Cosmos (1980): Season 1, Episode 12 - Encyclopaedia Galactica - full transcript
Carl Sagan examines the possibility extraterrestrial life and discusses his skepticism about UFOs.
SAGAN:
In the vastness of the cosmos...
...there must be other civilizations
far older...
...and more advanced than ours.
So shouldn't we have been visited?
Shouldn't there be...
...alien ships in the skies of Earth?
There's nothing impossible
in this idea.
And no one would be happier than me
if we were visited.
But has it happened in fact?
What counts is not what's plausible,
not what we'd like to believe...
...not what one or two witnesses
claim.
But only what is supported
by hard evidence...
...rigorously and skeptically
examined.
Extraordinary claims
require extraordinary evidence.
Since 1947, there have been hundreds
of thousands of reports of UFOs:
Unidentified flying objects.
This subject has...
...more to do with religion and
superstition than with science.
Let's consider one of the most famous
accounts of a supposed encounter...
...with alien beings.
On September 19, 1961...
...an American couple was driving home
through New Hampshire.
What's the matter, Delsey?
SAGAN: They were returning along
a lonely road, late at night...
...from a vacation in Canada.
Remember, we have only their word
for what happened next.
(TUNES RADIO)
(STATIC FROM RADIO)
I'm only getting static.
You still don't believe it, do you?
No, I don't. There must be
a reasonable explanation.
Oh!
SAGAN:
They had observed, so they said...
...a strange moving light in the sky.
By definition,
an unidentified flying object.
It seemed to follow them for miles.
Easy there.
What's the matter with that dog?
(HUMMING NOISE)
What's that sound?
I don't know.
After a time, the lighting patterns
on the UFO changed.
It appeared to land.
What the...
It blocked the road,
preventing them from driving on.
They said they saw
mouthless creatures approaching...
...who were not exactly human.
Barney!
Barney, what is that?
At this point, the story
becomes still stranger.
They lost all recollection of what
happened in the next few hours.
But weeks later, they said...
...they recalled some details and
discussed the experience with others.
26 months later, under hypnosis...
...they reported that
a UFO had landed...
...and that the crew had emerged.
They were captured, they said,
and taken aboard the craft.
(WHINES)
That was the story told by
Betty and Barney Hill.
Virtually all scientists
who've studied it are skeptical.
But UFO enthusiasts think
the Hill case is a classic example...
...of a "close encounter
of the third kind."
Why? What makes it so special?
While on board, Betty had noticed...
...a book written in an unknown
hieroglyphic writing.
She was also shown a strange window
through which she could see...
...a glowing pattern of dots
connected with lines.
It was, they told her, a star map...
...displaying the routes
of interstellar commerce.
Afterwards, they were released
and permitted to return home.
Or at least, this is their story.
Believers find this compelling,
or at least plausible...
...chiefly because of
the alleged star map.
Here's how Betty said it looked.
Why would we take this seriously?
Because here is a real map widely
publicized by UFO enthusiasts...
...of 15 selected nearby stars,
including the sun...
...as seen from one particular
vantage point in space.
This map includes stars...
...that were first cataloged
several years after...
...Betty Hill recalled what she says
she saw in the alien ship.
Her map required, we are told...
...information that wasn't
available on Earth.
There is a resemblance between
the two maps, but that's because...
...the lines corresponding
to navigation routes...
...have been copied from the Hill map
onto the real star map.
If we were to substitute
some other set of lines...
...for the Hill lines, we find that
the eye suddenly is biased...
...against seeing any agreement
between the two maps at all.
To make an objective test, however,
let's remove the lines altogether.
And then there's very little
resemblance left.
But these particular stars...
...are selected from a large catalog
of star positions.
Our vantage point is also
selected to make the best...
...possible fit with the Hill map.
If you can pick and choose
from a large number of stars...
...viewed from any vantage point
in space...
...you can always find a resemblance
to the pattern you're looking for.
I'm surprised that nobody found...
...a better fit to the Hill map.
The Hills' own psychiatrist described
their story as a kind of dream.
There's no corroborating evidence.
The star map argument is worthless.
And yet this is one of
the best attested cases...
...of UFO close encounters.
For all I know, we're visited...
...by a different extraterrestrial
civilization every second Tuesday.
But there's no support
for this appealing idea.
The extraordinary claims are not
supported by extraordinary evidence.
There are curious daylight photos
of UFOs.
Some look suspiciously like...
...hats or hubcaps thrown
into the air.
Photos can be faked.
More common are unidentified
lights at night.
They're often aircraft.
But if we can't identify a light,
that doesn't make it a spaceship.
Here's a movie of what
you might think is a UFO.
Actually it's a piece
of an asteroid burning up...
...as it enters the Earth's
atmosphere.
Most reports of UFOs turn out
to be something else, like...
...the refracted image of a planet or
re-entry of an artificial satellite.
Some are psychological aberrations.
Some are hoaxes.
Never is there any compelling
physical evidence...
...a detailed close-up photograph
of a strange spacecraft...
...or a small device of
extraterrestrial manufacture...
...or a book written in
alien hieroglyphics.
Never.
There are reports of such things,
but never the things themselves.
The search for alien civilizations
retains its importance despite...
...the striking failure
of the UFO evidence.
Most astronomers consider
extraterrestrial life...
...a subject worthy of vigorous,
if cautious, pursuit.
For myself, I find something
irresistible in the idea of...
...discovering a token,
maybe a simple inscription...
...which would provide the key to
understanding an alien civilization.
This is an appeal we humans
have felt before.
In 1801...
...a famous physicist was governor
of the French province of Is?re.
His name was Joseph Fourier.
On an inspection of the schools
in his province...
...Fourier discovered an exceptional
11-year-old boy:
Jean Francois Champollion.
The boy's precocious intellect and
remarkable flair for languages...
...had earned him the admiration
of local scholars.
Fourier too was impressed.
What Champollion first saw
in Fourier's house...
...determined the course
of his life...
...and unlocked the secrets
of an alien civilization.
Fourier had recently participated,
as one of many scientists...
...in Napoleon's expedition
to the Middle East.
He had been in charge of cataloging
the astronomical monuments of Egypt.
The boy was entranced by
Fourier's collection...
...of ancient Egyptian artifacts:
The mysterious fragments
of a lost world.
France at this time was flooded
with such artifacts...
...plundered by Napoleon...
...and now arousing intense interest
among scholars and the general public.
His attention was caught...
...by a specimen of
Egyptian hieroglyphics.
"What do they mean? " he asked.
"Nobody knows," was Fourier's reply.
Then and there,
Champollion resolved...
...he would understand this language
no one could read...
...he would decode the messages
from another world and another time.
He became a superb linguist and
immersed himself in the hieroglyphics.
Fourier edited the illustrated
description of Napoleon's expedition.
The young Champollion
studied it hungrily.
To the people of Europe...
...these exotic images revealed
an utterly alien civilization...
...a world of towering monuments
and magical names.
Dendera.
Karnak.
Luxor.
Every illustration was a riddle
posed by the past to the present.
And among them were pictures of
something called the Rosetta Stone...
...and portraits of the people who
lived among the ruins of the pharaohs.
Egypt became the land of
Champollion's dreams.
But it was not until 1828...
...27 years after his fateful
visit with Fourier...
...that Champollion
first set foot in Egypt.
With his companions, Champollion
chartered boats in Cairo...
...and sailed slowly upstream...
...following the course of the Nile.
It was a journey of many weeks...
...which Champollion recorded
in extraordinary detail.
This was an expedition through time...
...a voyage across the centuries...
...to another world.
Champollion, as an adult...
...had worked out a brilliant
decipherment of the hieroglyphics.
A word, incidentally,
that means "sacred carvings."
Now Champollion was making
a pilgrimage...
...to the scene of ancient mysteries
he had been the first to understand.
Champollion wrote:
"The evening of the 16th,
we finally arrived at Dendera.
We were only an hour away
from the temples.
Could we resist the temptation?
