The introduction to this book raised four “frontier questions”, science’s greatest unsolved mysteries. The first two frontier questions are addressed in this chapter alone. According to science, life and the universe appeared on the order of ten billion years ago.
The double timeline below shows the ten-billion-year timescale. The upper bar portrays some phases in the history of the universe, while the lower bar focuses on the Earth and solar system. The eons of Earth’s long-term history appear only at the tail end of this time scale.
Section II opens with the current understanding of the big bang. The long history of the early universe is essential to understanding the origins of the Earth and what we are made of, so it is covered in Section III. In section IV, we visit the sun and Earth as they were “under construction” during the hellish Hadean Eon, 3.8 – 4.5 billion years ago (BYA). Section V is devoted to Earth’s Archean Eon, when rocks solidified and chemistry advanced to the first signs of life.
- Big Bang, galaxy, sun, and Earth icons all reproduced by Pixabay license. Big bang by OpenClipart-Vectors, https://pixabay.com/vectors/bang-explosion-noise-onomatopoeia-148261/ . Galaxy icon by OpenClipart-Vectors, https://pixabay.com/vectors/galaxy-magical-adventure-spiral-1294347/ . Sun icon by CycledeKrebs, https://pixabay.com/illustrations/sun-day-rays-sun-s-rays-1075154/. Earth icon by eirabirkhammar, https://pixabay.com/illustrations/earth-icon-globe-world-4960147/ . Bacteria icon = Twitter’s open source “microbe” emoji, Unicode U+1F9A0, CC BY 4.0 license, https://creazilla.com/nodes/55938-microbe-emoji-clipart. All icons on this timeline accessed, saved, and archived 9/12/20. ↩
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