Client of Chinanews.com, Beijing, March 31 (Reporter Shangguan Yun) "Ever since ancient times, it has been called the universe, and the Quartet has been called the universe." This is the ancient Chinese's simple understanding of the universe. When humans look up at the stars, they can't help thinking about the vast universe.
A few days ago, "the universe on your birthday" became a hot search term on the Internet: NASA organized an event to celebrate the 30th anniversary of the launch of the Hubble Space Telescope. People can choose the date of birth on their official website to see the Hubble telescope that day. Universe image.
People's enthusiasm for this activity also reflects curiosity about the universe: how was it born? What is the age? What is a galaxy?
Where does the universe come from?
Regarding the universe, human beings have no shortage of exploration and imagination.
Data map: On March 21, 2013 local time, the European Space Agency released images taken by the Planck Space Telescope within 15 months. These images can prove the theory that the universe originated from the Big Bang, but the images also contain subtle differences that contradict some components of the standard model of cosmology, such as the "dark energy" thought to have inspired the Big Bang. This means that the current theory needs to be revised.
Looking up at the starry sky, the ancient Chinese have proposed the "Gaitian theory", "Xuanye theory" and "Huntian theory". Han scholar Zhang Heng also proposed the concept of the infinite universe, "the universe is infinite, and the universe is infinite."
Speaking of the origin of the universe, the most widely spread is probably the Big Bang theory. The theory states that the universe was born about 10 billion years ago. From a tiny, dense "fireball" that keeps expanding and slowly cooling, gradually stars, galaxies, etc. are formed.
The age of the universe is said to be 13.7 billion years, and it is also said to be 13.8 billion years. Due to algorithmic reasons, there are even 11.4 billion years of answers. But no matter which number, the universe is ancient enough for humans.
Gao Shuang, a doctor of astronomy and science writer Gao Shuang, said in an interview with China News.com that there is no particularly accurate statement about how the universe appeared. The matter that humans know includes humans themselves, and they make up only a tiny fraction of the universe.
Some galaxies are "quiet"
There are many galaxies in the universe. Many galaxies are actively making stars and glowing brightly, and are "lively" galaxies. Gao Shuang said that there are also some galaxies that stop starmaking for some reason, so-called "quiet" galaxies.
Earlier, it was reported that a research group composed of the National Observatory of Japan and other observations found a "quiet" galaxy that is stopping starmaking activities through the "Pluto star cluster" telescope and Keck telescope. Has been formed.
Others believe that understanding the galaxies that are becoming weaker and becoming "quiet" is the key to solving the mysteries of many galaxies.
Data Map: Earlier, the European Space Agency released a photo of the IC 63 "Phantom Nebula" about 550 light years from Earth. The nebula is classified both as a reflection nebula-because it reflects light from nearby stars-and as an emission nebula-because it emits hydrogen radiation. Both effects are caused by the giant Cassiopeia star. The star's radiation is also slowly dissipating the nebula.
"However, the core of a galaxy is generally quiet, meaning there is no violent activity." Gao Shuang said that when the universe was young, there were a large number of core-active galaxies, and the large black holes in their cores "swallowed" the surrounding material violently. The active galaxy cores will be particularly bright, and they can be seen at great distances.
Are elliptical galaxies relatively "old"?
According to Gao Shuang, galaxies can be divided into three categories: spiral galaxies, elliptical galaxies, and irregular galaxies.
It is generally believed that the elliptical galaxy is the result of the merger of multiple galaxies, because the collision merges gas and dust, causing a large number of stars to be born and consumes material. As a result, elliptical galaxies lack dust and gas and are relatively old.
Irregular galaxies may be special shapes born after colliding with each other and their size is generally not large. As the name suggests, a spiral galaxy looks like a spiral disk, such as the Milky Way.
In this spiral galaxy, stars rotate around its center, but in the process of movement, there will be some concentrated areas of gas and dust in these places, and more new stars will be born in these places.
"For example, driving on a highway, if you encounter a large truck, there will be a small area of congestion behind it, and the road in front of the large truck is relatively smooth." Gao Shuang said, for example, there may be a change in the spiral galaxy The type is a core-shaped structure with a core called a spiral galaxy. Our own galaxy is the great spiral galaxy.
Human exploration of the universe
In fact, in the long years, human beings have never stopped to explore the universe.
Data Map: Earlier, NASA released a high-resolution map of the galaxy 23 million light years away. The galaxy's huge black holes, shock waves, and a large amount of gas are intertwined, as if a beautiful fireworks show is being staged. Image source: NASA official website
Gao Shuang introduced that as far as the way to explore the universe is concerned, there is a more important way is telescope observation, there are also complementary methods, such as through gravitational waves, to obtain physical objects, etc. There are roughly four ways, "there have been many related progress. "
"It can only be said that the universe that can be observed at present may include hundreds of billions of galaxies." Gao Shuang said that from a certain perspective, there is no scientific definition of the universe, and it can only be roughly said that it includes all time and space.
In recent years, some other studies on the "parallel universe" have suggested that there are other universes that may exist in space and time. Gao Shuang said that to describe the universe, its main parameters include the average density of matter, which is used to describe how much matter it contains. Among them, the material atmosphere can be classified into ordinary matter, dark matter, and dark energy.
"At present, the diameter of the observable universe is about 90 billion light-years. This length is because the speed of light propagation is limited, so in a limited universe age, only such a wide range of light has time to propagate into our eyes. So this length is far from The universe itself, "he said. (Finish)