I ask the coldest of you mortals!
To dine and leave immediately
were the orders of the moment.
Alone and without guides,
we crossed the fields.
Presuming that the temples were
in a straight line from our boat...
...we walked thus for an hour and
a half without finding anything.
We discovered a man who put us
on the correct route...
...and ended up walking with us
with good graces.
The temple appeared to us at last.
I shall not try to describe
the impression which the porches...
...and above all,
the portico made on us.
We stayed there two hours
in ecstasy...
...running through the huge rooms
and trying to read...
...the exterior inscriptions
in the moonlight."
It was with no small rapture
that Champollion...
...entered the secret places of
the temple and scanned the words...
...that had waited patiently
through half a million nights...
...for a reader.
To his brother, Champollion
wrote of his joy...
...in confirming that he could
understand the writing on these walls.
"I am now proud," he said...
"...that having followed
the course of the Nile...
...I have the right to announce there
is nothing to modify in our letter...
...on the alphabet of hieroglyphics.
Our alphabet is good.
It is applicable with the same
success, first of all...
...in Egyptian monuments of
the Roman epoch...
...and, which is more interesting...
...to the inscriptions on all
temples, palaces and tombs...
...of the Pharaonic epoch."
Champollion was overwhelmed by
the grandeur which surrounded him.
"It is the union," he said...
"...of grace and majesty
in the highest degree.
We in Europe are only dwafts.
No nation, ancient or modern, has
conceived the art of architecture...
...on such a sublime, great
and imposing style...
...as the ancient Egyptians.
They ordered everything to be done
for people who are 100 feet high."
This is the great temple of Karnak...
...in upper Egypt...
...continuously constructed over
a period of more than 2,000 years...
...until the time of Ptolemy.
It was here Champollion wrote:
"That all the Pharaonic magnificence
appeared to me."
What he had seen elsewhere, he said...
..."Seemed to me, miserable...
...compared with the colossal
conceptions around me."
On these walls and columns
at Karnak...
...at Dendera and everywhere else
in Egypt...
...Champollion found that
he could read inscriptions...
...that his decipherment of a few
years earlier had been correct.
But how had he figured it out?
Many had tried and failed
to read the hieroglyphics.
A group of scholars thought they were
a picture code full of metaphors...
...mostly about eyeballs,
wavy lines and animals.
Birds, especially birds,
lots of birds.
Some deduced that the Egyptians
had been colonists from China.
There were those who deduced it
the other way around.
There's one who, from one look at the
Rosetta Stone, deduced its meaning.
He said that the quickness
of his decipherment...
...enabled him "to avoid
the systematic errors...
...which invariably arise
from prolonged reflection."
You get better results, he's saying,
if you don't think about it too much.
As in the search for
extraterrestrial intelligence today...
...the unbridled speculation
by amateurs...
...served to frighten many
professionals right out of the field.
Champollion was not frightened.
He was also not distracted
by the idea...
...of hieroglyphs as
pictorial metaphors.
Instead...
...using the insights of a brilliant
English physicist, Thomas Young...
...he proceeded something like this:
This is an exact replica
of the Rosetta Stone.
The original had been found
in the year 1799...
...by a French soldier working
on the fortifications...
...of the Nile delta town of Rashid...
...which the Europeans, in their
persistence not to learn Arabic...
...called "Rosetta."
It had been part of an ancient temple
which had been torn down.
If we look at it,
we see that it clearly...
...represents the same text
in three different languages.
Up at the top,
ancient Egyptian hieroglyphics.
In the middle, a kind of cursive...
...and later hieroglyphic
called "Demotic."
And down at the bottom,
the key to the enterprise: Greek.
Champollion could read ancient Greek,
he was a superb linguist...
...and discovered that this stone
had been inscribed...
...to commemorate the coronation...
...of King Ptolemy V
Epiphanes...
...in the spring of the year 196 B.C.
As expected, the Greek text includes
many references to King Ptolemy.
Here you can see it.
"Ptolemaeus."
In roughly the same positions
but in the hieroglyphic text...
...are these ovals or "cartouches"
as they are called.
And if this cartouche really
means "Ptolemy"...
...the individual hieroglyphs are not
likely to be pictograms or metaphors.
Much more likely, they're letters
or at least syllables.
Champollion had the presence
of mind...
...to count up the number
of Greek words...
...and the number of
individual hieroglyphics...
...in what are presumably
equivalent texts.
He found that the number of
individual hieroglyphs...
...is much larger than the number
of Greek words...
...again implying that the hieroglyphs
are mainly letters and syllables.
But which hieroglyphs correspond
to which letters?
Fortunately, Champollion had available
a kind of second Rosetta Stone...
...an obelisk which had been excavated
at the temple of Philae...
...and which had inscribed upon it...
...cartouches representing
the hieroglyphic equivalent...
...of another Greek name: Cleopatra.
So here we have
the Cleopatra cartouche.
And here, the Ptolemaeus cartouche.
Here, we've turned it around,
changing left to right...
...to right to left, and spread the
hieroglyphs out so we see them all.
Now, immediately we notice that
there are some similarities.
This first hieroglyph in Ptolemy
is a kind of square.
The fifth hieroglyph in Cleopatra
is a square.
But "Cleopatra"...
Both of them seem to represent a "p."
So Ptolemy and Cleopatra...
...both give us
the same interpretation:
A square is a "p."
Likewise, the fourth hieroglyph...
...in Ptolemy is a lion.
"P-t-o-I."
Likewise, the second hieroglyph
in Cleopatra is an "I."
So again it's consistent.
The pattern is emerging.
Likewise, this rope or
hangman's noose...
..."Ptolemy." It's an "o."
"Cleopatra." It's an "o."
And in this way, Champollion
was able to assign...
...letters for each of
the hieroglyphs we see here.
"Ptolemaeus."
And, likewise...
..."Cleopatra."
The eagle is an "a."
Notice there are two different
symbols for "t."
But in English, the same sort
of thing, "f" and "ph."
Champollion discovered that
the hieroglyphics...
...were a simple substitution cipher.
Now, there's other stuff in here.
All the rest of this:
What's that about?
Well, he was later able to find out...
...this is a symbol called
the "ankh" which means "life."
There's a "pt." That's an "ah."
It makes "Ptah"...
...name of a god.
And the whole cartouche read:
"Ptolemy, ever living...
...beloved of the god, Ptah."
And the end of the "Cleopatra"
is a short form...
...meaning "Daughter of Isis."
So it turns out that Champollion's
opponents were not wholly wrong.
Some of the hieroglyphs, for example,
the symbol "ankh"...
...which means life, are ideograms
or pictograms.
But the key to the enterprise...
...Champollion's success, rested
on his realization...
...that the hieroglyphs were
essentially letters and syllables.
In retrospect, it sounds almost easy.
But it took people hundreds of years
before they figured it out.
Champollion walked these halls and
casually read the inscriptions...
...which had mystified everybody else.
Answering the question he had
posed as a child to Fourier:
"What do they mean? "
What a joy it must have
been for him...
...to open this one-way communications
channel with another civilization...
...to permit a culture which
had been mute for millennia...
...to speak of its history,
magic, medicine...
...religion, politics, philosophy.
Today, we also are seeking messages...
...from an ancient and
exotic civilization.
A civilization hidden from us...
...not in time, but in space.
Today, we are searching for
a message from the stars.
We have not found it so far.
We have, as yet, no Champollion.
But we are just beginning.
Perhaps those who will decipher the
first interstellar communications...
...are alive at this moment,
somewhere on the planet Earth.
Extraterrestrial beings will
have a different biology...
...a different culture,
a different language.
How could we possibly understand
their messages?
Is there in any sense
a cosmic Rosetta Stone?
I believe there is.
All the technical civilizations in
the cosmos, no matter how different...
...must have one language in common:
The language called "science."
The laws of nature are
everywhere the same.
Every chemical element has
a specific signature in the spectrum.
So there are identical patterns in the
light of a candle flame on Earth...
