Our Universe we live in
A small journey through “our” universe.
Fourteen billion years ago, there was only chaos. Everything that we see, hear or touch today was inside a momentous point — a singularity. This was a point where time stood asymmetrical. The past beyond this point had no meaning. Now, a gigantic bang, a sudden expansion — we name it The Big Bang. This Bang gave birth to our universe. The remnants of this phenomenon can still be seen — even by tuning an old television to the correct frequency —a relic radiation of a massive explosion we now call the Cosmic Microwave Background Radiation (CMBR). This radiation is about 2.725 degrees (Kelvin) above absolute zero.
The idea if Inflation is an intriguing one. The Universe, before it was a hot mess, was cool and empty in matter, but filled with something called an Inflation Field. Picture some calm sea filling up the entire universe. This strange field made any given patch of space double every 10^-37 seconds. This is what sudden inflation is. After this inflation stopped, due to its energy field, the universe kept expanding and producing particles.
Universe, as it grew older, gave birth to stars. Quarks, gluons, electrons and other fundamental particles, as the universe expanded from The Bang, joined together forming larger particles, and elements, like Hydrogen and Helium were made. These elements formed clouds of gas (called Nebulae, for “mist” in Latin), spread in a vast arena in space, ultimately collapsed by their own gravitational attraction. These collapsed gasses, when their core temperature rose beyond 2,000K, began their ultimate journey as a star, by starting fusion reactions. After the stars gain the sufficient mass to sustain these reactions, they get officially crowned as main sequence stars (the definition uses two variables: Luminosity and Color), where they escape the ultimate fate of a protostar, which is a star that failed to ignite.
Life, hasn’t yet found its way. The origin of life, requires the universe to produce heavy materials — carbon based molecules. The Bang failed to produce Carbon [1]; it produced mostly Hydrogen and Helium, just to create nebulae. How did life appear?
Life, finds its way
Life appears following a great tragedy. The origins of life can be traced back to the stars themselves. More massive stars, once they end up the fuel supplies to essentially produce Helium by fusing Hydrogen atoms (and if the energy permits, Hydrogen fused into heavier materials such as Carbon), starts to lose the delicate balance between the gravitational pull of matter towards the center, and the force of pressure outwards generated by the heat produced in fusion reactions. When the latter diminishes, the star starts to collapse on its own weight, and depending on its initial weight, it will endure its doom either as a white dwarf, neutron star or a singularity (black hole), and all these forms curve spacetime significantly to increasing extents, since their density is too great. When the dead star stabilizes to its final state, a huge burst of energy is released, along with the materials which were produced inside the cores. The leftover debris (along with heavy materials) shine — we call it the “Supernova”.
“The nitrogen in our DNA, the calcium in our teeth, the iron in our blood, the carbon in our apple pies were made in the interiors of collapsing stars. We are all made of star-stuff” — Carl Sagan (Cosmos)
Our lonely habitat - “The Pale Blue Dot”
When the Sun, the star which lights us, was an early protostar, the leftover debris — essentially dust grains — in the space started to accrete, and attract to form clumps of debris, which was essentially the origin of planets. Small worldlets formed this way collided, and merged to form bigger, more massive worldlets, which were essentially molten metal. The birth of our home — The Earth — was a similar phenomenon. As the surface cooled, the crust solidified, and at the center lies a molten core of iron, which is responsible for Earth’s magnetic fields.
But not all the planets share the same nature. Mercury and Mars, due to their mass, have rocky cores all the way into their centers. Unlike terrestrial planets, the outer planets with larger cores like Jupyter and Saturn, are gaseous planets, that is, their composition is mostly of gas. This is due to their relatively massive cores, they attracted most of the remnant gas volumes leftover from sun’s condensation.
Our home, is ready
Life can find its way in many places now, since the ingredients are at place. But as far as we know, the Earth is the only place we know that life ascended (complex life). There is a missing ingredient: atmosphere.
