Although radio astronomy is a relatively young science, it can outperform any other in the number of amazing discoveries. Even the senseless noise picked up by the antennas of radio telescopes can tell a lot about the past and future of the universe. What can we say about the strange extraterrestrial signals that are often mistaken for messages from aliens.
LITTLE GREEN MEN
In the summer of 1967, Jocelyn Bell, a graduate student of the English physicist Anthony Hewish, worked on the meridian radio telescope of the Mallard Radio Astronomy Observatory, Cambridge University. The telescope, which is a whole antenna field, was designed to receive and analyze radiation coming from quasars - mysterious objects in the centers of galaxies with small dimensions and enormous luminosity.
Bell was engaged in the analysis of the data recorded by the recorders, and during the work she studied a total of fifty kilometers of paper tape and was able to distinguish by eye the signals from space sources from the interference created by earth radio stations and artificial satellites. Once she noticed a "comb" on the tape - regular peaks that were not like anything else recorded by a radio telescope. Bell didn't jump to conclusions, but the signal grabbed attention. It then disappeared, then appeared, and the peaks of radio emission were uniform - with a frequency of 1.33 seconds between the maxima. After it was possible to establish a connection of signals with a specific area of the sky, the graduate student reported the discovery of a pulsating source to her scientific advisor.
Initially, Anthony Hewish was skeptical of the discovery, deciding that the signal could only be of terrestrial origin, but Bell was able to prove that it came from space. Since no point source of radio emission with such a short periodicity (less than two seconds) was previously registered in nature, the conclusion was drawn: the observatory intercepted the signal of a radio beacon built by an alien civilization! Of course, astrophysicists did not rush to announce the sensational discovery, but, characteristically, they named the signal LGM-1 (from “Little Green Men” - “little green men”).
Soon Jocelyn Bell discovered three more similar rapidly changing radio sources. In February 1968, Hewish published the first article about them, which caused a real storm in the scientific world. It turned out that earlier astrophysicists had caught such signals, but dismissed them, thinking that they were of terrestrial origin. An active search began, and by the end of 1968, various observatories of the world discovered 58 more sources, which were named "pulsars".
The hypothesis of their artificial origin continued to be discussed (for example, it was defended by the famous Joseph Shklovsky), but in the end the British astronomer and science fiction writer Fred Hoyle was right, who suggested that pulsars are neutron stars that appear after a supernova explosion.
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RANDOM OPENING
The history of the discovery of pulsars is very instructive. More than once or twice, signals from space have been taken as proof of the existence of aliens, but all of them (except, perhaps, a single signal called "Wow!") Were explained as a rare natural phenomenon. Nevertheless, the search for a space "miracle" continues, and some of the findings amaze scientists.
The next discovery was made, as usual, by accident. In February 2007, a team led by Duncan Lorimer, professor at the University of West Virginia, processed the results of observations made six years ago with the Australian 64-meter Parks radio telescope. By the way, the purpose of the study was to discover new pulsars. Graduate student David Narkevich noticed an unusual radio signal - a single, powerful, but very short one, lasting a thousandth of a second. Today the signal appears in the scientific literature under the designation FRB 010724 (for "Fast Radio Bursts") and its own name "Lorimer's fast burst".
Painstaking calculations showed that the intercepted short signal came from a point located 3 ° from the Small Magellanic Cloud, from a distance of about 3 billion light years. Since no similar events were recorded for ninety hours of subsequent observations, scientists admitted: they were lucky to stumble upon a rare event, like, for example, a supernova explosion.
Further analysis of the archived data of the Parks radio telescope revealed eight more such single bursts. Moreover, their distribution in the sky was random. The fact that the duration of bursts is milliseconds indicates that the size of the radio-emitting region, if it is located billions of light years from us, does not exceed hundreds of kilometers, and the source energy is comparable to the energy generated by our Sun in a day or two.
For some time, scientists found radio bursts only in the archives of the Parks Observatory, but on February 11, 2012, a similar burst coming from outside our Galaxy was detected by the 300-meter radio telescope of the Arecibo Observatory in Puerto Rico.
FLASH IN SILENCE
When discussing the possible nature of the outbursts, most astronomers were inclined to believe that star outbursts, collisions of white dwarfs or neutron stars, and supernova explosions could be the source of this phenomenon.
However, further search revealed oddities. At the end of March 2015, German astronomers Michael Hippke and Wilfried Domenko published an article on an amazing pattern in the time-frequency shift of eleven radio bursts discovered by that time. It turned out that it is a multiple of 187.5, and the deviation from the pattern did not exceed 5%. An important conclusion follows from the discovery: the burst sources are located at strictly ordered distances from the Earth - multiples of each other! This assumption seems incredible, because modern cosmological concepts are based on the fact that planets, stars and galaxies are distributed randomly relative to the terrestrial observer. It turns out that if the revealed law 187.5 is not a consequence of a fantastic coincidence, then all the bursts are of artificial origin!
A year later, in March 2016, specialists working at the Arecibo radio telescope discovered ten bursts coming from the area where FRB 121102 was recorded while processing the observation archive. By the end of the year, graduate student Paul Scholz from the Canadian McGill University identified six more bursts from the same places. Thus, at the moment there is information about seventeen, including the very first of 2012, radio bursts emitted by the same source in the constellation Auriga. Thus, the hypothesis that all bursts are a trace of a short-term phenomenon such as a collision of neutron stars has to be rejected. But what remains?..
On April 18, 2015, astrophysicists were lucky again: they managed to detect a fast radio burst FRB 150418 not in the data archive, but a few seconds after its arrival. This made it possible to quickly connect teams from other observatories, which began to search for the source. A team of Australian astronomers was able to identify the fading radio emission attributed to the residual activity of the burst source - it was observed for another six days from the side of the old elliptical galaxy, which is 6 billion light years away.
The latest discoveries confirm that fast radio bursts are associated with some astronomical events, but, despite the similarity of characteristics, they can have a fundamentally different nature. Therefore, each of them requires separate study and understanding. So what or who is giving these cryptic signals? Research is ongoing and we will surely get an answer soon.
Anton Pervushin