Read 13 Things That Don't Make Sense Online
Authors: Michael Brooks
What’s more, it is not a fool’s errand. Piet Hut of the Institute for Advanced Study in Princeton, New Jersey, has offered
fifty-fifty odds of discovering intelligent aliens “out there” in the next fifty years. Hut knows it’s a reasonable bet because
we already understand that where there’s life, intelligence will surely follow. In 2003 the Cambridge University paleobiologist
Simon Conway Morris published a book called
Life’s Solution
. In it he argues that, in order to survive in the habitats available to it, life must diversify and evolve solutions to the
problems it faces. Life’s solutions are constrained by the laws of physics, so although it might seem that there are innumerable
solutions, there aren’t; really, there are just a few. Which means that, wherever it evolves in the universe, life will look
roughly the same. The chemicals involved might change, but the structures and machinery will necessarily converge toward a
small set of possibilities. And this convergence, Conway Morris argues, will always—given time—lead to the evolution of intelligence
because intelligence is one of the best survival tools available.
Once intelligence has evolved, an ability to use language to communicate confers a further advantage in the quest for survival,
Conway Morris points out. And so the idea that distant worlds might be populated by intelligent beings able to communicate
with each other, and eventually with civilizations alien to their own, isn’t implausible. Indeed, if our next anomaly is anything
to go by, Piet Hut may already have won his bet.
S
cience has a kind of golden rule, a principle that helps researchers distinguish between possible explanations for a phenomenon.
The principle is called Occam’s razor, and it says that, given a number of options, you should always go for the simplest,
most straightforward one. If we apply Occam’s razor to the signal received by the Ohio State University’s Big Ear telescope
in August 1977, we can conclude that it was a signal from an alien civilization. Why? Because it was exactly what we had been
told to look for.
In September 1959, sandwiched between an article on the electronic prediction of swarming in bees and one on X-ray-induced
metabolic changes in erythrocytes, the first scientific article on the likely characteristics of an alien communication was
published in the journal
Nature
. The article was written by Giuseppe Cocconi and Philip Morrison, two physicists from Cornell University in New York. Cocconi
had an unremarkable background, but Morrison’s was more interesting. He earned his PhD under J. Robert Op-penheimer and played
a vital role in the Los Alamos Manhattan Project. He was part of the team that traveled to Tinian Island in the West Pacific
to assemble the atomic bomb that destroyed Nagasaki. After surveying the destruction, Morrison became a tireless champion
of nuclear nonproliferation. He also helped found SETI, the search for extraterrestrial intelligence.
Morrison and Cocconi’s paper in
Nature
suggested that anyone wanting to attract another intelligent civilization’s attention would use radio frequency radiation.
It is relatively cheap and easy to produce, and it travels a long, long way with a small power input. When it came to selecting
a transmission frequency, they would choose one that spoke of some universal number in the cosmos. Morrison and Cocconi’s
best guess was that an alien civilization would use something associated with the most common element in the universe: hydrogen.
Any beings capable of communication would already have worked out and noted that hydrogen emits radiation at 1420 Mhz; this
would be a number that would have special resonance everywhere in the universe.
An alien signal, then, would come in at 1420 Mhz. And it would be, as far as possible, only at 1420 Mhz. Sending a signal
that is a composite of lots of frequencies uses a lot of energy; anyone wanting to get maximum distance per kilowatt on their
transmission will use a narrow frequency range—a “narrowband” signal. As an added bonus, no natural phenomenon emits narrowband
radio frequency radiation, so the signal would make any intelligent listener prick up their ears.
On August 15, 1977, an exact match for Morrison and Cocconi’s signal arrived in Delaware, Ohio.
IN
the movie
Contact
, Jodie Foster gets a signal from space, and all hell breaks loose. The U.S. National Security Agency tries to take over the
project, the president is briefed, and his advisers descend on the scene in sleek black military helicopters. Nothing like
that happened at the Big Ear. Around 11:16 p.m. Eastern Daylight Savings Time, the signal hit the first of the Big Ear’s two
receivers. The telescope’s computer recorded the signal’s arrival, a rise and fall in electrical current induced in the receiver’s
wire mesh by an electromagnetic wave, then carried on recording whatever else came in from the sky—nothing but noise, as it
turned out. Three minutes later, when the Earth had turned and brought the telescope’s second receiver around to stare at
that same point in the heavens, the signal had gone.
A few hours later—by coincidence, it should be emphatically noted—Elvis Presley died. It was only three days later, while
more than twenty thousand people filed past Elvis’s open casket in Graceland, that the technician arrived at the Big Ear to
stop the computer, print out the data, and wipe the hard disk clean. He came every few days; it was 1977, and the hard disk
could only hold one megabyte. Perpetual data storage would be an unconscionable luxury for this long-shot project. On his
way back up to Columbus, the technician dropped off the printout at Jerry Ehman’s house.