For an atmosphere to form and persist, it is said that the habitat should be placed in a Goldilocks Zone (the metaphor comes from the story “Goldilocks and the three bears”, where the little girl tastes soups of the three bears and finds the little bear’s soup not too hot, not too cold, just right). Mercury and Venus is too hot for life to arise, at least for life as we know it. Mercury is said to be the “winged messenger of Gods” [2], and Venus, the “goddess of love and beauty” [3]. Mercury orbits the sun over 47 kilometers per second, proving that it is a winged messenger (although we’ll never know whose message it carries). Venus is so named because its charming and elegant view in the night sky.
However, Venus and Mercury are fiery chasms. Venus, for all its beauty and serenity that seems to the Earth, is comprised of a runaway greenhouse effect which creates a light-diffracting atmosphere due to high pressure. It constantly rains sulfuric acid forms in the upper atmosphere, thus generating a heavily toxic environment for life to arise. Venus, for all we know, resembles Hera, the beautiful Greek goddess who sent two snakes to strangle Zeus’ son (Heracles) to death [4] (which eventually failed, but evil — an act of jealousy — seldom ceases; she caused Heracles to go insane and kill his family).
4.55 billion years ago, the Earth was good as new.
Life starts to arise
At first, our home was barren, but it was visited. It was visited by meteorites. It is now suggested that these alien visitors carried water and organic compounds that life inherits today [5]. Stray comets or asteroids traveling near the sun getting their icy-surfaces melt and careening towards the Earth might as well be the best (or worse, regarding how we treat to our planet now) thing that has ever happened to the Earth. Seas started to form, and inside those seas, a primordial “organic soup”. One mischievous molecule — now a creature — starts to create crude copies of itself, and the principle of survival takes hold. Natural selection makes these creatures flourish in the primordial waters. It was not sudden, but it was the efflorescence of life.
But we must take notes on one thing: by the time complex forms of life arose, the atmosphere was not barren. It was just right. Oxygen produced by early life forms (single-celled organisms taking cyanobacteria inside them and replicate themselves photosynthesizing) and carbon molecules in the atmosphere combined together made Carbon Dioxide, which warmed the planet forming a greenhouse effect. Without the greenhouse effect, life as we know it would not have flourished (although, a different kind may have appeared).
Age of Humans
History we now start to look for, was written by bone and blood. The early Earth flourished with creatures which aren’t familiar to us today. The Earth is a cleansing machine — it clears out the old for the new. There have been five massive extinction events in the history of our planet: Ordovician-silurian, Devonian Extinction, Permian-triassic Extinction, Triassic-jurassic Extinction, Cretaceous-tertiary Extinction. The first two were cleansing of small marine life forms. The next two left the dinosaurs to rule the planet. The last extinction shone the last sun in the last long day for the dinosaurs.
Prior to the last of the five massive extinctions — the Cretaceous extinction — dinosaurs ruled the earth. Mammals lived hidden. Thus, afterwards, mammals started to roam on lands they’ve never trod free. In the next 10 million years, the mammals started to evolve three times faster than in the previous 80 million years [6] — a speedy evolution.
Along the timescales of flourishing mammals, a strange creature started to appear in African savannas, migrated to different lands, and evolved. Either by another extinction — but this time, by war — or interbreeding with one another (two separate theories), this creature turned out to be modern-day humans, Homo Sapiens.
Progress! (Or, is it?)
Humans started to evolve more and more. Following the agricultural revolution, they artificially selected the creatures as they wanted. For example, the domestic dogs who naively do go-fetch, were once proud grey wolves strategically hunting their pray as a pack. But at an early point in time, in one of the Ice Ages when hunting was difficult, they were drawn to the leftover carcasses hunted by humans. Gradually, they started to form two-way relationships, where the wolves helped to hunt with men, and men provided leftovers in return. We tamed most of the creatures that we see today, both flora and fauna: including wheat, cattle, maize, potatoes, chicken, rice, horses, apples, and humans ourselves [7].
