Is there life anywhere in the universe other than Earth, and if it is, then how it remains a big question for scientists?
In June this year, the US government declassified a report related to Unidentified Flying Objects (UFOs), which said that so far no evidence of aliens has been found on Earth. However, the possibility of aliens has not been ruled out in the report.
For the past several decades, scientists have been trying to find the answer to this question. He is about to start looking for life in a constellation named Alpha Centauri, about four light-years away from Earth.
But will they be able to find the aliens? And is there life anywhere away from Earth? This week in the world, these questions were investigated.
Part One - Where, how the question arose
Natalie Haynes is a writer and is interested in science fiction. She tells that two thousand years ago, when there was neither a space observatory nor a spacecraft was conceived, at that time a Greek writer named Lucians has mentioned life away from Earth in his book.
She says, "In her book 'A True History, Lucian writes the story of some travelers who got trapped in a tornado and reached the moon. This journey took them seven days, whereas nowadays it takes a rocket to reach the moon. It takes about half the time. There is a war going on between the King of the Moon and the Emperor of the Sun, and they have strange-looking armies."
The British painter William Faethorne drew inspiration from a 17th-century stone statue of Lucian.
In his book, Lucians mentions fleas on the moon as large as winged horses, giant vultures, and twelve elephants. He has written about strange people whom it would not be wrong to call aliens.
About eight hundred years later, another science fiction story "The Bamboo Cutter's Daughter" was written in tenth-century Japan.
Natalie says, "The story is such that a person who cut bamboo saw a bright light inside the bamboo one day. He found a little girl there whom he brought home and raised him like his own daughter. Later the girl Told that he is from the moon."
But why is it that in the first stories in which aliens are mentioned, the moon is also mentioned?
According to Natalie, "It is true that the moon has been written about for a long time. Perhaps this is because the moon is visible from Earth but Venus or Mars is not visible."
But soon Mars also became a topic of discussion on Earth. In the 1870s, an Italian astronomer, Giovanni Virginio Schiaparelli, observed Mars with a telescope and wrote about it in detail.
Natalie recounts, "He saw ridges on the surface of Mars, which he called 'candles'. People thought he was talking about canals. At that time the work of the Suez Canal was completed. After this, the assumption started that Mars The inhabitants of the planet have dug canals there."
A few years later, in 1881, a fictional story of Mars attacking Earth appeared in a magazine called London Truth. A few years later, Elleriel - A Voyage to Other Worlds, a Polish clergyman.
Wrote a book called, in which he mentioned about nine feet tall vegetarian people living on Mars. For the first time, he used the word Martian for them.
After this, many people made claims like seeing a ray of bright light from Mars.
Search for life on other planets
In the 1960s a young scientist, Frank Drake, suggested that radio technology developed during World War I could be used to send signals from one solar system to another and that aliens might be doing the same. be. In such a situation, to find their existence, we just have to catch their signal.
Seth Shostack is a senior astronomer at the Search for Extraterrestrial Intelligence (SETI). For the last four decades, they have been trying to hear similar signals from aliens.
He says, "Frank turned the current radio antenna at the Observatory in West Virginia to the nearest star. He was trying to catch if the aliens were sending signals. He was looking at two stars. Funny. The thing was that they did not get any signal from one star but heard some sound from the other. They thought they had found the aliens. Although it could have been an army plane.
Soon scientists all over the world were looking for traces of aliens. In the 1980s, the US government began funding the SETI Institute to search for aliens.
Radio waves can travel through space easily, and the sound that Seth wanted to hear on the radio receiver was different from ordinary sounds. Seth used the simulation to create a sound that sounded like an alien signal so that it could be understood what they were looking for.
He says, "Listening, it sounds like someone is playing the flute standing near Niagara Falls. The sound of Niagara Falls on the receiver will sound like the sound of the emptiness of space but it will sound like a sound rather than a tune."
Seth and his team knew what they were looking for, but the difficulty was that they had to look at millions of radio frequencies, then how did they know which to look first.
He says, "It was a big problem. The aliens didn't send me this message on which frequency I wanted to tune in. So I had to check every frequency. But doing that was a waste of time. We need receivers that can tune in." Listen to all channels at once.
By 1990 this also became possible and such computers were made which could listen to millions of frequencies simultaneously.
When an astronomer at Ohio University was looking at radio telescope data, he found signals of extremely high intensity and frequency. They thought it was a signal of aliens.
Seth explains, "He was very happy that he wrote 'Wow' near the data. But we don't know what he found. Many other people also searched in the same part of the sky, but they never found anything like this. I had two possibilities, either they were aliens or there was a sound of something on Earth itself."
For many people, this was the best example of the signal of aliens. But even after years of searching in the true sense, no concrete sign could be found about the aliens.
The question arose that how far is it right for governments to spend billions on such projects, which do not yield any result. In the early 1990s, the government aid to the SETI Institute stopped. But this was not the end of the search for aliens.
Kepler
David Grinspoon is an astrobiologist and senior scientist at the Planetary Science Institute. He has been an advisor to NASA on space research.
He says that confidence in the discovery of aliens also decreased because till that time more planets could not be discovered. But since the early 90s, scientists discovered new small planets and dwarf planets in our solar system.
And once again the question arose whether there could be such planets outside our solar system where there is life.
In March 2009, NASA launched the Kepler spacecraft. It had an observatory with a telescope whose purpose was to find life outside Earth.
David says, "Kepler was a clever idea. It was such that you put him in such a place away from Earth from where he can keep an eye on the whole space."
Kepler kept an eye on the stars for many years. His job was to see whether the light coming from a star changed or not.
He explains, "If there is a change in the light, then it means that something is passing between us and that star, it may be a planet. If there is a pattern in the twinkling of a star, then it is known that something has revolved around it." has been."
Kepler hoped to find some planets, but in its nine years, it found 2,600 planets outside our solar system. In 2013, scientists estimated that according to this there could be billions of such planets in our galaxy.
But how many of these could have the potential for life?
DeWitt says, "This is a rough estimate because we do not know under what conditions life flourishes. We have only the example of Earth before us. But we can assume that if there is a planet the size of Earth If it is in a particular climate zone, then there can be a possibility of life. According to this, it can be said that there can be at least 300 million such planets in our galaxy.
According to David Grinspoon, this discovery was the revolution that changed the thinking of scientists about the possibility of life outside the earth.
He says, "Most astronomers or scientists will say that they believe that there will be life on some other planet. Till now nothing special has been known about Earth to say that life could have flourished only here. "
Meanwhile, some such creatures like extremophiles have been discovered on earth, which proves that life can flourish even in very difficult conditions. Scientists are confident that these tiny creatures that have been the basis for the beginning of life are spread throughout the universe.
This discovery has once again increased interest in the search for aliens.
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