Timeline of human history - Timeline 1: 13,800,000,000 BP to Present. Origin of the Universe. Origin of the Sun, the Earth, the Moon. Origin of Life

Timeline of human history
version 2 - by Finn Sivert Nielsen

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Timeline 1 - 13,800,000,000 BP to Present
Origin of the Universe. Origin of the Sun, the Earth, the Moon. Origin of Life

According to physicists who concern themselves with such matters, the universe originated about 13.8 billion years ago in what is known poetically as the "Big Bang", when an essentially massless, sizeless and timeless bubble of some unknown but highly concentrated kind exploded and sent the debris of its explosion rocketing outward in all directions (thereby no doubt creating direction, which could not exist in a sizeless pre-Bang state) at immense, but slowly decelerating speeds. At an early stage of the explosion (i.e. after about 0.00000000001 seconds) it becomes clear that there is more matter than anti-matter out there, thus assuring that the universe being created - our universe - consists of positively charged protons and negative electrons, rather than vice versa. (What that means in practical term is anyone's guess, but no doubt the consequences are fundamental.) Once this crucial stage is reached, atoms may form, and out of them the first stars and the heavy elements that can only be created inside stars. About halfway between the universe's origin and the present day, two pivotal events take place. First, about 8.8 billion years ago, the first stars of the same type as our sun appear, and around such stars it is more likely that the carbon-oxygen-hydrogen environment that characterizes our Earth's atmosphere will form. It took another 4 billion years for that likelihood to be realized here on Earth, but perhaps, in the course of all that time and all that space, similar conditions may previously have occurred elsewhere. Secondly, and perhaps of less immediate (but definitely more long-term) relevance, at around 7.5 billion years BP (Before Present) the still-expanding universe had thinned out its limited stock of matter to the extent that gravity (which attracts matter to matter) ceased to slow the universe's expansion. Instead, obscure forces in what is known as "dark matter" assure that the universe from now on will expand at an accelerating rate, and that in some distant future, a creature possessing eyes and a brain with similar visual faculties as our own, may look out into a clear night sky and see no stars at all. Around 4.5 billion years ago on the timeline, the abstractions of physicists are replaced by the somewhat livelier and more concrete data of geologists. We see the solar system condense out of a gas cloud, with the sun at its center, taking up most of the available matter, and the planets formed from tiny fractions of the matter left over. During the early days, the sun was orbited by a disk of large and small debris, constantly colliding and reforming. Some agglomorations were more successful than others and became planets, not all of which followed regular orbits. Thus, less than 300 million years after its formation, the Earth was hit by a mars-sized planet, drawing out a great plume of the mass of both planets that in time congealed to form the Moon. A mere 130 million years later, the Earth has a stable crust, its first oceans are forming, and plate tectonics, the movement and collision of continents, the opening and closure of seas, the rise of mountains and rifting of land, will soon commence. But even before that, a mere 150 million years after the first seas form, paleontologists find the first evidence of life on Earth in those primal seas. Life, it would seem, is endemic to Earth, and perhaps to any planet with a chemistry and gravity similar to Earth's. Life, as the timeline also shows, seems able to survive just about anything. Two planet-wide glaciations lasting several hundred million years did not even phase it. However, the endemic and all-surviving life we're talking about is very simple: unicellular bacteria and simple multicellular microorganisms - i.e. slime. For most of Earth's history, that's what life amounted to. Complex life - i.e. more complex than slime - arises a mere 542 million years ago, in what is known as the Cambrian Explosion. We shall return to this event in the next timelines, but you should note the following immediately: Slime-life may be endemic to Earth-type planets, but the chances are that complex life is not endemic. On the timeline, it arises so late as to be almost an afterthought.