At first glance, astrophysics and medical pathology have little in common. What can the relationship between sunspots and age spots be? How could the Big Bang be associated with cystic fibrosis?
In their book with the title Living with the stars: How the human body is connected to the life cycles of the earth, the planets and the stars and published in 2015, Karel Schrijver, an astrophysicist, then a senior researcher at Lockheed Martin’s Astrophysics and Solar Laboratory, and his wife, Iris Schrijver, a professor of pathology at Stanford University, established the connections between the human body and the stars and to the planets.
When their book was published, from their home in Palo Alto, California, they explained to us that everything that makes us up comes from cosmic explosions that took place billions of years ago, that our body is in a constant state of decay and regeneration, and that singer Joni Mitchell had figured it all out.
IN WoodstockJoni Mitchell sang that we were star dust. Was she right?
Irises: Take effect ! Everything we are and everything that exists in the universe and on Earth comes from stardust, and it constantly hovers through us, even today. It connects us directly with the universe, and rebuilds our bodies again and again throughout our lives.
It was one of our biggest surprises. We were not really aware of how perishable we are and that our bodies are made of remnants of stars and massive explosions in galaxies. All the materials in our bodies come from this residual stardust, which finds its way into plants and from there to the nutrients we need for everything we do: think, move, grow. And in a few years, most of our body will be renewed.
Can you give me some examples to illustrate how star dust formed us?
Karl: When the universe began to form, there was only hydrogen and a little helium and very little else. We do not have helium in our body. On the other hand, we have hydrogen, but it does not represent the bulk of our weight. Stars are like nuclear reactors. They take a fuel and turn it into something else. Hydrogen turns into helium, and helium turns into carbon, nitrogen and oxygen, iron and sulfur: all the elements that make up us. When stars reach the end of their lives, they swell and implode, releasing their outer layers. If a star is heavy enough, it explodes into a supernova.
Most of the materials we are made of therefore come from dying stars, or stars that died in explosions. And these stellar explosions keep happening. We have elements in us that are as old as the universe, and other elements that landed here perhaps only a hundred years ago. And all this mixes in our bodies.
Your book makes the connection between two sciences that are perceived to be different: astrophysics and human biology. Can you describe your respective professions and how you combined them to create this book?
Irises: I am a doctor, specializing in genetics and pathologies. Pathologists are the medical specialists who diagnose diseases and their causes. We also study the body’s reactions to these diseases and to the treatments given. I do this at the DNA level and I run the Molecular Pathology Diagnostic Laboratory at Stanford University. I also care for patients by diagnosing hereditary diseases and cancers and monitoring responses to treatments in these cancer patients based on the changes we may detect in their DNA.
Our book is based on many conversations that Karel and I had together, where we talked about topics from our daily professional lives. These areas are very different. I’m interested in the code of life. He is an astrophysicist who explores the secrets of the stars. But the more we kept asking each other our questions, the more we discovered that our domains were much more connected than we thought.