The Cosmos
The Cosmos
The symphony of complexity and structure in the universe and how it came to be.
“A FIERCE UNREST SEETHES AT THE CORE
OF ALL EXISTING THINGS:
IT WAS THE EAGER WISH TO SOAR
THAT GAVE THE GODS THEIR WINGS.
THERE THROBS THROUGH ALL THE WORLDS THAT ARE
THIS HEART-BEAT HOT AND STRONG,
AND SHAKEN SYSTEMS, STAR BY STAR,
AWAKE AND GLOW IN SONG.”
-DON MARQUIS
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—The cosmos is the totality of complexity and order that has arisen in the universe; the opposite of chaos.
—13.8 billion years ago (13.8 Gya): The Big Bang
—13.5 Gya: First stars and galaxies begin to take shape
—9 Gya: The Milky Way forms
—4.6 Gya: The Solar System forms
—4.5 Gya: Earth forms
—4.1 Gya: Life emerges on Earth
I. The Cosmos is Real
The night’s sky might not give us pause. We’ve seen it thousands of times. It comes and goes. Why waste energy losing ourselves in its infinite depth?
The Earth is round and we don’t fall off because we’re being pulled towards its center. When we watch the Sunrise, what we’re seeing actually took place eight minutes ago. Right now, the universe is 93 billion light years wide, but it used to be smaller than a baseball.
So what?
Like most things we don’t understand, we tend to wipe the cosmos from our awareness. We assort it into the same mental category as other stories, like the origin of Sauron, the origin of the Jedi, or World War II—you know, things that are so removed from our immediate reality that they don’t exist. Except we probably find the Star Wars universe more interesting than our own.
We should, however, resist this psychological tendency. We should do our best to truly embrace the cosmos as something that’s real. If we find ourselves bored, unimpressed, like our lives are bereft of magic, we really only have to look up at the stars, and acknowledge the things I’m about to describe, to be reminded that we’re all floating in this dark dream, living out the deepest of mysteries.
II. A Brief History of the Cosmos
In the beginning, there was nothing, as far as we can tell. Then 13.8 billion years ago, from a single point smaller than the size of a pinhead, emerged all the energy, space, and time that would ever make up the universe. We call this event the Big Bang. It was not an explosion, but rather an abrupt appearance of rapidly expanding spacetime containing an enormous amount of energy.
This rapid expansion lasted a fraction of a second before slowing down, and resulted in a universe the size of a grain of sand. The universe would continue to expand indefinitely from that point onward, but at a much slower rate.
At this point, the universe was incomprehensibly hot plasma with temperatures that far exceed what we’re able to recreate in labs on Earth. This plasma soup was a thick, opaque fog of highly energized particles, which mixed and mashed together. Expansion relieved pressure, and eventually allowed for the fusing of complex entities like protons and neutrons.
After about 377,000 years, the expanding universe cooled down to around a temperature of 4000 K—cold enough for protons to capture negatively charged electrons and form the very first atoms: hydrogen (1 proton). Each reaction that produced a hydrogen atom released a photon and, once the conditions surpassed the proper threshold, this happened rapidly across the universe. There was a great flash of light photons were released universally, propagating outward through space, indefinitely. We can still see the photons involved in this great flash today. We call it the cosmic microwave background radiation, and it provides us with a great deal of information about the early universe.
This capturing of particles into hydrogen atoms, and the subsequent release of photons, made the universe suddenly go from a thick, opaque fog to being completely transparent—much like it is today. We call this phase of the universe the Dark Ages, because there were no light sources other than this background radiation. Stars and galaxies—the structures we normally think of as light-producers—did not exist yet. The universe was truly dark.
Gravity is a force that brings all things with mass or energy—even light—towards one another. It appears to have unlimited range, meaning all objects in the universe are actually linked to one another, like a gigantic web of gravitational pull. Gravity is not the only force at play in the universe, but this network results in mass and energy assembling itself into patterns—very loosely at first, but increasingly organized over time into an emergent landscape with hills and valleys of complexity and order.
During the Dark Ages, the universe continued to expand, with the edges of the universe moving away from each other at a rate faster than the speed of light. As a result of this expansion, the temperature of the universe cooled from around 4000 K down to around 60 K. Under these conditions the newly formed hydrogen atoms began to approach one another and gather into hydrogen clouds. As more hydrogen gathered, the density of these clouds increased; more mass in one location meant more gravitational pull to that spot. Little celestial gatherings began to emerge everywhere, throughout the universe.
