Exobiology
Of all mysteries of the universe, the possibility of meeting other intelligent species must be the most provocative. It would be the greatest achievement in the History of humankind to contact other intelligent species. Unfortunately, as I debate below, I don't know whether we would survive.
Galactic Civilizations
Geological time is in the order of millions of years. Life, which depends on the chemistry and conditions of a planet, also follows such large cosmological scales. Thus other intelligent species in the universe are not likely to be in the Bronze Age or in any age that happened to us in the last thousands of years. Possibly, if they are less intelligent than us, they would still be animals. But if we are to face a more advanced civilization they will be millions of years ahead of us because, by chance, they originated millions of years before.
At a cosmological time scale, energy manipulation is a good method to classify a civilization. Nikolai Kardashev and Freeman Dyson developed the following classification for alien civilizations:
| Type | Level of Energy Control |
| I | Absolute control over a planet's energy. |
| II | Domination of stellar energy (e.g., Dyson's sphere). |
| III | Galactic civilization where several stars are controlled. |
| IV | Space-time manipulation (something we don't understand very well yet, as discussed elsewhere). |
A type IV civilization is almost a God and we are mere dust to them. A type III civilization will likely try to conquer an inferior species like us, because they are a spacefaring society likely dedicated to conquest. The other civilizations probably won't have the power to attack us but neither will we be able to attach them in a near future. Cooperation among us might be a possibility, though eventually one civilization would prevail through science or warfare.
Alien civilizations will have nuclear power and therefore the power to exterminate themselves. Why didn't they solve their problems with the element 92 is one of the most important questions to ask, which is similar to the question Ellie, the main character in Carl Sagan's Contact, would ask an alien if she was only allowed one question. Perhaps some aliens have a genetic structure such as ants in which a queen controls everyone. The most likely answer is what I think will happen to humankind: one or a few entities -- either human, computer or hybrid -- will gain control over humankind, as I discuss elsewhere. I think this is inevitable for our civilization and our only hope is that a few humans escape to other planets carrying the seeds of freedom. Possibly, alien civilizations also have to suppress individual freedom to a large extent. Anyway, advanced alien civilizations must have their individuals united if they are to survive, and that is why I don't think humans would be able to cooperate with alien civilizations in the long term.
Are Aliens Around Us?
Probably the single most important evidence of extraterrestrial intelligent life is the "Wow!" Signal. Without going through much details, the signal's origin was at least lunar distance, it had an intelligent origin, no known satellites where in the position where the signal was detected, the frequency used was forbidden by international agreements, and the signal was coming from no particular star system or planet. It could have been a secret satellite but, if so, why would it send a signal? It could always be some unknown natural phenomenon. For example, in 1967 Jocelyn Bell, working at Cambridge University, detected signals that strongly indicated the presence of extraterrestrial life; unfortunately, it was later proven that these signals had a natural origin, a celestial entity called a pulsar. Today, the "Wow!" Signal is one of the few signs of extraterrestrial intelligent life.
Not having other intelligent civilizations contact us is a good proof that they don't exist, the so-called "Great Silence." Briefly, if there were ancient intelligent civilizations in our galaxy they would have reached us by now or at least made their presence felt. Perhaps the emergence of intelligent life is harder than we think. On the other hand, we don't know how other civilizations think and they might not want to interfere with us on purpose.
Many claim to have established contact with aliens and ETs, as popularized in science fiction like the X-Files. UFO sightings have also been widely reported, particularly in the United States, some of which by credible witnesses. On the other hand, many claim to have been contacted by God, which as an atheist I find impossible.
We must keep an open mind, though. Not far into the past people thought meteors where impossible to occur and those who claimed to have seen them where labeled as idiots. I do think aliens exist. I think it's possible for them to come here. But I don't think it's likely they would just abduct people and perform tests without being detected.
"I think that it is much more likely that the reports of flying saucers are the results of the known irrational characteristics of terrestrial intelligence than of the unknown rational efforts of extra-terrestrial intelligence." — Richard Feynman
Sources and Links
Bizony, Piers; "The Rivers of Mars: Searching for the Cosmic Origins of Life" (1997).
Brookesmith, Peter; "The Complete Sightings" (1995).
Caidin, Martin; "Ghosts of the Air" (1991). Excellent book.
Sagan, Carl.; "Contact" (1997). It doesn't feature Jodie Foster but it's nice.
Malta UFO Research; excellent site.
The Alien Jigsaw; mainly dedicated to alien abductions.
The Great Filter; interesting.
UFO Documents; at the NSA.