
Or it could reveal that what looked like
an invitation was a signal
with an entirely different function.
Now consider a second choice: send a
minimal acknowledgment.
Something intended to indicate that a
receiver exists here and has
recognized a pattern. It sounds modest
until you try to define minimal.
Which part of the received signal do you
repeat?
Does repetition indicate comprehension,
mimicry, error, or interference?
What new information does the reply
disclose about the sender on Earth?
Even a simple acknowledgment depends on
conventions.
When a person waves, waving back usually
makes sense.
When a machine flashes an error indicator,
copying the flash doesn't
fix the problem. You need some
understanding of the activity before
you can be confident that your response
belongs to it.
The third choice is more generous.
Send a deliberate introduction.
Describe our world, our biology, our ways
of representing information.
Include enough structure to help a
recipient learn how the message
works. This carries the emotional appeal
of the Golden Record, but
in our scenario it would be directed
toward evidence of another technology.
The attraction is obvious. Perhaps we
could begin learning from one
another. Perhaps the most important
exchange in human history would
start because somebody was willing to
offer more than a cautious echo.
The concern is also obvious. We would be
deciding what to reveal before
understanding who might receive it or what
they could do with it.
We should resist claiming certainty in
either direction.
We cannot infer that a reply would doom
us.
We also cannot infer that any intelligence
capable of receiving it
must be benevolent. Technological ability
answers questions about capability.
It does not, on its own, answer questions
about values.
There is another practical complication.
Radio communication travels at the speed
of light.
Suppose, for a simple example, the sender
is one hundred light-years
away and remains roughly that far from us.
A signal reaching us now began its journey
about a century ago.
A reply would need another century to
reach that location.
An immediate answer from there would take
a further century to return.
That calculation assumes ordinary light-
speed communication and ignores
small changes in the distance.
It isn't a prediction about any actual
source.
It gives us a scale for the experience.
The people celebrating the first
confirmation might never hear a response
to the reply they helped compose.
What does a conversation become under
those conditions?
You cannot casually clarify a
misunderstood phrase.
You cannot rely on the same individuals
remaining available.
You are communicating through
institutions, records, and generations.
Every message has to carry more of its own
context because another
round of questions may be impossibly
expensive in time.
Imagine writing a letter that your
grandchildren will inherit responsibility
for answering. You would probably explain
more than you would in a
text message. You might include the
question that prompted the letter,
the assumptions behind your response, and
a description of what you
don't know. You would want the future to
distinguish your uncertainty
from your mistakes.
You might also try to prevent the message
from becoming sacred merely
because it was old. A statement sent
during the first excitement of
discovery could acquire authority its
writers never intended.
Future people would need permission to
understand it historically,
rather than treating every choice in it as
the permanent voice of Earth.
The recipient could have the same problem.
Their transmission might have been made
under circumstances that no
longer exist. We could be reacting to the
last work of a vanished project,
or to a routine operation whose makers
never expected an outside audience.
Those are possibilities, not claims.
They remind us that distance separates
events in time as well as in
space.
And if a message revealed that its sender
was in danger, the delay
would become heartbreaking. Would the
emergency still be happening?
Could a response arrive in time to matter?
Might understanding the account be the
only help available to us?
A signal could establish another life in
our awareness without giving
us the ability to enter its circumstances.
It is tempting to escape that difficulty
by introducing a technology
that ignores the distance. Science fiction
often does, and the resulting
stories can be wonderful. For this thought
experiment, the distance
itself is doing important work.
It asks what care, responsibility, and
curiosity mean when there is
no quick feedback.
We already know, within human life, that
an action can matter even
when the person taking it won't see its
result.
We plant things, preserve things, and
teach things for people who will
live after us. An interstellar exchange
could make that familiar act
of trust vastly larger.
I would want the people composing a reply
to remember the ordinary
room where the news first reached them.
The scale might be cosmic, but the
decision would still be made by
beings with limited knowledge, emotional
attachments, and an imperfect
understanding of consequences.
We should bring our finest thinking to it
without pretending that awe
makes us infallible.
So where does that leave our hypothetical
choice?
With reasons to listen carefully, reasons
to consider an answer, and
reasons to avoid confusing urgency with
wisdom.
I don't have a universal reply that would
be right for every possible
discovery. The evidence would matter.
The form of the signal would matter.
What we could actually learn before acting
would matter.
But beneath the decision is a question
that would remain even after
a successful exchange. Suppose we had
established that another intelligence
existed. Suppose we could even trade
information.
How much would we need to know before we
felt we understood the mind
on the other side?
I believe there is other intelligence
beyond us.
That belief is part of why I find this so
compelling.
But I can't tell you who—or what—was
responsible for that signal.
What I can tell you is that I want us to
keep listening.
I want us to be capable of recognizing
something extraordinary, even
if understanding it takes much longer.
