The Cosmic Calendar

This is a different calendar. No, it is not a 2023 calendar. At 00:00:00.0000000000000000000000000000000000000000001 hours, a new drama begins, albeit a cosmic one. The story of space and time, violently bursting from a singularly dense point, containing all the matter-energy content of an entire universe. But the fascinating event, outshining the creation event, will not happen until 11:00 on the night of December 31 of the cosmic calendar. Whoever you are, whatever you are, whenever you are, can you guess the event?

I am talking about future humans. Their modern civilization will only start on the mark of the last second of this cosmic year. This cosmic calendar, as they will later name it, will help them identify their place on a colossal scale of events. When they finally learn of their part in this cosmic drama, they will find it very hard to explain their origins and the origin of the universe they experience. When it first arises, life will seem to be the universe's attempt to break away from mathematical abstraction. You can not mold life into a fixed set of mathematical equations. Life has the immense potential to spontaneously arise on some particular planet in ultra-simplistic forms and evolve into complex organisms and intelligent beings. As far as I can see, life has the potential to conquer different planets, leave its mark across the entire universe, create its universe, and escape into a different universe or a multiverse, worlds without end in an endless multiverse of multiverses. Who am I, if you shall ask? I am someone who likes to read the Book Of Nature. I have come across a very obscure page filled with mathematical equations that say something about the birth of a particular universe and what happened before. Unfortunately, I can not read that far. As it goes, this page tells me that something incredible will occur on the night of December 31. 

This page that I am on condenses the events of the next 13.8 billion years into a single calendar year, with the big bang happening at 00:00:00.0000000000000000000000000000000000000000001 hours on January 1. On this mega calendar, each month of cosmic time represents 1.15 billion years of ordinary time, nearly 40 million years for a day, a minute for every 30,000 years, and 437.5 standard years equals a cosmic second. Since a lot happens within the first cosmic second, the book advises me to change scales, following the human notion of time. In fact, at this hour, events occur so quickly that in about 3 (regular) minutes after the big bang, the standard model nears completion. 

As per their mathematics, time, as they will know it, began somewhere during the Planck Epoch - 10⁻⁴³ seconds after the explosion of the initial space-time singularity. Before the first second elapses, the universe cools from its initial temperature of more than 10³² K to 10¹⁰ K and forms the cosmic neutrino background. The three fundamental forces, electromagnetism, the weak nuclear, and the strong nuclear force, diverge from the gravitation force at 10⁻³² seconds. Inflation expands space by a factor of 10²⁶, and the mean temperature of the universe drops down to 10²² K from a staggeringly high 10³² K, also known as the Planck Temperature. At this stage, the strong nuclear interaction becomes distinct from the electroweak interaction. At the nick of 10⁻¹² seconds, the Higgs bosons and the W and B vector bosons go through various fundamental interactions. The observable universe radially extends to 300 light seconds. Quarks fully form on the mark of 10⁻⁵ seconds. Quacks, on the other hand, December 31. By 1 second, quarks bound into hadrons. Neutrinos break part from the thermal equilibrium and form the cosmic neutrino background. Baryons form. By this time, the observable universe extends to a radius of 10 light-years. Leptons form on the mark of 10 seconds. And in the next 100 seconds, protons and neutrons become stable entities. As the universe cools down to 10⁷ K at the end of the Big Bang Nucleosynthesis Era, light atoms such as hydrogen, helium-4, deuterium, helium-3, and lithium-7 form. Space expands to a radial extent of 300 light years. The Photon Epoch begins at 10 seconds. By this time, the universe cools down to 4000 K, and the spherical volume of the observable universe expands to 42 million light years in radial extent. 

The Photon Epoch lasts from 10 seconds after the Big Bang to 370,000 years. In terms of cosmic time, it lasts for 14 minutes or so. From one minute into the cosmic year, i.e., when the universe is more than 25,000 years old, atoms exist as neutral species, and photons are no longer in thermal equilibrium with the nascent universe. They are free to wander. Up to this point, the universe was so dense that photons (aka light) could not find their way to travel freely from one part to the other part of the universe because the mean particle density plummets to 500 million hydrogen and helium atoms per cubic meter of space. The universe progressively dilutes away with each passing second into the cosmic year. The Cosmic Microwave Background starts to leave its impression as the oldest form of electromagnetic radiation, filling all of space and acting as a barrier, hiding the initial singularity from the reach of future humans. But who knows, they might find it one day. The CMBR forms somewhere after 14 minutes into the cosmic year. As the CMBR starts to leave its imprint, the universe enters the Dark Ages, lasting for the next few days of the cosmic year. 

A spectacular event happens on January 10. The first star is born. In this period, corresponding to 378 million years of the human scale, give or take a few, the universe has gone through the Cosmic Dark Ages, an epoch sandwiched between that of Recombination and the formation of the first stars. During this time frame, the universe expands, and the CMB photons redshift to infrared. As a result of this continued expansion, the universe becomes completely dark, and therein the dark rises the first population of stars. In ten days since the big bang, the universe cools down to 60 K, a temperature low enough for gravity to attract the hydrogen molecules, the major constituents of the nascent universe, into isolated clumps and initiate nuclear fusion, thereby creating the first stars. One by one, each star blazes up like a bright beacon slicing its way through the cosmic darkness. From this day onwards, until a trillion years into the far future, the universe will not be dark anymore. By January 13, gravity gathers these earliest stars into the first minor galaxies and then into massive galaxies. The stars at this epoch grow to enormous sizes, with their surface temperatures crossing the 100,000 K mark. Some even directly collapse into black holes. Regrettably, these stars have short lives. They die in cataclysmic supernovae the day after they are born. As they die, they enrich the interstellar molecular clouds of hydrogen gas by blasting them with radiation, triggering the formation of the next generation of stars. Stars and galaxies continue to evolve for the next few months of the cosmic year. 

