- 4197 - HOW THE ELEMENTS FORMED? The formation of the elements starts in the earliest moments of the Big Bang, when our universe was only a few seconds to a few minutes old. The universe contains a vast array of some 100 unique elements, ranging from light gases, such as helium, to heavy metals, like lead. But where did all of these elements come from?
--------------------- 4197 - HOW THE ELEMENTS FORMED?
- The formation of
the elements starts in the earliest moments of the Big Bang, when our universe
was only a few seconds to a few minutes old. At that time, the entire universe
was crammed into a volume millions of times smaller than it is today.
-
- Due to the
incredibly high densities, the average temperature of all the material in the
universe was well over a billion degrees, which is more than hot enough for
nuclear reactions to take place. It was so hot that even protons and neutrons
could not exist as stable entities. Instead, the universe was just a sea of
more fundamental particles, called quarks and gluons in a raw plasma state.
-
- But the universe
would not stay that way for long. It was expanding, which means it was also
cooling. Eventually, the quarks could bind together to form the first protons
and neutrons without instantly getting demolished. Protons are ever so slightly
lighter than neutrons, which gave them an edge in this initial phase of
particle production.
-
- Once the universe
was a few minutes old, it was far too cold to create new protons and neutrons. So
those first heavy particles were the only ones the universe was ever going to
make (outside of future rare high-energy interactions).
-
- By the time the
heavy particles finally froze out, there were roughly six protons for every
neutron. Neutrons by themselves aren't stable; they decay with a half-life of
around 880 seconds. Immediately, some of the neutrons began to decay away,
while the remainder started binding with protons to form the first atomic
nuclei.
-
- Of all the light
elements, helium-4, which consists of two protons and two neutrons, has the
largest binding energy, which means it's the easiest to form and the hardest to
break apart. So almost all of those neutrons went into the production of
helium-4.
-
- Cosmologists can
predict that the universe started out with a mixture of roughly 75% hydrogen
(which is just a bare proton), 25% helium and a small scattering of lithium.
-
- The next stage of
new elements had to wait for the first generation of stars, which didn't start shining
until hundreds of millions of years after the Big Bang. Stars power themselves
through nuclear fusion, transforming hydrogen into helium. This process leaves
a tiny bit of energy left over. But stars have so much hydrogen available that
they can burn for billions, or sometimes trillions, of years.
-
- Near the ends of
their lives, stars like the sun switch to fusing helium instead, turning it
into carbon and oxygen before they die as planetary nebulae. This is why carbon
and oxygen are so abundant in the universe; after hydrogen and helium, they are
the most commonly produced elements. In fact, oxygen is the most common element
on Earth, although most of it is bound up with silicates to form the ground
beneath your feet.
-
- More massive stars
with at least eight times the mass of the sun fuse even heavier elements in
their cores. Especially in their final weeks, days and even hours, the most
massive stars in the universe create nitrogen, neon, silicon, sulfur,
magnesium, nickel, chromium and iron.
-
- That's the end of
the line for the formation of elements within stars. Their intense energies are
perfectly capable of producing heavier elements, but fusing anything above iron
saps energy, rather than producing it, so those heavier elements appear only
rarely in the cores of massive stars.
-
- Instead, the rest
of the elements in the periodic table are produced when stars die. Smaller
stars slowly turn themselves inside out, spewing their guts all across their
stellar systems. Larger stars explode in violent cataclysms known as
supernovas. Both kinds of deaths leave remnants. In the case of small stars,
they leave white dwarfs, which are made almost entirely of carbon and oxygen.
Larger stars leave behind incredibly dense spheres of neutrons known as neutron
stars.
-
- Gas from a
companion star can fall onto a white dwarf, causing it to trigger its own kind
of supernova blast. Neutron stars can collide with each other, releasing an
enormous amount of energy in an event known as a kilonova.
-
- No matter what, all
of these processes involve a lot of radiation, a lot of energy and a lot of
particles flying around at high speed — in other words, the perfect soup for
fashioning new elements. It's through these calamities for the rest of the periodic
table of elements.
-
- It's also through
these energetic events that these elements spread beyond the bounds of their
home stars and out into the interstellar mix. There, those elements join new
gas clouds, which eventually coalesce to form new generations of stars that
continue the process of elemental recycling and regeneration, slowly enriching
the universe with more elements for life.
-
- Ok, then how did we get here?
-
-
October 24, 2023 HOW
THE ELEMENTS FORMED?
4197
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