And I want to be honest about the kind of
understanding I mean.
There is knowing that something exists.
There is knowing how it works.
There is knowing what it wants.
We can make progress on one while
remaining profoundly uncertain about
the others.
Think of meeting someone whose work you
have admired for years.
You may know what they can do.
You may recognize the structure of their
thinking in what they create.
Then a conversation reveals a person more
complicated than the figure
you assembled from a distance.
The work was real. The person you imagined
around it was partly your
own construction.
With another intelligence, that distance
could be far greater.
We might infer remarkable capabilities
from a signal and begin supplying
the rest of the character ourselves.
Ancient wisdom. Perfect cooperation.
Ruthless efficiency. A desire to teach.
A desire to dominate. Each image says
something about the future we
hope for or fear.
Some of those possibilities could turn out
to resemble reality.
We would still need a way to distinguish
them.
A beautiful mathematical structure might
impress us without expressing
affection. An unfamiliar signal might
frighten us without carrying
a threat. Our emotional response would be
a real human event, but it
would not necessarily describe the sender.
This is where I think wonder needs
patience.
If we insist that another intelligence fit
a role in our story immediately,
we may make it harder to recognize what is
actually there.
We might demand a savior, an enemy, a
parent, or a mirror.
A mind from elsewhere could be none of
those things.
Let's imagine a very limited exchange.
Again, this is a thought experiment.
We send a sequence that represents a
simple mathematical relationship.
An answer returns that correctly extends
it.
We now have something stronger than an
isolated unusual observation.
There is a relationship between what we
sent and what came back.
That would be astonishing. It could show
that information had been
received and processed in a way responsive
to our message.
It still wouldn't tell us how the
responding system experiences anything,
or whether it experiences anything at all.
A machine could perform the task.
A person could direct the machine.
A collective could have established the
rules long before the exchange
began.
Now suppose the answer includes a diagram
we can use to make a new
prediction. We test the prediction, and it
succeeds.
Our confidence in the usefulness of some
of the information grows.
Does that establish goodwill? Perhaps it
supports the possibility of
a cooperative exchange. It doesn't answer
every question about why
the information was offered.
Within human life, help can be generous,
strategic, obligatory, manipulative,
or several of those at once. I wouldn't
assume an unfamiliar intelligence
shares that exact range of motives.
I also wouldn't assume that giving us
something useful makes all questions
about motive unnecessary.
That is where the unease lives for me.
It doesn't require an image of a monster.
It comes from realizing that a
relationship could be important before
it becomes understandable. We could be
learning from something while
still struggling to understand the
conditions of the exchange.
There is a hopeful side to the same
uncertainty.
If our first assumptions about another
mind are incomplete, then our
fears may be incomplete too. We might
discover forms of cooperation
we had not anticipated. We might encounter
priorities that make some
of our conflicts seem painfully narrow.
We might learn that intelligence can
organize itself around kinds of
experience we have barely considered.
Those are possibilities I find worth
imagining.
They are not promises made by the size of
the universe.
A vast cosmos gives us room for many
scenarios; it does not select
the one that would comfort us most.
I also wonder about the experience of
being understood.
Suppose we eventually find a way to
explain something simple about
life here. A physical need. A pattern of
development.
A relationship between living things.
And the reply makes clear that the
recipient has grasped it.
What would that feel like? Would it be
recognition on a scale we have
never experienced before?
You can imagine the opposite as well.
We explain ourselves with tremendous care,
and the answer suggests
that something central to us is barely
relevant to them.
They can describe our bodies more
precisely than we can, yet fail to
understand why a particular loss matters.
They can predict an event we couldn't
predict, yet misread the meaning
we attach to it.
That imagined difference does not make
them cruel.
It may mean we have reached a boundary in
shared experience.
Crossing it could require patience,
invention, and a willingness to
stop treating our first translation as the
final one.
Even between humans, a technically correct
description can miss the
center of an experience. You can describe
the vibrations of a piece
of music and still leave out why someone
plays it after a death.
You can identify every object in a
childhood photograph and never know
why one corner of the room makes its owner
smile.
An unknown recipient might first meet us
through precisely those external
descriptions. Measurements. Images.
Chemistry. Signals. Perhaps something more
personal could emerge only
through a long accumulation of examples.
Perhaps there would be parts of us that
remained difficult to communicate,
just as there could be parts of them for
which we had no useful analogy.
I don't find that possibility
discouraging.
I find it humbling in a way that leaves
room for discovery.
Understanding another intelligence would
not have to mean reducing
it to a version of ourselves. It could
mean learning enough to recognize
both a connection and a difference.
There is a danger in assuming that every
advanced intelligence must
have completed the moral journey we would
like humanity to complete.
There is another danger in assuming that
intelligence inevitably produces
domination. Both ideas can become
shortcuts around the work of observing
a particular case.
