Are We Alone?


While SETI deals with searching for messages from aliens, the alternative scheme is the attempt to send messages to intelligent extraterrestrial life in the form of radio signals. Messaging to Extra-Terrestrial Intelligence or METI (sometimes called Active SETI), is a term was coined by Russian scientist Alexander Zaitsev. In his paper “Rationale for METI”, Zaitsev argues that transmission of the information into the Cosmos is one of the pressing needs of an advanced civilization. This view is, of course, not universally accepted, and it does not agree with many who believe that the act of transmitting interstellar radio messages is imprudent.In a new documentary series made for the Discovery Channel, Stephen Hawking has said: “we should have been wary of answering back, until we have evolved” further. On encountering a more advanced civilization, Hawking says “might be a bit like the original inhabitants of America meeting Columbus. I don’t think they were better off for it.”

David Brin, the famous Sci-Fi Author who helped develop the original SETI protocols has warned of the implications of METI: “Let there be no mistake. METI is a very different thing than passively sifting for signals from the outer space. Carl Sagan, one of the greatest SETI supporters and a deep believer in the notion of altruistic alien civilizations, called such a move deeply unwise and immature.”

Figure 14-1: The gold plaque placed upon Pioneer 10, the first human artifact to be launched on a trajectory out of the solar system. Image Credit: NASA

That view is not shared by many people, notably by NASA. A few years ago, in 2008, NASA beamed the Beatles’ song “Across the Universe” towards the vicinity of Polaris, in the hope that an alien civilization would intercept the transmission. Broadcasted over NASA’s Deep Space Network, the event commemorated the 40th anniversary of the day The Beatles recorded the song, as well as the 50th anniversary of NASA’s founding and the group’s beginnings.

The Pioneer 10 spacecraft, the first man-made object to escape our solar system, carried a plaque containing a message (Figure 14-1) for inhabitants of some advanced civilization, who might intercept the spacecraft millions of years after the spacecraft was launched. The message, devised by Carl Sagan and Jon Lomberg, was intended to communicate the location of the human race, the appearance of an adult male and female of our species, and the approximate era when the probe was launched. A line-drawing of a couple standing in front of the Pioneer probe is accompanied by an ingenious scheme for conveying distance, direction, and time information about the spacecraft’s origins.

Even before this, on November 16, 1974, the first message was beamed into space by SETI researchers at the Arecibo radio telescope in Arecibo, Puerto Rico. The Arecibo message was sent toward the star cluster, Messier 13, in the Hercules constellation, which is situated 25,000 light years away from the Earth. The three minute binary transmission consisting of roughly 210 bytes was composed by Frank Drake, Carl Sagan, and other scientists. It was transmitted using frequency modulated radio waves.

Figure 14-2: A representation of the 1679-bit Arecibo message.

The Arecibo message consisted of (1) the numbers one to ten (2) the atomic numbers of the elements that form deoxyribonucleic acid (DNA) (3) the formulas for the sugars and bases in the nucleotides of DNA (4) the number of nucleotides in DNA, and the double helix structure (5) a human figure, the physical dimensions of an average man, and the human population of Earth (6) a representation of the Solar System (7) a graphic of the Arecibo radio telescope and the dimension (the physical diameter) of the transmitting antenna dish.

The Arecibo Message will undoubtedly be seriously degraded by its interaction with cosmic dust in the interstellar medium on its 25,000-year-long journey. The loss of even a few bits of information would render the signal undecipherable.

Following the Arecibo transmission, a debate began (which continues to this day) on the wisdom of attempting Communication with ExtraTerrestrial Intelligence (CETI). The US diplomat Michael Michaud suggested that the Message had consequences that went beyond science into the realm of politics and proposed a public discussion of the possible benefits and risks of establishing contact. Sir Martin Ryle, the British Nobel Prize Laureate who developed revolutionary radio telescope systems and used them for accurate location of weak radio sources, argued that “any creatures out there [may be] malevolent or hungry.” He requested that the International Astronomical Union approve a resolution condemning such attempts at CETI.

In a letter to Sir Ryle, SETI pioneer Frank Drake pointed out that:

“It’s too late to worry about giving ourselves away. The deed is done. And repeated daily with every television transmission, every military radar signal, every spacecraft command[2] … I think that hostile tribes bent on war, be they terrestrial or extraterrestrial, destroy themselves with their own weapons, before they have any notion of how to attempt interstellar travel.”

All of this did not deter others from attempting to send messages to intelligent extraterrestrial life. Subsequent transmittals had built-in redundancy so that a recipient should be able to reconstruct the message in spite of bit loss due to noise. Some of them had contents based on mathematics and physics. The rationale behind that is, any civilization capable of building a device to receive radio waves from outer space needs to know mathematics and physics to accomplish that task. A list of projects involving messaging to extraterrestrial intelligence can be found in the Wikipedia article entitled “Active SETI.”

Interestingly, METI is a scientific effort that has always attracted wide popular curiosity. A high-powered digital radio signal called “Message from Earth” (AMFE) was sent on 9 October 2008 towards the Earth-like extrasolar planet, Gliese 581 c, orbiting a red dwarf star, Gliese 581, just 28 light years away from us. The signal contained 501 messages selected from a competition on the social networking site Bebo. The message was broadcast using the RT-70 radar telescope of Ukraine’s National Space Agency. The signal will reach the planet Gliese 581 c in early 2029. More than half a million people including celebrities and politicians participated in the AMFE project, which was the world’s first digital time capsule where the content was selected by the public.

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