I was going to start this post with an Arthur C. Clarke quote but I found three I like:
The fact that we have not yet found the slightest evidence for life — much less intelligence — beyond this Earth does not surprise or disappoint me in the least. Our technology must still be laughably primitive, we may be like jungle savages listening for the throbbing of tom-toms while the ether around them carries more words per second than they could utter in a lifetime.
I’m sure the universe is full of intelligent life. It’s just been too intelligent to come here.
Two possibilities exist: Either we are alone in the Universe or we are not. Both are equally terrifying.
This question “Are we alone?” has been asked many times, and I’m sure that everyone has their own opinion on the subject. Some are based on religious beliefs, scientific evidence, gut feelings, or pure probability. In my opinion there are two branches of this search. One is the search for intelligent life. Life that can build and create things. The other is a search for any life. The main organization focusing on the search for intelligent life is SETI. SETI stands for the Search for Extraterrestrial Intelligence. Probably one of the more aptly named organizations in the world. The search for life is carried out by just about anyone with any interest in space (NASA, ESA, universities, amateur astronomers).
This is more of an opinion piece, but it is a subject that I spend a lot of time thinking about. The coolest thing about this search (other than the possibility of finding life on other planets) is that it involves just about every major field of science: astronomy, physics, chemistry, biology, climatology, geology, etc. The more we find out about life on earth the more possibilities open up for life elsewhere in the universe. After all, the universe is huge.
Let’s start with SETI. Many of us are aware of SETI’s work at some level. Carl Sagan, the poster child of Science!, had a big role to play in SETI. He wrote the book Contact and acted as a consultant for the movie. A lot of people think that scientists at SETI sit around all day with headphones on listing to space noise. This is not true. They have computers do the listening for them. You can actually lend your computer’s processing power to SETI with SETI@Home. It runs as a screen saver when you are not using your computer. They are not listening for specific messages either, and even if they did get a hit, we probably won’t be able to decode the message anyway due to the nature of the analysis; it basically destroys any incoming signal and averages it out over a small time frame. They are only looking for signs and patterns, not communication. The most probable source for a SETI hit is some kind of beacon. It could be a navigation beacon, or something put near the center of the galaxy to attract the attention on any intelligence. This is assuming that any intelligence in the galaxy would want to announce it presence. Other possible sources are Dyson spheres. There are a massive array of satellites that orbit a star, harnessing a large percentage of its energy. Only a very advanced civilization would be able to build one. These would give off a very unique signature that would allow for us to detect them.
There are two ways SETI is looking. There is Radio SETI (looking for radio waves) and Optical SETI (looking for optical communication, like high power lasers). And this brings us to the first major criticism of SETI, as seen in the first quote above. We have only been using radio for around 100 years. This is not a lot of time. Long ago radio was the bee’s knees. It was the fastest way to communicate. Now we have fiber-optic cables that go everywhere. Radio is no longer the most efficient way to communicate here on earth over long distances. Things like cell phones, local TV broadcasts, and Wi-Fi networks are still common for communications over short distances, but how much longer will that last? Radio is moving to the internet, more and more people are using cable. 126 million homes in the U.S. currently get some kind of cable service. Sure, satellites bounce the signals around, but they are very directional. The era of blasting TV into space is coming to a close.
People still listen to radio, but the way we broadcast and receive radio is changing with satellite radio. It’s tough to see the future of satellite radio, but if it becomes the norm our second largest source of radio waves being broadcast into space will slowly disappear. There will still be lots of radio use though. It is an effective way to communicate short distances (like between aircraft, solders in the field, cell phones) but it won’t have the same power as TV and radio broadcasts. The biggest use of radio today is in the form of radar. These blasts of electromagnetic waves have the potential of catching the eye of any passing aliens, but its power is greatly diminishes it travels further away (per the inverse square law)
The point is radio might be a brief blip in the development of communication technology. That is where optical SETI come in. You can focus a lot of energy in a laser, and it is very directional, which allows for privacy, after all, you don’t want people eavesdropping into your conversations. These will be hard to detect though, they will have to be pointed right at us. It’s worth a shot , and who knows, they might be aimed at us for a reason. Or any advanced civilization might be using a form of communication way beyond our ability to detect.
What else is there?
