A short history of the entire universe, or an apple pie recipe

“If you wish to make an Apple pie from scratch, you must first invent the universe.”

Carl Sagan

This is my attempt to summarize the history of the entire universe into a single post. Understanding the deep history and underlying principles (entropy, complexity, natural and cultural evolution) are some of the most critical things you can possibly know about. What else could be more fundamental, more profoundly satisfying? As complex assemblies of particles, the very by-products of this deep cosmic history, we stand here as conscious, self-aware bags of atoms that can peer into the inner workings of reality and contemplate the nature of existence.

From our fiery cosmic origins, the birth of stellar engines, the evolution of staggeringly complicated replication machines known as life, to the marvelous invention of civilizations, there’s nothing more intellectually humbling and illuminating than the story of how the universe generated such exquisite levels of complexity.

Chapter 1: The cosmic egg
There’s no debate about the existence of the Big Bang. Using telescopes, we can currently observe stars moving farther away from each other at a specific acceleration and velocity. Wind the clock backward, and we can mathematically determine that around 14 billion years ago, everything started from a singular point. While we have no idea what created that singular point of infinite density, we do have an understanding of how that point unfolded with high precision. It was a singularity that was unimaginably hot, dense, and literally bursting with potential, rapidly erupting into all of space, time, and energy within a billionth of a second.

This volatile energy eventually cooled and coalesced into electrons and protons, the first concrete building blocks of the material universe. For a yawning 200 million years after, the universe was a cold, dark, and uninteresting place. Only the simplest of elements, helium, and hydrogen, existed as dull clouds in an endless abyss. 

Chapter 2: Stars are born
You might have heard the phrase, we are all made of stardust. This isn’t some new-age aphorism about the uniqueness of individuals. The statement is literally true, and it’s poetically profound.

As diffuse clouds of inert hydrogen and helium drifted aimlessly within this lifeless cosmos, there was another force at play: Gravity. Every minuscule particle exerted a whimsical force of gravitational attraction, weakly tugging at each other and closing the empty void between them. These particles started to clump together, collectively exerting an even stronger gravitational force and pulling even more of their fellow companions in their union of particles. 

Eventually, the clumps of helium and hydrogen reached such colossal masses that they get crushed under their own immense gravitational pressure. When they hit this certain critical mass and these particles get too uncomfortable close to each other, something remarkable happens. Their positively charged nuclei, usually separated by strong electrostatic repulsive forces from their whizzing electrons, are forcefully squished together and combined into a larger atom. This reaction, known as nuclear fusion, results in a prodigious amount of energy released as photons and radiation. 

For the first time in a few hundred million years of sheer darkness, the lights were turned back on. This is the birth of the first star.

At the core of this massive heap of particles, lies a stellar crucible where atoms are constantly fed in and explosively fused into larger atoms - creating an unending nuclear explosion. The only thing keeping the entire system from obliterating itself is the massive amount of gravity holding it together. That burning ball you see in the sky that you call the sun? It’s a giant nuclear bomb with trillions of detonations every second, held together only by its sheer weight. 

**Chapter 3: The party of elements
**
Flip open any chemistry textbook and you will find a neat array of elements listed in row and columns known as the periodic table. Almost every element is forged within the nuclear furnaces of stars. They are compressed one by one, creating heavier elements such as carbon and nitrogen, harmoniously composing the chemical symphony that makes up the periodic table. But how do they ever escape their stellar prisons to form all the interesting molecules that make planets, bacteria, skyscrapers, and humans? 

When stars use up most of their fuel or start to create heavy and destabilizing elements such as iron, they begin to collapse unto themselves under their own immense weight. The collapse happens rapidly, causing a shockwave from the release of gravitational potential energy in a catastrophically violent phenomenon known as a supernova. This is the most explosive event in the known universe, creating bursts of light that dwarf the normal radiance of a star millions of times over. The star spills its guts into space from the resulting explosion. Elements that have been forged over billions of years inside this cosmic factory are thrust into the galaxy.

The universe is no longer a boring place. It’s now teeming with a variety of exotic elements, swirling and coalescing into new stars and planets, setting the stage for the next phase of cosmic complexity.

Some of these particles repeat the same theatrical display again, forming a new star. The remaining debris, with sufficient angular velocity to escape the death spiral towards the star, start bumping into each other to form planets. One particular planet fell within conditions between extreme heat and cold - also known as the goldilocks zone. It eventually cooled from a molten ball of colliding asteroids into our cherished home, the life-harboring pale blue dot known as earth.

**Chapter 4: The spark of life
**
The definition of life itself is notoriously difficult to define. The actual process that led to the origin of life still remains one of the greatest mysteries. However, we do have some clues as to how it may have started.

