to the Scottish mathematician James Clerk Maxwell who lived in the nineteenth century, We owe them the discovery of electromagnetism, one of the four fundamental forces of nature. Without Maxwell, astronomers could not probe the sky in the same way because the waves of visible light, which we see with our eyes, are not the only types of radiation that exist.
In fact, There’s a whole hidden truth that we simply can’t see with the naked eye, because our senses are limited.
radio waves -For example- They are a class of electromagnetic radiation whose frequency ranges from 0 to 300 GHz and are invisible., Beyond 300 GHz we talk of electromagnetic waves which range from infrared to visible light, through ultraviolet, X-rays, and gamma rays.
the waves said As we throw a stone, waves rise in the pond. They spread through space and decrease in intensity as they move. Of the source that created the waves.
Some objects in the universe, such as the stars that make up galaxies, emit electromagnetic radiation at certain frequencies and wavelengths, Thanks to instruments such as radio telescopes, astronomers can analyze and interpret such waves to determine what objects they belong to and how far away an object is, no matter how far away.
A few days ago, for example, a group of astronomers from McGill University in Canada announced the discovery of a radio signal from deep space that appears to come from a galaxy located near the Sun. about 8,800 million years, means that the signal was emitted When the universe was barely a third of its present age.
To achieve the discovery, he used a very powerful radio telescope, the Giant Metric Wave Radiotelescope (GMRT), is located in India.
through this device – and is also using a technique based on the principles of the general theory of relativity Albert Einstein– were able to determine that the signal corresponds to a primordial element that formed at the origin of the universe: the so-called neutral hydrogen.
This element emits radiation at a specific and always fixed frequency: 1.420 MHz or 21 cm.
It has been known for some years that, just after the big bang that gave birth to the universe about 13.6 billion years ago, was a very “light” chemical element That served as the fundamental building blocks for the formation of the first stars and galaxies, as well as all the chemical elements that shape reality.
This element is hydrogen which is seen in the periodic table of elements is the first to appear Because, in addition to being the most abundant in the universe, It is the “lightest” because it is composed of only one proton and one electron.
Although: How did astronomers detect hydrogen in a galaxy millions of light years away from Earth?
As I mentioned in the previous paragraph, the researchers resorted to Einstein’s general theory of relativity, which states in clear terms, That gravity is nothing more than the curvature of space-time imposed by massive objects like planets, stars, and entire galaxies.
Electromagnetic waves can also be changed by spacetime curvature done by objects. And when a massive object like a galaxy warps the fabric of space-time (some specific region of the universe), So the radio signal passing through it will not only bend but it will also be scaled up, making it more powerful.
The phenomenon of magnification of, for example, a radio signal or other type of radiation is called gravitational lensing these lenses are one of the results of the general theory of relativity. said lens They act like a magnifying glass. which, as we well know, Magnifies the image of an object.
When radio waves emitted by hydrogen or any other chemical element travel to Earth from another galaxy, The said wave can be amplified by a galaxy or any other object that comes in between. And indeed, this magnification was what astronomers at McGill University were able to see until recently.
Studying the early universe is a difficult but not impossible task, because low-intensity, long-wavelength radio signals (such as neutral hydrogen) Very often they “drown” and lose strength over great cosmic distances.
There is no doubt about the astronomical significance of this radio signal and others that may be discovered in the future by means of more powerful radio telescopes. will prove essential for scientists to better understand the origin of the universe And how were the first stars made.
For at least the first few minutes after the Big Bang, as protons and electrons came together to form hydrogen, They roamed freely in the universe, without being bound by any bonds.
When the first hydrogen atoms began to form, the universe experienced a so-called “dark ages” that preceded the formation of the first stars. This dark age is believed to have occurred 400,000 years after the Big Bang.
In short, the detection and study of neutral hydrogen can provide astronomers with very valuable information for reconstructing the lives of the first stars and also to make more plausible scenarios about the time before these stars were formed.