This is the first in a three-part series on the search for extraterrestrial life.
Ever been to a party and wondered why no one was talking to you? That’s kind of how SETI scientists feel — but on a cosmic level.
For more than half a century, astronomers have been listening to space. They use powerful radio telescopes, hoping to pick up signals from civilizations in distant space. They call this project the Search for Extra-Terrestrial Intelligence, or SETI. The trouble is, they’ve never heard a single ping, beep or “howdy.” The number of aliens who want to talk to us seems to be exactly zilch.
So how can we get the conversation started? Scientists disagree.
Some want to follow your mom’s advice: Introduce yourself nicely. They think Earthlings should start beaming signals out into the universe. Maybe it would improve our chances of hearing back from aliens if we let them know we’re friendly and want to chat.
This so-called “active SETI” would deliberately beam signals out in hopes of reaching space beings. Seth Shostak is an astronomer at the SETI Institute in Mountain View, Calif. He supports the idea. He also concedes that it is “extraordinarily controversial.”
Indeed, some scientists question the wisdom of advertising our presence. After all, maybe the aliens aren’t exactly what you’d call warm and cuddly. Do we really want to shout out to whomever will listen: “Here we are! Come invade our planet!”? At the very least, these scientists argue, people should discuss the idea and decide as a species whether we should try to actively put ourselves onto the radar screen of more technologically advanced beings.
“There are some people who think it’s dangerous, because you don’t know who’s out there,” Shostak says. “Maybe the aliens are just into yoga and poetry. But it could be that one percent of them are aggressive Klingons.”
Shostak doesn’t share these fears. But some people worry that if the aliens are not peaceable travelers, their response to even a friendly “hello” could be downright hostile. Some worry that instead of a friendly chat, those aliens might, as he puts it, “launch an attack and obliterate the Earth.”
David Brin doesn’t appreciate the Klingon jokes. He’s a scientist and science fiction writer. He also is one of those people who argues that Earthlings should proceed with caution. It’s not a matter of being afraid of some alien invasion, he says. “I know how unlikely those scenarios may be.” Instead, he thinks of active SETI almost like a potential environmental hazard.
Broadcasting powerful signals would change the nature of our planet. It would make Earth more observable from space. Other projects must go through an environmental review, he says, and this should too. “What’s so hard about that to understand?”
As an astrobiologist, David Grinspoon studies the possibilities of life throughout the universe. He works for the Planetary Science Institute in Washington, D.C. Whatever Earthlings do, Grinspoon thinks it’s important for them to decide as a group.
“The more I think about it,” he explains, “the more it seems almost anti-human to say, ‘I’m just going to be the ambassador for the whole human race and start broadcasting to aliens on my own.’”
Alien life is likely, many scientists suspect
Inviting contact with space aliens might sound like the plot of one of Brin’s sci-fi novels. Yet plenty of researchers are taking this idea quite seriously. Even though we haven’t found extraterrestrials yet, many scientists believe that it’s quite likely that life exists on other worlds.
For one thing, science recently has shown that planets are much more common than astronomers had once thought. There are probably billions of them in the universe.
Biology also has turned up plenty of life on Earth that can survive and thrive in extreme environments — conditions that once were thought uninhabitable. These include places that are very hot, very cold, very dry or even bathed in acid.
“Everything we’ve learned about other planets and the diversity of life on Earth points us in the direction of believing there is abundant life elsewhere in the universe,” argues Grinspoon.
What’s more, even if life truly needed many of the same conditions found on our world, planets have been turning up that may host Earth-like temperatures, atmospheres — and perhaps even water. Such worlds exist in what’s known as “Goldilocks” zones. These are not too hot or too cold — but just right to sustain liquid water somewhere.
Whatever such alien life might be like — even if most of those organisms are just algae or worms — some would likely be intelligent, Grinspoon suspects. “It’s not just a fantasy that someone might pick up a signal if we broadcast it,” he says. “It’s my belief that there probably are creatures out there. And some of them probably have much more advanced technology than we do.”
Striking up a conversation
So how would people try to contact other worlds? Scientists have a few ideas. Like a message in a bottle, people could put something into a capsule and shoot it into space. Or scientists could flash lights at the aliens, training the beams of super-powerful lasers at nearby star systems. Think of it like Boy Scouts waving their flashlights at girls who might be camping on the other side of a lake. Researchers would send radio broadcasts out across the vast expanses of space.
Douglas Vakoch is president of METI International in San Francisco, Calif. (METI stands for Messaging Extraterrestrial Intelligence.) In addition to other ideas for sending out signals, he recommends beaming radio messages at other stars with huge radio telescopes, like the Arecibo (Air-eh-SEE-boh) observatory in Puerto Rico.
