In 1950, Nobel Prizewinning physicist Enrico Fermi famously asked his colleagues at lunch, Where is everybody? His question became known as the Fermi Paradox. He wanted to know why we havent met any aliens if there are so many habitable planets in the universe.
There are a lot of theories as to why we havent made contact yet (that we know of). But perhaps, we simply made a cosmic mistake in our calculations. We began by assuming that alien life would be like us. If that assumption is wrong, all of our calculations about finding alien life make no sense. So now were changing that assumption, broadening our thinking and our strategies to make contact with alien life that isnt like us.
10The Sunset Of Radio Wave SETI
Photo credit: SETI
For over 50 years, SETI has been listening for radio signals from space. In 1974, astronomer Frank Drake sent the first radio wave message, the Arecibo Message, directed to aliens in outer space. As far as we know, we havent received an answer. Listening to NASA these days, youd think that searching for alien life is their priority. Yet, Drake complains that NASA isnt funding the search. In fact, they may dismantle our two biggest radio telescopes, the Arecibo telescope and the Green Bank Telescope. If that happens, then SETI will be effectively shut down on the radio side. China has unveiled a complex radio telescope, although Drake isnt sure if they can get the technology working correctly.
On the other hand, optical SETI, which scans for laser flashes, is going strong from a funding standpoint due to private gifts. Unlike radio wave messages, optical messages depend on aliens targeting their narrow beams right at us. The signals are so strong that we only need a small telescope to receive them, said Drake. Smaller telescopes can offer more observational time, and that is good because we need to search many stars for a chance of success. Drake likes to think that if aliens are willing to target us, they may be altruistic.
Not everyone shares his optimism. Experts are engaged in a heated debate about whether we should send messages into outer space at all. Many scientists believe we could be jeopardizing our safety by contacting aliens before were advanced enough to protect ourselves. According to John Elliott of SETI, there are members of the SETI community who are already sending messages despite the controversy. For the record, Drake is against actively sending signals to extraterrestrials, a project called active SETI. He prefers to simply listen for their signals.
9Talking To Aliens 101
John Elliott of the UK SETI Research Network believes we should go beyond looking for alien signals and instead determine the difference between an alien language and random sounds. By studying more than 60 human languages, he found a common signature of rhythms and structures in each language. For example, we have content words and short function words (such as if and but) that bond phrases together. Regardless of the language, humans use nine content words at most in one phrase.
Some animal species, like dolphins, have the same language signature. Although we cant speak dolphin language yet, we recognize about 140 distinct sounds in their speech. They always identify themselves by an individual name or call sign when they begin to communicate, limiting themselves to no more than five words per content chunk. Elliott believes that limit is consistent with their smaller brain size and ability to process information.
Hes developed a series of small computer programs, the Natural Language Learner, to analyze alien signals for the complexity and internal structure of language. However, he probably couldnt decipher the content yet.
Communicating with intelligent animals on Earth may be a first step toward developing our ability to talk to aliens. Weve taught dolphins hundreds of our words, the difference between questions and statements, concepts like none, and other syntax. As a first attempt to establish two-way, interactive communication between animals and humans, biologist Denise Herzing created a game where dolphins and humans could learn to talk to each other with a primitive, shared language. Female dolphins were more interested in talking than male dolphins. The female dolphins also invited dolphins from other species to join in.
Weve also learned that wild Campbells monkeys add suffixes to certain sounds to warn others about different dangers. For example, krak signals that a leopard, their natural predator, is near. But krak-oo just generally warns of danger from a branch falling or other monkeys invading their territory. Diana monkeys also understand the calls from Campbells monkeys.
Another study found that adult chimpanzees from the Netherlands slowly changed their call for apples to match the local chimp language after they moved to a Scotland zoo and became friends with the local animals. However, its debatable whether its a change in accent or actually a second language that indicates bilingualism.
8Party Like Its AD 1015
The success of SETI depends on intelligent alien life using technology to send signals. While beings who use technology must be intelligent, the reverse isnt necessarily correct. Again, we come back to dolphin intelligence. Dolphins dont have the limbs to invent and use complex tools, but theyre intelligent. Other types of alien life may be like that. Is it the use of technology or the ability to communicate and socialize that defines intelligence?
Are we being too arrogant in believing were more intelligent than creatures like dolphins? As Carl Sagan pointed out, While some dolphins are reported to have learned Englishup to 50 words used in correct contextno human being has been reported to have learned dolphinese. They dont use technology to kill each other, either.
To prepare for alien contact, Laurance Doyle of SETI also intends to research communication between trees. They use chemicals to tell each other about pests and other threats. Who knows? Brains might not be necessary, he said.
In either of those two cases, wed have to travel to where the aliens live instead of waiting for them to contact us.