Ehman, the man who spotted our best candidate for an extraterrestrial signal, is practically a legend. Other people would
have spotted it too, he points out, with his typical modesty. But who else would have had the naive enthusiasm, the passion
to write “Wow!” in the margin? Other people might have marked the printout with an asterisk or an arrow. Jerry Ehman wrote
the exclamation that properly captures the profundity of the moment.
Much to his surprise, the name stuck, but he shouldn’t be surprised.
Wow!
is a good summation of the importance of detecting an alien signal. It may even be an understatement. Talk to almost any astronomer—in
private—and he or she will tell you it’s the biggest thing there is. We are pouring huge amounts of energy into the biological
effort to understand where life came from, how it arose on planet Earth, because it matters to us; it is, perhaps, our deepest
question. Really, it boils down to this: Are we special? The best summation has been attributed to the science fiction writer
Arthur C. Clarke: “Sometimes I think we’re alone in the universe, and sometimes I think we’re not,” he said. “In either case
the idea is quite staggering.”
Clarke is right. If we are alone, that’s extraordinary. If we are not, that’s even better. Were we to discover that we are
one of many life-forms on a planet that is one of many inhabited worlds, we would have a new perspective on being human—on
being alive, even. And if we discover that some of that life beyond Earth is intelligent, a whole new vista of possible human
experience opens up before us. We might, for the first time, have meaningful communication with another species.
That, really, is why we are looking for life beyond Earth—or, more accurately, suitable conditions for life. As we have already
seen, the Mars Rovers were looking not for life but for the signature that there is, or has been, liquid water on Mars. It’s
not just Mars, though; the same search for the signs of water is going on with the Huygens probe on Titan, Saturn’s giant
moon. Jupiter’s moon, Europa, has also had its conditions analyzed and been declared a potential haven for life. And these
planets and moons within our solar system are just the beginning; the possibilities for life range across a whole universe
full of planets.
We are living at a time of extraordinary progress in finding
extrasolar planets
; we did not spot the first one until 1988, but by August 2007 there were 249 confirmed sightings. There are several ways
to do it. One is to identify anomalies in a star’s orbit, due to a planet’s mass pulling on the star. Or you can look at the
starlight and see if it has become polarized—if the orientation of its magnetic and electric fields has shifted—by passing
through a gaseous planetary atmosphere. Perhaps you’ll see a “lensing” effect where the planet’s gravitational field warps
space around it and thus alters the path of the star’s light. Then there’s the “transit” method, where a star dims ever so
slightly because a planet has passed across its face.
These are only a few of the techniques; there are plenty more, and they are all bearing fruit. In fact, it has got to the
point where, if you want to make the news, just discovering an extrasolar planet is not enough. These days, to grab the front
page you have to find a planet in its star’s
Goldilocks zone.
As with the idea of a Goldilocks universe, the name comes from the conditions: in the Goldilocks zone, the temperature is
neither too hot nor too cold, but just right for the stable existence of liquid water on the planet’s surface. So far, we
have only found a few planets that orbit within the Goldilocks zones of their stars. In May 2006, for example, scientists
announced they had discovered three planets, each with a mass equivalent to Neptune’s, orbiting a star about forty-one light-years
away. The outermost of these was in the Goldilocks zone. The following April, researchers announced the discovery of Gliese
581c, a planet orbiting a star in the constellation Libra. It too lay in its star’s Goldilocks zone.
Though we are making great progress with finding suitable extrasolar planets, when it comes to detecting alien life there’s
a problem: the planets are
so
far away. There is a chance we might see signatures of possible life, or at least suitable conditions for life, in the spectrum
of radiation from their surfaces or atmospheres, but we have little more to go on. If there are dormant life-forms on their
surface, we won’t ever know for sure. Without some dramatic leap in our technological abilities, there is no way for us to
send probes or people to extrasolar planets. What we really need, then, is for that life to get in touch with us. It has never
happened, or at least not in a way that convinces everyone who looks at the evidence. But the Wow! Signal remains our most
tantalizing—indeed our only—possibility.
JERRY
Ehman was in his kitchen when he read the printout from Big Ear. He was sitting at the table, with three days of data in front
of him.
On the printout, the signal came in as “6EQUJ5.” The letters and numbers are, essentially, a measure of the intensity of the
electromagnetic signal as it hit the receiver. Low power was recorded with numbers 0 to 9; as power got higher, the computer
used letters: 10 was
A
, 11 was
B
, and so on. 6EQUJ5 was the signature of a signal that steadily grows in intensity, reaches a peak, then falls away again.