Let’s do a quick thought experiment. Let’s say that we are the first intelligent race in our galaxy to develop all this fancy technology and not destroy ourselves (or be destroyed by some massive cataclysm). We develop computers, and they get faster and faster until one day they are faster than our brains. There is a group of people out there who believe that there will be a merging of man and machine (that came out really cheesy). That the next step of evolution is to, in a way, become robots, or at least begin incorporating computers into ourselves. We are starting to do this today. With smart phones we have access to almost all of the internet 24/7. I think of my iPhone as an extension of myself. It is with me at all times. I am not alone in this way of thinking either. When I first realized this it scared me a little, but I quickly accepted it. For me it is easy to see the benefits of merging with computers. Instant access to an unlimited amount on knowledge. It will also make it easier to travel very long distances in space. Your computer doesn’t get lonely if you haven’t used it in a week, a thousand years can feel like a second to a computer. Humans can live around 70-80 years. How long can we survive as machines? Who knows. But we will be much less susceptible to the harsh conditions in space and we’ll probably care less about the effects of relativity. So lets assume that when a civilization reaches a certain point it will be more efficient for them to take the form of machines.
Now, as the first intelligent civilization to exist in the galaxy, what is there to stop us from exploring and colonizing everything in it? We are machines, so time and distances are no longer an issue. There are no other races (yet) to stop us. The Galaxy is ours. Let’s spread out, explore and multiply, kind of like a virus.
Even if we don’t merge with machines, they are still the most efficient way to explore. It is much easier for us to send a robot to Mars than to send a man. John von Neumann was one of the early 20th century’s greatest thinkers. He developed the idea of a self-replicating machine as a way to explore the galaxy. It would arrive somewhere, collect data, and reproduce itself using the natural resources around it, sending off more probes to other parts of the galaxy. If you add artificial intelligence to them, you now have a way to communicate (or creatively destroy) any intelligence you come in contact with.
I guess the question is (as put by Enrico Fermi) “Where is everyone?”
Well, I dunno.
In theory the universe should be swarming with these things. 13 billion years is plenty of time do do just about anything. Maybe they’ve come and gone a long time ago, passing off Earth as some stupid little backwater planet with a bunch of weird pinkish things blowing each other up. Or maybe we are truly alone as the only intelligent species in the galaxy (or universe?). Or any civilization that reaches a certain age (around the point where we are) destroyed themselves or suffer some giant cataclysm that wipes them out.
Another question is do we actually want to come in contact with aliens? We have absolutely no way of knowing what there motives are. We are working from a sample size of one right now: us. Stephen Hawking looked at the behavior of humans and applied that to any alien races we might encounter. He thinks that Earth would be pillaged for its resources, a theme explored in lots of science fiction (see ID4). It almost makes sense that any species that has survived long enough to develop intergalactic travel would be war-like.
Once again, we are only working with a sample size of one, but look at humans. We became the dominate species on this planet though violent means. In all likelihood, we killed off our nearest relatives, the Neanderthals. War was a means to control resources like food and water. If you kill your competition, the spoils are all yours. For now, we will assume that any life developing on other worlds will follow the same principles that shape its development here. Evolution, survival of the fittest. I believe that it would be safe to assume that any species that came to dominate its planet would carry on its bellicose tendencies into space as it expanded. This does not bode well for us. Also, knocking off a species on another planet before it developes the technology to destroy you is another way to ensure the success of your race.
But then again, where are they?
So maybe intelligent life is not a common thing. As far as we know it is unique to Earth. But what about other life? It doesn’t have to be complex, single cell organisms will suffice. This is where our search shows real promise. I firmly believe that we will have proof of life on other planets by the end of this decade. I should modify that to life in this solar system. Its the moons we should be looking at, and it is the moons that we are looking at.
I just spent the last 30 minutes trying to find the name of a bacteria I saw on a BBC program called “Wonders of the Solar System.” It is a really fantastic five part show hosted by Brian Cox, and in the last part he goes into a cave and shows us a single celled organism that breathes a toxic gas, and does not require oxygen to survive. They are called Snottite. Delicious. Let’s head to Wikipedia for a bit more information on these things:
The bacteria derive their energy from chemosynthesis of volcanic sulfur compounds including H2S and warm-water solution dripping down from above, producing sulfuric acid. Because of this, their waste products are highly acidic (approaching pH=0), with similar properties to battery acid.
I repeat, woah.
We (and as far as we know 99.99 percent of all life on this planet) need either the sun or oxygen to survive. And those using the sun produce oxygen. So oxygen is important. Plants breath in carbon dioxide (oxygen involved) and exhale oxygen. We breath in the oxygen and exhale carbon dioxide. Oxygen everywhere. Nowhere do these bacteria use or produce oxygen. The idea that life can survive without oxygen is important to finding life on other worlds, and this discovery is proof that life can do that. Want more?
