The end of everything (In terms of astrophysics) Katie Mack Scribner (2020)
Scientists know how the world will end. The sun will run out of fuel and enter the red giant stage. Its eventual glorious explosion will expand and engulf the nearest planets, leaving Earth a charred, lifeless rock. Our planet is about five billion years left.
With this grim picture, theoretical astrophysicist Katie Mack begins her book on the end of the Universe ̵1; a much more uncertain perspective. Cosmologists often look back, because all the evidence they can examine with a telescope is far-fetched and related to things that have happened long ago. Using the movements of distant stars and galaxies to predict the possible future involves more speculation.
In Mack’s hand, this speculation makes a compelling story. Humans are, she writes, “a species poised between our awareness of our ultimate importance and our ability to go beyond our mundane life, into space, to solve fundamental mysteries.” most of the universe ”. She is a talented communicator in complex physics, her passion and curiosity about astronomy have made her a popular speaker, and Twitter’s presence is evident here. (Like some goofy jokes and a less engaging coda about new physics research related to the central topic.)
Mack started from scratch, with the Big Bang explosion. Next is inflation – a period of rapid expansion. Then dark matter structures form and the building blocks of stars, planets, life and galaxies are reassembled. Currently, dark energy, thought to be pervasive throughout the Universe, somehow resists gravity to continue to drive expansion.
The fate of the Universe depends on whether that expansion will continue, accelerate or reverse.
The Big Crunch
Astrophysicists have long regarded the most likely sign as the Inversion of the Big Bang – The Big Bang. Outside of our cosmic vicinity, every galaxy is shrinking from us; a clear sign of expansion. If the Universe contains enough matter, including dark matter, the combined gravity of everything will gradually stop this expansion and lead to eventual collapse. Over time, galaxies, then individual stars, will crash into each other more often, killing any life on nearby planets. In the last moments, as density and temperature rise in a shrinking hell, all that remains is extinguished at a single point.
But dark energy could mean another ending awaits. The early years of the evolution of the Universe were determined by the amount of matter it contained; Over the past few billion years, dark energy has begun to dominate, pushing the universe outwards. Existing data from the European Space Agency’s Planck telescope and other sources consistent with this expansion will continue forever.
Called Tropical Death or The Great Freeze, this apocalypse will be “slow and painful,” writes Mack. In terms of thermodynamics, she explained, the Universe would enter a state of minimum temperature and maximum entropy. As things get further apart, the matter of the dead stars will scatter, preventing new stars from forming, and the galaxies they are part of will gradually stop growing. It’s like the suffocation of all astrophysics, because the fuel for growth and reproduction becomes too diffuse to use. It was an ending “marked by growing isolation, irreversible decomposition, and a long-lasting demise in the eons”.
The third collapse that Mack discusses is the Big Rip. This is true if dark energy increases the rate of expansion even more than is currently expected. Eventually, when the universe rose, gravity would be unable to hold clusters of galaxies together. The stars will be separated from each other, and solar systems like ours will not have the strength to stay together. The remaining stars and planets will explode. Eventually, the atoms will eventually be ripped apart.
The latest measurements show Dead Temperature, but the Big Bang or Big Rip is within their uncertain capacity.
The final doomsday scenario that Mack describes is extremely unlikely: vacuum decay. A small bubble of ‘true vacuum’ can form, due to the instability in the field associated with the Higgs boson. That can happen if a black hole evaporates incorrectly. Such a bubble will expand at the speed of light, destroying everything, until it destroys the universe. Vacuum decay may have started somewhere far away. We won’t see it coming.
No worries, though. As Mack’s advice, whatever it looks like, the end probably won’t be as early as at least 200 billion years away.