The discovery of water 12.8 billion light-years away, the scientists' findings are truly incredible. How exactly does this work? And what does it mean?
We know that water is an extremely important substance, and without water, many chemical reactions cannot be carried out. Water is even more important to life. The reason is the same, without the various biochemical reactions supported by water, life cannot survive.
Therefore, when looking for habitable planets in the universe and even possible signals of extraterrestrial life, water is also regarded as the most important target for detection, and is "treated specially" by scientists.
But this time, being able to find water 12.8 billion light-years away is truly astonishing.
(Image caption: spt0311-58 galaxy)
The place where scientists found the water was in a galaxy called spt0311-58, which is actually two galaxies, first discovered by scientists at the University of Illinois at Urbana-Champaign in 2017 using the Atacama Large Millimeter Wave/Submillimeter Wave Array (ALMA) in Chile. It is so far away from us that this discovery is the most distant water molecule ever discovered by humans.
12.8 billion light-years away means that it takes 12.8 billion years for its light to travel to Earth, and what we see it today is actually what it was 12.8 billion years ago.
How do scientists know how far away this galaxy is from us?
There is an effect in physics called the Doppler effect, which refers to the phenomenon in which the wavelength is elongated when the wave source is far away from the observer, and vice versa. On the road, a car with a horn passes in front of a person, and the tone of the horn rises first and then decreases, which is the embodiment of the Doppler effect. In the universe, distant galaxies are moving away from us, and they embody the Doppler effect, also known as redshift, from electromagnetic waves. By the redshift value, we can judge the distance of a galaxy from us.
Sreevani Jarugula, an astronomer at the University of Illinois who was one of the participants in the study, said: "This galaxy is the most massive galaxy known to have a high redshift value, and it was formed at a very young age in the universe.
(Caption: Redshift diagram)
For now, scientists usually use spectroscopy to find water in the universe. Because the spt0311-58 galaxy is too far away, the study also "zoomed in" it with the help of the gravitational lensing effect, resulting in better observations.
What is shocking about this discovery is not only its long distance, but also time is also key. According to the results of current scientists, our universe is only 13.8 billion years old. The spt0311-58 galaxy we see so far is what it looked like just 1 billion years after the Big Bang.
And, 3.8 billion years after the Big Bang, our universe entered a dark period when the universe was filled with neutral hydrogen and had no other matter. It took hundreds of millions of years, through reionization events, for our universe to form a variety of celestial bodies.
Even at this time, there are basically only two elements in the universe, that is, hydrogen and helium. As the first stars died, extreme events such as supernova explosions took place, allowing more intense nuclear fusion reactions to take place, forming carbon, nitrogen, oxygen, and even heavier chemicals.
Water molecules are made up of two hydrogen atoms and one oxygen atom, and water must wait until the supernova explosions of the first stars begin. You can calculate that from the Big Bang to the Dark Ages of the universe, to the reionization period, to the birth, evolution and death of the first stars, there is finally a chance to form water. Considering such a complex and lengthy process, the discovery of water molecules this time appeared 1 billion years after the Big Bang, which is indeed very special.
It can be said that the water molecules discovered this time are basically the oldest batch of water molecules in the universe. At the same time, scientists from NASA also lamented the short life cycle of early stars. Most stars in the universe have a lifespan of more than 10 billion years, and the stars in spt0311-58 were born and died in less than 1 billion years, which is really short-lived.
The researchers point out that the discovery of water has indeed expanded our understanding, but also brought up some new questions about how stars and galaxies at that time formed rapidly in the early universe.
The first stars had a very short lifespan, and even though human telescopes were enough to see the universe 13 billion light-years away, they didn't see these most primitive stars. Even the upcoming James Webb Space Telescope, which is expected to be able to observe 13.6 billion light-years away, scientists don't expect it to see the first stars.
(Photo caption: James Webb Space Telescope)
Not only are these stars themselves short-lived, but the primitive galaxies they are in are producing stars at a rate that is not comparable to today's galaxies. According to Jarugula, early galaxies bred stars at rates thousands of times higher than in the Milky Way.
Not only that, but spt0311-58 is unique in that it has more gas and dust than other early galaxies, which gives scientists many opportunities to look for the various molecules here and understand what role this matter played in the early universe.
In addition, the observation and study of these gases and dust can also help us understand how many stars formed at that time, the rate at which gas was converted into stars, and how galaxies interact with other galaxies or interstellar media, which are of great significance for us to understand the evolution of galaxies and the universe today.
We began by mentioning that water is considered an important basis for the search for habitable planets and extraterrestrial life, but in this study, the presence of these water molecules is too far away for scientists to carry out research in this regard. Moreover, these water molecules exist in interstellar space, not on a planet, so it is difficult to hook up with life.
However, the fact that water was able to appear in such an early universe is also quite noteworthy. In addition to water, the researchers also found carbon dioxide here. It can be said that this discovery has broken many previous understandings of scientists.
(Photo caption: Chemicals found in this study)
In short, compared with extraterrestrial life, the results of this research are more to help scientists understand the early situation of the universe, to help us sort out a timeline, and to understand how the universe became what it is today. This is also very important for scientists.
Creation is not easy, if you think the article is OK, just like it and go again. Want to see more wonderful popular science articles, please pay attention to me, we will see you in the next issue ~