"Seeing a world in a grain of sand", the 200 million-year rhythm of the earth's crust, disaster omens and the advent of life

William Blake, the first important romantic poet in Britain, wrote at the beginning of his poem: "Seeing a world in a grain of sand". This state of mind is not only a humanistic romance, but also carries scientific principles.

Even the most inconspicuous grains of sand contain the truth of the world.

In the past, people thought about the structure of our planet itself by understanding mineral grains thinner than a human hair and then inferring the chemical processes that formed them.

Now, scientists have taken that focus to a whole new level - linking tiny crystalline grains to Earth's position in the context of the Milky Way galaxy.

Looking into the universe

Thinking on a larger scale, astrophysicists try to understand our place in the universe. They use the laws of physics to create models that describe the orbits of celestial bodies.

Although we may think of Earth's surface as being shaped by processes within the planet, the planet is undoubtedly influenced by its cosmic environment - this includes periodic changes in Earth's orbit, variations in the Sun's energy, gamma-ray bursts, and of course meteorite impacts.

We only need to look at the pockmarked face of the Moon to be reminded of meteorites. Indeed, recent scientific work has pointed to the importance of meteorite impacts in the formation of Earth's continental crust, especially when the Earth was young (for example, some argue that there is evidence that giant meteorites created Earth's continents).

A swirl of blue and white glowing stars against a dark background, our Milky Way is thought to be similar to other barred spiral galaxies such as NGC 4394

The rhythm of Earth's crustal production

Many rocks on Earth are formed from molten or semi-molten magma.

These magmas come either directly from the mantle - the solid, slow-flowing layer beneath Earth's crust - or from the reheating of pre-existing, older crust.

As liquid magma cools, it eventually freezes into solid rock.

Through the cooling process of magma crystallization, mineral grains "grow" out, which can capture elements such as uranium, which decay over time and create a precise "stopwatch" to record their age. Not only that, the crystals also capture other elements that can trace the composition of their parent magma, just as we use a surname to trace a person's family lineage.

With these two pieces of information — age and composition — scientists can reconstruct a timeline of Earth's crust.

Next, its dominant frequency can be decoded using a mathematical trick called a Fourier transform - a tool that essentially decodes the frequency of an event, like, for example, what ingredients are in a cake.

Our results from this method suggest that the crust of the early Earth had a rhythmicity of about 200 million years.

Our Place in the Universe

Scientists have discovered that there is another similar rhythm.

The solar system and the four spiral arms of the Milky Way all revolve around the supermassive black hole at the center of the Milky Way, but of course, they move at different speeds.

Glowing image of a spiral galaxy with blue arms and a pale golden center

The spiral arms have an orbital speed of 210 kilometers per second, while the Sun's speed is 240 kilometers per second, meaning that our Solar System is "surfing" on the galaxy's spiral arms, moving in and out.

The result of this model is that our solar system enters the spiral arms of the Milky Way every 200 million years.

Therefore, scientists have concluded that there seems to be a possible connection between the time when the Earth's crust was formed and the time it orbits the spiral arms of the Milky Way.

Verification

In the distant regions of our solar system, a cloud of icy and rocky debris known as the Oort Cloud is thought to orbit our sun.

As the Solar System periodically moves into the spiral arms of the Milky Way, interactions between it and the Oort Cloud move material out of the cloud and closer to the inner Solar System. Some of this material may even strike the Earth.

Earth is hit relatively frequently by rocky bodies from the asteroid belt, at an average speed of 15 kilometers per second, but comets ejected from the Oort cloud arrive much faster, at an average of 52 kilometers per second.

Scientists believe that these periodic high-energy impacts are traceable evidence - comet impacts cause the mantle to decompress and melt, and the elements are preserved in tiny mineral grains that can be traced as a record of the Earth's crust.

This molten rock, rich in light elements such as silicon, aluminum, sodium and potassium, effectively floats on top of the denser mantle. While there are many other ways to create continental crust, it's likely that impacts created the crustal "seeds" of our planet early on. Later geologic processes created magma that attached itself to these early seeds.

A harbinger of doom, or a gardener of life on Earth?

The continental crust is crucial in most of the Earth's natural cycles - it interacts with water and oxygen to form new weathering products and carries most metals and biogenic carbon.

Large meteorite impacts are catastrophic events that could wipe out life. Yet at the same time, they are likely key to the development of the continental crust on which we depend.

With the recent passage of interstellar asteroids through the solar system, some even believe they are transporting life between universes.

How did life arrive on this planet? No one is sure.

Drive to the suburbs, look up at the sky on a clear night, and be mesmerized by the stars. Then look down at your feet and feel the mineral particles, rocks, and even the crust of the entire continent. All of this is amazing and is connected by a very grand galactic rhythm.

Heaven and earth are not kind, and treat all things as straw dogs. All the great things we care about are insignificant. When you are alive, do your best and leave the rest to fate. Relax your mind.

Source: Cosmic Decoding