BEGINNINGS
From The Big Bang To Human Beings
1. BEGINNING OF THE UNIVERSE
About 14 billion years ago, all matter and energy were compressed in a dime-sized area of infinite density called a singularity. There was no time, no space and no natural physical laws. In a super-fast smooth and silent expansion paradoxically called The Big Bang, the universe was created.
1 second after the Big Bang, atomic nuclei of hydrogen and helium began to form. This lasted about 3 minutes. 1 million years later, stable hydrogen atoms form and 100 million years later, the first star began to shine.
90% of all matter is unseen dark matter which provided the gravity that is required to form galaxies; and 75% of all energy is dark energy which is causing the continuing acceleration in the universe's expansion.
2. BEGINNING OF THE GALAXIES
A galaxy is a cluster of stars, dust and gas held together by gravity, measuring from thousands to hundreds of thousands of light-years across (one light-year is about 9.46 trillion km). The first galaxies formed about 2 billion years after the Big Bang and most were formed by 7 billion years. There are about 125 billion galaxies.
Our Sun is one of 100 billion stars in our Milky Way galaxy which is a spiral galaxy with a huge black hole at its center. Our Milky Way galaxy is just one of 30-odd galaxies in the Local Group.
3. BEGINNING OF A STAR
A nebula is a cloud of dust and gas in space and when disturbed from within, collapses into a ball of gas called a protostar. As its hotness increases, thermonuclear fusion turn hydrogen into helium causing radiation of heat and light.
As the star ages, its hydrogen fuel is used up and it begins to cool, swell and become a red giant. Later, its outer layers begin to drift away leaving behind a small, hot, dense and luminous white dwarf. But the red giant of the biggest stars will instead undergo a supernova explosion leaving a dense core called a neutron star while causing shockwaves that trigger the birth of new stars. Sometimes, the shrinking core spins and emits radiowaves causing the appearance of a pulsar. A neutron star may shrink further into a black hole.
4. BEGINNING OF OUR SUN
Our Sun is a middle-aged star at about 30,000 light-years from the core of the Milky Way galaxy, on the spiral arm in the Orion constellation. From a cloud of cosmic dust which was battered by shockwaves of a supernova, it was formed about 4.57 billion years ago. It has been estimated that its hydrogen fuel will run out in 1.5 billion years, will swell to become a red giant while destroying the Earth and other inner planets in 5 billion years, and eventually become a white dwarf.
5. BEGINNING OF THE EARTH
Earth was created more than 4.5 billion years ago shortly after the formation of our Sun. Only a few tens of millions of years later, it collided with possibly another planet shearing off material into space which was later to become the moon. For its first 500 million years, it was in a molten state whereby under the influence of gravity, heavier elements sank to its core and the lighter elements floated to its surface. About 4.1 billion years ago, a crust formed when increased gravity attracted gases, including water vapor, to its surface. Between 4.1 to 3.8 billion years ago, it underwent the Late Heavy Bombardment period when it was battered by meteoroids, asteroids and comets which added mass to it.
6. BEGINNING OF LIFE
Water which is an absolute prerequisite for life was present together with an atmosphere of nitrogen, carbon dioxide and hydrogen 3.8 billion years ago. Life on Earth began 3.5 billion years ago when clay crystals, formed from silicates, trapped carbon, hydrogen and nitrogen molecules to their surfaces, modifying them and allowing them to free themselves from the clay environment. Thus freed, they replicate independently and assemble themselves into nucleotides which joined together to form DNA. Self-replication of DNA and RNA and through catalysis by enzymes formed amino acids which also joined to form proteins. Another essential step was the formation of a primitive cell wall that encapsulated and kept the polymers together.
Alternative theories include the formation of the primordial soup in niches on the ocean floor called hydrothermal vents and the possibility of life on Earth starting after seeding with microbes from space.
7. BEGINNING OF HUMANS
The earliest human ancestor skull of the bipedal species Sabelanthropus tobadensis ('Toumai') was discovered in Chad in 2001-2002 and was dated to be 7 million years old. A 5.8 million year-old fossil of a Orrorin tugenesis species, also upright-walking, was found in northern Kenya in 1974.
A 3 million year-old almost complete skeleton of the species Australopithcus afarensis ('Lucy') was uncovered in Ethiopia in 1974. This species not only walked on 2 legs, it had human teeth, though it still had a smaller brain than us. Yet, in 1964, the 2 million year-old larger-brained and tool-using Homo habilis ('Handy Man") which possessed opposing thumbs was discovered in Tanzania.
Next, Homo erectus ('Upright Man') was able to control fire and cook his food from 2 million to 200,000 years ago. The Homo sapiens species ('Wise Man') found in Ethiopia walked the earth between 200,000 to 150,000 years ago used their brains to develop language and culture, and had a much less ape-like face. We are the direct descendants of the Cro-Magnon Man of the Homo sapiens sapiens species who lived 40,000 to 10,000 years ago.
The Neanderthal Man (Homo Neanderthalis) was our extinct cousin species which vanished 30,000 years ago.
8. NEXT JOURNEY
It took us 14 billion years to get from Big Bang to Homo sapiens sapiens. Where do we go from here?
