Fermi Paradox – The Apparent PuzzleThe Fermi Paradox is in search of the answer to the question of where the aliens are, given to understand that our stars and the Earth are part of a young planetary system when compared to the rest of the universe and interstellar travel could be quite easy to achieve.
The theory states that the Earth should have been visited by the aliens by now and if the universe is packed with aliens ... Where is everybody? Enrico Fermi, an Italian physicist, had first come out with the theory during his casual lunchtime remark in 1950 and the implication had extra-terrestrial researchers speculating on it since then.
The Search for Extra-terrestrial Intelligence had commented on its website that `Fermi had realized that any civilization with a modest amount of rocket technology and an immodest amount of imperial incentive could rapidly colonize the entire galaxy.
The Fermi paradox is the apparent puzzle between high estimates as in Drake equation of the probability of the existence of extra-terrestrial life civilizations as well as the lack of contact with or evidence for, such civilization. Points of debate made by physicists Enrico Fermi and Michael H Hart are –
- The Sun seems to be a typical star with billions of stars in the galaxy which are billions of years old
- With high probability, some of the stars tend to have Earth like planets and if the earth is typical, some could develop intelligent life
- Some of the civilization could develop interstellar travel, a step which the Earth is investigating
- Though at a slow pace of presently envisioned interstellar travel, the Milky Way galaxy could be totally crossed in about a million years.
Conflict Between Argument of Scale/ProbabilityAs per this line of thinking, the Earth could have already been visited by extraterrestrial space invaders though Fermi did not come across any convincing evidence of this nor any indications of alien intelligence anywhere in the observable universe, which lead him to ask, `Where is everybody?’ Fermi paradox is considered to be a conflict between arguments of scale and probability which tend to favour intelligent life being common in the universe when compared with a total lack of evidence of intelligent life that could have come up anywhere except the Earth.
First characteristic of the Fermi paradox is a function of the scale of the large numbers involved and there is an estimate of around 200 – 400 billion stars in the Milky Way with around 70 sextillion in the observable universe. Even though intelligent life occurs on only a minuscule percentage of planet surround these stars, there could still have been a great number of civilization existing in the Milky Way galaxy alone. This gave rise to the notion that Earth is purely a typical planet.
The other feature of the Fermi paradox is the debate of probability – given intelligent life’s capability in overcoming scarcity, with its tendency in colonizing new habitats. There could be a possibility that some civilization could be far advanced, technologically seeking out new resources in space as well as colonize their own star system and thereafter surround the star systems.
In the Absence of Definite Evidence – Battling with a ResolutionIn the absence of definite evidence on Earth or anywhere else in the known universe of other intelligent life after 13.8 billion years of history of the universe we are still battling with a resolution. Examples of possible resolutions are that intelligent life could be rarer than we had imagined and our assumptions on the general progress or behaviour of intelligent species could be faulty or radically that our present scientific understanding on the nature of the universe is fairly incomplete.
The Fermi paradox could be asked in two ways, first is `why are there no aliens or their artifacts found anywhere on Earth? If there could be a possibility of interstellar travel, even a slow kind almost with the reach of Earth technology, it would probably take from 5 million to 50 million years to colonize the galaxy. This is comparatively brief on a geological besides a cosmological one.
As there are thousands of star much older than the Sun, and since intelligent life could have evolved earlier anywhere, the question that comes up is `why the galaxy has not been colonized so far?’ Large scale exploration of the galaxy could have been possible through various means of exploration even if colonization was impractical or undesirable to the alien civilization.
The time for travel could provide an explanation on the lack of alien visits to Earth though adequately advanced civilization could possibly be observed over some important fraction of the size of the observable universe. The scale argument portrays the even if such civilizations are rare; they could have existed elsewhere at some point during the history of the universe.
Since they could be observed or noticed from far away over a long period of time, several more possible sites for their existence are within range of observation. However it is not clear if the paradox is strong for our galaxy or for the universe.