Thursday, January 21, 2010

Search for ET Intelligence

In 19th century, it was mythologies and science fiction writer's brilliant thinking which were running the field of Cosmology. There was only speculations and lots of conflicting theories running around, the genuine data in hand was very less. As a result of cold war, we had a great period of cosmic exploration. Now we do have some data in hand, we do know some secrets of the universe. We know our place within this enormous void. New findings and theories are getting written and rewritten every day; still the ink is wet on the pages.

In the first half of 20th century, our knowledge about the cosmology was very limited, which also limited our Search for Extra Terrestrial Intelligence to be with in our solar system. The twin voyager spacecrafts sent to deep space also carried invitations for aliens to visit earth. Each of those spacecrafts carried a 'Golden Record' with greetings in 54 different human languages and images of life on earth encoded in analogue form. On the other side of the record, the location of earth in our solar system and its place in the milky way galaxy were printed as a line drawing. The probes are not targeting any star system, They are just traveling on their way in the deep space. As the probes are extremely small compared to the vastness of interstellar space, it is unlikely that they will ever be accidentally encountered by any intelligent being. But still if they are encountered by any beings, it will act as a time capsule or a message to the alien species or may be to the future humans.

In those days Mars and the Moon were the most popular candidates for hosting the alien life. After the human landing on moon, scientists thought the planet Mars might be a good candidate to host life. Using the telescopes in earth some even thought they found huge canal system stretching across the planet Mars; But probes sent to Mars have failed to detect even bacteria-like creatures. Now it seems that we have to go beyond the solar system to find the first planet which hosts life other than earth.

In mid of 20th Century, The Milky way galaxy, stretching across millions of light years was considered as the whole universe. But this thought was changed over a night. In 1990 when the Hubble space telescope took a baby picture of the Universe and calculated the distance between the stars and galaxies. Over a night the Universe expanded from millions of light years to trillions of light years with billions of galaxies. Now the best hope for intelligent life seems to be across the void of interstellar space in other parts of our galaxy. If there is intelligent life in places other than earth, where might they be? If they are so far, how do we reach them with our current technology? We need to travel at-least at the speed of light to find them in this enormous immensity. But traveling at the speed of light seems to be impossible with our current technology. Then how do we reach them?

We may not be able to visit their places but we can communicate with them using our current technology at the speed of light. If those intelligent life forms out there are technologically advanced and aware of radio signals, then we can communicate with them using the radio waves. The radio waves are much faster; they travel at the speed of light, we can also reach or search them at the speed of light. We can send messages to them and let them know that they are not alone. On 16 November 1974, A message was beamed into space  via frequency modulated radio waves. It was aimed at the globular star cluster M13 which is around 25,000 light years away. It will take 25,000 years for the message to reach its intended destination of stars and an additional 25,000 years for any reply. But the fact is, in 25000 years time, those star cluster will no longer be in the same location, the message will not reach its intended destination. But it was more like a demonstration of human technological achievement than a real attempt to enter into a conversation with extraterrestrials.

Knowingly and unknowingly we have been sending signal into the void for decades, every broadcast of this planet, every FM radio waves, every television transmission goes out into the infinite space. The radio signal from earth will take 4.5 years to reach the nearest star and it will take only 100 years to reach the second nearest star. Some of our early transmissions might be getting closer to them by now if they are there and listening.

In that case then what about the reverse? Could alien civilization be sending signals into the void for thousands or millions of years? We should be able to received them by now. This thought gave raise to SETI (Search for Extra Terrestrial Intelligence) program. The United States government contributed to earlier SETI projects, but recent work has been primarily funded by private sources. Now scientist are listening the radio waves from space using some advanced radio antennas. SETI has conducted a number of programs on trying to use radio waves to detect the existence of other civilizations. One by one SETI is listening to every star in sight. So far no SETI program has been successful in finding intelligent life. But Absence of evidence is not evidence of absence. There are millions of stars in our galaxy alone some might have planets that could harbor life. There is no great achievement that is not the result of patient working and waiting. One day we may receive a Hi! signal from them.

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