When did the universe “wake up”?

Beijing time on February 13, according tomedia reports, for our universe, the first star awakening is undoubtedly an important moment. But this moment has always been a mystery to scientists. But in a new study, a team of astronomers has successfully discovered some of the oldest galaxies ever seen. Scientists point out that these objects were fully formed when the universe was only 680 million years old. They also found evidence that these galaxies had sent a lot of extremely ultraviolet radiation around them.

This surging ultraviolet radiation created many giant bubbles in the universe, in which neutral gases were excitation and ionist, providing astronomers with the first visual images of this period of great change in the universe.

Before dawn

Once upon a time, there was no star in the universe. In the early days of the universe, all matter was very uniform, and the density was similar everywhere, quite uninteresting.

The universe was also very “neutral” at the time, which was not the same as when the universe first formed. In the hundreds of thousands of years after the Big Bang, the universe was so hot and dense that it was filled with plasma. Atoms are also pulled down by huge pulls, separated into electrons and nuclei.

But by the time the universe reached 380,000, the chaos was finally over. The universe expanded large enough to drop the temperature to a low enough temperature that electrons were finally able to combine with the nucleus to form the first hydrogen and helium atoms. In the course of this series of events, a huge amount of radiation has also been released, which is what we now call the “cosmic microwave background”.

For millions of years after that, the universe remained in this quiet neutral state. But as the universe expands further and temperatures decrease further, small “seeds” begin to form, i.e. occasional clusters of gases with a slightly larger density than those around them. This gives them a greater gravitational pull than the surroundings, attracting the matter around them. As mass grows, so does their gravity, attracting more and more material. As time went on, the silent, dark, neutral universe gave birth to the first stars and galaxies.

Dawn is coming

We don’t know exactly when the first stars formed, but they must have been spectacular. Because the universe is no longer neutral, but ionized.

Most of the material we normally come into contact with is made up of complete atoms, the nuclei of which are surrounded by outer electrons. These electrons fly back and forth in the outer layer of the atom, combining with other electrons to produce what we call a chemical reaction.

But this situation is very unique. So far, most of the matter in the universe is plasma, just as long ago, electrons and nuclei were separated. The sun is made up of plasma, other stars are made up of plasma, nebulae are also made up of plasma, and the matter between stars and nebulae is plasma.

At one point, plasma was converted into neutral gas when the universe was formed 380,000 years ebb. But 13 billion years later, most of the matter in the universe is back into plasma. Something special must have happened in the meantime, tearing the atoms in the universe apart again. Since all of our observable universeist is plasma, until the first universes and galaxies appear in the universe, the events that caused this “re-ionization” must have occurred a long time ago.

Astronomers believe that perhaps the large amount of ultraviolet radiation from the first generation of stars (and the supernova eruptions at the time of their death) has turned the entire universe back into plasma. But we don’t know exactly when the incident happened. Even the most powerful telescopes and deep space exploration missions couldnot be seen for so long. We can clearly see the cosmic microwave background, and we can clearly see the universe today, but what happens between the two is still an open mystery. In other words, we don’t know when the first stars came along (what astronomers call the “dawn of the universe” or when the “reionization period” began there after that.

“Blowing bubbles”

But that has changed. To understand this critical “adolescence” in the growth and evolution of the universe, we are looking for increasingly ancient galaxies and investigating the gases around them. Just recently, a team of international researchers discovered three very faintly light, tiny, and extremely distant galaxies.

These galaxies have been fully formed since the universe was only 680 million years old. This is not surprising, after all, we have found such an ancient galaxy before. But in the study, researchers analyzed radiation from the surroundings of the three galaxies and found that these galaxies had begun to blow a “bubble” of electrochemical plasma into the surrounding universe. In other words, the radiation emitted by these galaxies has begun to transform the surrounding universe. This is the first time we have found clear signs that the universe is in a period of reionization. Although astronomers have previously speculated that reionization would have ended before the universe reached 1 billion years, no one thought it would have started so early.

These galaxies will be excellent observations for the soon-to-be-launched James Webb telescope, which was designed to study this period in the history of the universe. If the observations match scientists’ guesses and find more examples of reionization, we may finally be able to learn something about this ancient and turbulent past of the universe. (Leaf)