The Cosmic Calendar spiraling outwards from the Big Bang event that happened 13.8 billion years ago until the present day
Image Credits: Public Domain, via Wikimedia Commons

March 15 of the cosmic year. Another important day. The Milky Way Galaxy continues evolving from this date onwards. Humans are yet a long way from throwing their first cry into this universe. Do you wonder why? It is because their galaxy is still young and metal-poor. Life requires heavy elements like carbon, oxygen, nitrogen, calcium, magnesium, iron, and silicon, including other species of the periodic table. Stars that shine through this phase of the universe are acting like giant cauldrons, cooking in their hearts, the entire periodic table. Stars are like phoenixes - arising from the gases of the dead. Metal-rich Population I stars will begin to shine one by one from April onwards as more and more Population III and II stars go banging into the night. Mankind's life-giving Sun is being conceived somewhere within the Milky Way Galaxy. Bit by bit, somewhere in the Milky Way, clumps of gas are collapsing onto a central region, with more and more gas accreting around the proto-star.

August 31. Sol is born. 

Earth forms on September 2. Within days, another protoplanet, the size of Mars, collides with the young rocky Earth, giving birth to the moon, the only natural satellite Earth will ever have. The future humans will mark this day, September 6, as the moon's birthday. The rest of the solar system - Venus, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto, are all born on the first week of September. Across the universe, hundreds of billions of stars and galaxies evolve into exotic star systems, galaxy clusters, globular clusters, voids, filaments, and large-scale structures into a complicated mesh qualitatively mimicking the future human brain. 

September 14. A special day for mankind. For the past eight days, Earth has developed giant landmasses, island chains, and a great expanse of liquid water ocean, seas, rivers, and lakes. Now somewhere in the water, life arises for the first time. The first organisms are microscopic little beings capable of self-replicating and leaving behind progenies, which in the long run, a couple of months into the cosmic year, evolve further to walk the surface of the Erath as upright men. 

A series of remarkable happenings happened in the last three months of the cosmic year to the last second on 31st December of the cosmic year. Let me try my best at a comprehensive list. 

• September 21 - Prokaryotic life evolves.
• September 30 - The mechanism of photosynthesis begins. 
• October 29 - The net oxygen content of the Earth's atmosphere gradually increases.
• November 9 - Complex cellular organisms, eukaryotes, come to life.
• December 5 - Multicellular life kicks in. 
• December 7 - Simple animals evolve.
• December 14 - Arthropods evolve. 
• December 17 - Fish and early amphibians make their mark. 
• December 20 - Land plants. Hours later, Earth witnesses a devastating event. The first mass extinction - the Ordovician-Silurian Extinction, eliminated nearly 85% of all marine species.
• December 21 - Life rebounds. Insects and plants continue evolving. 
• December 22 - Amphibians roam across the land. For the second time, life on Earth goes through another mass extinction event. The late-Devonian extinction wipes off 50% of all genera.  
• December 23 - Life rebounds once again. Reptiles dominate the land. The next day, 57% of all biological families and 83% of all genera go extinct through the Permian-Triassic Extinction event. 
• December 25 - Dinosaurs tower over the land. 
• December 26 - Primitive mammals hide in the shadows. All life on Earth faces the fourth mass extinction event. The Triassic-Jurassic Extinction wipes away the dinosaurs, clearing the Earth for primates due three days. 
• December 26 - Birds take the sky. 
• December 28 - The first flower blooms. 
• December 28, 6:24 A.M. - A massive asteroid strikes Earth, with the Cretaceous-Paleogene Extinction event marking the rise of the first primates.

Once again, I have to change scales, for I have come to the last day of the cosmic year.

• 06:05 hours - Apes dominate on the land.
• 14:24 hours - Hominids arrive.
• 22:24 hours - Primitive humans leave their footprints on the wet Earth. They start making stone tools.
• 23:44 - Humans domesticate wild animals.
• 23:52 - Modern humans stand upright, staring at the distant horizon. 
• 23:58 - Humans learn to sculpt and paint.
• 23:59:32 - Humans discover agriculture.
• 23:59:47 hours - Humans invent writing.
• 23:59:48 hours - Ancient civilizations flourish.
• 23:59:55 hours - Ptolemy writes about astronomy.
• 23:59:59 hours - The last second. All of the modern human civilization exists in this final second. In this second, humanity learns the art of flying, leaves its footprint on the lunar soil, and within a blink of an eye, launches the JWST. But somewhere, almost heartachingly, they threaten their own existence. Every once in a while they follow the wrong turn. 

In the Book of Nature, I find the next page blank. I suppose the best story is yet to be written. 

Inspired by Carl Sagan and Neil deGrasse Tyson.