Do you remember the humid summer months when you would sit outside with your friends, a cool beer nestled against your palm, the youth of adolescence planting a rosy restlessness within yourself? A restlessness that called out for adventure, for thrill, for excitement? And remember that one frozen moment in time when you would look skywards, at the millions of twinkling galaxies, and sigh, wondering how it would be if you could talk to another sentient being from somewhere out there? Well, do you? I do. As did Carl Sagan. Or Frank Drake, for that matter. A bunch of mad hatters chasing the galactic goose, some may say, but you and I know better, don't we? After all, the 'elusive dream' of touching first base with beings from another space has always tickled our fancy. So where are we now? Are we looking for aliens or are we waiting for them to find us? If we are looking for them, then how are we going about it? The answers, my friend, are floating on the web. First Things First While mankind has forever been fascinated by space and the possibility of life therein, the progress in this area of scientific research had been remarkably slow for a long time; the prime reasons being a severe lack of disciplined technological development in astronomical sciences so far as search for extraterrestrial life was concerned, and the problem of discouraging mathematics. The real push in the right direction, even if only arguably so, came only in the late fifties, with the start of Project Ozma at the National Radio Astronomy Observatory in Green Bank, West Virginia, in 1959. Organized by Frank Drake, the project involved observing and trying to intercept possible radio signals from two nearby stars, Epsilon Eridani and Tau Ceti. However, the results were not very encouraging, though not entirely unexpected―the possibility of finding intelligent life on another distant planet is probably less than one in a million. The Background Before we move on, we must first understand the technicalities involved in the search for extra terrestrial intelligence. The first and foremost problem is to identify solar systems where life is possible, in whatever form it may be. Sadly, in spite of the tremendous rate of growth in the past couple of centuries towards understanding the sciences, a lot still remains to be deciphered. For example, one important question is if life can evolve only in an oxygen-breathing, water-drinking atmosphere. Could we have a culture that breathes nitrogen, or better still, that does not need to respire at all? We do not know. Another problem has been the mode of communication. What would be the cheapest and fastest way of transporting messages back and forth? The scientists on our planet have crystallized on radio waves―it forms a relatively cheaper mode of communication, and radio waves travel at the speed of light, the fastest speed that can be achieved if we are to listen to Albert Einstein. The third problem is the most fundamental one, aptly titled the Fermi Paradox. The paradox puts forth a very simple question―our galaxy consists of roughly a few hundred thousand stars, and even if a very small fraction of these stars have planets with technologically developed civilizations, then why have we not been visited so far? The paradox argues that If any of these civilizations produce cultures which colonize over interstellar distances, even at a small fraction of the speed of light, the galaxy should have been completely colonized in no more than a few million years. So, with the age of the galaxy being more than a billion years, Earth should ideally have been visited and colonized long ago, even before the development of life on the planet. Therefore, is it not likely that Earth is unique so far as life systems are concerned? However, scientific quests cannot be bound by doubts and paradoxes. While there have been arguments and counterarguments, some of the more hopeful scientists have been working silently on the project, basing their search on some core assumptions. These assumptions include: • There is the possibility of life evolving elsewhere. • Such life forms are biologically similar to us, that is, their basic building blocks consist of amino acids, just like us. • There have been adequate technological developments in these civilizations to be able to communicate with us. Based on these and similar assumptions, as early as in 1961, Dr. Frank Drake had conceived an approach to bind the terms involved in estimating the number of technological civilizations that may exist in our galaxy. The equation proposed by him, which came to be known as the Drake Equation, is represented as N = R* • fp • ne • fl • fi • fc • L, where N = The number of civilizations in the Milky Way whose electromagnetic emissions are detectable. R* = The rate of formation of stars suitable for the development of intelligent life. fp = The fraction of those stars with planetary systems. ne = The number of planets per solar system, with an environment suitable for life. fl = The fraction of suitable planets on which life actually appears. fi = The fraction of life-bearing planets on which intelligent life emerges. fc = The fraction of civilizations that develop a technology that releases detectable signs of their existence into space. L = The length of time such civilizations release detectable signals into space. While the equation is largely dependent on estimates, it does, at the very least, provide a rational approach towards determining the probability of life elsewhere. The Search The first real, organized step in the search for extraterrestrial life began with a project titled SETI (Search for Extra Terrestrial Intelligence) under the guidance of Professor Carl Sagan of Cornell University. The project envisages detecting radio signals from outer space, segregating possible 'messages' from cosmic interference, and decoding such messages to identify their origin and purport. For this purpose, the giant radio telescope at the Arecibo Observatory in Puerto Rico is routinely monitoring radio signals from outer space, which are then fed into a computing network to identify possible intelligent 'messages'. Also, during a ceremony to inaugurate a major upgrade to the Arecibo radio telescope, Frank Drake, then director of the center which operates the telescope, arranged to have a cryptic message of binary bits transmitted in the direction of M13, the Great Cluster in Hercules, using the telescope's half-million-watt radar transmitter, at a frequency of 2388 MHz, corresponding to a wavelength of 12.6 cm. The focusing of the transmission by the 305-meter antenna resulted in a beam with an effective radiated power of about 2×1012 watts―brighter than the Sun at that frequency. Traveling at the speed of light, it will take 22,800 years for the message to reach the approximately 300,000 stars in M13, so if there are intelligent aliens living on planets of those stars, and by some fluke chance they are tuned into the right frequency at the right time, and if they choose to reply, we can expect a reply in 45,000 years! Sounds disappointing? Perhaps, but one must keep in mind the enormous distances involved. Also, who says that the ones who are to receive our message haven't already transmitted theirs some 22,800 years back, meaning that we might just receive the message tomorrow at Arecibo? The distances are huge, but the possibilities are infinite. And SETI is constantly monitoring the skies keeping in mind just those infinite number of possibilities. One major problem which the SETI team faces is the computing time. With 'n' number of cosmic radio signals constantly bombarding the Earth, even the fastest supercomputers would be hard-pressed to decode and segregate the data in real time. However, the SETI team has found a way around this problem with the SETI@home project―they distribute the free SETI@Home screensaver from their website http://setiathome.berkley.edu, which, once installed, routinely downloads packets of information from the central server and analyzes them. Thousands of personal computers are linked in this way to the project, and with more and more people registering every day, and the computing speed is tremendously enhanced. Also, in the erstwhile Soviet Union, a state commission had been established which was devoted to organizing a search for extraterrestrial intelligence. The large, 600-meter diameter "RATAN-600" radio telescope in the Caucasus was also developed to be devoted part-time to this effort. The Final Word As with many technological research efforts, the one question that is forever being asked about the search is why. Why waste so much money, manpower, and energy on what might turn out to be just a wild goose chase? The answer to that is perhaps the answer that a famous mountaineer offered on being asked as to why he had chosen to climb Mount Everest― "Because it is there". Yes, the primary objective behind any scientific query remains exactly that―to seek an answer, because the answer is there. We may not be able to locate another sentient being in the next five thousand years, or we may just intercept a message tomorrow, who knows? If we succeed in the search, would the knowledge that we are not alone in the universe not be enough reward? And if we fail, would it not make us view our little planet with greater respect because it is unique? The reward lies in the effort, whichever way the balance might tilt―that is the greatness of this scientific venture. As professor Sagan said of the Search: "In the deepest sense the search for extraterrestrial intelligence is a search for ourselves".