Find radio waves to detect aliens

US scientists say they are not looking for messages from aliens and how to decode them, but only focus on finding radio transmitters that suggest that aliens exist.

Stop radio waves looking for aliens

According to Science, Edward Snowden, the world-famous person with the secret disclosure of the US national security agency, thinks that humans cannot understand alien messages because they are encrypted.

However, the SETI Institute of Technology scientists seeking life out of space rejected the argument, saying that searches for extraterrestrial civilizations do not focus on decoding the understandable signals. OK.

"We are not looking for messages, but signals that someone has a transmitter , " said Seth Shostak, director of the SETI Research Institute's Research Center on September 23.

Snowden mainly talks about coding, according to Shostak, data encryption is only a secondary factor. Every search for alien signals ever used radio waves.

In theory this is the easiest and cheapest way to transmit signals away in space. SETI uses very powerful radio telescopes to search for narrow band signals, or signals focusing on a single frequency. Many natural objects can generate noise radio signals, but only radio transmitters can emit narrow band signals , according to the latest theory.

SETI's ATA telescope hunting radio frequencies from aliens.(Photo: SETI).

So if you get this signal, it must be sent from a radio transmitter created by someone, even if the message contained in it is unreadable.

Snowden refers to the hypothesis that humans can "eavesdrop" on signals from aliens communication devices, so it cannot be understood because they will be "invisible" in the myriad of radio signals. of the universe.

However, Shostak denied this claim. According to him, any broadcast signal will have narrow band components that people can recognize.

The current difficult problem is that technologies cannot yet detect signals at a distance, according to Doug Vakoch, SETI researcher in charge of contact with aliens.

"Even our radio and television signals emitted in space cannot be detected from another star system closest to us , " Vakoch said.

In the next few hundred years, technology can grow to increase the distance to receive signals. In other words, Snowden's conjecture about encryption only makes sense when the remote signal acquisition problem is solved. In addition, encryption is not the biggest challenge if you want to "eavesdrop".

"If a civilization wants to hide its presence, they don't need to worry about coding," Vakoch said. "With today's telecom technology, we have left so many signals out into space. Currently, the use of optical or telecommunication satellites limits this loss of signal." .

So, if another civilization wants to learn them, they have received signals from Earth and sent their signals in thousands or even millions of years. If this does not happen, we will simply not catch each other's signals due to the vast space and space. The hope of finding the best alien life so far is still trying to find their intentionally sent messages.

If aliens deliberately send a message to us, they must find a way that we can understand, it is impossible to encode too hard for us to receive but cannot read.

Signals from Earth

The opposite is the same. In 1974, scientists sent "Arecibo messages" from Arecibo radio telescopes located in Puerto Rico to outer space. This is a three-minute broadcast, with a capacity of 1,679 bits, consisting of 73 lines made up of 23 characters, representing numbers 1-10, the atomic number of several important elements with life on the Left. Earth, information about DNA, human shape, solar system graphics and telescope image.

Only two primes when multiplied together result in 1,679 as 73 and 23. According to Vakoch, if aliens can acquire radio waves, they must know about mathematics. They may not fully understand the content of the message, but they may recognize symmetrical forms in the image when recovering, helping them realize they were right to arrange them.

"We want to create a form of anti-code, a message that can be easily decoded , " Vakoch said. This signal packet is sent over and over again, to make sure that no part of the information is lost during the sending process.

In addition to the method of using radio waves , SETI is also conducting experiments to search for space life by other radiation such as visible light or infrared. However, infrared waves cannot transmit as far as wireless, and are more expensive.

In theory, it is also possible to determine whether a planet has life by sweeping the entire outer atmosphere . This method has not been implemented due to technological limitations. If a planet has life, its atmosphere will have unnatural gases. For example, on Earth, humans have emitted into CFC (refrigerant) atmosphere for decades, before realizing its effects on the ozone layer and seeking to reduce or use fossil fuels. Excessive release of carbon dioxide into the atmosphere. Even with high CO ₂ levels, it is not possible to confirm that the planet has life, as in Venus.

It is also possible to detect life thanks to infrared heat radiation emitted from a planet. If there is a civilization, it is possible that infrared radiation from that planet will be higher than normal. However, the current human technology has not allowed to determine the amount of infrared of a planet. We can only determine the amount of infrared emitted from a star.

There is another basis that rejects Snowden's arguments. A study published in 2013 estimated that about 22% of stars have planets located at the right distance for life to appear as Earth. Life can be anywhere in the universe, and people always have the opportunity to accidentally discover other civilizations.