...and in the light of
a distant galaxy.
The spectra show not only...
...that the same chemical elements
exist throughout space...
...but also that the same
laws of quantum mechanics...
...govern atoms everywhere.
Beings growing up on any world...
...must come to grips with
the identical laws of nature.
Galaxies billions of light-years
distant evolve a spiral form.
So does our own Milky Way.
The same gravitational forces
are at work.
And on planets also:
There are spiral storm
systems on Jupiter.
The same patterns are common on Earth.
The intelligent beings on every
world will, sooner or later...
...understand the laws of nature.
Someday, perhaps soon...
...a message from the depths of space
may arrive on our small world.
If we wish to understand it...
...we first have to understand
science.
We do not expect an advanced
technical civilization...
...on any other planet
of our solar system.
If they were only a little behind us,
10,000 years, say...
...they would have no advanced
technology at all.
If they're a little ahead of us...
...we who are already exploring
the solar system...
...then they should be here by now.
To communicate with other
civilizations...
...our technology must reach across
not merely...
...interplanetary distances...
...but interstellar distances.
Ideally, the method
should be inexpensive.
A huge amount of information could
be sent and received at little cost.
It should be fast...
...so an interstellar dialogue
is eventually possible.
It ought to be obvious...
...so that any technical civilization,
no matter its evolutionary path...
...will discover it early.
Surprisingly, there is such a method.
It's called radio astronomy.
This is the largest
radio/radar telescope...
...on the planet Earth,
the Arecibo Observatory.
It's located in a remote valley
on the island of Puerto Rico.
It sends and receives radio signals.
But it's so large and powerful...
...it can communicate with
an identical radio telescope...
...15,000 light-years away...
...halfway to the center
of the Milky Way galaxy.
The Arecibo Observatory has been
used, although sparingly...
...to search for signals
from civilizations in space...
...and, just once...
...to broadcast a message
to a distant star cluster...
...called "M13."
But is there anyone out there
to talk to?
With 400 billion stars in
the Milky Way galaxy alone...
...could ours be the only one
with an inhabited planet?
How much more likely it is...
...that the galaxy is throbbing and
humming with advanced societies.
Perhaps near one of those
pinpoints of light in our night sky...
...someone quite different from us...
...is glancing idly at
the star we call the sun...
...and entertaining,
just for a moment...
...an outrageous speculation.
There are an enormous number
of stars.
Only some of them will have
planets suitable for life.
On only some of those worlds
will intelligence arise.
And perhaps a few of those
civilizations will avoid...
...the trap jointly set by their
technology and their passions.
If there are many civilizations,
one of them should be rather close by.
If there are few civilizations...
...then even the nearest
may be very far away.
This is one of the great questions:
How many advanced civilizations...
...capable at least of radio astronomy
are there in the Milky Way galaxy?
Let's call the number of such
civilizations by capital letter "N."
It's a number.
It depends on many things.
It depends on the number
of stars in the Milky Way.
Let's call that N sub-star.
The fraction of stars
that have planets...
...is called f sub-p.
The average number of planets
in a given solar system...
...ecologically suitable for life...
...is called n sub-e.
The fraction of suitable planets
in which life actually arises...
...is called f sub-I.
The fraction of inhabited planets...
...on which intelligence emerges...
...is called f sub-i.
On the fraction of those planets in
which the intelligent beings evolve...
...a technical, communicative
civilization...
...call that f sub-c.
Finally, it depends on the fraction
of a planet's lifetime...
...that's graced by
a technical civilization.
Call that f sub-L.
If we multiply all these
numbers together...
...we've estimated N,
the number of civilizations.
This equation, due mainly to
Frank Drake of Cornell...
...is only a sentence.
The verb is "equals."
So let's try to go through
the program of this equation.
By carefully counting
the number of stars...
...in small but representative regions
of the sky...
...we find that the total number
of stars in the Milky Way...
...is about 400 billion.
That's a lot of stars.
What about planets?
Well, in studies of double stars...
...and investigations of
the motions of nearby stars...
...and in many theoretical studies...
...we get a strong hint that many...
...perhaps even most stars...
...are accompanied by planets.
So let's take f sub-p...
...the fraction of stars that
have planets as a quarter.
Then, the total number of
planetary systems in the galaxy...
...is 400 billion times a quarter...
...or 100 billion.
We'll write down our running totals
in red.
Now if each system were
to have, say...
...ten planets as ours does, there
would be 100 billion times ten...
...or a trillion worlds in the galaxy.
A vast arena for the cosmic drama.
In our own solar system...
...there are several bodies that
might be suitable for life...
...life of some sort.
There's the Earth, of course...
...but there are possibilities for
Mars, for Titan, perhaps for Jupiter.
If other systems are similar, there
may be many suitable worlds per system.
But to be conservative,
let's choose...
...n sub-e equal two.
Two worlds suitable for life
per system.
The planets that are
suitable for life...
...would be 100 billion times
two, or 200 billion.
Now what about life?
Under very general
cosmic conditions...
...the molecules of life are readily
made and spontaneously self-assemble.
It's conceivable there might be
some impediment, like some...
...difficulty in the origin of
the genetic code, say.
Although that's very unlikely, given
billions of years for evolution.
On the Earth, life arose very fast
after the planet was formed.
So let's choose f sub-I...
...the fraction of suitable worlds in
which life does arise, as a half.
The number of planets in the Milky Way
in which life has arisen once...
...is 100 billion times
two, times a half.
Or again, 100 billion.
100 billion inhabited worlds.
Now the estimates get tougher.
Many individually unlikely events
had to occur for...
...our species and our technology
to emerge.
On the other hand, there might
be many different roads...
...to high technology.
Some scientists think that...
...the path from trilobites to radio
telescopes, or the equivalent...
...goes like a shot
in all planetary systems.
Other scientists disagree.
Let's take some middle ground
and choose f sub-i...
...as a tenth...
...and f sub-c as also a tenth.
Meaning that only one percent,
a tenth times a tenth...
...of inhabited planets eventually
produce a technical civilization.
If we were to multiply
all these factors together...
...we would find 100 billion
times a tenth times a tenth.
Or one billion planets...
...on which civilizations
have arisen at least once.
Now what percentage of
the lifetime of a planet...
...is marked by a technical
civilization?
Earth has harbored a civilization
capable of radio astronomy...
...only for a few decades,
the last few...
...out of a lifetime of
a few billion years.
It's hardly out of the question
that we might...
...destroy ourselves tomorrow.
If that's a typical case,
then f sub-L...
...would be a few decades divided
by a few billion years...
...or one hundred millionth...
...a very small number.
And then, N would be a billion
times a hundred millionth.
Or N may be just...
...ten civilizations.
A tiny smattering, a pitiful few...
...technological civilizations
in the galaxy.
But civilizations then...
...might take billions of years
of tortuous evolution to arise...
...and then snuff themselves out
in an instant of...
...unforgivable neglect.
If this is a typical case...
...there may be few others...
...maybe nobody else at all
for us to talk to.
But consider the alternative:
That occasionally civilizations
learn to live with high technology...
...and survive for geological or
stellar evolutionary time scales.
If only one percent
of civilizations can...
...survive technological
adolescence...
...then f sub-L would be
not 100 millionth...
...but only a hundredth.
And then the number of civilizations
would be a billion times a hundredth.
The civilizations in the galaxy
would be measured...
...in the millions.
Millions of technical civilizations.
So if civilizations do not
always destroy themselves...
...shortly after discovering
radio astronomy...
...then the sky may be
softly humming...
...with messages from the stars...
...with signals from civilizations
enormously older...
...and wiser than we.
If there are millions of civilizations
in the Milky Way...
...each capable of radio astronomy...
...how far away is the nearest one?
If they're distributed randomly
through space...
...then the nearest one will be
some 200 light-years away.
But within 200 light-years...
...there are hundreds
of thousands of stars.
To find the needle in this haystack...
...requires a dedicated
and systematic search.
