In its opening chapters, the following is asked: What would happen if the strong nuclear force, which binds protons and neutrons together, were slightly stronger or weaker? Would life still be possible? We know today that pushing the nuclear force off balance by just a few percent would create a different universe, unlike our own. Also, for life to exist, there must be a slight imbalance in the way matter and antimatter were created in the Big Bang. If matter and antimatter were exactly in balance, then our universe would not exist. These are just two examples of the fine tuning of physical laws that must happen for the cosmological conditions to be right for life to exist. If the universe wasn't "just so," you wouldn't be here to read about it!
Even with a favorable universe, how did life on Earth begin? How did it survive all this time without being wiped out by a cosmic event? Can human life continue to exist for millions of years, or will we cause our own extinction? These topics are considered in the latter chapters of the book and provide a fascinating look at our existence on Earth and the possibility of life elsewhere.