Right now, Arecibo uses radar to probe our solar system. The telescope sends out a pulse of radio waves. How long it takes those signals to bounce off things, such as asteroids, tells us how far away those things are. Under Vakoch’s plan, the telescope would send out those same radar pulses. But he’d aim them at nearby star systems. If all went well, intelligent aliens would notice those radio tweets and answer our “beep” with a “boop.”
“Maybe some civilizations out there are doing what we’re doing,” Vakoch says. “They’re listening, but they’re not transmitting.” If they are, “we just wouldn’t discover them,” he notes. Active SETI, he explains, “is an attempt to let any civilization out there know not only that we’re here, but also that we’re interested in making contact.”
So why do we even want to talk to aliens? The search for extraterrestrial intelligence — or ETI — is part of humanity’s larger quest to explore the universe, and understand the nature of life, Vakoch says. “Perhaps more importantly, it holds a mirror up to ourselves.”
Throughout human history, any time civilizations have met, they have exchanged ideas, knowledge and technology. Meeting a more advanced culture could give our species a new perspective about life on Earth, says Vakoch. It might also show us new tools to solve Earthly problems, he adds.
Brin sees it a bit differently: “It’s worth bearing in mind that every time human civilizations that didn’t know about each other came into contact, there was pain.” Think about what happened to Native Americans or Africans when European explorers arrived on the scene, he says. Europeans coming to the “New World” brought along never-before-seen diseases. And their advanced technology, such as guns and metal, led to the destruction of the Native Americans’ way of life.
That’s one reason Brin thinks scientists and government leaders should not act too quickly. He advises that they think and talk it over before deciding what to do next. If we do contact aliens, studying our own history might give us ideas about ways to keep our interactions peaceful.
“Why did some contact situations [in history] go better than others?” Brin asks. “It turns out, there were some commonalities in the ones that were less painful. This should be something we study, not something we avoid.”
E.T. may already know about us
It’s probably too late to hide from advanced space civilizations, many scientists observe. Supporters of active SETI point out that FM radio and television signals both emit a high enough frequency that they could be picked up in space. Then there are all of those signals flying around between satellites, and those powerful radar pings from telescopes like Arecibo.
While people debate the issue, maybe the aliens are already watching our TV shows and listening to our music, says Philip Lubin. He’s a physicist at the University of California, Santa Barbara. “When someone says we shouldn’t transmit,” he notes, “you kind of have to say, ‘Okay, what planet do you live on?’ Because we’ve been transmitting for 100 years.”
Active SETI would take those transmissions to the next level. It would beam out more powerful signals, focusing them on the closest star systems. “The real question,” Lubin asks, “is should we transmit with the intention of being understood?”
Any civilization so advanced that it could visit Earth would already have the technology to pick up our signals, Vakoch agrees. So it would likely already know we’re here. In that case, he cautions: Maybe it’s in the best interest of the people of Earth to offer a peaceable greeting before those aliens pay us a visit. “There’s the idea that doing something is more dangerous than doing nothing,” Vakoch says. “But maybe it’s more dangerous not to say anything.”
He doesn’t want to wait to start active SETI. He does, however, agree that society should talk openly about the search for extraterrestrial life — and decide what to do if aliens respond. Most scientists have agreed to the “Protocols for an ETI Signal Detection.” This is a plan for what to do if aliens make contact with us. (Step one: Tell other scientists so they can confirm the discovery.) But Vakoch would like to see those policies debated and agreed to by the United Nations.
He concedes, though, “So far, we haven’t convinced [U.N. officials] that this should be at the top of their list.”
Grinspoon does think we should debate the issue before we broadcast messages into space. But it’s not because he’s afraid of ET. Discussing the welfare and future of our planet “is the kind of thing we humans need to get better at,” he says. In fact, the biggest threat to human civilization isn’t alien invasion, he argues. It’s things like climate change, war and pollution.
The only solution to those problems is to learn how to think and act not as different races and countries, but as one species, he says. “It’s actually more important to try to have a conversation with our fellow human beings than it is to have a conversation with aliens,” he says. “That is our survival challenge.”
aggressive (n. aggressiveness) Quick to fight or argue, or forceful in making efforts to succeed or win.
algae Single-celled organisms, once considered plants (they aren’t). As aquatic organisms, they grow in water. Like green plants, they depend on sunlight to make their food.
alien A non-native organism. (in astronomy) Life on or from a distant world.
asteroid A rocky object in orbit around the sun. Most orbit in a region that falls between the orbits of Mars and Jupiter. Astronomers refer to this region as the asteroid belt.
atmosphere The envelope of gases surrounding Earth or another planet.
biology The study of living things. The scientists who study them are known as biologists.
broadcast To cast — or send out — something over a relatively large distance. A farmer may broadcast seeds by flinging them by hand over a large area. A loudspeaker may send sounds out over a great distance. An electronic transmitter may emit electromagnetic signals over the air to a distant radio, television or other receiving device. And a newscaster can broadcast details of events to listeners across a large area, even the world.