But theres an even simpler reason we may not hear from aliens in our lifetime, even if theyre just like us. When we use telescopes to view outer space, we dont see things as they are today. We see the past. We . . . see back in time because light takes time to get from there to here, explained Jonathan Gardner of NASA. So, as we look further and further away, it takes longer and longer for the light to get from where its emitted to here and we can actually see backward in time. And if we look far enough away, were actually looking back to when the universe was much younger than it is today, when the light was emitted from these galaxies.
If aliens are looking at us through their telescopes, they would see us in the past, too. For example, aliens who live 1,000 light-years from us would see us in AD 1015. With radio amplifiers only invented in 1907, it may take at least another 900 years before aliens can pick up radio signals from Earth (if theyre even using that technology).
7The Social Scientists Weigh In
Usually, we look to the hard sciencesastronomy, computer science, engineering, physicsto lead the way to communicating with aliens in space. But Doug Vakoch, the SETI Institutes Director of Interstellar Communication, has edited a free book called Archaeology, Anthropology, and Interstellar Communication that tackles the topic from the perspective of social scientists.
Every day, archaeologists and anthropologists try to unravel the secrets of ancient civilizations from mere fragments of information. We can never be sure if their interpretations are correct. Too often, we base our conclusions about past civilizations on the beliefs of our current cultures. But at least we have a common human ancestry. How will we go about deciphering messages from an alien culture about which we know nothingaliens who may have different sensory organs than we do, causing them to interpret messages differently as well?
We also assume there will be one culture in alien civilizations. But, in fact, this may be the one common thread between humans and aliens. We must face the fact that we could be dealing with a world fragmented into different cultural frameworks, much as our own is, and consisting of beings who may not respond to contact with us in a uniform way, says John Traphagan in the book. Technological advancement on Earth has not always been associated with increased political and social integration (think World Wars I and II) . . . It seems reasonable to think that we will be dealing with beings shaped by common memories (among themselves) and who will share, but who will also debate and contest, ideas developed within the frameworks of those common memories and experiences about what to do with the fact of having contacted humans.
Theyre pretty much saying we have no hope of deciphering an alien communication at this point or of responding in a coherent manner.
Using data from 100,000 galaxies observed by NASAs Wide-field Infrared Survey Explorer (WISE) spacecraft, scientists looked for heat signatures that would suggest the existence of advanced alien civilizations. Whether an advanced spacefaring civilization uses the large amounts of energy from its galaxys stars to power computers, spaceflight, communication, or something we cant yet imagine, fundamental thermodynamics tells us that this energy must be radiated away as heat in the mid-infrared wavelengths, said researcher Jason Wright of Pennsylvania State University. This same basic physics causes your computer to radiate heat while it is turned on.
Unfortunately, scientists didnt find irrefutable evidence of an advanced civilization. It was an odd outcome considering that the galaxies have been around for billions of years. In that time, they should have become filled with aliens. The researchers concluded that either the aliens arent there or they simply arent advanced enough to show a heat signature.
Even so, the team found 50 galaxies with abnormally high mid-infrared radiation levels. Theyll need to do more studies to see if this heat is coming from the natural environment or if its an alien heat signature.
Even though we dont explicitly say it, our assumptions about aliens have included the belief that they have unlimited resources with which to communicate. Weve been acting like they should spend every moment of their day trying to send us signals. If not, aliens cant possibly be out there.
Thats human arrogance at its finest. If NASA has to cut funding to conserve resources, why wouldnt it be possible that aliens face the same problem? In 2010, a study from Microwave Sciences suggested that aliens may be broadcasting signals at higher frequencies than monitored by SETI to save money. SETI researchers listen to 1.421.72 gigahertz wavelengths because certain interstellar clouds emit radiation at that frequency. However, the scientists from Microwave Sciences believe that aliens would be more likely to use a frequency near 10 gigahertz because they could create a strong beam more easily and cheaply at that frequency.
To further conserve resources, aliens may broadcast brief pulses, similar to a tweet on Twitter, rather than a continuous signal. Possibly, the aliens would construct a powerful beacon and swing it across the Milky Way disc to broadcast to most of the galaxys stars. That way, they could send a 35-second burst of pulses to every star within 1,080 light-years.
With that type of strategy, the aliens would only send a signal a few times a year. Astronomers have seen some unexplained signals that lasted for tens of seconds then were never seen again, says Benford. Some of those could have been extraterrestrial beacons, but there wasnt enough observing time to wait for any repeats.
This may explain the 72-second WOW signal that was detected by a SETI researcher in 1977. Some scientists believe this was an alien signal. Its called the WOW signal because the man who heard it wrote Wow in the margin of his notes. Its still a mystery, both what it was and where it came from. It has never been detected again.
Photo credit: Edgar181/Wikimedia
For the most part, weve assumed that water is necessary for life. But now, scientists are studying whether other liquids, such as the hydrocarbon methane that covers Saturns moon Titan, could work, too. Wed need different types of molecules called ethers to produce the chemical interactions for life, preferably in a warmer environment than Titan. Strung together, ethers may combine into complex polyethers to create living things. The DNA and RNA molecules found on Earth cant dissolve in hydrocarbons. In fact, theyd become clogged up.