How about this: a multicellular organism that does not require oxygen to survive. Just discovered:
Electronmicroscopy shows that instead of aerobic mitochondria, these animals possess organelles resembling the hydrogenosomes found previously in unicellular organisms (protozoans) that inhabit anaerobic environments.
Translation: they don’t need oxygen. This is huge. This is undoing what I learned in middle school biology. Screw oxygen, life can do without it.
Let’s look at three worlds where we might find life: Mars, Titan, and Enceladus. Three very different worlds. Mars is a giant desert with frozen carbon dioxide ice caps, Titan is a cold world with a thick methane atmosphere, and Enceladus is a frozen iceball. But they are all alive.
Enceladus is a small frozen iceball orbiting Saturn. For a long time we thought it was solid. Then we sent the Cassini-Huygens mission to Saturn. Huygens we will get to later, but Cassini has been orbiting Saturn since 2004, and it seems that with every picture it sends back a new discovery is made. We have known since the 80s that the surface of Enceladus is not marred with crates, like every other “dead” world is, like our own moon. Even stranger, it has large gashes in its surface. Perhaps signs that it is being stretched and pulled by the gravity of Saturn. One day, Cassini was doing a flyby of Enceladus when it saw this:
Those are geysers. As Saturn tugs on Enceladus, it heats it up, creating pockets of liquid water. Water is a key ingredient of life. Cassini did another flyby of Enceladus and found something else. Ammonia. From a NASA press release:
On Earth, the presence of ammonia means the potential for sparkling clean floors and counter tops. In space, the presence of ammonia provides strong evidence for the existence of at least some liquid water…
…”Where liquid water and organics exist, is there life?” asked Jonathan Lunine a Cassini scientist from the University of Arizona, Tucson. “Such is the case for Earth; what was found on Enceladus bolsters this moon’s promise for containing potential habitable environments.”
How is that for potential.
My favorite moon is Titan. It has an atmosphere. It also has weather. It rains there. It has lakes and oceans and rivers. They are not made up of water though; they are hydrocarbons: methane and ethane. These two chemicals are the water of Titan. Nitrogen makes up most of Titans atmosphere, much like Earth’s. It is here on Titan where the exciting possible discovery of life-without-oxygen come in. We have seen that life can survive harsh conditions here on Earth. Titan is an organically rich planet. I find it much harder to believe that there is no life in Titan than to believe that there is life there.
Want to see a cool video? How about one where the Huygens probe lands on Titan:
Notice the landscape when it lands, how oddly Earth like it is. The smooth rounded stones are a sign of weathering. It looks like it landed in a riverbed. And it probably did. No one is expecting to find little critters running around, but I don’t think many scientists will be surprised to find microbes and bacteria there.
And finally we have Mars. Mars was once very alive (not necessarily in the biological sense). It had valleys and canyons carved by flowing water. Chemical analysis of its soil shows evidence of water on the surface of mars in its past. Take a trip there through Google Mars and see how the landscapes look a lot like the American southwest.
But what about Mars today? There has been evidence of liquid water recently. Check this out . It is a video explaining how recent impacts on mats have reveled water on Mars. It is ice, but it is water. And there might be liquid water too. Look at this picture taken by HiRISE:
Those gullies are very, very similar to ones found in deserts on Earth. The water flows down and gets absorbed by the ground before it reaches the bottom. These guys think that is exactly what is happening in this image. And like I said earlier, water is a key ingredient for life.
We are lucky. Next year we are sending a new probe to Mars. It’s called the Mars Science Laboratory. Its goal:
The first step in understanding the possibility of past or present life on Mars is to determine whether the red planet ever had environmental conditions able to support life. Now that NASA’s two Mars Exploration Rovers, Spirit and Opportunity, have found compelling evidence that liquid water once persisted on the surface of Mars, scientists hope to determine if other things necessary for life were also present. With a single rover bigger than both the Viking landers sent to Mars in the 1970s, Mars Science Laboratory will look for chemical elements that are the building blocks of life. These building blocks include six elements necessary to all life on Earth: carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur.
Be excited. We might once and for all get the proof that there is (or was) life on Mars, and that is HUGE.
We are very close to finding very solid evidence of life outside earth, be it on the moons of Saturn or on a planet far away. With the new Allen Telescope Array dedicated to this search, we might have proof of intelligence in the next decade. Personally I don’t care what we find, any life would be amazing. Life on mars or Titan would be the most important discovery of the last century. If SETI got a hit, that could be the most important discovery in the history of mankind. To find out that we are not alone.
Confessions of an Alien Hunter by Seth Shostak
Death from the Skies by Phil Plait (he has a chapter on alien invasions)