Many cosmic radio sources have nothing
to do with intelligent life.
So how would we know that
we were receiving a message?
The transmitting civilization can make
it very easy for us, if they wished.
Imagine we're in the course
of a systematic search.
Or in the midst of some more
conventional observations.
And suppose one day...
...we find a strong signal
slowly emerging.
Not just some background hiss...
...but a methodical series of pulses.
(SIGNAL PINGS)
The numbers one, two, three, five...
...seven, eleven, thirteen.
A signal made of prime numbers.
Numbers divisible only
by one and themselves.
There is no natural astrophysical
process that generates prime numbers.
We would have to conclude...
...that someone fond of
elementary mathematics...
...was saying hello.
(SIGNAL PINGS)
This would be no more than a beacon
to attract our attention.
The main message will be subtler...
...more hidden, far richer.
We may have to work hard to find it.
But the beacon signal alone
would be profoundly significant.
It would mean someone has learned to
survive technological adolescence...
...that self-destruction
is not inevitable...
...that we also may have a future.
Such knowledge, it seems to me...
...might be worth a great price.
Very likely...
...some new Champollion
would go on...
...to decode the main message,
using our interstellar Rosetta Stone:
The common language of science
and mathematics.
Think of the glories of
an exotic civilization...
...far more advanced than we...
...collected by the great
radio telescopes of Earth.
Perhaps they'd send a compilation of
the knowledge of a million worlds:
The Encyclopedia Galactica.
Receiving an interstellar message...
...would be a major event
in human history...
...and the beginning of the
deprovincialization of our planet.
A serious and systematic
radio search...
...for extraterrestrial
civilizations may come soon.
Preliminary steps are being taken
both in the United States...
...and in the Soviet Union.
It's comparatively inexpensive.
A search taking decades would cost
less than the budget overruns...
...on a single modest weapons system
in a single year.
Our technology is now
fully adequate...
...for this great challenge.
But no systematic search program...
...has ever been approved
by any nation on Earth.
When will we decide to search for...
...what other civilizations there
may be in the vast cosmic ocean?
But whether there are only a few
advanced galactic civilizations...
...or millions...
...shouldn't some of them
have voyaged to Earth?
On one hand, if even a small fraction
of technical civilizations...
...learned to live with their
potential for self-destruction...
...there should be enormous
numbers of them in the galaxy.
On the other hand, despite claims
about UFOs and ancient astronauts...
...there's no creditable evidence that
Earth has been visited, now or ever.
But isn't this a contradiction?
If the nearest civilization is,
say, 200 light-years away...
...it'd take them only 200 years
to get from there to here...
...at light speed.
Even if they were traveling
1000 times slower than that...
...aliens could've come here during...
...the tenure of human beings
on Earth.
So why aren't they here?
There's many possible answers.
One is that...
...maybe we're the first.
Some technical civilization
has to be first...
...to emerge in the history
of the galaxy.
Or maybe all technical civilizations
promptly destroy themselves.
That seems to me very unlikely.
Maybe there's some problem
with space flight...
...that we've been too dumb
to figure out.
Or maybe they are here,
but in hiding...
...because of an ethic of
non-interference...
...with emerging civilizations.
We might imagine them,
curious and dispassionate...
...watching us to determine
whether this year again...
...we manage to avoid
self-destruction.
But there's another explanation which
is consistent with what we know.
And that's that it's a big cosmos.
If years ago, an advanced interstellar
spacefaring civilization emerged...
...200 light-years away,
why would they come here?
They'd have no reason to think
the Earth was special.
There are no signs of technology,
not even our radio transmissions...
...which have had time
to go 200 light-years.
From their point of view,
all nearby planetary systems...
...might seem equally attractive
for exploration.
How would an interstellar
civilization set out to explore...
...its neighboring star systems?
It might establish staging posts...
...colonies,
on planets of nearby stars.
But this would take time.
Time to find and modify
favorable planets.
Time to build new spacecraft.
Eventually, later generations
of explorers would set out...
...wending their way
among the worlds...
...creating an interstellar
nervous system...
...binding up the stars.
Perhaps they'd come upon another
expanding civilization...
...and encounter beings
previously known...
...only from their radio
transmissions.
Star wars are unlikely.
One civilization certainly would be
far more advanced than the other.
It would be no contest.
Perhaps they would cooperate...
...exploring together a small province
of the Milky Way.
But even nearby civilizations
could spend millions of years...
...roving between the stars...
...without ever stumbling upon
our obscure solar system.
In a galaxy of 400 billion suns...
...perhaps no one has found us
just yet.
Advanced interstellar civilizations
would know about many worlds.
Some inhabited, some barren.
Perhaps they would share
their findings...
...assembling some vast repository...
...of the knowledge of
countless worlds.
They might compile an
Encyclopedia Galactica.
Suppose we could browse through
that encyclopedia.
We would choose some nearby
province of the galaxy...
...a region that's fairly
well-explored.
And then slowly leaf through
the worlds.
The young Champollion was inspired...
...by reading Fourier's
description of Egypt.
Imagine the impact on us...
...if we could study
a rich compilation...
...of not merely one world...
...but billions.
Just possibly, not too far
from our solar system...
...we might find
a technical civilization...
...only a little more
advanced than we.
Let's look them up in
the Galactic Encyclopedia.
What would a civilization
far more advanced than ours...
...be up to?
There may be engineering on a scale...
...that dwafts our proudest
achievements.
There may be cultures that disassemble
other planets in their system...
...and reassemble them around
their world to make a ring...
...or a shell with
their planet inside.
Imagine the energy crisis of a really
advanced planetary civilization.
They've used up all their fuels.
They depend on solar power.
But their growth is still severely
limited by the energy available.
An enormous amount of energy
is generated by the local star.
But most of the star's light
doesn't fall on their planet.
So perhaps they would build a shell...
...to surround their star...
...and harvest every photon
of sunlight.
Such beings, such civilizations...
...would bear little resemblance
to anything we know.
Perhaps someday there will be an entry
in the Encyclopedia Galactica...
...for our planet.
Or perhaps even now
there exists somewhere...
...a planetary dossier, garnered
from our television broadcasts...
...or from some discreet
survey mission.
They may summon up the index of blue
worlds in our part of the Milky Way...
...until they came to
the listing for Earth.
What would they know about us?
What would they think of us?
We have always watched
the stars and mused...
...about whether there are other
beings who think and wonder.
In a cosmic setting vast and old...
...beyond ordinary human
understanding, we are a little lonely.
In the deepest sense, the search
for extraterrestrial intelligence...
...is a search for who we are.
Since Cosmos was released...
...interest in UFOs has persisted.
It seems to me that there
are fewer sightings of...
...strange objects in the skies
these days...
...and more stories of encounters
with alleged extraterrestrials...
...like the account of Betty and Barney
Hill that we dramatized.
There are still people who claim
to have been abducted by aliens...
...or even sexually abused,
or even impregnated by them.
Best-selling purportedly serious books
have been written about such claims.
But the critical fact remains
that all we have still is...
...just anecdote.
There are no close-up photos,
no artifacts...
...nothing that'd convince a skeptic.
All there are is stories.
And stories just aren't good enough
on a matter of this importance.
I'm still waiting for hard evidence.
The radio search for extraterrestrial
intelligence has been picking up.
In Harvard, Massachusetts, a radio
telescope monitoring 8 million...
...separate radio channels...
...has been scanning the skies
for signals.
This program, called META,
is supported entirely by...
...the Pasadena, California-based
Planetary Society.
Paid for by members' contributions.
A similar planetary society search...
...to examine the southern skies
and the center of the Milky Way...
...is to be performed in Argentina.
These searches are by far...
...the most sophisticated
ever attempted.
A much more sensitive program...
...covering almost the entire
accessible radio spectrum...
...is to be mustered by NASA.
The search for extraterrestrial
intelligence is central...
...to our understanding of the universe
and our view of ourselves.
It's well worth doing.
But the simple fact is that...