Like water, hydrocarbons can be liquids, solids, or gases. Solids and gases wont allow biomolecules to interact to create life, so liquid hydrocarbons are what we need to finda kind of oily Earth, so to speak. Octane stays liquid over the largest temperature range, providing the most favorable condition for life. Propane and methane also work in smaller temperature ranges. Unfortunately, it appears that Titan is too cold to support life.
Within our own solar system, we do not have a planet big enough, close enough to the Sun, and with the right temperature to support warm hydrocarbon oceans on its surface, said researcher Steven Benner of the Foundation for Applied Molecular Evolution. But with the number of new solar systems were finding, it may not be long before we discover a planet or moon with the right temperature to support life in a hydrocarbon ocean.
Although it seems unlikely that well make face-to-face contact with intelligent aliens soon, its possible that theyre living underground on one of the planets or moons in our solar system. They may also be living in the asteroid belt.
In 1950, the US military devised Seven Steps to Contact, a plan to handle first contact with intelligent aliens. First, we would surveil them from a distance, gathering as much data as we could. Next, we would visit them covertly to assess the level of their weapons and vehicles. If we had superior technology, then we would approach the aliens planet to see if they were hostile. If not, we would briefly land in remote, unpopulated areas of the planet to take samples of plant and animal life. The military also intended to abduct some aliens without harming them.
After that, we would engage in low-level approaches to be seen by the aliens while staying out of reach. Wed want to have as many aliens as possible observe our craft, yet wed want to appear friendly. Finally, if we thought it was safe, wed land and try to meet them.
This is one procedure thats remained roughly the same, but were getting closer to the day that we may use it. Its unclear what would happen if we encounter a race with superior intelligence. Wed have to hope they were friendly. If not, wed probably be goners.
When we look for life on other planets, we usually try to detect a biochemical signature. As we talked about earlier, scientists have observed biosignatures that indicate life on lifeless planets with lifeless moons. So our current methods can easily yield a false positive.
MIT scientists Sara Seager and William Bain believe we should expand our search beyond methane, oxygen, and the most well-known biosignatures. We know there will not be huge numbers of accessible planets, said Seager. We want to make sure we do not miss any signatures, by trying our best to think outside the box. Oxygen is a great biosignature gas for Earth, but what are the chances it will be present on an exoplanet?
Reinforcing the idea that alien life may be quite different from us, Seager and Bain point to the zoo of diverse exoplanets weve found so far. A specific, astonishing finding is that the most common type of planet in our galaxy are those with sizes between those of Earth and Neptunea new class of planet that is neither terrestrial nor giant and one without an accepted theory for its formation, wrote Seager and Bain in a paper.
To get around some of these limitations, researchers from Belgium and Switzerland have recently tested a new device that detects life without identifying biosignatures. Using a cantilever (a beam fixed at one end), the nanomotion detector scans a surface for small fluctuations in the metabolic activity of cells or in their movement. The scientists successfully tested their device on bacteria, human cells, mouse cells, plant cells, and yeast. Afterward, they killed the cells and retested to prove that the device could correctly distinguish between life and background signals. The nanosensor also performed well with soil and water samples containing microorganisms. Each experiment takes about 10 minutes.
While researchers need to do more testing, the nanomotion detector could be a breakthrough method for finding alien life. Its simple, fast, small, and needs no biochemical information. If we combine it with biochemical detectors, wed have an especially powerful way to look for life on places like Saturns moons.
1The Best Place To Look For Life
While largely ignoring the outer solar system, weve tied up a lot of capital, human or otherwise, in exploring Mars, with the hopes of finding alien life there. Its possible well find something on the Red Planet. But the icy moonssuch as Enceladus (Saturn), Europa (Jupiter), and Ganymede (Jupiter)in the outer part of our solar system may have the greatest chance of supporting life. Many of them have buried oceans. Currently there are five orbiters and two surface robots exploring Mars, said Corey Powell of Discover magazine. Here are the equivalent numbers for the four moons: Europa, 0. Ganymede, 0. Enceladus, 0. Titan, 0. We may have been looking for life in all the wrong places.
Part of the reason weve ignored the outer solar system in the past is the cost and time it takes to get there. We can fly to Mars in approximately eight months. But we may need six to seven years to get to Jupiter and Saturn, respectively. However, weve already sent the Cassini spacecraft to Saturn, while the Europa Clipper may be looking at a 2022 launch. The Hubble Space Telescope and the Galileo probe also gathered information from Ganymede and Enceladus.
At the moment, the best place to look for alien life seems to be Enceladus. In addition to liquid water under its icy surface, researchers have found evidence of active hydrothermal vents on the moons seafloor. Heat and water are important to life. In addition, its subsurface oceans appear to be in contact with the moons mantle, so the water is mixing with rich minerals like sulfur that could lead to life. The water is quite alkaline, with a pH of 11 or 12. However, life has formed in similar alkaline environments on Earth.