As clouds became more and more dense in a kind of gravitational runaway, the protons at the center of each hydrogen atom were forced together closer and closer. After the pressure reached a certain point, the gravitational forces overcame the electromagnetic forces that cause protons to repel one another, the atoms collapsed, and the protons fused together, forming a new atom: helium (2 protons).
Every time this fusion happened it released energy, and if it happened enough in one spherical cloud of hydrogen, it would heat up from the core outward and eventually ignite into a star. Within the first billion years after the Big Bang, stars everywhere ignited into existence, filling the universe with light. The Dark Ages came to an end and the universe began to look much like it does today.
A star is an achievement of temporary equilibrium, where the inward-pushing gravitational forces causing hydrogen atoms to collapse towards the core are counterbalanced by the outward-pushing energy released by the fusion of helium. This process of fusion continues within the star, producing increasingly heavier elements, like neon (10 protons) or silicon (14 protons).
Nature dictates that as elements get heavier, they release less energy with each fusion. So as stars produced heavier and heavier elements, the force radiating outward to counteract gravitational collapse gradually depleted. Once a star began fusing iron (26 protons), the inward gravitational force surpassed the outward fusion energy force, which caused the star to implode.
Depending on the size of the star, the implosions resulted in a supernova or a black hole.
In the case of the supernova, the collapsing star contracted from, let’s say, the size of the Sun to the size of the Moon, rapidly driving its electrons into its protons, causing a sudden burst of neutrinos that resulted in an immense shockwave. The explosion distributed all the heavier elements produced within the star—like iron, silicon, and carbon—throughout the surrounding space to be combined into new planetary disks surrounding other newly forming stars. Eventually, that stardust evolved into planets like Earth.
In the case of the black hole, a star may be so massive that the gravitational force causing it to implode essentially nullified the ensuing explosion outward. Instead the star kept collapsing into a sort of gravitational feedback loop until it ripped a hole in spacetime. A black hole exhibits such strong gravitational pull that nothing with mass or energy—not even light—can escape from it.
A massive enough black holes exerted forces on vast regions of space, where other stars, remnants of supernovae, and clouds of dust got get pulled in. Due to conservation of angular momentum, these celestial objects began to rotate around the black hole, gradually aligning into the shape of a disk. These black holes, and their rotating disk of materials became galaxies. Our galaxy is the Milky Way.
The Milky Way took shape around 9 billion years ago. It has a diameter between 150,000 and 200,000 light-years. It is estimated to contain 100–400 billion stars and more than 100 billion planets. At the center of the Milky Way is the supermassive black hole known as Sagittarius A, which is about four million times the mass of the Sun. Its rotational period is about 240 million years and the Milky Way as a whole is moving at a velocity of approximately 600 km per second.
Within the Milky Way’s galactic disk, gas and dust and the remnant of exploded stars collected into their own, smaller systems of gravitational interactions. These nebulae gradually accelerated in their accretion and eventually spun into their own rotating disks. Larger debris within these disks gathered mass and formed kilometer-sized proto-planets, orbiting the more massive centers of the nebula.
The center of the nebula, not having much angular momentum, collapsed rapidly, the compression heating it until nuclear fusion of hydrogen into helium began and it ignited into a star. This is the process that evolved our Sun about 4.6 billion years ago.
Rotating around the Sun, successively larger fragments of dust and debris clumped together to form planets. This is the process that formed Earth 4.5 billion years ago. Evidence suggests the proto-Earth was struck by another proto-planet, which ejected part of the mantle and crust into space and created the Moon.
Several hundred million years later, life would emerge on Earth.
III. A Strange Reality
The universe is evolving. There was nothing but white hot plasma, then there were particles, then atoms, then clouds of atoms, then stars and galaxies, then planets, then goo, then motile blobs, then fish, then squirrels, then hominids, then consciousness, then culture, then information systems, and then dogs with their own social media followings.
Again, if you don’t find this strange, then you’re not paying attention. The universe moves towards greater complexity over time. It constructs these massive celestial spheres and sends them twirling into the darkness, dancing with each other to these stellar vibrations, sending forth their fire and light. Systems within systems within systems rise up and march down a divine path.
We observe this tendency in the universe, but we have trouble making sense of it. We can describe the process, recite the timeline, but we cannot make claims as to why. There is so much we don’t see, so much that doesn’t compute. We try to make sense of our cosmic surroundings, but we fall very short. The universe boggles the mind.
A few examples to illustrate:
—Space and time are not separate; they exist in a four-dimensional continuum we call spacetime. We find this difficult to conceptualize, but time passes more slowly for an individual traveling through space at high speed than for a person at rest. As an object approaches the speed of light, it’s rate of time, relative to other objects, approaches zero. Massless particles, like photons, are unaffected by the passage of time. A photon takes eight minutes to travel from the Sun to the Earth, but from the ‘perspective’ of the proton it’s at the Sun and the Earth at the same time.
