In the center of the Milky Way, there is a supermassive black hole. Black holes, in our minds, seem to be something that only threatens life, but in fact, it may be crucial to the evolution of life.
Now, this black hole called Sagittarius A* is in a silent state, but there are signs that it was active millions of years ago, and its brightness is more than 100 million times higher than it is now. When it swallows material, it emits a large amount of high-energy radiation, including X-rays.
What effect will these high-energy radiation have on the abundance of chemical substances (organic molecules such as water and methanol) that are vital to the evolution of life? In order to clarify this problem, Chinese scientists have recently conducted simulations.
When a high-energy photon (such as an X-ray photon) hits a molecule, it can knock out the electrons on the molecule. The resulting ions and free electrons are more likely to attract other atoms or molecules to initiate a series of chemical reactions. The result is that the molecules become larger and larger, eventually resulting in complex organic molecules.
The researchers found that even at a distance of 26,000 light-years from Sagittarius A* (equivalent to the distance between the galactic black hole and the earth), if the black hole has been active, the abundance of many organic molecules will be higher than that of the black hole. The lower is much higher. According to calculations, this effect may persist for millions of years after the black hole activity ends.
However, the radiation from the galactic black hole can also cause great damage to planets that are too close to the black hole, blowing away their atmosphere, and turning the surface of the planet into a barren land.
Therefore, the evolution of life on Earth does have unique conditions. It not only makes full use of the beneficial side of this radiation to life, but also avoids its disadvantageous side.