climate The weather conditions prevailing in one area, in general, or over a long period.
climate change Long-term, significant change in the climate of Earth. It can happen naturally or in response to human activities, including the burning of fossil fuels and clearing of forests.
cosmic An adjective that refers to the cosmos — the universe and everything within it.
culture The sum total of typical behaviors and social practices of a related group of people (such as a tribe or nation). Their culture includes their beliefs, values, and the symbols that they accept and/or use. Culture is passed on from generation to generation through learning. Once thought to be exclusive to humans, scientists have recognized signs of culture in several other animal species, such as dolphins and primates.
diversity (in biology) A range of different life forms.
environment The sum of all of the things that exist around some organism or some device and the condition those things create for that organism or device. Environment may refer to the weather and ecosystem in which some animal lives, or, perhaps, the temperature, humidity and placement of components in some electronics system or product.
E.T. (n.) An abbreviation made famous by the 1982 Universal Pictures movie, E.T. the Extra-Terrestrial. The main character was a charming space alien called E.T. His most famous line from the movie was “E.T. phone home.” E.T. has since come to be used as a colloquial term for any intelligent and potentially friendly space alien.
extraterrestrial Anything of or from regions beyond Earth.
frequency The number of times a specified periodic phenomenon occurs within a specified time interval. (In physics) The number of wavelengths that occurs over a particular interval of time.
intelligence The ability to collect and apply knowledge and skills.
laser A device that generates an intense beam of coherent light of a single color. Lasers are used in drilling and cutting, alignment and guidance, in data storage and in surgery.
Native Americans Tribal peoples that settled North America. In the United States, they are also known as Indians. In Canada they tend to be referred to as First Nations.
observatory (in astronomy) The building or structure (such as a satellite) that houses one or more telescopes.
organism Any living thing, from elephants and plants to bacteria and other types of single-celled life.
physicist A scientist who studies the nature and properties of matter and energy.
planet A celestial object that orbits a star, is big enough for gravity to have squashed it into a roundish ball and has cleared other objects out of the way in its orbital neighborhood. To accomplish the third feat, the object must be big enough to have pulled neighboring objects into the planet itself or to have slung them around the planet and off into outer space. Astronomers of the International Astronomical Union (IAU) created this three-part scientific definition of a planet in August 2006 to determine Pluto’s status. Based on that definition, IAU ruled that Pluto did not qualify. The solar system now includes eight planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.
planetary science The science of planets other than Earth.
protocol An accepted or agreed-upon procedure for doing something.
radar A system for calculating the position, distance or other important characteristic of a distant object. It works by sending out periodic radio waves that bounce off of the object and then measuring how long it takes that bounced signal to return. Radar can detect moving objects, like airplanes. It also can be used to map the shape of land — even land covered by ice.
radio To send and receive radio waves; or the device that receives these transmissions.
radio waves Waves in a part of the electromagnetic spectrum; they are a type that people now use for long-distance communication. Longer than the waves of visible light, radio waves are used to transmit radio and television signals; they are also used in radar.
satellite A moon orbiting a planet or a vehicle or other manufactured object that orbits some celestial body in space.
scenario An imagined situation of how events or conditions might play out.
science fiction A field of literary or filmed stories that take place against a backdrop of fantasy, usually based on speculations about how science and engineering will direct developments in the distant future. The plots in many of these stories focus on space travel, exaggerated changes attributed to evolution or life in (or on) alien worlds.
SETI An abbreviation for search for extraterrestrial intelligence, meaning life on other worlds.
society An integrated group of people or animals that generally cooperate and support one another for the greater good of them all.
solar system The eight major planets and their moons in orbit around our sun, together with smaller bodies in the form of dwarf planets, asteroids, meteoroids and comets.
species A group of similar organisms capable of producing offspring that can survive and reproduce.
star The basic building block from which galaxies are made. Stars develop when gravity compacts clouds of gas. When they become dense enough to sustain nuclear-fusion reactions, stars will emit light and sometimes other forms of electromagnetic radiation. The sun is our closest star.
technology The application of scientific knowledge for practical purposes, especially in industry — or the devices, processes and systems that result from those efforts.
telescope Usually a light-collecting instrument that makes distant objects appear nearer through the use of lenses or a combination of curved mirrors and lenses. Some, however, collect radio emissions (energy from a different portion of the electromagnetic spectrum) through a network of antennas.
terrestrial Having to do with planet Earth, especially its land. Terra is Latin for Earth.
tool An object that a person or other animal makes or obtains and then uses to carry out some purpose such as reaching food, defending itself or grooming.
transmit (n. transmission) To send or pass along.
tweet Message consisting of 140 or fewer characters that is available to people with an online Twitter account.
universe The entire cosmos: All things that exist throughout space and time. It has been expanding since its formation during an event known as the Big Bang, some 13.8 billion years ago (give or take a few hundred million years).