The vast universe is so mysterious and fascinating. Since human beings embarked on the road of science and technology and walked out of the earth, we have seen a beautiful, mysterious and vast cosmic space.
In front of the universe, the earth is so small, and the human beings living on the earth seem small, but in fact, they are using great science and technology to understand the universe step by step, until they finally stand on the top of the universe and become the overlord of the universe.
How big is the universe, no one can give an answer, the small Milky Way is 100,000 light-years in diameter, and the current observable universe of human beings has 93 billion light-years, and this is only part of the universe, with the rapid expansion of the universe, more galaxies continue to move away from us, once the expansion speed exceeds the speed of light, our observation ability will be limited.
It is obviously unrealistic to rely on probes to travel through the universe, even the speed of light is as slow as turtle speed in the universe, ordinary faster-than-light flight, the range of exploration is very limited.
Human beings want to know more about the universe, astronomical telescopes are the most important tool, through which we can see the distant cosmic starry sky and see the mysteries of the depths of the universe that cannot be crossed.
Astronomical telescopes can be divided into radio telescopes, infrared telescopes, optical telescopes (visible telescopes), ultraviolet telescopes, X-ray telescopes and γ-ray telescopes according to the detection band, among which radio telescopes are the most important tools for us to understand the depths of the universe.
Radio telescope is the basic equipment for observing and studying the radio waves emitted by celestial bodies, its observation range, accuracy are very high, powerful strong electric telescopes can even observe tens of billions of light years away celestial objects.
At present, the most powerful radio telescope on Earth is the Continental Sky Eye, which began construction in 2011 and was completed in 2016, with an aperture of 500 meters, a reflective surface equivalent to 30 football fields, and a sensitivity more than 2.5 times that of the world's second largest telescope.
Since its operation, China's Sky Eye has discovered more than 780 pulsars, discovered the first continuously active repeating fast radio burst, discovered the shortest pulsar binary system with the shortest orbital period to date, and so on.
According to the latest news, the Chinese pulsar timing array research team, composed of researchers from the National Astronomical Observatory of the Chinese Academy of Sciences and other units, recently used the "Chinese Sky Eye" FAST to detect the key evidence of the existence of nanohertz gravitational waves, which is an important breakthrough in the search for nanohertz gravitational waves.
What are nanohertz gravitational waves?
For gravitational waves, I believe friends have heard of it, it refers to the ripples of space-time curves in physics, transmitted from the radiation source in the form of waves, which was predicted by Einstein in 1916 through the general theory of relativity, and later through detection and research, scientists discovered the existence of gravitational waves in the universe.
The discovery of gravitational waves has important significance for human exploration of the universe, you know, the vast universe is vast and boundless, there are too many celestial bodies and mysterious phenomena, our general method of detecting celestial bodies is through optical principles, the celestial body itself emits light or there is a light source around, we can observe it through astronomical telescopes.
If the celestial body itself is very dark or does not emit light and heat at all, then we want to detect it, which cannot be done using optical principles, and the discovery of gravitational waves provides us with a new direction for detection.
Through gravitational wave detection, we can find more faint celestial bodies and non-luminous celestial bodies, as long as this celestial body has a strong gravitational wave production, it can not hide its existence, and the detection sources that can emit strong gravitational waves include white dwarfs, neutron stars and black holes, these celestial bodies, traditional detection means are basically unobservable, especially black holes.
We can observe the black hole, not to see the black hole itself, but because the supermassive black hole in the process of constantly devouring the celestial body, in the surrounding formed a material-dense space-time interface, in this range, a large number of materials rubbing and colliding with each other to produce light and energy, what we observe is actually this energy circle, not the black hole itself.
Only around massive black holes can form an obvious space-time interface, which is easy to be observed by us, but some small black holes, the space-time interface they form is relatively dark or there is no space-time interface at all, such black holes want to be observed, only through gravitational waves.
Nanohertz gravitational wave is a kind of gravitational wave, is a very low frequency disturbance in the universe, its frequency is 10 minus 9 hertz, through the low-frequency vibration of gravity, it can release the energy of the deviated celestial body closure, thereby sending gravitational waves, also known as celestial vibration.
A nanohertz gravitational wave is a low-frequency vibration that exists in space-time and is emitted by gravity acting on an object. Because the nanohertz gravitational wave is very subtle, it is very difficult to observe, and it requires a radio telescope with high sensitivity, which was once considered unobservable by scientists, and even some scientists doubted its existence.
The first detection of nanohertz gravitational waves was in 2015, when a team of American physicists successfully measured them using two gravitational wave detectors across the continent, which shows how difficult it is.
Now China's sky eye has also successfully detected the existence of nanohertz gravitational waves, which shows its strength, and the detection of nanohertz gravitational waves is more helpful for us to understand the universe, which can provide information about the structure and early history of the universe.