...while we may consider
extraterrestrial intelligence likely...
...there is as yet
no evidence at all...
...that it exists.
The search continues.
In the vastness of the cosmos...
...there must be other civilizations
far older...
...and more advanced than ours.
So shouldn't we have been visited?
Shouldn't there be...
...alien ships in the skies of Earth?
There's nothing impossible
in this idea.
And no one would be happier than me
if we were visited.
But has it happened in fact?
What counts is not what's plausible,
not what we'd like to believe...
...not what one or two witnesses
claim.
But only what is supported
by hard evidence...
...rigorously and skeptically
examined.
Extraordinary claims
require extraordinary evidence.
Since 1947, there have been hundreds
of thousands of reports of UFOs:
Unidentified flying objects.
This subject has...
...more to do with religion and
superstition than with science.
Let's consider one of the most famous
accounts of a supposed encounter...
...with alien beings.
On September 19, 1961...
...an American couple was driving home
through New Hampshire.
What's the matter, Delsey?
SAGAN: They were returning along
a lonely road, late at night...
...from a vacation in Canada.
Remember, we have only their word
for what happened next.
(TUNES RADIO)
(STATIC FROM RADIO)
I'm only getting static.
You still don't believe it, do you?
No, I don't. There must be
a reasonable explanation.
Oh!
SAGAN:
They had observed, so they said...
...a strange moving light in the sky.
By definition,
an unidentified flying object.
It seemed to follow them for miles.
Easy there.
What's the matter with that dog?
(HUMMING NOISE)
What's that sound?
I don't know.
After a time, the lighting patterns
on the UFO changed.
It appeared to land.
What the...
It blocked the road,
preventing them from driving on.
They said they saw
mouthless creatures approaching...
...who were not exactly human.
Barney!
Barney, what is that?
At this point, the story
becomes still stranger.
They lost all recollection of what
happened in the next few hours.
But weeks later, they said...
...they recalled some details and
discussed the experience with others.
26 months later, under hypnosis...
...they reported that
a UFO had landed...
...and that the crew had emerged.
They were captured, they said,
and taken aboard the craft.
(WHINES)
That was the story told by
Betty and Barney Hill.
Virtually all scientists
who've studied it are skeptical.
But UFO enthusiasts think
the Hill case is a classic example...
...of a "close encounter
of the third kind."
Why? What makes it so special?
While on board, Betty had noticed...
...a book written in an unknown
hieroglyphic writing.
She was also shown a strange window
through which she could see...
...a glowing pattern of dots
connected with lines.
It was, they told her, a star map...
...displaying the routes
of interstellar commerce.
Afterwards, they were released
and permitted to return home.
Or at least, this is their story.
Believers find this compelling,
or at least plausible...
...chiefly because of
the alleged star map.
Here's how Betty said it looked.
Why would we take this seriously?
Because here is a real map widely
publicized by UFO enthusiasts...
...of 15 selected nearby stars,
including the sun...
...as seen from one particular
vantage point in space.
This map includes stars...
...that were first cataloged
several years after...
...Betty Hill recalled what she says
she saw in the alien ship.
Her map required, we are told...
...information that wasn't
available on Earth.
There is a resemblance between
the two maps, but that's because...
...the lines corresponding
to navigation routes...
...have been copied from the Hill map
onto the real star map.
If we were to substitute
some other set of lines...
...for the Hill lines, we find that
the eye suddenly is biased...
...against seeing any agreement
between the two maps at all.
To make an objective test, however,
let's remove the lines altogether.
And then there's very little
resemblance left.
But these particular stars...
...are selected from a large catalog
of star positions.
Our vantage point is also
selected to make the best...
...possible fit with the Hill map.
If you can pick and choose
from a large number of stars...
...viewed from any vantage point
in space...
...you can always find a resemblance
to the pattern you're looking for.
I'm surprised that nobody found...
...a better fit to the Hill map.
The Hills' own psychiatrist described
their story as a kind of dream.
There's no corroborating evidence.
The star map argument is worthless.
And yet this is one of
the best attested cases...
...of UFO close encounters.
For all I know, we're visited...
...by a different extraterrestrial
civilization every second Tuesday.
But there's no support
for this appealing idea.
The extraordinary claims are not
supported by extraordinary evidence.
There are curious daylight photos
of UFOs.
Some look suspiciously like...
...hats or hubcaps thrown
into the air.
Photos can be faked.
More common are unidentified
lights at night.
They're often aircraft.
But if we can't identify a light,
that doesn't make it a spaceship.
Here's a movie of what
you might think is a UFO.
Actually it's a piece
of an asteroid burning up...
...as it enters the Earth's
atmosphere.
Most reports of UFOs turn out
to be something else, like...
...the refracted image of a planet or
re-entry of an artificial satellite.
Some are psychological aberrations.
Some are hoaxes.
Never is there any compelling
physical evidence...
...a detailed close-up photograph
of a strange spacecraft...
...or a small device of
extraterrestrial manufacture...
...or a book written in
alien hieroglyphics.
Never.
There are reports of such things,
but never the things themselves.
The search for alien civilizations
retains its importance despite...
...the striking failure
of the UFO evidence.
Most astronomers consider
extraterrestrial life...
...a subject worthy of vigorous,
if cautious, pursuit.
For myself, I find something
irresistible in the idea of...
...discovering a token,
maybe a simple inscription...
...which would provide the key to
understanding an alien civilization.
This is an appeal we humans
have felt before.
In 1801...
...a famous physicist was governor
of the French province of Is?re.
His name was Joseph Fourier.
On an inspection of the schools
in his province...
...Fourier discovered an exceptional
11-year-old boy:
Jean Francois Champollion.
The boy's precocious intellect and
remarkable flair for languages...
...had earned him the admiration
of local scholars.
Fourier too was impressed.
What Champollion first saw
in Fourier's house...
...determined the course
of his life...
...and unlocked the secrets
of an alien civilization.
Fourier had recently participated,
as one of many scientists...
...in Napoleon's expedition
to the Middle East.
He had been in charge of cataloging
the astronomical monuments of Egypt.
The boy was entranced by
Fourier's collection...
...of ancient Egyptian artifacts:
The mysterious fragments
of a lost world.
France at this time was flooded
with such artifacts...
...plundered by Napoleon...
...and now arousing intense interest
among scholars and the general public.
His attention was caught...
...by a specimen of
Egyptian hieroglyphics.
"What do they mean? " he asked.
"Nobody knows," was Fourier's reply.
Then and there,
Champollion resolved...
...he would understand this language
no one could read...
...he would decode the messages
from another world and another time.
He became a superb linguist and
immersed himself in the hieroglyphics.
Fourier edited the illustrated
description of Napoleon's expedition.
The young Champollion
studied it hungrily.
To the people of Europe...
...these exotic images revealed
an utterly alien civilization...
...a world of towering monuments
and magical names.
Dendera.
Karnak.
Luxor.
Every illustration was a riddle
posed by the past to the present.
And among them were pictures of
something called the Rosetta Stone...
...and portraits of the people who
lived among the ruins of the pharaohs.
Egypt became the land of
Champollion's dreams.
But it was not until 1828...
...27 years after his fateful
visit with Fourier...
...that Champollion
first set foot in Egypt.
With his companions, Champollion
chartered boats in Cairo...
...and sailed slowly upstream...
...following the course of the Nile.
It was a journey of many weeks...
...which Champollion recorded
in extraordinary detail.
This was an expedition through time...
...a voyage across the centuries...
...to another world.
Champollion, as an adult...
...had worked out a brilliant
decipherment of the hieroglyphics.
A word, incidentally,
that means "sacred carvings."
Now Champollion was making
a pilgrimage...
...to the scene of ancient mysteries
he had been the first to understand.
Champollion wrote:
"The evening of the 16th,
we finally arrived at Dendera.
We were only an hour away
from the temples.
Could we resist the temptation?
I ask the coldest of you mortals!
To dine and leave immediately
were the orders of the moment.
