The Atheist's Guide to Reality_ Enjoying Life Without Illusions - Alex Rosenberg [19]
So long as our best physics tells us that the other fundamental laws are symmetrical and that the universe started in a highly improbable, very energetic, concentrated state, it is going to behave as the second law says it does. This will also hold for all the regions of the universe as well. In the short run, there will be some regions of space, like your body, where energy is stored and not immediately wasted. But in the long run and as the regions of space under consideration enlarge, the probability of energy loss will approach certainty as closely as anything can.
Of course, we experience time as a fixed past, an instantaneous present, and an unfixed future. In our experience, things can only happen in one direction: a match can’t go from being put out to being lit to being struck. But at the basement level of reality, the opposite of any sequence of events can and does happen. Given the present state of the universe, the basic laws of physics can’t determine in which temporal direction we are headed. You can’t read off which way is past and which way is future from these laws and the sequence of events can go in either direction from the present. At least none of the basic laws of physics do this except for one: the second law of thermodynamics. It makes a difference between earlier times and later times: the later it gets, the more entropy, or disorder, there is. In fact, the second law creates the direction of time from earlier to later.
NO ROOM AMONG THE PHYSICAL FACTS FOR PURPOSE OR DESIGN
With that, we can turn to some of the persistent questions that physics answers.
Where did the universe come from, how long ago, and where is it going? These are questions to which physicists are getting more and more precise answers, both through cosmology—studying the universe as a whole—and through high-energy physics—studying the basic building blocks of matter and fields that had to exist at the beginning of the universe. There is general agreement that the current universe began with a big bang about 13.69 ± 0.13 billion years ago (and every few years cosmologists increase the precision of the date by another decimal point). As noted, it started out as something smaller than a Ping-Pong ball, and a lot denser, but then expanded. Once it got to orange-size, something happened called “inflation,” and during the next 300,000 years, all the subatomic particles—the fermions and bosons—were formed and matter started to take shape in the form of hydrogen atoms. Even now, 13.69 billion years later, there is still a great deal of evidence for these events left in the cosmic background radiation. In any direction we point microwave detectors, the amount they detect is always the same except for one small region of slightly greater intensity—the source of the big bang. The better our detection gear, the more we learn about the big bang by examining its debris. What’s more, the recent evidence, from other kinds of radiation from distant galaxies, suggests not only that the universe is still expanding, but that the expansion is accelerating . . . with no end in sight.
So reality is an unimaginably large number of stars. By the fall of 2010, the best estimate was 70,000,000,000,000,000,000,000 of them (that’s 7 × 1021 stars, 70 sextillion) clumped together in galaxies—125 billion of them, all moving away from each other in every direction at vast speeds that are getting ever faster. Recent astronomical observations of the most distant regions of space suggest the number might be three times higher.
Where did the big bang come from? The best current theory suggests that our universe is just one universe in a “multiverse”—a vast number of universes, each bubbling up randomly out of the foam on the surface of the multiverse, like so many bubbles in the bathwater, each one the result of some totally random event. Some pop immediately. Others expand for a while till they pop. Still others keep expanding. The ones that pop immediately are unstable: the values of their basic physical constants don’t allow