I have been involved in the Seti@home program since 1999: so far without any results. For those who have no idea what SETI is: it is an acronym for the Search for Extra-Terrestrial Intelligence and SETI@home (“SETI at home”) is a grid computing (distributed computing in the project’s own terminology) project using Internet-connected computers, hosted by the Space Sciences Laboratory, at the University of California, Berkeley, in the United States. The purpose of SETI@home is to analyze data incoming from the Arecibo radio telescope (located in Puerto Rico), searching for possible evidence of radio transmissions from extraterrestrial intelligence. Or, as some have condensed the story: we are looking for ET trying to “phone home”.
Although the project is running for years now and the amount of computer-analyzed data is humongous (1,2 million data packets a day, some thousands of years of computing time already) not a ‘bleep’ has been received. So the big question is: “Where is ET”?
A very interesting question indeed.
Obviously I am not the first person to ask that question. In fact a well-known atomic scientist called Enrico Fermi, asked the same question one day, back in the 1940’s. And it is this simple question has sparked a lot of – very intriguing – debate.
The story goes that a group of atomic scientists (from the Oppenheimer team), including Enrico Fermi, were sitting around one night, looking at the stars and talking, when the subject turned to extraterrestrial life. Fermi believed that aliens must have had more than enough time to pepper the Galaxy with their presence. But looking around, he didn’t see any clear indication that they’re out and about.
Fermi is supposed to have then asked, “So? Where is everybody?” Now, what he meant was: “ok, If there – supposedly – are all these billions of planets in the universe that are capable of supporting life, and millions of intelligent species out there, then how come none has visited earth or left any evidence they did?”
This simple question has come to be known as ‘The Fermi Paradox’.
The age of the universe and the vast number of stars in our galaxy alone suggest that extraterrestrial life should not be rare — a notion later supported by many estimates based on the so-called ‘Drake equation’. So why haven’t we seen any evidence, such as probes, spacecraft or radio transmissions? The paradox can be stated as follows:
The belief that the universe contains many technologically advanced civilizations, combined with our lack of observational evidence to support that view, is inconsistent. Either this assumption is incorrect (and technologically advanced intelligent life is much rarer than we believe), our current observations are incomplete (and we simply have not detected them yet), or our search methodologies are flawed (we are not searching for the correct indicators).
Those who believe that the lack of such overt evidence is a conclusive argument for the non-existence of technologically advanced extraterrestrial civilization within communication distance of earth, refer to this lack of evidence as ‘the Fermi principle’.
Now, logically speaking, the fact that aliens don’t seem to be walking our planet, apparently implies that there are no extraterrestrials anywhere in the vast tracts of the Galaxy. Right? Seeing is believing.
Well, maybe not: many well-known researchers consider this to be a bit too radical conclusion to draw from such a simple observation. I mean: if you look for water in the desert, at first you might not find it. But even in the desert you can find water if you know how to find it and what to look for.
So, if this is the case, then surely there is another straightforward explanation for the Fermi Paradox. There must be some way to account for our apparent loneliness in a galaxy that we assume is filled with other clever beings?
Despite the belief by many that the existence of an alien technological civilization is not impossible, as of 2006 there (still) has been no unambiguous evidence of intelligent extraterrestrial life. While many believe this is a vindication of the idea that we are alone in our galaxy (if not the universe) many theoreticians have proposed alternate explanations as to why the skies appear to be silent.
Possible solutions to Fermi’s Paradox fall in the following categories:
They Are Here:
They were here and they left evidence + UFO’s, Ancient Astronauts, Alien Artifacts: all fall under the heading of proposals that aliens are here now (and they call themselves Republicans) or have been here in the recent past. Problem: evidence for aliens (so far) is non-existent.
They Are Us:
Humans are the descendents of ancient alien civilizations. Problem: where are the original aliens? Where are all the other alien civilizations?
Zoo/Interdict Scenario:
The aliens are here, and they are keeping us in a well-designed zoo (cut off from all contact) or there is an interdiction treaty to prevent contact with young races (us). Problem: scenario lacks the ability to be tested. Takes only one ET to break embargo.
They Exist But Have Not Yet Communicated
They Have Not Had Time To Reach Us:
Speed of light slows communication levels, relativity makes space travel long. ET’s message may not have reached us yet. Problem: Galaxy has been around for billions of years, even if one ET civilization formed a few million years before us, the Galaxy would be filled with Bracewell-von Neumann probes.
They Are Signaling, But We Do Not Know How To Listen:
EM radiation, gravity waves, exotic particles are all examples of methods to signal. Problem: they may use methods we have not learned yet, but if there are many civilizations someone would use EM methods.
Berserkers:
The Galaxy is filled with killer robots looking for signals. ET is keeping low. Problem: where are the berserkers coming after us?
They Have No Desire To Communicate:
ET has no interest in conversing with lesser beings. Problem: with millions of possible civilizations, someone would have some curiosity.
They Develop Different Mathematics:
Mathematics is the universal language. But humankind may have a unique system of mathematics that ET cannot understand. Problem: then where are their incomprehensible signals?
Catastrophes:
Civilizations only have a limited lifetime, They are all dead.
They Do Not Exist:
We are the First; Life is New to the Galaxy. Life is new to the Galaxy, evolution takes time, and we are the first civilization. Problem: the Sun is an average star, if other stars formed a million years ahead of us, then they would/should be a million years ahead of us in technology.
Planets With the Right Conditions are Rare:
Planetary systems are rare. Habitable zones, proper distance from star for liquid water, are narrow Galaxy is a dangerous place (gamma-ray bursters, asteroid impacts, etc) Earth/Moon system is unique (large tides needed for molecular evolution).
Life Is Rare:
Life’s Genesis is rare. Intelligence/Tool-Making is rare. Language is unique to humans. Technology/Science is not inevitable.
And there are many, many more explanations.
But how do we know which one is the right explanation? To me it seems that a lot of the debate about ET existing or not has to do with our current human limitations. Either we do not accept the idea or other intelligent life out there (mostly religious groups) or we just do not know what to look for (scientific explanations).
All I can I tend to believe that there is intelligent life out there. We just not have encountered it. Funny thing is that my “belief” is based on what I consider more or less scientific assumptions whereas religious groups just base their opinion solely on “belief” based on the bible. But in all honesty: why would my belief be more true then theirs?
All I can conclude – so far – is, that absence of evidence isn’t evidence of absence.