Alone and without guides,
we crossed the fields.
Presuming that the temples were
in a straight line from our boat...
...we walked thus for an hour and
a half without finding anything.
We discovered a man who put us
on the correct route...
...and ended up walking with us
with good graces.
The temple appeared to us at last.
I shall not try to describe
the impression which the porches...
...and above all,
the portico made on us.
We stayed there two hours
in ecstasy...
...running through the huge rooms
and trying to read...
...the exterior inscriptions
in the moonlight."
It was with no small rapture
that Champollion...
...entered the secret places of
the temple and scanned the words...
...that had waited patiently
through half a million nights...
...for a reader.
To his brother, Champollion
wrote of his joy...
...in confirming that he could
understand the writing on these walls.
"I am now proud," he said...
"...that having followed
the course of the Nile...
...I have the right to announce there
is nothing to modify in our letter...
...on the alphabet of hieroglyphics.
Our alphabet is good.
It is applicable with the same
success, first of all...
...in Egyptian monuments of
the Roman epoch...
...and, which is more interesting...
...to the inscriptions on all
temples, palaces and tombs...
...of the Pharaonic epoch."
Champollion was overwhelmed by
the grandeur which surrounded him.
"It is the union," he said...
"...of grace and majesty
in the highest degree.
We in Europe are only dwafts.
No nation, ancient or modern, has
conceived the art of architecture...
...on such a sublime, great
and imposing style...
...as the ancient Egyptians.
They ordered everything to be done
for people who are 100 feet high."
This is the great temple of Karnak...
...in upper Egypt...
...continuously constructed over
a period of more than 2,000 years...
...until the time of Ptolemy.
It was here Champollion wrote:
"That all the Pharaonic magnificence
appeared to me."
What he had seen elsewhere, he said...
..."Seemed to me, miserable...
...compared with the colossal
conceptions around me."
On these walls and columns
at Karnak...
...at Dendera and everywhere else
in Egypt...
...Champollion found that
he could read inscriptions...
...that his decipherment of a few
years earlier had been correct.
But how had he figured it out?
Many had tried and failed
to read the hieroglyphics.
A group of scholars thought they were
a picture code full of metaphors...
...mostly about eyeballs,
wavy lines and animals.
Birds, especially birds,
lots of birds.
Some deduced that the Egyptians
had been colonists from China.
There were those who deduced it
the other way around.
There's one who, from one look at the
Rosetta Stone, deduced its meaning.
He said that the quickness
of his decipherment...
...enabled him "to avoid
the systematic errors...
...which invariably arise
from prolonged reflection."
You get better results, he's saying,
if you don't think about it too much.
As in the search for
extraterrestrial intelligence today...
...the unbridled speculation
by amateurs...
...served to frighten many
professionals right out of the field.
Champollion was not frightened.
He was also not distracted
by the idea...
...of hieroglyphs as
pictorial metaphors.
Instead...
...using the insights of a brilliant
English physicist, Thomas Young...
...he proceeded something like this:
This is an exact replica
of the Rosetta Stone.
The original had been found
in the year 1799...
...by a French soldier working
on the fortifications...
...of the Nile delta town of Rashid...
...which the Europeans, in their
persistence not to learn Arabic...
...called "Rosetta."
It had been part of an ancient temple
which had been torn down.
If we look at it,
we see that it clearly...
...represents the same text
in three different languages.
Up at the top,
ancient Egyptian hieroglyphics.
In the middle, a kind of cursive...
...and later hieroglyphic
called "Demotic."
And down at the bottom,
the key to the enterprise: Greek.
Champollion could read ancient Greek,
he was a superb linguist...
...and discovered that this stone
had been inscribed...
...to commemorate the coronation...
...of King Ptolemy V
Epiphanes...
...in the spring of the year 196 B.C.
As expected, the Greek text includes
many references to King Ptolemy.
Here you can see it.
"Ptolemaeus."
In roughly the same positions
but in the hieroglyphic text...
...are these ovals or "cartouches"
as they are called.
And if this cartouche really
means "Ptolemy"...
...the individual hieroglyphs are not
likely to be pictograms or metaphors.
Much more likely, they're letters
or at least syllables.
Champollion had the presence
of mind...
...to count up the number
of Greek words...
...and the number of
individual hieroglyphics...
...in what are presumably
equivalent texts.
He found that the number of
individual hieroglyphs...
...is much larger than the number
of Greek words...
...again implying that the hieroglyphs
are mainly letters and syllables.
But which hieroglyphs correspond
to which letters?
Fortunately, Champollion had available
a kind of second Rosetta Stone...
...an obelisk which had been excavated
at the temple of Philae...
...and which had inscribed upon it...
...cartouches representing
the hieroglyphic equivalent...
...of another Greek name: Cleopatra.
So here we have
the Cleopatra cartouche.
And here, the Ptolemaeus cartouche.
Here, we've turned it around,
changing left to right...
...to right to left, and spread the
hieroglyphs out so we see them all.
Now, immediately we notice that
there are some similarities.
This first hieroglyph in Ptolemy
is a kind of square.
The fifth hieroglyph in Cleopatra
is a square.
But "Cleopatra"...
Both of them seem to represent a "p."
So Ptolemy and Cleopatra...
...both give us
the same interpretation:
A square is a "p."
Likewise, the fourth hieroglyph...
...in Ptolemy is a lion.
"P-t-o-I."
Likewise, the second hieroglyph
in Cleopatra is an "I."
So again it's consistent.
The pattern is emerging.
Likewise, this rope or
hangman's noose...
..."Ptolemy." It's an "o."
"Cleopatra." It's an "o."
And in this way, Champollion
was able to assign...
...letters for each of
the hieroglyphs we see here.
"Ptolemaeus."
And, likewise...
..."Cleopatra."
The eagle is an "a."
Notice there are two different
symbols for "t."
But in English, the same sort
of thing, "f" and "ph."
Champollion discovered that
the hieroglyphics...
...were a simple substitution cipher.
Now, there's other stuff in here.
All the rest of this:
What's that about?
Well, he was later able to find out...
...this is a symbol called
the "ankh" which means "life."
There's a "pt." That's an "ah."
It makes "Ptah"...
...name of a god.
And the whole cartouche read:
"Ptolemy, ever living...
...beloved of the god, Ptah."
And the end of the "Cleopatra"
is a short form...
...meaning "Daughter of Isis."
So it turns out that Champollion's
opponents were not wholly wrong.
Some of the hieroglyphs, for example,
the symbol "ankh"...
...which means life, are ideograms
or pictograms.
But the key to the enterprise...
...Champollion's success, rested
on his realization...
...that the hieroglyphs were
essentially letters and syllables.
In retrospect, it sounds almost easy.
But it took people hundreds of years
before they figured it out.
Champollion walked these halls and
casually read the inscriptions...
...which had mystified everybody else.
Answering the question he had
posed as a child to Fourier:
"What do they mean? "
What a joy it must have
been for him...
...to open this one-way communications
channel with another civilization...
...to permit a culture which
had been mute for millennia...
...to speak of its history,
magic, medicine...
...religion, politics, philosophy.
Today, we also are seeking messages...
...from an ancient and
exotic civilization.
A civilization hidden from us...
...not in time, but in space.
Today, we are searching for
a message from the stars.
We have not found it so far.
We have, as yet, no Champollion.
But we are just beginning.
Perhaps those who will decipher the
first interstellar communications...
...are alive at this moment,
somewhere on the planet Earth.
Extraterrestrial beings will
have a different biology...
...a different culture,
a different language.
How could we possibly understand
their messages?
Is there in any sense
a cosmic Rosetta Stone?
I believe there is.
All the technical civilizations in
the cosmos, no matter how different...
...must have one language in common:
The language called "science."
The laws of nature are
everywhere the same.
Every chemical element has
a specific signature in the spectrum.
So there are identical patterns in the
light of a candle flame on Earth...
...and in the light of
a distant galaxy.
The spectra show not only...
...that the same chemical elements
exist throughout space...