Then came the industrial revolution, where we developed many artifacts — the steam engine, factories and other industries took hold. Better healthcare systems helped the population skyrocket. Industrial waste also skyrocketed, along with releasing toxic gaseous clouds of Carbon Dioxide and Methane into the atmosphere.
Citizens of the Cosmos
Ever since we’ve revolutionized the industries, we’ve developed long networks of roads, plastics, nuclear waste and toxic chemicals which lay down doom to our only home. Some of us — the educated, a subset of people — acknowledge the harm we have doomed upon, and have started to act. Clean energy without burning fossil fuels have become one of the fundamental priorities in the world. This subset knows that even after the Holocene extinctions, life found its way. Life evolved even after catastrophe, and it left traces of what it once was. The Anthropocene — human-driven change to our planet — also will leave traces for future archeologists. These footprints will not be written in bone and blood; they’ll be written in the very same network of roads, toxic materials and the like we produce today.
Different epochs, different fossils.
Meanwhile, the technological development bestowed by the growth of our intellectual prowess is magnificent. We have already ventured to the moon, and have sent robot emissaries to Mars, 72 million kilometers away from home. We have achieved the impossible, and we keep expanding the horizons. We’ve found water molecules on the moon [8], and will plan on having temporary refueling stations there when we set sail on to Mars [9], or to another distant planet. We have sent emissaries out of our solar system, and they are still active up to this date. We have uncovered the grandest of mysteries, including the birth of the universe and the supermassive black holes lying at the center of the galaxies. We’ve observed images of black holes, where light goes to its doom leaving only a ring of fire for us to see.
In ancient Samos, following a giant awakening of intellectual prowess, great theories emerged. We’ve followed most of those theories, and ventured into places where no one has ever gone before. The early Ionians knew that we were part of the universe, and the place we live is just a speck in the cosmic ocean. Following great tragedies, the great Ionian civilization broke down, along with most of their grand theories. A few survived, and they keep amaze us to this day.
The great Ionians dreamt of venturing into the stars. And we are on our way. We are on our way to our own birthplace.
If we heal our home that we ourselves have wounded now, if we can remedy the great man-made extinction that is apparent just beyond the horizon, we, as we’re packing to venture into a different galaxy in the future, can bid a warm farewell to our home when the sun is on its death throes. We, as a species, can be satisfied of a life well lived — made mistakes, yes, but rebuilt, together — on a once-desolate planet, turned into a beautiful home teeming with life. We’ll be grateful for the shelter our blue planet gave us as we board our fusion-powered interstellar spaceships, and it will wish us back on its death throes, a good luck, with no hard feelings.
Then, and only then, we become citizens of the cosmos.
References
[1] Life in the universe: https://wmap.gsfc.nasa.gov/universe/uni_life.html
[2] Mercury: https://en.wikipedia.org/wiki/Mercury_(mythology)
[3] Venus: https://en.wikipedia.org/wiki/Venus
[4] Hera: https://greekgodsandgoddesses.net/goddesses/hera/
[5] Zimmer, C. (2005). How and Where Did Life on Earth Arise? Science, 309(5731), 89–89. doi:10.1126/science.309.5731.89
[6] Our ancestors evolved faster after dinosaur extinction (Science Daily): https://www.sciencedaily.com/releases/2016/06/160628221710.htm
[7] Roberts, A. M. (2018). Tamed: Ten species that changed our world. London: Windmill Books.
[8] Water on moon: https://www.npr.org/2020/10/26/927869069/water-on-the-moon-nasa-confirms-water-molecules-on-our-neighbors-sunny-surface
[9] Refuelling on Moon: https://www.space.com/30838-manned-mars-mission-moon-refueling.html
The facts are mostly from:
- Sagan, C. (1985). Cosmos: Carl Sagan. NY, NY: Ballantine Books.
- KUKULA, M. (2016). INTIMATE UNIVERSE: How the stars are closer than you think. S.l.: QUERCUS PUBLISHING.
- FARRIER, D. (2021). FOOTPRINTS: In search of future fossils. S.l.: PICADOR.
