Two questions have agitated human mind since always: how the world (read universe) came into being and how and when it will end. We know that the cosmos had a beginning. Religions have explained it. Religions have also tried to guess the death of the universe. The sciences have tried to explain the beginning of the universe with different theories including the Big Bang theory. Explaining the Big Bang theory in The End of Everything, Katie Mack says that about 13.8 billion years ago, the universe went from a state of unimaginable density, to an all-encompassing cosmic fireball, to a colling, humming fluid of matter and energy, which laid down the seeds for the stars and galaxies, we see around us today. She writes, “A rocky planet orbiting an ordinary star near the edge of a spiral galaxy developed life, computers, political science, and spindly bipedal mammals who read physics books for fun.” Notwithstanding this popular picture of the Big Bang, the Big Bang was not an explosion within the universe, it was an expansion of the universe, and it didn’t happen at a single point, but at every point. Katie Mack says that the logic of the Big Bang theory is simple. The universe is expanding – we can see that distances between galaxies are getting larger over time – which means that the distances between galaxies were smaller in the past. Many people will insist that it is just a guess. Katie agrees but says that it is a guess but a scientific guess. There is some truth in it. And science will continue to refine this theory.
But the other question is how this universe would come to an end. Katie Mack says that science tells us, in about five billion years, the Sun will swell to its red giant phase, engulf the orbit of Mercury and Venus and leave the Earth a charred, lifeless, magma-covered rock. Even this sterile smoldering remnant is likely fated to eventually spiral into the Sun’s outer layers and disperse its atoms in the churning atmosphere of the dying star. You can call it a mere speculation. But Katie Mack says that it is a science-based speculation. And this is surely not the only science-based speculation.
Katie Mack gives another plausible explanation of how the cosmos will end. In about four billion years, Andromeda — a spiral disk of about a trillion stars and a super massive black hole, all of which are hurtling toward us at 110 kilometers per second — and our own Milky Way galaxy will collide, creating a brilliant light show. Stars will be flung chaotically out of their orbits, forming stellar streams that stretch across the cosmos in graceful arcs. Katie Mack continues that the sudden smashing together of galaxies together of galactic hydrogen will spark a minor explosion of star birth. Gas will ignite around the previously dormant central supermassive black holes, which will meet in the middle of everything and spiral into each other. Jets of intense radiation and high energy particles will pierce the chaotic tangle of gas and stars, while the central regions of the new Milkdrmeda galaxy is irradiated with the X-ray -hot glow of a whirlpool of doomed matter falling into the new, even more supermassive black hole. There are several other plausible ways in which the universe may meet its end such as Heat Death, Big Rip, Vacuum Decay and Bounce.
The End of Everything is an exciting possible explanation of how this world might come to an end. Katie Mack’s deep scientific and astrophysical knowledge of cosmos makes the book extraordinarily interesting and enjoyable. The End of Everything is packed with knowledge, analysis and new perspectives on the topic. In Katie Mack’s hands, the story of the death of our universe becomes fun instead of depressing. Katie Mack puts an end to religious concepts like the creation theory and the end of time theory. She is surely an accomplished theoretical astrophysicist.