The Goldilocks Zone

Author: Mark Yates

I first learned about our body’s electron transport chain (ETC) while working in a biochemistry lab. This complicated process, which uses digested sugars to create an ion gradient that acts like a hydroelectric station for producing cellular fuel, has more belts and levers than a Rube Goldberg machine and can twist the mind like an M.C. Escher print.

Given the genius way ETC utilizes electrons, for days I couldn’t believe I was actually walking around. One of the lab’s doctoral students concurred. A practicing Catholic, Brenda told me that the more she learned about how our bodies work, the more awed she was by God’s creation.

It turns out that the electron transport chain is just the mystifying tip of an improbability iceberg so enormous as to be nearly ineffable. This biochemical process depends on atoms and ions. Physicists tell us these items, once created, cannot be changed or destroyed (except under the extreme conditions of stars and black holes). At a more basic level, this means that the atoms that compose our bodies, which swirl and spin and flow through us to give us energy and make us who we are in tens of thousands of different ways, have been around for billions of years. Compared to the relatively short time our consciousness occupies one of their creations, the elements always have been and always will be.

To be conscious, we need cobalt, which gives glass a radiant blue color. Part of vitamin B12, cobalt helps ensure we produce red blood cells to carry oxygen to muscles, organs and bones. It also helps form the myelin sheaths protecting our nerve cells. Without cobalt, we would suffer from anemia and our bodies would tingle with pins and needles. Perhaps more frightening, our brains would fog over, and we would forget who we are.

From the heavens

This indispensable mineral comes from the heavens. In fact, cobalt is part of the dust left over from stellar explosions known as supernovas. For solitary stars nine or more times more massive than our sun, life ends with what is the most powerful and spectacular explosion in the known universe. If one of our neighboring stars were to go supernova, the starburst would be visible during daylight and outshine the moon at night, no doubt inspiring myths, poems and songs.

Supernovas occur after a star has burned up its fuel, which the star needs to create enough energy to combat its own gravity. In other words, when the fuel is gone, gravity kicks in. The force that pulls apples to the earth also pulls the star into itself. In a matter of seconds, the outer surface — which may be large enough to encompass the entire orbit of Mars — is yanked inward. All those atoms smash into each other and create so much pressure that the small atoms merge into larger ones. Temperatures spike to over 100 billion degrees C (180 billion F). The pressure and heat blasts the new atoms into the cosmos.

Only supernovas pack the energetic punch necessary to create elements more massive than iron, like selenium, gold, mercury, tungsten and cobalt. For most of the lighter elements, a regular star does the trick.

Oxygen is one of these elements. Given our relationship to it and its role as a metaphor for purity and life, it is strange to think that it was born in the violence of stellar furnaces. That cool breeze on a summer day, that deep breath to calm us down, that crisp feeling in an alpine forest — all conjure the binary molecule that enables the electron transport chain and the life-sustaining masks of emergency rooms and surgery theaters.

Together with hydrogen, oxygen forms water, which is fundamental to not just our existence but to life in general. In fact, many scientists believe that life, let alone intelligent life, is impossible without water. But unlike oxygen, hydrogen has an exotic and still poorly understood origin: the Big Bang.

One theory says that before there was anything, there was a void — no matter, no space, no time. It was the state of things before the God of Abraham said: “Let there be light.” Using complicated mathematics, physicists turned this void into the chaos that birthed the Greek gods, an infinitely creative vacancy, swirling with particles and infinitesimal universes.

For every spontaneous appearance, a companion particle or universe pops into being. But the companion is an exact opposite. Since opposites attract, an instant after a companion springs to life, the particle and its companion race toward each other and their energies cancel and they cease to exist. In this timeless and spaceless abyss, chance eventually cranks out a particle the size of our current universe that somehow breaks from its opposite and erupts into life.

After 380,000 years or so, the elementary particles condense into neutral hydrogen and helium — the same hydrogen that imbues all aspects of our life. Every time we take a drink, breathe out or set the electron transport train in motion, we utilize atoms that have been around since creation.

Which happened nearly 14 billion years ago. Physicist Leonard Susskind argues that the human mind is not wired to consider such a large number. Because of the financial crisis, however, today many of us probably have a better understanding of what a billion means than we did a few years ago. A billion dollars is two space shuttle launches or enough to run Minneapolis schools for two years. A billion grains of sand fill a cube with edges just over 4 feet in length.

Still, when it comes to time, perspective is more difficult. A billion seconds ago Jimmy Carter was in the White House. A billion minutes ago, Romans fed Christians to the lions. A billion hours ago, early modern humans had spread over Africa and possibly to Southeast Asia, but not yet to Europe. A billion days ago, mammals were making their move and taking over the planet. A billion years ago it was multicellular organisms that were oozing through the muck to stake their claims.

Hydrogen and helium soared into space nearly 14 billion years ago. They then collected in massive clouds that contracted into stars. Many went supernova, jetting heavier elements into galaxies and nebulae. Roughly 4.5 billion years ago, the nebula that eventually formed our sun captured these star-produced elements in its gravity and coalesced them into balls of solid matter. On one of these balls, oxygen and hydrogen burned to form water. Minerals from stars and supernovae continued to rain down on Earth and blended with the water to establish the primordial soup needed to create life.