For this reason, I would want our
curiosity to remain active after
the first apparent success. After the
first pattern recognized.
After the first correct prediction.
After the first exchange that seems
friendly.
Not because trust is impossible, but
because a consequential relationship
deserves more than our relief at having
found one.
And I would want room for the possibility
that their curiosity might
be as complicated as ours. A sender could
contain disagreements, competing
projects, different ways of understanding
us.
The word they can flatten a civilization
into a single intention before
we have any evidence that it acts as one.
Think back to the message you chose
earlier: one image and one sound.
Someone else on Earth would have chosen
differently.
A third person might object to both of you
speaking at all.
That diversity isn't a minor detail added
after the message.
It is part of the world the message tries
to represent.
If another intelligence sends something,
we might need to ask similar
questions about its authorship.
Who made the choice? Who was included?
Who was absent? What circumstances shaped
it?
The engineering of a transmission might be
the first part we understand
and the social meaning the part that takes
generations.
All of that can follow from a single,
extraordinary moment of recognition.
Someone notices that a pattern is more
than noise.
A second person checks. Others begin to
understand.
The event opens a door, but it does not
furnish the room beyond it.
And if there is no second message, we
would have to learn how to live
with that opening. With a discovery that
changes what we believe is
possible, while leaving the relationship
itself unfinished.
Come back to the page where we began.
By now, it should look a little different.
The characters are measurements.
The handwritten response belongs to a
person.
Around that small piece of paper is the
work of building an instrument,
keeping it operating, recognizing an
anomaly, preserving its record,
and returning to it with new questions.
The page cannot tell us that another
civilization tried to speak.
It can remind us how much may depend on
the care with which we pay
attention.
Elsewhere in this journey, a deliberately
constructed puzzle became
an image through the work of people who
refused to stop at its first
appearance. And humanity's own messages
carried our choices outward:
what to explain, what to preserve, what we
hoped an unfamiliar recipient
might recognize.
There is a thread connecting those acts.
Someone believes there may be something
worth understanding beyond
the limits of their present view.
They make an effort without being
guaranteed the result.
They leave something that another person
may be able to carry further.
For me, that is a hopeful way to think
about the search.
Hope doesn't have to mean that every
unusual event is the one we have
been waiting for. It can mean that the
question is worth approaching
with enough care that, if something
extraordinary does arrive, we have
given ourselves a chance to recognize it.
It can also mean remaining interested when
the answer is unexpected.
A new natural phenomenon would enlarge our
picture of the universe.
A mistake understood would improve the way
we listen.
A pattern left unresolved might become a
question another generation
can answer better than we can.
None of that removes the longing at the
center of this subject.
I think many of us want more than an
additional fact in a catalog.
We want to know whether experience extends
beyond the life we can currently
see. Whether another mind has looked
outward and felt something that
could ever meet our own curiosity.
We may not get that answer in the form we
expect.
There may be no arrival, no shared
language, no moment when every uncertainty
falls away. The first convincing evidence
could be impersonal.
Its implications could take years to reach
us emotionally, even after
the measurements had been accepted.
Imagine stepping outside after such a
discovery.
The stars would not have moved because of
our announcement.
The sky would not owe us a demonstration.
Yet the act of looking might feel altered.
Somewhere within that darkness, the
possibility of another perspective
would have acquired a different weight.
And the ordinary people around you would
still matter.
The existence of another intelligence
would not make a kindness here
smaller. It would not make a human life
disposable.
If anything, I hope it would help us see
how remarkable it is that
any part of the universe can become aware
enough to care what happens
to another.
That is my hope, rather than a forecast.
A discovery would not automatically make
us wiser.
What we did with it would still be our
responsibility.
I find something hopeful in the
possibility that another mind has looked
into the darkness and wondered about us.
There may be ways of seeing existence that
we have never imagined.
There may be beauty we have no words for
yet.
And if a message ever reaches us, we may
need time to understand the
intelligence behind it. What matters to
them.
What they recognize in us. What kind of
relationship, if any, they
are offering.
The thought leaves me with a desire to
keep listening, and a respect
for everything a signal alone could never
tell us.
I can imagine the relief of discovering
that other minds exist.
I can also imagine the long silence after
the celebration, when we
begin asking what that discovery asks of
us.
Perhaps the first message would be the
beginning of something generous.
Perhaps it would be a fragment from a life
so different that we could
spend generations trying to place it.
Either way, there would be a difference
between being noticed and being
known.
We have spent this journey thinking about
what it would mean to hear
them once. I want to leave you with the
moment after that, when wonder
has had time to settle and the decision
belongs to us.
If we finally knew someone was there, what
would we need to know before
we answered?
That question is the basis of this show.
Unknown Origin.
Stay curious, think deeply, and look for
deeper meaning in everything
you do.
