"Astrophysics for People in Hurry" is a book by the famous American astrophysicist Neil deGrasse Tyson, who was able to fit a lot of information about astrophysics into a small volume of the book, and it is no less important, interesting and easy to present it.

1.No one knows what existed before the universe, but scientists understand it began as an infinitesimally small dot that contained everything and expanded rapidly. In the first trillionth of a second, the laws of physics emerged, but it took 380,000 years before light could separate from matter and things became visible. Today, nearly 14 billion years later, the universe contains 100 billion galaxies that each contain up to hundreds of billions of stars. One is our own Sun and its planets—including Earth, which is not too warm and not too cold, so life can thrive on it and evolve to create humans, who wonder about the universe. 

2.Newton’s laws of gravity function everywhere, not just on Earth. The theory offered the first proof that the laws of physics apply to the entire universe and that the realm beyond our planet isn’t a separate, heavenly space but instead is made of the same materials and follows the same rules as on Earth. 

3.Cosmologists could only speculate on the nature of the universe until they discovered the cosmic microwave background, which is ancient light that gives evidence of the early universe. With that information, scientists now know the age, size, and shape of our cosmos and that most of its matter and energy is made of stuff we don’t yet understand. 

4.Spread across the cosmos like lit-up cities, the billions of galaxies capture our attention, but between them lie vast areas filled with hydrogen gas and other matter that weigh up to 10 times as much as the galaxies themselves.

5.Only one-sixth of the mass in the universe is made of the galaxies and gas clouds we can observe. The rest consists of something we cannot detect, except it exerts a huge gravitational influence on everything around it. This dark matter has puzzled science for decades, but the inability to detect it through ordinary means suggests it represents an entirely new principle about the universe yet to be discovered. 

6.The universe is expanding, and it’s doing so much faster than expected. Einstein thought the universe was stable, so he added a constant to his equations that kept gravity from collapsing everything. The discovery that the universe is expanding made Einstein’s constant obsolete, but still later observations showed the cosmos expands at an ever-increasing rate, so Einstein’s constant once again makes sense. No one yet knows what this expansive force is, but it alone is two-thirds of the universe’s total makeup. Scientists call it dark energy.