The
U
was the highest power signal the telescope had ever seen. The signal’s spread was astonishing too: less than 10kHz. That’s
somewhere around a millionth of the transmission frequency. By anyone’s definition, it was a narrowband signal at 1420 Mhz.
Ehman knew what Morrison and Cocconi had said about the likely shape of alien signals. This fit exactly.
6EQUJ5 came up early in the printout—Ehman marked it with that
Wow!
and went through the rest of the printout to see if it happened again. It didn’t.
It was enough, though. Eighteen years before the Wow! Signal hit Earth, before SETI had even been conceived, two physicists
had predicted what an alien communication would most probably look like, and their prediction looked uncannily like the signal
Ehman saw. If you believe that science should progress through theoretical predictions that are followed up by confirming
observations, the alien hypothesis is a slam dunk.
So where has ET been hiding? The signal came from a single point in the heavens. Immediately on recognizing the signal, Ehman
and his boss, Robert Dixon, consulted their star maps to see what astronomical body might be emitting it. The signal came
from the constellation of Sagittarius, also known as the Teapot. Just to the northwest of the globular cluster M55 (to the
east of the Teapot’s handle) to be exact. There was nothing there.
Although the signal’s shape didn’t look at all like it had been created by accident, the researchers also looked for satellites
or spacecraft—or even aircraft—that might have emitted a signal or interfered with terrestrial signals, creating something
that looked like the Wow! Signal. Not only were there no man-made objects that could do it, the signal was of a frequency
that global governments agreed was banned from use. There was no good explanation.
Three decades later, there still isn’t. And there’s very little more that one can say. The Big Ear researchers never saw anything
like the Wow! Signal again. They looked for it more than one hundred times. Nothing. All the subsequent printouts were bland
numbers, signifying the stubborn absence of anything interesting coming to us from the deep reaches of the cosmos. Most of
our searches for alien intelligence have been similarly long, dark, eventless efforts. Occasionally something interesting
has spewed out of the telescopes, but it has always turned out to be a spurious reflection off a satellite or a spacecraft,
or interference from some piece of cosmic rock.
Though many have tried, no one has ever come up with such an explanation for the Wow! Signal. The researchers at Big Ear have
analyzed a wide variety of possibilities: satellite transmissions, the harmonic frequencies of ground-based radio transmitters
reflected off space debris, aircraft signals, terrestrial TV or radio signals, and anything else they could think of. Nothing
could explain the characteristics of the observed signal. The first time I had contact with Ehman, he told me he was “still
waiting for a definitive explanation that makes sense.” Not that he believes it was aliens; he doesn’t like to “believe” anything.
It’s just that it’s the only satisfying explanation—if a one-off contact with ET can be classed as something satisfying.
In fact, it’s this, the singular nature of the signal, that is its Achilles’ heel. In
Contact
, Jodie Foster recorded hours, days, even weeks of extraterrestrial messages. The Big Ear received just one. Even the second
receiver that looked at the same spot in the sky three minutes later saw nothing.
That certainly makes it tempting to dismiss the signal. It must have been some flutter in the electronics, or a bubble exploding
in the telescope’s nitrogen cooling system, or … something. If it was ET, then he, she, or it didn’t broadcast for long—surely
any deliberately broadcast signal would last for longer than three minutes?
The problem with that theory is that there’s no reason for the assumption. Worse, everybody searching for extraterrestrial
intelligence knows that intelligent beings could quite feasibly send one signal out into space followed by absolutely nothing
else. They know that because we have done it ourselves.
In 1974 NASA arranged for the Arecibo telescope to beam a message out toward M13, a star-studded galaxy that seemed a good
candidate for our nearest extraterrestrial homestead. The message was a stream of binary digits that, if you put them together
right (carefully placed prime numbers provided clues), showed a crappy Atari Pong-style picture of a person, a DNA double
helix, and our solar system. Anyone in M13 who picks it up—which won’t happen for about twenty-one thousand years—may well
conclude there is intelligent life out here. They may even be able to pinpoint where it came from. For that civilization on
M13 it is likely to be a momentous event—their first contact with intelligent aliens. However, if they are anything like us,
M13’s brightest skeptics will smugly point out that you can’t draw definitive conclusions from just one signal, no matter
how well crafted. As any intelligent civilization knows, a sample of one is useless, statistically speaking. If ET really
wanted to get in touch, there’d be two signals, at least. Wouldn’t there? What a thought: we might have messed up our first
communication with our cosmic neighbors. So perhaps we can take comfort in the fact that they seem to have made the same mistake.