Around a billion years after our planet formed, a bolt of lightning kicked the soup into gear, forming molecules that laid the foundations for self-replication. These bumped into each other tens of trillions of times, exchanging elements and building more and more complex structures. This led to RNA, DNA, lipid membranes and, eventually, rudimentary life. Over the next 3.5 billion years, minerals and bases and proteins created prokaryotes, then eukaryotes, then fish, amphibians, reptiles, rodents, prosimians, apes and homo erectus. Finally, homo sapiens stretched its back and grabbed its tools to hunt for prehistoric wildebeest and gather berries and wild tubers.

Given ideal environmental conditions like those found on Earth, astrobiologist Andrew Watson puts the odds at 10,000-to-1 against life appearing.

But what are the chances of those conditions occurring? First the sun has to be in just the right spot. Any closer to the center of the galaxy and the radiation would burn through molecules attempting to form life. Any further out and there would not have been enough of the heavier elements to support life. Astronomer Donald Brownlee and paleontologist Peter Ward call this the Goldilocks zone, because it is “just right” for sustaining life.

It doesn’t end with the sun. Our solar system contains a Goldilocks planet: Jupiter. Because of its size it has the gravity to clean out all the asteroids that would have otherwise crashed into us. We also have a Goldilocks moon to stabilize our orbit, which is thankfully circular: an elliptical orbit would make our climate too variable for life. Our planet is also a Goldilocks size, just big enough to have the gravity to hold in the atmosphere but not so big that it flattens it against the surface.

All told, the chance of these multiple Goldilocks Zones aligning in just the right way is not a million-to-one or a billion-to-one or even tens-of-trillions-to-one, but something much higher. Attempting to compute the probabilities of each zone and apply them to Earth comes with so many assumptions that cosmologists have yet to settle on an answer. They do agree, however, that the odds are remote at best and near impossible at worst.

Still, for all practical purposes, the observable universe is essentially infinite. Current estimates give it at least 125 billion galaxies. Most galaxies have between 300 and 800 billion stars (with some having more than a trillion). Given those numbers, some of those stars will be the right distance from the center of their galaxies and have planets of the right size with the right orbits at the right distance from their suns. These just-right planets will have big sister planets to keep out the asteroids and little brother moons to keep them stable. After the planets cool, water could form and at some point life will crawl onto land and perhaps, just perhaps, evolve like it did on Earth.

Even if this is true, we are not out there. We are not a warlike alternative life form with a scaled head and an appetite for honor or a peaceful, wide-eyed botanist who uses musical notes to communicate. We are here, in the outer spiral arm of the Milky Way on 21st century Earth. So even if life is likely in the universe, this life isn’t. We don’t need to leave the planet to see that the possibilities are still mind-boggling.

Assuming natural events hadn’t nudged evolution in another direction or that historical events hadn’t unfolded differently, we could have ended up doing backbreaking labor among the first farmers in the Fertile Crescent. We could have lived in dire poverty at the edge of the Roman Empire before being sold into slavery and killed by Nero for ladling the soup wrong. We could have been burned in a Wicker Man or slaughtered by Genghis Khan or executed by an English monarch trying to stamp out Catholicism. And today we could have been born in war-torn Sudan, earthquake-stricken Haiti, genocide-suffering Rwanda, Taliban-ruled Afghanistan — when you consider all the possibilities of where we might have been given life, the chance to be alive today, in the developed world, in a land of relative plenty, is nothing short of miraculous.


When looking at the grandeur of the cosmos and marveling at how it led to life, the issue of whether there is a creator may be beside the point. Most of us believe great works of art should be maintained for no other reason than that they are beautiful. We do not need to know who painted the Sistine chapel or designed Notre Dame Cathedral to be awed and comforted by their magnificence. The same applies to life. As we venerate it, admire it, and stand in awe of its engineering and aesthetics, we must also take every opportunity to preserve it and share its blessings.

I do not know if life is a gift from God, a turn of the karma wheel or just pure chance (I prefer the first but suspect the last). But I share my former lab colleague’s reverence, particularly in light of all we’ve learned from cosmologists and biologists.

This means actively polishing our spirits and thus the spirits of others. By the time we reach our 30s, most of us have read enough philosophy and spiritual tracts, heard enough homilies or sermons, seen enough morality plays disguised as sitcoms, and meditated and prayed enough to know how to do this. In some cases, it may be nothing more than a kind word to a troubled cashier. In others it may be volunteering at the food bank. In still others, it may mean putting policies in place that protect the less fortunate or supporting international aid organizations through career choices or donations.

Of course it is hard. And we all know that getting cut off in traffic or waiting in a long line at the grocery store are trivialities compared to the suffering in the world. Yet they bring out the worst in us. (This is why the eponymous devil in C.S. Lewis’ Screwtape Letters advises his nephew to tempt people with these little things.) We also have our own context-specific pain to deal with, like breakups, losses, death, clinical depression, economic hardships, troubled children — you name it. This is why we need to keep studying and listening and meditating on the world around us.

Reflecting on the immensity of the universe can be part of that. The abyss may unnerve us when it stares back, but it still helps smash self-importance by placing our own unlikely being against that of others and that of creation as a whole. It humbles the ego and releases the spirit, allowing it to stand in awe at infinity, which can actually make it easier to wait in lines and handle close relationships while reducing hate, spite, jealousy and whining to energy-wasting indulgences. It helps remind us of our good fortune and that we also have the luxury to realize it.

By embracing the majesty of creation and acknowledging the miracle of our own blessed existence — including all the material struggles and emotional and psychological trials — we help ourselves and others sparkle like the stardust we are.

Mark Yates lives and works in the Czech Republic, where he has generated a drawer full of unpublished novels.