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3. Cosmological
factories
To truly figure out our origins in the universe and understand
how and why nature created us, we have to understand where atoms
come from. And to do that we have to look not at Earth but to
the stars.
The Big Bang is the cosmologist’s story about how everything
in the universe was created in a giant fiery explosion nearly
14 billion years ago. But the story of creation doesn’t
end with the Big Bang. The early universe was nothing like it
is today; the building blocks necessary to create complex living
things simply did not exist. The rich variety of atoms that
exists now hadn’t been created. The universe was nothing
more than a diffuse, uniform gas consisting of just two of the
most basic types of atoms – hydrogen and helium.
But nature somehow turned these fundamental atoms into the 92
atoms we have today. ‘The main force that changed the
universe from being simple and boring to being rich and complex
was gravity,’ says Max Tegmark. Because it attracts everything,
gravity was able to draw great loads of these hydrogen and helium
atoms together to form objects that we now see all across the
sky – stars.
All
the atoms we see around us are found in stars, but to begin
with stars were made of just hydrogen and helium. Stars are
the atomic factories of the universe, creating new atoms in
a fusion reaction. As the temperature at their cores rose
higher and higher, one by one smaller atoms fused and transformed
into bigger atoms building up all the 92 atoms. Then when
the star runs out of nuclear fuel, its core collapses which
causes it to spectacularly explode in what is called a supernova.
In the process, these explosions spew out all these manufactured
atoms, the raw ingredients of everything.
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