Author : Sean Carrolldo things, left by themselves, tend to become messier and more chaotic? What would Maxwell's Demon say to a Boltzmann Brain?
The answers can be traced to the moment of the Big Bang -- or possibly before.
Time pervades our lives -- we keep track of it, lament its loss, put it to good use. The rhythms of our clocks and our bodies let us measure the passage of time, as a ruler lets us measure the distance between two objects. But unlike distances, time has a direction, pointing from past to future. From Eternity to Here examines this arrow of time, which is deeply ingrained in the universe around us. The early universe -- the hot, dense, Big Bang -- was very different from the late universe -- cool, empty, expanding space -- and that difference in felt in all the workings of Nature, from the melting of ice cubes to the evolution of species.
The arrow of time is easy to perceive, much harder to understand. Physicists appeal to the idea of entropy, the disorderliness of a system, which tends to increase according to the celebrated Second Law of Thermodynamics. But why was entropy ever small in the first place? That's a question that has been tackled by thinkers such as Ludwig Boltzmann, Stephen Hawking, Richard Feynman, Roger Penrose, and Alan Guth, all the way back to Lucretius in ancient Rome. But the answer remains elusive.
The only way to understand the origin of entropy is to understand the origin of the universe -- by asking what happened at the Big Bang, and even before. From Eternity to Here discusses how entropy relates to black holes, cosmology, information theory, and the existence of life. The book tells a story that starts in the kitchen, where we can turn eggs into omelets but never the other way around, and takes us to the edges of the universe. Modern discoveries in cosmology -- dark energy and the accelerating universe -- and quantum gravity -- the possibility of time before the Big Bang -- come together to suggest a picture of a multiverse in which the arrow of time emerges naturally from the laws of physics.