—Dark matter is a theoretical substance responsible for most of the gravitational effects observed in the universe. It’s called ‘dark matter’ because we cannot find it anywhere—we only see its effects. For every hydrogen atom in the universe, it’s as if there’s five other hydrogen atoms that are invisible, exerting the same amount of gravitational pull on the objects around it. This invisible matter is scattered throughout the universe and strongly influences where and when galaxies come into existence. This observation arises because galaxies could not have formed as they have, or rotate as they are seen to, unless they contained far more mass than can be directly observed.
Evidence from galaxy rotation curves suggests that about 90% of the mass of the Milky Way is dark matter; invisible to telescopes, neither emitting nor absorbing any light. The gravitational effects of dark matter are well understood, as it behaves like a cold fluid that forms haloes around galaxies. Dark matter has never been detected in the laboratory, and the nature of dark matter remains completely unknown.
—The universe is expanding. A common misconception is that the Big Bang was an explosion that gave everything in the universe a big push, and galaxies and stars and planets are still flying through space because of that initial push.
Our observations tell a different story. In every direction we look, galaxies are receding from Earth. And if Earth is not in some special, privileged, central position in the universe, then it would mean that all galaxies are moving apart, and the further away they are from us, the faster they are moving.
This is strange. The only explanation is that space itself is expanding. The theoretical force causing this to happen is called dark energy.
For instance, imagine you and a friend are standing 100 sidewalk tiles apart and every sidewalk tile is five feet in length. In this magical dreamworld, let’s say each sidewalk tile expands by 10%, every minute. You and your friend start out 500 feet apart. You both stand completely still, but a minute passes, the tiles expand, and now you’re now 550 feet apart; another minute and you’re 605 feet apart; five minutes pass and you’re 805 feet apart; an hour passes and you’re 138,400 feet apart. Both of you have remained on your respective tiles, and the amount of tiles between you hasn’t changed, but now you’re speeding away from each other at a rate 160 mph, and increasing by the second.
Another friend of yours is 1000 sidewalk tiles behind you. You started out 5000 feet apart, but after an hour, the two of you are 1,384,000 feet apart and traveling away from each other at a speed of 1,600 miles an hour.
This is happening to everything, everywhere in the universe. The sidewalk tiles are expanding, and all objects are flying away from each other. The further away an object is from us, the more tiles between us that are expanding, the faster the object is speeding away from us. All the galaxies we observe are receding away, and the further away the galaxy is, the faster it’s receding.
Some galaxies are so far away, there is so much space expanding in between, that they’re receding away from us at a rate faster than the speed of light. These distant galaxies will effectively disappear from our observable universe forever, vanishing because their light is traveling towards us slower than the galaxies themselves are traveling away from us. Their light can never reach us.
This expansion of space is happening on Earth, in our living rooms, in our bodies, just like it is everywhere else in the universe. We don’t observe this expansion because it is counteracted by gravitational and electromagnetic forces, which are far stronger than the effects of dark energy. The space between your face and your computer screen is actually expanding, but with such little magnitude that the effect is negligible.
Ω
What does all this mean?
It means we have no clue what’s going on. It means the true nature of the universe exceeds our sense-making faculties. As humans, we have a strong desire to illuminate all things, to know all there is to know, to master all mysteries of existence.
However, it doesn’t take long, if you study cosmology, to understand that that’s not going to happen. Ever. Physical reality exceeds our grasp.
Time emerged with the Big Bang. So when we ask, “Did anything exist before the Big Bang?” our best answer is, There was no before. But we don’t like this answer. We can’t make sense of it. What is nothing? What does the absence of time look like? It doesn’t look like anything. It’s not a coherent question. It’s beyond us.
The human mind is grasping, reaching out desperately for answers, but these are not answers our brains were designed to ingest. We evolved to ask, “What’s over the ridge? What happens tomorrow?” because these questions aided us in our journey of survival. We attempt the same questions with physical reality and get responses like, There is no ‘over the ridge’. ‘Tomorrow’ doesn’t exist.
That’s what our conversation with the cosmos is like.
We should embrace our limitations, bask in the unknown, learn to walk in the darkness. The universe is a place of such divine machinery, a clockwork from which light emerges from darkness, harmony emerges from disorder, minds emerge from dust.
We are made of stars. The same energy that brings galaxies together also brings us together. Hand in hand, we reach towards the sky and, through our eyes, the cosmos sees itself.