Stardust
An Excerpt from The Universe Within, by Neil Shubin
All the galaxies in the cosmos, like every creature on the planet, and every atom, molecule, and body on Earth are deeply connected. That connection begins at a single point 13.7 billion years ago… As a species whose history has been in oceans, streams, and savanna plains, we humans have had our senses tuned to the chemical and physical world of land and water—to our predators, prey, and mates we can see or hear. Nowhere in our history has there been a premium on the ability to perceive extra dimensions, times on the order of billions of years, or distances in a virtual infinity of light-years. To achieve these insights, we repurpose tools that served us so well in our terrestrial existence to new ends. Logic, creativity, and invention project our senses and ideas to the far reaches of time and space.
The physics of the point that existed 13.7 billion years ago is mostly beyond our imaginations, not to mention our conceptual tools. Gravity, electromagnetism—all the forces at work around us did not have an independent existence. Matter as we know it didn’t exist either. With everything that would become the universe packed so tightly in one spot, there was an enormous amount of energy. In such a universe, the physics of small particles, quantum mechanics, and that of large bodies, general relativity, were somehow part of a single, overarching, and still unknown theory. Just what that theory is awaits the next Einstein.
By about .000000000000000000000000000000000000000001 second the universe was roughly 1,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000 degrees Fahrenheit, and the state of things starts to come more clearly into focus. This time begins the period of very rapid expansion of the universe. The big bang is not like an explosion where objects are projected from each other; space itself expands. With this expansion comes cooling over time. As the universe cooled and expanded, the forces and particles that make our world today emerged…
… We live in a daily marketplace of electrons, with trades measured in millionths of seconds. I write this book and you read it based on the energy released from these exchanges. The molecules in our bodies exchange these tiny charged particles as part of the daily business of their interactions. Some electron movements release energy; reactions involving oxygen tend toward this outcome. Other reactions serve to bind atoms into molecules or molecules with one another. These daily trades define the reactions between the planet’s atmosphere, its climate, and the metabolisms of every creature on Earth. When you eat an apple, electrons from that material course through your cells to drive the metabolism to power your body. The electrons inside the apple to begin with were derived from the minerals in the ground and the water that fell from the sky. The electrons in both have cycled through our world for eons. And all of these came about well before the formation of the planet, the solar system, or even the stars…
… As a star consumes all of the lighter elements, and marches ever higher in the periodic table in the fuels it consumes, iron accumulates in the center. As more and more iron accumulates, the fuel for fusion is consumed, nuclear fusion reactions cease, and the star begins to emit less heat. Iron nuclei, under the right conditions, can absorb energy, almost like a nuclear explosion in reverse. With so much energy released only to be absorbed, these conditions can set off a massive chain reaction that ends as a vast and catastrophic explosion. In seconds, these explosions release more energy than stars like our sun emit in their entire lifetime.
This blast is one kind of supernova (another kind can be triggered by collisions of stars). Supernovae work something like Teller and Ulam’s crude device. The energy of one explosion brings new kinds of fusion reactions. Recall those fusion reactions for elements heavier than iron? Supernovae release so much energy that these expensive reactions happen. All the elements heavier than iron, such as the cobalt and cesium in our bodies, derive from supernovae.
Here comes the important part, at least for us. The blast of the supernova spreads atoms of the dead star across the galaxies. Supernovae are one engine that powers the movement of atoms from one star system to another.
The smallest parts of our bodies have a history as big as the universe itself. Beginning as energy that converted to matter, the hydrogen atoms originated soon after the big bang and later recombined to form ever-larger atoms in stars and supernovae.
The sky, like a thriving forest, continually recycles matter. With the heavens so full of stars manufacturing elements, then occasionally exploding and releasing them, only to recombine them again as a new star forms, the atoms that reach our planet have been the denizens of innumerable other suns. Each galaxy, star, or person is the temporary owner of particles that have passed through the births and deaths of entities across vast reaches of time and space. The particles that make us have traveled billions of years across the universe; long after we and our planet are gone, they will be a part of other worlds.
Neil Shubin is Professor of Anatomy and Senior Advisor to the President at the University of Chicago, where he also serves as an associate dean. Educated at Columbia, Harvard, and the University of California at Berkeley, he is the author of The Universe Within and Your Inner Fish.
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*All of the excerpts on my blog are from books that have stayed with me for some reason—because the concept was awe inspiring, changed how I view the world, was beautifully expressed, or all three. I personally curate all of the book excerpts, and I always obtain the author’s final approval before posting their work on my blog.