XVII. Why Are We Here?
This is your story- the entire history of your many incarnations- and it is a beautiful story. The details of this story have changed over time, and they will most assuredly change in the future as we learn more and more about ourselves and the Universe around us. But this is the best information we have at the moment, and our observations and calculations seem to say that we are getting remarkably close to a detailed and accurate understanding of All That Is. Here’s what we think we know at this point:
Around 13.7 billion years ago, all matter in the Universe was condensed into pure energy in an immensely hot and dense space smaller than an atom. We’re not exactly sure what came before that or how this energy came to be, but we have ideas, and we are working to find the answers even now (it has even been mathematically proven that something could have, in fact, arisen from nothing, although it depends on your definition of nothing). This tiny, incredibly hot and dense ball of energy suddenly expanded from something smaller than the nucleus of an atom to something the size of a baseball in less than a trillionth of a second. In just under 2 minutes, the Universe has expanded to something the size of our solar system, and it only got bigger from there. It’s still expanding, even today. All of the forces and laws of physics and nature, as well as the first subatomic particles, were created in these first few seconds of Time. Minutes later, the first simple atoms of Hydrogen and Helium formed. The radiation from this expansion is still around and flying straight through your body even now. If you have seen “snow” static on a television screen, then you have seen this radiation, as 1% of that static was due to radiation from the Big Bang.
Between a few thousand years and a few hundred million years after the Big Bang, atoms in the great cloudy mess of Hydrogen and Helium gravitated toward each other in massive amounts and ignited, and the the first stars lit the heavens. For the first time, the Universe produced visible light.
A few hundred million years after the first stars ignited, gravity caused the first galaxies to form from the ocean of newly created matter.
Sometime between 9 billion and 13.6 billion years ago, the matter that makes up your body found itself in the newly formed Milky Way spiral galaxy. The red circle in the rendering of our galaxy below encompasses all of the stars and constellations that we can now see from our home planet with the naked eye.
Stars are formed when hydrogen and helium gravitate together and become so hot that the hydrogen atoms fuse together and become more helium. After the star ignites, this process continues for billions of years. (This nuclear fusion is basically the opposite of the process that humans use to create power in reactors and atomic bombs, which is called fission.) This energy of nuclear fusion, produced in our own Sun even now, is responsible for all of life on Earth. As really big stars get older, they deplete almost all of their hydrogen, and the core becomes so hot that helium and remaining hydrogen fuse together to form lithium. This begins a chain reaction of fusion that causes even bigger and bigger atoms to combine until the heavier elements, like carbon, oxygen and iron are formed. At this point, the star becomes incredibly unstable and collapses in on itself and becomes a supernova, violently exploding and sending all of its guts out into the space around it.
The stars that formed our solar system were supernovae that died and exploded around 5 billion years ago. The molecules of oxygen that these stars sent out into the cosmos are the same molecules that you are breathing in now. The iron that they spewed forth is the very same iron found in metal and in your blood. And mind-blowing as it is, the atoms in your left hand are more than likely from a completely different star than the atoms in your right. The following picture shows the Crab Nebula, which was a supernova star that exploded in the year 1054.
The stardust of supernovae form clouds of dust, where hydrogen atoms come together and form helium, and new stars are born all over again. The picture below shows a region of new star growth in the Carina Nebula.
Sometimes, heavier elements in a dust cloud will begin to orbit around a new star. Clouds of gas form, and chunks of debris constantly and violently slam into each other in the dust field and eventually form planets and moons. Our own solar system formed around 4.6 billion years ago.
The earth and its moon formed around this same time. The atoms that would eventually become you ended up on this early molten planet.
Eventually, the Earth began to cool and the constant bombardment of meteorites and comets, as well as processes within the Earth itself brought liquid water to the planet.
Developments in the field of abiogenesis have helped us conceptualize how biological life formed from inorganic matter through natural processes. Experiments in the laboratory have shown that amino acids, nucleotides and saccharides, all the basic building blocks of life, could have formed in Earth’s early conditions. There is also the possibility that these building blocks or something more complex was deposited on Earth via meteorites. Of course, if life did arise on other planets and made its way here, it would have to have either come from another planetary source itself, or it originated independently on its home planet.
All life on Earth evolved from a common ancestor that had a lipid cell wall, the ability to metabolize, and the ability to replicate. These physical components and processes took billions of years to eventually come together in the forms that gave rise to all life. Our very earliest ancestors probably looked something like the picture below.
Natural selection began working on these early organisms, which remained as simple cells for 3.8 billion years. Then, life changed dramatically when one form of life began to photosynthesize carbon dioxide into oxygen (these were the ancestors of today’s plants). Oxygen was toxic to many forms of life at that time, so this resulted in the death of many, many organisms. 3 billion years later, simple cells became more complex, and 2 billion years after that the first multicellular life formed on Earth. 600 million years ago, the first simple animals began to take over the planet. Around 420 million years ago, our early ancestors left the oceans and moved onto land.
The atoms that made up these organisms are still around today, and they are in the computer in front of you and in the hand that holds the mouse. You have atoms in your body right now that were also in the bodies of dinosaurs. You are drinking the same water now that the first forms of life developed in. You are breathing in the very same oxygen that the first plants released into the atmosphere. You are literally the result and recombination of everything that has come before you, going all the way back to the Big Bang. There is no difference between you and me and the rest of the Universe. All cliches aside, we are literally all one. You can never, ever be alone.
Between 85 and 55 million years ago, the first primates evolved. Humans, gorillas and chimps all share a recent common ancestor, and we began evolving independently between 4 and 8 million years ago. After that point, our lineage went through many changes and phases. Our species, Homo sapiens, is only about 250,000 years old.
Between 200,000 and 100,000 years ago, our early ancestors began migrating out of Africa and began to explore and populate the world. At this point, we only had the basic tools that we could carry with us. In the history of the Earth since life began, we have survived 6 major extinctions, 5 major ice ages, and countless natural disasters. It’s simply amazing and awe-inspiring to think about how curious, courageous and resilient our ancestors must have been. We all come from incredibly brave pioneer stock.
Our species has changed the very face of the world remarkably and dramatically ever since then, arguably more than any other species that has ever existed. Just look at how the world looks at night now. From the time we first began to gather together around ancient fires to our modern discovery of electricity, we have been fighting off the darkness for ages.
So, now that we find ourselves at the beginning of the 21st century, what lies ahead? Likely millions and perhaps billions of years of more evolution, even if our particular species is not a part of it. Sometime between 4 and 5 billion years from today, our now middle aged Sun will deplete its hydrogen and swell to 250 times its current size, becoming a red giant that will incinerate and envelop the Earth. Our star is too small to form a supernova, but eventually it will explode and shrink into a white dwarf, which will then slowly fade out over billions of years.
But do not be afraid, and do not worry. There is an entire immense Universe to explore if we can make it off this rock before it burns or we kill ourselves. Thanks to advanced telescopes on Earth and in space, we now know that galaxies are they themselves clumped together into clusters, and these clusters are clumped into superclusters. These superclusters are organized into stringlike structures called filaments. The picture below shows a simulation of this large scale structure of the Universe. The bar of measurement shown is 31.25 megaparsecs in length, meaning that if you were traveling at the speed of light, it would take you 103 million years to get from one end of the bar to the other. It simply boggles the mind.
The following amazing video takes you from the scale of an atom to the grand scale of the Universe. I warn you, it is not for the faint of heart. Enjoy and take in the enormity of what and where you are.