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Imagine our Earth is like an island in the universe, and humans are the only lonely intelligent beings. Like those stranded on a desert island, astrophysicists once intended to draw a map containing the location of the Earth, put it in a bottle and throw it out into the vast universe, with hope hope to have”who’s that” will pick them up.
And in fact, they did during the two Pioneer probe missions that were sent into space in 1972 and 1973. But this is not the only way for humans to communicate with other civilizations in space. . When it comes to this, the answer of most scientists is “send a strong radio wave“, said Martin Rees, an astronomer from the UK.
“But if you’re trying to let someone know where you are, you need to have some common references, right? An ideal kind of permanent landmark in the universe”, said Héctor Socas-Navarro, an astrophysicist at the Institute of Astrophysics of the Canary Islands, a Spanish archipelago in the Atlantic Ocean.
The problem is that in our universe nothing is fixed. The stars and planets are constantly changing, moving around each other in a slow dance. So how did scientists solve that?
Can we look forward to the day when the aliens will pick up the bottles or catch our signal and visit Earth?
Use of electromagnetic radiation: Radio waves and lasers
Electromagnetic radiation, which includes everything from visible light to radio waves to infrared rays, remains the number one choice for transmitting information from Earth into space. And because electromagnetic waves are directional, any alien that picks up a signal from Earth can trace its path back to our civilization.
Of all the types of electromagnetic waves, scientists often prefer radio waves as their regular means of communication. That’s because the frequency of radio waves fills a convenient gap in the electromagnetic spectrum, known as “l .”.the water”.
According to NASA, at frequencies between 1420 and 1720 megahertz, the hydrogen and hydroxyl molecules (oxygen and hydrogen bond), two components of water that act as a kind of “soundproof” chemical, they absorb low vibrations higher and higher leaves only a relatively free channel in the cosmic background radiation. Frequencies above and below the relative waterhole”noise” because they are filled with quantum vibrations and radiation left over from the Big Bang.
Scientists have used radio waves to try to communicate with extraterrestrials in the past. In 1974, they beamed a radio-frequency message from the Arecibo telescope in Puerto Rico toward the star cluster M13, about 21,000 light-years away.
The message is a simple binary image depicting a DNA molecule, our Solar System, a human and many other representative elements. Since then, many radio messages have been fired into space, including a Beatles song called “Across the Universe”.
However, a potential problem with radio waves is that they will diffract or expand as they travel. Like a ripple expanding in a lake, that means the farther a radio wave travels, the more diffused it becomes. By the time it reaches a distant galaxy, the message that the radio waves reach there may no longer be clear enough to be picked up.
Svetlana Berdyugina, an astrophysicist at the Leibniz Institute for Solar Physics in Germany, said that if humans wanted to send a clearer message into space, humans should send them as visible laser light.
A message targeted with polarized laser light is capable of traveling much farther than a radio signal without attenuation with distance. However, because optical waves are a more tightly packed signal, they can only travel at very narrow angles.
That means, before sending them out, scientists need to know the location of their recipients. In other words, we must know where the aliens are in the universe before sending them lasers. Otherwise, that entire beam of light would be lost in the universe in vain.
Throw a bottle of maps into space
Imagine the Earth is like an island and we humans are lonely intelligent beings in the universe. There is an older way to show someone the way to get here, which is to draw a map, put it in a bottle and throw it into the sea.
“That’s exactly what astrophysicists do, they send a letter in a bottle out between the stars.”, Socas-Navarro said. One of the most famous letters is called “Pioneer board” in gold. It was attached to the Pioneer 10 probe by astrophysicists Carl Sagan and Frank Drake in 1972.
A second board, identical to the first, was mounted on Pioneer 11 a year later. These plaques are engraved with two people – a man and a woman – accompanied by a “map” Directions to our Solar System using 14 cosmic landmarks: pulsars.
Pulsars are remnants of dead neutron stars, which emit beams of electromagnetic radiation through their poles. As they rotate, these beams look as if they are flashing like a lighthouse. Because pulsaes represent a metronome-like point in the galaxy, they are extremely useful for navigation, Berdyugina said.
In fact, NASA also plans to use the pulsar as a kind of space GPS for future deep space missions. By measuring the small changes in the occurrence of each pulse of 3 or more pulsars, a spacecraft can determine its position in the galaxy.
Going back to the Pioneer plaque, each pulsar is marked on it with straight lines indicating its distance from Earth, as well as a series of openings to indicate its rotational speed.
However, the characteristic of pulsars is isotropic, this lighthouse cannot be seen from all angles. So if an alien civilization picked up the Pioneer plaque and read it like a map, “they’ll have to figure out what we see” said Berdygina.
When designing the tablet, Sagan and Drake envisaged that any civilization advanced enough to find and capture messages from the Pioneer probe, they would also have a deep enough understanding of the pulsar to read the message. message from it.
But the Pioneer sign isn’t just a letter in a bottle – it’s also a time pill. The opening marks on the pulsar map indicate the rotational speed of each pulsar from the angle observed at Earth in 1972. The pulsars have since been slowing down.
In a few hundred million years, some pulsars may no longer rotate. As Socas-Navarro points out, it could take longer for an intelligent civilization in space to find the two Pioneer probes, and the odds of them following the map to Earth would be even lower. a lot of.
So, while there are countless ways scientists are showing the way to Earth, another key factor in this quest is patience.
We have to wait patiently, sometimes even pray for luck to see the first visitor to our planet. And we also have to pray it will be friendly aliens, not a belligerent civilization.
Refer to Space
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