How could the author of Genesis possess knowledge about the events of creation that occurred before his own existence?

 He didn’t. He made shit up, in part inspired by Gilgamesh during the Exile to Babylon.

Genesis has a specific order of things.

·         God creates heaven and earth. Earth was formless and a void, and there was darkness and water.

·         1st day: God creates light, and divides day from night.

·         2nd day: God creates a firmament, separating waters above from water below. He also calls the firmament “Heaven”.

·         3rd day: God separates the waters below into one place so that dry land appears. He then creates grass, herbs, fruit-trees (i.e. flowering trees).

·         4th day: God creates stars, the Sun and the Moon.

·         5th day: God creates wild animals.

·         6th day: God creates domesticated animals and humans, in that order.

 

Big Bang cosmology, stellar formation, abiogenesis and theory of evolution has a completely different view of things:

 

·         The universe comes to be. How it happened is unknown. It is by this time incredibly small, smaller than an atom. We know this because the Cosmic Microwave Background is incredibly smooth in temperature.

·         Inflation epoch. The universe expands rapidly. We know this because of the minute fluctuations in the CMB that are frozen in time.

·         Matter forms. First as gluon/quark plasma, then as regular plasma. Nucleosynthesis happens and the first elements (deuterium, tritium, helium, beryllium, lithium) forms. Nucleosynthesis happens at about 2–20 minutes after the bang.

·         Recombination: free electrons and atomic nuclei forms up to form gas, rather than plasma. The universe clears up. CMB is the afterglow of this event. This happens about 380,000 years after the bang.

·         Dark ages of the universe. No stars have yet formed.

·         The first stars light up. Population III stars probably burn fast and furious and then explodes, causing heavier elements and leaving neutron stars behind. Population II stars follow, and burn slower, also causing heavier elements and leaving white dwarfs and neutron stars behind. This happened about 0.5–1 billion years after the bang.

·         Neutron stars collide, some white dwarfs steals matter from neighbouring stars to then explode. These explosions causes the heaviest elements to form.

·         Population I stars form, with planetary disks formed by the heavier elements.

·         On one such planet around one such star, life appears. Exactly how is unknown, although we have some pretty good ideas of the general process, from simple chemistry to complex chemistry, chemistry complexes, self-replicating chemistry complexes and chemistry complexes with metabolism in some order, life-like complexes, and then life. This happened about 3.5–4 billion years ago.

·         Evolution of single-celled organisms. Photosynthesis happens. The Great Oxygenation Event happens, killing off almost all life. Eukaryotes evolve as a response, about 1.2 billion years ago.

·         Multicellular life evolves, first as colonies, then as multi-celled creatures.

·         Life colonises the surface, first as lichen, then as other flower-less plants. Eventually, sea creatures evolve to live on land, around 600 million years ago.

·         Land animals diversifies through evolution. Mammals branch off from reptiles about 240 million years ago. Birds branch off from dinosaurs about 70 million years ago. Flowering plants appear.

·         One particular branch of mammals evolve intelligence, tool making, abstract language and upright stance, starting from about 3–7 million years ago. Our particular species appear 150,000 years ago. They start to domesticate animals and plants, starting with dogs around 20,000–40,000 years ago. Plants were domesticated around 13,000 years ago.

To reconcile these two views of how the universe and us came to be requires a lot of squinting. I’m not talking about the “day” thing in Genesis; that is a particular use in English, and the Hebrew word can be interpreted as “era” or “epoch” rather than “day”.

However, Genesis and science do not agree on the order or even on the nature of things. For example, the Genesis story explicitly says that fruit-bearing trees (i.e. flowering trees) appear before animals; however, fruits are linked to flowers, and flowers require something to do pollination (insects or small birds) which are only created the following day. The Genesis story also places the creation of domesticated animals before the creation of humans; from archaeology and anthropology, we know that wolves were the first animal to be domesticated to dogs by humans.

So in order to make the Genesis story compatible with the evidence at hand, you have to squint a lot and assume that the Bible authors completely misunderstood when God tried to teach them about big bang cosmology, astrophysics and biology.