Messages from extraterrestrial intelligence

The search for extraterrestrial intelligence (SETI) is a collective term for scientific searches for intelligent extraterrestrial life, for example, monitoring electromagnetic radiation for signs of transmissions from civilizations on other worlds.

There are great challenges in searching the universe for signs of intelligent life, including their identification and interpretation. As various SETI projects have progressed, their claims have been criticized by some researchers as being too "euphoric".

Scientific investigation of the potential phenomenon began shortly after the advent of radio in the early 1900s. Focused international efforts to answer a variety of scientific questions have been going on since the 1980s. In 2015, Stephen Hawking and Russian billionaire Yuri Milner announced a well-funded effort, called the Breakthrough Initiatives to expand efforts to search for extraterrestrial life.

There have been many earlier searches for extraterrestrial intelligence within the Solar System. In 1896, Nikola Tesla suggested that an extreme version of his wireless electrical transmission system could be used to contact beings on Mars. In 1899, while conducting experiments at his Colorado Springs experimental station, he thought he had detected a signal from that planet since an odd repetitive static signal seemed to cut off when Mars set in the night sky. Analysis of Tesla's research has ranged from suggestions that Tesla detected nothing, he simply misunderstood the new technology he was working with, to claims that Tesla may have been observing signals from Marconi's European radio experiments and even that he could have picked up naturally occurring Jovian plasma torus signals. In the early 1900s, Guglielmo Marconi, Lord Kelvin and David Peck Todd also stated their belief that radio could be used to contact Martians, with Marconi stating that his stations had also picked up potential Martian signals.

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