...but also that the same
laws of quantum mechanics...
...govern atoms everywhere.
Beings growing up on any world...
...must come to grips with
the identical laws of nature.
Galaxies billions of light-years
distant evolve a spiral form.
So does our own Milky Way.
The same gravitational forces
are at work.
And on planets also:
There are spiral storm
systems on Jupiter.
The same patterns are common on Earth.
The intelligent beings on every
world will, sooner or later...
...understand the laws of nature.
Someday, perhaps soon...
...a message from the depths of space
may arrive on our small world.
If we wish to understand it...
...we first have to understand
science.
We do not expect an advanced
technical civilization...
...on any other planet
of our solar system.
If they were only a little behind us,
10,000 years, say...
...they would have no advanced
technology at all.
If they're a little ahead of us...
...we who are already exploring
the solar system...
...then they should be here by now.
To communicate with other
civilizations...
...our technology must reach across
not merely...
...interplanetary distances...
...but interstellar distances.
Ideally, the method
should be inexpensive.
A huge amount of information could
be sent and received at little cost.
It should be fast...
...so an interstellar dialogue
is eventually possible.
It ought to be obvious...
...so that any technical civilization,
no matter its evolutionary path...
...will discover it early.
Surprisingly, there is such a method.
It's called radio astronomy.
This is the largest
radio/radar telescope...
...on the planet Earth,
the Arecibo Observatory.
It's located in a remote valley
on the island of Puerto Rico.
It sends and receives radio signals.
But it's so large and powerful...
...it can communicate with
an identical radio telescope...
...15,000 light-years away...
...halfway to the center
of the Milky Way galaxy.
The Arecibo Observatory has been
used, although sparingly...
...to search for signals
from civilizations in space...
...and, just once...
...to broadcast a message
to a distant star cluster...
...called "M13."
But is there anyone out there
to talk to?
With 400 billion stars in
the Milky Way galaxy alone...
...could ours be the only one
with an inhabited planet?
How much more likely it is...
...that the galaxy is throbbing and
humming with advanced societies.
Perhaps near one of those
pinpoints of light in our night sky...
...someone quite different from us...
...is glancing idly at
the star we call the sun...
...and entertaining,
just for a moment...
...an outrageous speculation.
There are an enormous number
of stars.
Only some of them will have
planets suitable for life.
On only some of those worlds
will intelligence arise.
And perhaps a few of those
civilizations will avoid...
...the trap jointly set by their
technology and their passions.
If there are many civilizations,
one of them should be rather close by.
If there are few civilizations...
...then even the nearest
may be very far away.
This is one of the great questions:
How many advanced civilizations...
...capable at least of radio astronomy
are there in the Milky Way galaxy?
Let's call the number of such
civilizations by capital letter "N."
It's a number.
It depends on many things.
It depends on the number
of stars in the Milky Way.
Let's call that N sub-star.
The fraction of stars
that have planets...
...is called f sub-p.
The average number of planets
in a given solar system...
...ecologically suitable for life...
...is called n sub-e.
The fraction of suitable planets
in which life actually arises...
...is called f sub-I.
The fraction of inhabited planets...
...on which intelligence emerges...
...is called f sub-i.
On the fraction of those planets in
which the intelligent beings evolve...
...a technical, communicative
civilization...
...call that f sub-c.
Finally, it depends on the fraction
of a planet's lifetime...
...that's graced by
a technical civilization.
Call that f sub-L.
If we multiply all these
numbers together...
...we've estimated N,
the number of civilizations.
This equation, due mainly to
Frank Drake of Cornell...
...is only a sentence.
The verb is "equals."
So let's try to go through
the program of this equation.
By carefully counting
the number of stars...
...in small but representative regions
of the sky...
...we find that the total number
of stars in the Milky Way...
...is about 400 billion.
That's a lot of stars.
What about planets?
Well, in studies of double stars...
...and investigations of
the motions of nearby stars...
...and in many theoretical studies...
...we get a strong hint that many...
...perhaps even most stars...
...are accompanied by planets.
So let's take f sub-p...
...the fraction of stars that
have planets as a quarter.
Then, the total number of
planetary systems in the galaxy...
...is 400 billion times a quarter...
...or 100 billion.
We'll write down our running totals
in red.
Now if each system were
to have, say...
...ten planets as ours does, there
would be 100 billion times ten...
...or a trillion worlds in the galaxy.
A vast arena for the cosmic drama.
In our own solar system...
...there are several bodies that
might be suitable for life...
...life of some sort.
There's the Earth, of course...
...but there are possibilities for
Mars, for Titan, perhaps for Jupiter.
If other systems are similar, there
may be many suitable worlds per system.
But to be conservative,
let's choose...
...n sub-e equal two.
Two worlds suitable for life
per system.
The planets that are
suitable for life...
...would be 100 billion times
two, or 200 billion.
Now what about life?
Under very general
cosmic conditions...
...the molecules of life are readily
made and spontaneously self-assemble.
It's conceivable there might be
some impediment, like some...
...difficulty in the origin of
the genetic code, say.
Although that's very unlikely, given
billions of years for evolution.
On the Earth, life arose very fast
after the planet was formed.
So let's choose f sub-I...
...the fraction of suitable worlds in
which life does arise, as a half.
The number of planets in the Milky Way
in which life has arisen once...
...is 100 billion times
two, times a half.
Or again, 100 billion.
100 billion inhabited worlds.
Now the estimates get tougher.
Many individually unlikely events
had to occur for...
...our species and our technology
to emerge.
On the other hand, there might
be many different roads...
...to high technology.
Some scientists think that...
...the path from trilobites to radio
telescopes, or the equivalent...
...goes like a shot
in all planetary systems.
Other scientists disagree.
Let's take some middle ground
and choose f sub-i...
...as a tenth...
...and f sub-c as also a tenth.
Meaning that only one percent,
a tenth times a tenth...
...of inhabited planets eventually
produce a technical civilization.
If we were to multiply
all these factors together...
...we would find 100 billion
times a tenth times a tenth.
Or one billion planets...
...on which civilizations
have arisen at least once.
Now what percentage of
the lifetime of a planet...
...is marked by a technical
civilization?
Earth has harbored a civilization
capable of radio astronomy...
...only for a few decades,
the last few...
...out of a lifetime of
a few billion years.
It's hardly out of the question
that we might...
...destroy ourselves tomorrow.
If that's a typical case,
then f sub-L...
...would be a few decades divided
by a few billion years...
...or one hundred millionth...
...a very small number.
And then, N would be a billion
times a hundred millionth.
Or N may be just...
...ten civilizations.
A tiny smattering, a pitiful few...
...technological civilizations
in the galaxy.
But civilizations then...
...might take billions of years
of tortuous evolution to arise...
...and then snuff themselves out
in an instant of...
...unforgivable neglect.
If this is a typical case...
...there may be few others...
...maybe nobody else at all
for us to talk to.
But consider the alternative:
That occasionally civilizations
learn to live with high technology...
...and survive for geological or
stellar evolutionary time scales.
If only one percent
of civilizations can...
...survive technological
adolescence...
...then f sub-L would be
not 100 millionth...
...but only a hundredth.
And then the number of civilizations
would be a billion times a hundredth.
The civilizations in the galaxy
would be measured...
...in the millions.
Millions of technical civilizations.
So if civilizations do not
always destroy themselves...
...shortly after discovering
radio astronomy...
...then the sky may be
softly humming...
...with messages from the stars...
...with signals from civilizations
enormously older...
...and wiser than we.
If there are millions of civilizations
in the Milky Way...
...each capable of radio astronomy...
...how far away is the nearest one?
If they're distributed randomly
through space...
...then the nearest one will be
some 200 light-years away.
But within 200 light-years...
...there are hundreds
of thousands of stars.
To find the needle in this haystack...
...requires a dedicated
and systematic search.
Many cosmic radio sources have nothing
to do with intelligent life.
So how would we know that
we were receiving a message?
