By Amit Winder
From the hydrogen formed at the beginning of the universe to the iron in hemoglobin: the elements in our bodies tell a cosmic story billions of years old
Our cells are made of material that passed through stars, gas clouds, and Earth before reaching us. This is another installment in the "Connecting Everything" series.
Look at your hands for a moment: the network of bluish veins beneath the skin, the tissues and bones. In everyday life, we are used to seeing our bodies as a biological system separate from the world around it. But every cell in the body bears witness to the history of the universe.
The statement that we are all made of “stardust” is not just a poetic image. The elements that make us up were created in cosmic processes that began long before the formation of the Earth. To understand the connection between human biology and the universe, we will follow three stations on the journey of the elements.
The ancient legacy from the Big Bang
About 60% of the mass of the human body is water, and hydrogen is the most abundant element in our bodies by number of atoms. Most hydrogen nuclei originate in a very early universe: they were formed in the first minutes after the Big Bang, about 13.8 billion years ago. The first neutral atoms, in which electrons were bound to nuclei, were formed only after the universe cooled, about 380 years later. The measurements of The ancient abundance of helium Helping researchers test the predictions of this model.
The hydrogen in the water you drank this morning is therefore part of a material heritage that dates back to the beginning of the universe. It has since passed through stars, gas clouds, planets, and living things; its context has changed again and again.
The fusion reactors in the cores of stars
Hydrogen alone is not enough to build life as we know it. Carbon, nitrogen, and oxygen—key elements in cell molecules—were created primarily by nuclear processes in stars of different generations. Stars fuse lighter elements into heavier elements, and at certain stages in their lives scatter some of the material they form into space.
Carbon is the chemical backbone of many organic molecules, including amino acids, sugars, and DNA. Some of the carbon in our bodies was formed in stars that existed before the solar system formed. This material was incorporated into the cloud from which the sun and Earth were born, and from there it later found its way into our food and bodies.
Supernovae and iron in the blood
In massive stars, fusion processes can progress to the point of forming iron-group nuclei. When such a core collapses, the star may explode as a supernova, releasing elements created during its life and during the explosion into space. Explosions of white dwarfs also contribute iron to the universe. Supernova remnant Cassiopeia A Demonstrate how material ejected from a star spreads through its surroundings.
An iron atom is found in the heme group of the hemoglobin molecule in red blood cells; it allows it to bind oxygen. The iron in the blood does not indicate a specific star or a specific moment of explosion, but it does link an everyday biological process to the long history of the formation of elements and their distribution in the galaxy. You can also read about the role of iron in the body inArticle about iron balance in cells.
The body as a process of flow
The body is not a fixed collection of the same particles throughout life. With every breath, meal, and drink, matter enters it, participates in the processes of life, and some of it leaves it. The carbon atoms in our bodies were previously in the air, in plants, and in animals; in the more distant past, their nuclei were formed in stars.
This is one way to understand the name of The series "The Connection of Everything": Like the fossils hidden in building blocks, the material that makes us up has also undergone a long journey between systems that seem separate from each other. In a previous episode, Amit Winder also examined The connection between the perception of time and the processes around us.
From the cosmos to the question of who we are
Atoms do not know whether they are part of a person, a tree, or a stone. Yet, when they are arranged in a complex biological system, consciousness is also possible, exploring the laws of nature and their origins. Carl Sagan described this in the idea that the universe, through thinking beings, can observe itself.
Looking at the night sky is not a look at a completely foreign world: it takes us back to the physical and chemical origins of the matter we are made of. The universe is not just “out there.” Part of its history flows through our veins.
Sources for expansion
- NASA: The Early Universe and the Formation of Atoms
- NASA: The Life Cycle of Stars and the Distribution of Elements
- The Giant Fires in Australia: The Media Downplays the Connection to the Climate Crisis
- Ancient stardust may point to the reasons for man's fall from the trees
- Cosmic dust factories: variable stars and the origin of life
2 תגובות
Hey Mishu
You're absolutely right. The early universe was composed almost entirely of hydrogen and helium, and didn't have enough heavy elements like carbon, oxygen, and iron to build rocky planets or complex biological molecules.
It took generations of stars to be born, fuse elements, explode in supernovae, and enrich the galaxy until the cosmic matter became "rich" enough to allow solar systems like ours and life as we know it. This is precisely why complex life is part of a relatively late stage in cosmic history!
What is important to understand from this article is that **according to the knowledge available today** ancient civilizations that were created many billions of years ago are not possible because by then not enough heavy elements had been created that our bodies, today, are built of.