Look around you. What can you see?
If you are at home, you might see family members, a sofa, or a TV. If you are sitting in a coffee shop, you might see a street scene with cars and buses.
Everything you see is made up of a multitude of different atoms from iron to carbon. But when the Universe formed over 13 billion years ago, the first atoms were mostly hydrogen and helium.
Somehow, something happened. Some physical process turned hydrogen and helium into the stuff we see in the Universe today.
The Magic Happens Inside Stars
The processes that cause this almost magical change occur deep inside stars.
After the Universe formed bringing with it a seething, boiling soup of energy matter in the form of hydrogen and helium eventually emerged. Over time, this gas began to accumulate into localized regions until the pressures inside became so high that nuclear fusion started to take place.
Fusion is a physical process where atoms join or fuse together to form another type of atom.
The onset of fusion marks the birth of a new star. This first generation of stars would have been almost entirely composed of hydrogen and helium.
The Delicate Dance of Gravity vs. Fusion
For millions of years, these new stars sat quietly, fusing hydrogen into helium in their cores. As a byproduct, they emitted energy in the form of heat and light (among other emissions). Eventually, each star ended up with a helium-rich core.
Skipping forward a few billion years: the stars we see in the night sky start their lives in much the same way and can remain stable like this for billions of years.
This stability is a beautiful balance between:
- Gravity trying to collapse the star- Thermonuclear pressure from fusion trying to rip the star apart
When Stars Grow Old
Once a star has a helium core, the temperature and pressure in the core are not high enough for helium fusion to occur. This leads to a decrease in thermonuclear pressure.
For a short while, gravity starts winning. The core contracts, leading to an increase in core temperature and pressure and the start of helium fusion.
The fusion of helium creates carbon in the core of the aging star. For stars like our Sun, this is the end of the road. The star will soon die.
But more massive stars live longer.
Eventually, carbon fuses into oxygen, then into silicon, and finally iron. Even for the most massive stars in the Universe, this is as far as they can go. The thermonuclear pressure drops, and the star collapses in an instant under the immense force of gravity leading to a massive explosion.
Stardust Scattered Across the Galaxy
The process of synthesizing elements inside stars like this is known as nucleosynthesis. As the stars die, the elements created inside them are scattered throughout the Galaxy.
With the new elements distributed around space, they eventually get caught up in new regions of star formation. As new stars form, the heavier elements can now play their part in the formation of planets and ultimately life.
It is true that every atom in your body has, at some point, been through the core of a star.
You are not just looking at the Universe. You are made of it.
0 comments:
Post a Comment