The transmitting civilization can make
it very easy for us, if they wished.
Imagine we're in the course
of a systematic search.
Or in the midst of some more
conventional observations.
And suppose one day...
...we find a strong signal
slowly emerging.
Not just some background hiss...
...but a methodical series of pulses.
(SIGNAL PINGS)
The numbers one, two, three, five...
...seven, eleven, thirteen.
A signal made of prime numbers.
Numbers divisible only
by one and themselves.
There is no natural astrophysical
process that generates prime numbers.
We would have to conclude...
...that someone fond of
elementary mathematics...
...was saying hello.
(SIGNAL PINGS)
This would be no more than a beacon
to attract our attention.
The main message will be subtler...
...more hidden, far richer.
We may have to work hard to find it.
But the beacon signal alone
would be profoundly significant.
It would mean someone has learned to
survive technological adolescence...
...that self-destruction
is not inevitable...
...that we also may have a future.
Such knowledge, it seems to me...
...might be worth a great price.
Very likely...
...some new Champollion
would go on...
...to decode the main message,
using our interstellar Rosetta Stone:
The common language of science
and mathematics.
Think of the glories of
an exotic civilization...
...far more advanced than we...
...collected by the great
radio telescopes of Earth.
Perhaps they'd send a compilation of
the knowledge of a million worlds:
The Encyclopedia Galactica.
Receiving an interstellar message...
...would be a major event
in human history...
...and the beginning of the
deprovincialization of our planet.
A serious and systematic
radio search...
...for extraterrestrial
civilizations may come soon.
Preliminary steps are being taken
both in the United States...
...and in the Soviet Union.
It's comparatively inexpensive.
A search taking decades would cost
less than the budget overruns...
...on a single modest weapons system
in a single year.
Our technology is now
fully adequate...
...for this great challenge.
But no systematic search program...
...has ever been approved
by any nation on Earth.
When will we decide to search for...
...what other civilizations there
may be in the vast cosmic ocean?
But whether there are only a few
advanced galactic civilizations...
...or millions...
...shouldn't some of them
have voyaged to Earth?
On one hand, if even a small fraction
of technical civilizations...
...learned to live with their
potential for self-destruction...
...there should be enormous
numbers of them in the galaxy.
On the other hand, despite claims
about UFOs and ancient astronauts...
...there's no creditable evidence that
Earth has been visited, now or ever.
But isn't this a contradiction?
If the nearest civilization is,
say, 200 light-years away...
...it'd take them only 200 years
to get from there to here...
...at light speed.
Even if they were traveling
1000 times slower than that...
...aliens could've come here during...
...the tenure of human beings
on Earth.
So why aren't they here?
There's many possible answers.
One is that...
...maybe we're the first.
Some technical civilization
has to be first...
...to emerge in the history
of the galaxy.
Or maybe all technical civilizations
promptly destroy themselves.
That seems to me very unlikely.
Maybe there's some problem
with space flight...
...that we've been too dumb
to figure out.
Or maybe they are here,
but in hiding...
...because of an ethic of
non-interference...
...with emerging civilizations.
We might imagine them,
curious and dispassionate...
...watching us to determine
whether this year again...
...we manage to avoid
self-destruction.
But there's another explanation which
is consistent with what we know.
And that's that it's a big cosmos.
If years ago, an advanced interstellar
spacefaring civilization emerged...
...200 light-years away,
why would they come here?
They'd have no reason to think
the Earth was special.
There are no signs of technology,
not even our radio transmissions...
...which have had time
to go 200 light-years.
From their point of view,
all nearby planetary systems...
...might seem equally attractive
for exploration.
How would an interstellar
civilization set out to explore...
...its neighboring star systems?
It might establish staging posts...
...colonies,
on planets of nearby stars.
But this would take time.
Time to find and modify
favorable planets.
Time to build new spacecraft.
Eventually, later generations
of explorers would set out...
...wending their way
among the worlds...
...creating an interstellar
nervous system...
...binding up the stars.
Perhaps they'd come upon another
expanding civilization...
...and encounter beings
previously known...
...only from their radio
transmissions.
Star wars are unlikely.
One civilization certainly would be
far more advanced than the other.
It would be no contest.
Perhaps they would cooperate...
...exploring together a small province
of the Milky Way.
But even nearby civilizations
could spend millions of years...
...roving between the stars...
...without ever stumbling upon
our obscure solar system.
In a galaxy of 400 billion suns...
...perhaps no one has found us
just yet.
Advanced interstellar civilizations
would know about many worlds.
Some inhabited, some barren.
Perhaps they would share
their findings...
...assembling some vast repository...
...of the knowledge of
countless worlds.
They might compile an
Encyclopedia Galactica.
Suppose we could browse through
that encyclopedia.
We would choose some nearby
province of the galaxy...
...a region that's fairly
well-explored.
And then slowly leaf through
the worlds.
The young Champollion was inspired...
...by reading Fourier's
description of Egypt.
Imagine the impact on us...
...if we could study
a rich compilation...
...of not merely one world...
...but billions.
Just possibly, not too far
from our solar system...
...we might find
a technical civilization...
...only a little more
advanced than we.
Let's look them up in
the Galactic Encyclopedia.
What would a civilization
far more advanced than ours...
...be up to?
There may be engineering on a scale...
...that dwafts our proudest
achievements.
There may be cultures that disassemble
other planets in their system...
...and reassemble them around
their world to make a ring...
...or a shell with
their planet inside.
Imagine the energy crisis of a really
advanced planetary civilization.
They've used up all their fuels.
They depend on solar power.
But their growth is still severely
limited by the energy available.
An enormous amount of energy
is generated by the local star.
But most of the star's light
doesn't fall on their planet.
So perhaps they would build a shell...
...to surround their star...
...and harvest every photon
of sunlight.
Such beings, such civilizations...
...would bear little resemblance
to anything we know.
Perhaps someday there will be an entry
in the Encyclopedia Galactica...
...for our planet.
Or perhaps even now
there exists somewhere...
...a planetary dossier, garnered
from our television broadcasts...
...or from some discreet
survey mission.
They may summon up the index of blue
worlds in our part of the Milky Way...
...until they came to
the listing for Earth.
What would they know about us?
What would they think of us?
We have always watched
the stars and mused...
...about whether there are other
beings who think and wonder.
In a cosmic setting vast and old...
...beyond ordinary human
understanding, we are a little lonely.
In the deepest sense, the search
for extraterrestrial intelligence...
...is a search for who we are.
Since Cosmos was released...
...interest in UFOs has persisted.
It seems to me that there
are fewer sightings of...
...strange objects in the skies
these days...
...and more stories of encounters
with alleged extraterrestrials...
...like the account of Betty and Barney
Hill that we dramatized.
There are still people who claim
to have been abducted by aliens...
...or even sexually abused,
or even impregnated by them.
Best-selling purportedly serious books
have been written about such claims.
But the critical fact remains
that all we have still is...
...just anecdote.
There are no close-up photos,
no artifacts...
...nothing that'd convince a skeptic.
All there are is stories.
And stories just aren't good enough
on a matter of this importance.
I'm still waiting for hard evidence.
The radio search for extraterrestrial
intelligence has been picking up.
In Harvard, Massachusetts, a radio
telescope monitoring 8 million...
...separate radio channels...
...has been scanning the skies
for signals.
This program, called META,
is supported entirely by...
...the Pasadena, California-based
Planetary Society.
Paid for by members' contributions.
A similar planetary society search...
...to examine the southern skies
and the center of the Milky Way...
...is to be performed in Argentina.
These searches are by far...
...the most sophisticated
ever attempted.
A much more sensitive program...
...covering almost the entire
accessible radio spectrum...
...is to be mustered by NASA.
The search for extraterrestrial
intelligence is central...
...to our understanding of the universe
and our view of ourselves.
It's well worth doing.
But the simple fact is that...
...while we may consider
extraterrestrial intelligence likely...
...there is as yet
no evidence at all...
...that it exists.
The search continues.