As far as we know, there are three main ingredients required for life to exist. Firstly, it requires a mechanism to store information - a code of instructions that enables it to construct the vast machinery of proteins required for a living system, and a method to replicate that information down to another generation. We know this structure today as DNA. Secondly, it needs energy to power it. It requires a metabolic system to fuel the reactions and breathe life into the code. Without this energy gradient, there would be nothing to generate the intricate dynamism of the system. Lastly, it needs a boundary between the external environment and itself. It needs something to contain the concentrated mix of reactions and keep it from diffusing out into the world. 

This is where the big dispute among scientists come in. Some firmly fall within the “information first” camp, declaring that without a mechanism to retain and replicate the information, there is no starting point, no original source code to work with. Others fall into to “metabolism first” camp, arguing that without an existing energy gradient, there can’t be any active dynamics within the cell - information is useless if there’s nothing to drive the processes. The last problem of having a boundary seems to be the easiest to solve. Phospholipids, or fatty acids that have a hydrophilic and hydrophobic end (one side like water the other doesn’t), naturally form bubbles or membranes that can help create the walls to house proteins and processes. 

It seems like some rudimentary form of information storage and metabolic process must have occurred simultaneously, an event bordering the miraculous, to kickstart the gears of life. There are many candidate hypotheses for this, including RNA world and deep thermal vent conditions that may facilitate both. It’s beyond the scope of this story, but I do hope you will continue to explore this fascinating topic on your own.

What we do know is that a single cell, out of sheer will against entropic forces, managed to bootstrap its way into existence and become the first progenitor for all life on earth. Once that cell began replicating, it set the stage for the greatest show on earth: Nature, in all its dazzling variety and forms.

**Chapter 5: Life explodes
**
Evolution might be one of the most widely known concepts, but also one of the most poorly understood. Darwinian evolution is usually referenced as one of the most brilliant insights of modern science. The process is so simple, so elegant, yet capable of generating unfathomable complexity and variety. The way it works is as follows. First there must be a population that has unique traits and characteristics. Next, there has to be a selective process, picking out winning combinations of genes that survive in the environment. Lastly, there needs to be a way for this legacy of winning traits to be passed down to the next generation. The last part is tricky, the information must be copied with high precision for the adaptive traits to be passed down successfully, but not too perfectly as to prevent new mutations that could prove advantageous. It’s a blind process without an end goal. It does not aim to make living things smarter, stronger or faster, it simply selects the survivors. This simple mechanism, known as natural selection, drives the endless beautiful and cruel existence of all living creatures.

Now back to our lonely cell. Once that single cell came to be, single celled organisms quickly enveloped the globe, inventing complex internal mechanisms and a multitude of varieties. However, to an outside observer, things stayed relatively uninteresting for the next billion years. Despite the flood of single celled organisms giddily proliferating across the globe, there were no obvious signs of life. No flora grasping towards the skies, no elegantly streamlined fish darting through the oceans.

Some cells evolved to become Cyanobacteria - think of them as the original plant like cells. They had the ability to absorb photons from the sun and convert them into energy. The ingenuity of how molecular machines were able to capture single photons and process them is simply astounding. 

In a massive oversimplification, they are able to capture a photon, and through a series of chemical engineering steps, push an electron to a higher energy state in a molecule. This molecule is known as ATP, and is the universal energy currency that powers all life. Electrons naturally want to fall into their lower energy state, much like how a ball would have the tendency to roll down in a flight of stairs. This is the same mechanism that powers every living process. ATP uses its electron in a higher state to “roll down” and power a biochemical process. As it’s famously been said, “All life is an electron trying to find its resting place”. 

Without the invention of photosynthesis, there would be no way to capture the infinite source of energy pouring of the skies, and they wouldn’t have flooded the atmosphere with oxygen, the necessary precursor for all complex life. 

**Chapter 6: Complex life takes the stage
**
Vision, movement, warm blood, sex - once evolution started churning it’s gears, it produced unbelievable biological inventions, each deserving a book on it’s own. For our purposes, those single cells eventually turned multicellular, and that led to an explosion of forms over the next billion years.

Humans, believe it or not, are ancestors of these ancient cells. We are part of an unbroken chain, with the original DNA molecule that existed 2.5 billions years ago replicating itself and passing down it’s code to the next generation, all the way down to you. Well not just you, but every other living thing. That’s right, every single life form is your distant relative. We’re not just talking about chimpanzees and dogs, we’re talking about fish, bananas and bacteria. With the cracking of the genetic code, we can statistically work out how distant we are from other species with high precision. We are all part of that same tree of life; a common ancestor and heritage links us all.
Our closest cousins are Chimpanzees. We were once the same species before diverged around 6 million years ago. Each species slowly accumulated slight changes every generation since to look the way we do now.

For a long time, we existed very much like the rest of our cousins. Like screams in the wind, we toiled and suffered to simply exist, but faded out of existence just as quickly. But out of nowhere, something happened. We started to tear away from the pack, wrecking ecosystems, and transforming the lands around us. And no, this isn’t after the industrial revolution and pollution, this was before we even learned how to write.

Stay tuned for part 2, where the story of humans begin. I promise that there will be an apple pie recipe at the end too.