Difference between SETI and METI ( Subject: Astronomy )

It can be considered as the biggest question or an enigma in the scientific world regarding whether life exists on any other planets in the universe or any other milky way or billions of galaxies. There are two strategies that have been implemented within the scientific world are SETI and active SETI or METI. SETI is the acronym of Search for Extraterrestrial Intelligence that solely concentrates on detailed monitoring of electromagnetic radiation that is being transmitted by the aliens from any other planets. The members are segregated between groups where one group is engaged in radio signals and other group relayed that the aliens who live in other planets applies powerful lasers that has optical wave length to generate communication. As referred by the renowned particle physicist, Richard Carrigan, the communication in the form of radio signal can be lethal as they might be in the form of powerful computer virus that can destroy the entire internet system. The specific two issues of optical SETI are that lasers are generally in the form of high monochromatic, hence there is a single frequency which creates an issue on which range of frequency to look after. The other one is that lasers are single-directional as compared to the multi-directional radio broadcast. Therefore the emission of laser can be conveniently forming a wall by the clouds or the axis of the earth might be in the same line.

There is another way to detect the presence of aliens with the help of Active SETI or METI (Messaging to Extraterrestrial Intelligence) by sending radio signals in the universe that might be received by the aliens. Even in the year 1974, there was a broadcast from the Arecibo observatory to 25,000 light-years Globular Cluster. Several actions were further taken in the year 1999, 2001, 2003 and 2008. As published in the journal named Nature, METI was brought into attention in the year 2006. It was concluded that even a benevolent alien civilisation is considered to be lethal and lead to extreme conditions to the earth (Cosmos, 2017).