The first chapter of this logarithmic history has already encompassed 80% of the universe’s lifetime. This epic epoch will always have a grip on our imaginations. Everything that is familiar to us had its origins in something so different and baffling that we can only approximate it with mathematics or mythology. Though I am an atheist, I share the religious sense of awe for the beginnings of the universe, the world, and life, and I can completely understand how this combination of reverence and mystery can inspire imagination about God or gods.
Science’s greatest unsolved mysteries include the cause of the big bang and the origin of life. These burning questions are the gateway to religion, because, so far, they have eluded complete explanations in terms of known principles of nature. However, the “answers” that religious explanations provide are not as satisfactory as we think they are. For example, even if we “explain” that the big bang came from God, we are only replacing hard questions with harder ones – how did God do it, and how did God get there in the first place? The existence of God is an unscientific question, which means that no experiment could ever be designed to prove God false. It is a matter for personal belief.
Once we get past the creation mystery, the universe’s early history follows conventional physics. Nature is driven by forces, which do not require a guiding hand. This chapter took us quite authoritatively from a “quark soup” in the universe’s first instant to a “primordial soup” deep under the sea of newborn planet Earth. The details of life’s origin are far from solved, shrouded in complex chemistry and long-lost environmental conditions. But the gap between chemistry and biology is not nearly as big as a “something from nothing” problem. The basic building blocks of life are well understood.
All life on Earth today descends from LUCA, the Last Universal Common Ancestor. LUCA was probably a community of microbes in a state of horizontal gene transfer that lived almost 4 BYA. Microbes, particularly bacteria, archaea, and simpler forms such as viruses, had the world to themselves for two billion years before life became visible. Bacteria, slowly evolving generalists, used this time to perfect chemical pathways and cell membrane features that would eventually be handed down to all living things.
Congratulations. You have now survived the brain-rattling odyssey of the universe’s ten-billion-year timescale. In the next chapter, we will slow down the clock, zoom in to the last few billion years of life here on Earth, and address science’s third great frontier question.
Continue to CHAPTER 9: THE LAST FEW BILLION YEARS
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