THE SEARCH FOR EXTRATERRESTRIAL INTELLIGENCE

Posted by admin_akashic on Jun 27th, 2022 in Space

X-ray astronomy

This branch of astronomy began in 1949 when it was discovered that the Sun emits X-rays. X-ray and Gamma-ray techniques facilitated observations of neutron stars and even the vicinity of black holes. In December 1970, NASA’s Explorer 42, Uhuru, was launched off the coast of Kenya. This small satellite had on board two X-ray detectors which for the next three years scanned the entire sky as it orbited the Earth, revealing countless X-ray sources, some associated with our galaxy, and others with different galaxies. One advantage of the Uhuru satellite was that individual objects could be observed over extended intervals of time. This enabled accurate identification of the optical source responsible for the X-rays. Furthermore, it enabled identification of star masses, sizes and densities, providing evidence regarding their past and future histories. In 1978 NASA’s Einstein satellite was launched, carrying an X-ray telescope, thus initiating the era of X-ray astronomy, providing fresh information about quasars, neutron stars and black holes.

Other forms of radio communication

For many SETI scientists sending physical objects to the stars is regarded as too costly in time and energy. For them the best option for contact is by means of electromagnetic communication. The most popular current option for communication with an ETI is by means of low frequency radio waves, which travel at the speed of light and are easy to transmit and receive. The idea of radio communication with ETI gripped two of the early pioneers of radio, Nikola Tesla and Guglielmo Marconi, who listened earnestly for either Venusian or Martian signals. In 1901 Marconi transmitted the first transatlantic radio signal. That same year Tesla recorded rhythmic signals on his radio receiver in Colorado Springs and was convinced that they came from an ETI on either Venus or Mars. In 1902 Lord Kelvin, the British physicist, supported Tesla and announced his belief that as New York was so well lit, it was the best place for Martians to observe and the most likely place for them to make contact. During the 1920s Tesla’s rival, Marconi, believed that he too had discovered Martian signals, but in both cases there was no verification. In the early days radio reports of an unknown radio sound were often explained as ETIs. Marconi tended to explain any unexplained radio signals as evidence of ETI. The reasoning is as fallacious as the belief that unexplained bumps in the night prove the existence of ghosts.

There was popular speculation that an ET signal had been detected in 1968 when Jocelyn Bell, who was then a Cambridge graduate student, discovered rhythmic sounds from interstellar space. ETI was ruled out when it was discovered that they were from pulsars, spinning neutron stars from supernova remnants. In fact the first pulsar was named LGM1 (Little Green Man 1). In 1969, when astronomers found a pulsar at the heart of the Crab Nebulae, which was part of the remains of the supernova of 1054, another wave of popular

ETI speculation ended. Many other sounds attributed to ETI have turned out to have come from terrestrial origins: the effects of electrical motors, radio stations or natural signals called ‘whistlers’ which are produced by distant lightning.

Enthusiasm over alleged ET signals in the early decades of the twentieth century was nourished by Lowell’s popular theories about Martian life. It provided the background to the hysterical response to Orson Welles’ notorious War of the Worlds broadcast in 1938. Even when it was broadcast again fifty years later there were worldwide reports of panic and pandemonium, thus revealing the extent to which popular beliefs are removed from scientific theory. This event was so embarrassing that discussion of ETI fell into disrepute among astronomers. Interest in SETI was not to recover until 1957, when the space age opened with the launching of Sputnik.

The early pioneers of SETI in the late 1950s were Giuseppi Cocconi, Philip Morrison, Frank Drake and Carl Sagan, who marshalled arguments based on what we know about terrestrial life and its origins, and applied them to astronomical data on conditions elsewhere in the universe. In 1959 SETI achieved scientific respectability when the scientific journal, Nature, published a paper by the two scientists, Cocconi, a cosmic ray specialist and Morrison, a physicist. This paper addressed the question of radio communication from ET sources. The problem of communicating with ETs is that first there has to be an agreement on a medium, which in the 1950s was radio, and then agreement on a frequency. If it is assumed that ETs want to communicate by radio, then the problem of which noise-free frequency out of millions has to be considered. Cocconi and Morrison proposed a frequency which was based on the rate at which hydrogen atoms emit radiation when the spin axis of the electron orbiting the nucleus flips over from being parallel to the nucleus’s spin to being opposite to it. They argued that the hydrogen frequency ‘has a universal uniqueness, not set by anthropocentric considerations, that fits it as the outstanding choice for potential communicators who have not had the opportunity to reach agreement on a frequency’ (Cocconi and Morrison, 1959: 844). Hydrogen is one of the most abundant elements in the universe; about 999 out of every 1,000 atoms that exist are of this substance. The characteristic frequency for hydrogen is 1,420,405,752 times per second, which can be expressed as 1,420 megahertz (MGz) – a band in the noise-free area. Another band in the noise-free area represents the hydroxyl radial (OH) and is known as the ‘Waterhole’. The hydroxyl radial emits radiation when it changes its rate of spin. Because hydrogen and hydroxyl combine to make water, the frequency corresponding to its radiation emission is known as the ‘Waterhole’. The Waterhole has several lines near 1.65 GHz. The letters GHz mean gigahertz, and 1GHz is equal to 1,000 million vibrations per second. In comparison an AM music station is broadcast around 100KHz, which is 100,000 vibrations per second. Because these frequencies have associations with life, it is assumed that intelligent ETs would choose to communicate through them.