Through the Trees

A Place to Stand

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The Big Bang

The universe began approximately 13.8 billion years ago with the Big Bang, an event describing the rapid expansion of space from an extremely hot, dense state. In the first fraction of a second, the universe underwent a phase of Cosmic Inflation, an exponential expansion that smoothed the cosmos and laid the foundation for the large-scale structure we see today.

The Laws of Physics

In the immediate aftermath of the Big Bang, the universe was an incredibly hot, dense plasma of fundamental particles. The laws of physics as we know them, including the four fundamental forces—gravity, electromagnetism, and the strong and weak nuclear forces—are thought to have separated and taken on their current forms as the universe rapidly cooled. Before this cooling, all forces may have been unified. The current structure of the universe, including the ratios of matter and energy, is explained by the actions of these forces operating from this early epoch.

Creation of Elements

A few minutes after the Big Bang, the temperature dropped low enough for protons and neutrons to fuse in a process called Big Bang Nucleosynthesis (BBN). This created the first, and lightest, elements: Hydrogen (about 75% of the total mass) and Helium (about 25%), along with trace amounts of Lithium.

All of the heavier elements essential for life and planets (like carbon, oxygen, and iron) were created much later in the cores of stars and scattered through the universe by supernova explosions.

All elements heavier than Helium were forged much later inside stars and during their explosive deaths, a process called stellar nucleosynthesis.

  • Lighter Elements (up to Iron): Stars sustain themselves by fusing lighter nuclei into heavier ones in their cores. Smaller stars fuse hydrogen into helium, while massive stars can continue this process through the CNO cycle and successive burning stages, creating elements up to Iron (Fe)—the most stable nucleus.
  • Heavier Elements (beyond Iron): Elements heavier than iron, such as gold, silver, and uranium, are created during catastrophic events like supernova explosions and neutron star mergers. The immense energy and dense flux of neutrons during these events trigger rapid neutron capture processes (r-process), building the heaviest nuclei. This expelled stellar material enriches the interstellar medium, providing the building blocks for new stars, planets, and life.

Creation of the Earth

The creation of complex structures, including planets, was a late event in cosmic history, occurring roughly 9 billion years after the Big Bang. Our solar system began to form about 4.6 billion years ago from a massive, rotating cloud of gas and dust called the solar nebula. This nebula consisted of the primordial hydrogen and helium, enriched by heavy elements produced by earlier generations of stars.

The Earth formed approximately 4.54 billion years ago through the process of accretion, where dust and rock particles in the young solar system’s nebula collided and clumped together under gravity. This process generated immense heat, causing the early Earth to be largely molten. As it cooled, denser materials sank to form the core, while lighter materials rose to form the mantle and the earliest, thin crust.

The permanent, buoyant continental crust began to form about 4 billion years ago. This crust is chemically distinct from the denser oceanic crust and is created primarily through volcanic activity, where basaltic rocks are partially melted and chemically processed, often at early subduction zones. The oldest parts of these early continents are called cratons, which remain the stable cores of modern landmasses.

Almost all igneous rocks are composed predominantly of silicate minerals, meaning the essential ingredients are Silicon (Si) and Oxygen (O). The other major elements, or “building blocks,” that determine the specific type of igneous rock formed include: aluminum, iron, calcium, sodium, magnesium and potassium. The ratio of these elements, especially the percentage of silica (SiO2​), determines the rock’s mineralogy, color, and density. Coarser grained (plutonic) rocks come from magma from deep in the earth’s crust. Finer grained rocks come from lava from volcanoes. Sedimentary rocks are formed from weather erosion, deposition and compaction. Metamorphic rocks, such as marble and slate and formed when existing rocks are pulled down under the crust.

Continents and Oceans

The arrangement of the continents is not static; it is dictated by Plate Tectonics. The Earth’s rigid outer layer (the lithosphere) is broken into large plates that float and move slowly over the semi-molten mantle below. Over billions of years, this movement has caused continents to periodically collide and fuse into vast supercontinents, only to break apart again.

For example, around 335 million years ago, nearly all landmasses assembled into the supercontinent Pangaea (“All Lands”). Starting about 175 million years ago, Pangaea began to break up, slowly drifting its fragments—which became today’s continents—into their current positions, a process that continues today.

The creation of Earth’s oceans is thought to have resulted from a combination of processes that occurred as the planet cooled about 4.5 to 3.8 billion years ago.

The main source of water was volcanic outgassing (H2​O vapour and other gases released from the Earth’s interior through constant volcanic eruptions). As the Earth’s surface cooled below the boiling point of water, this water vapor in the atmosphere condensed, leading to centuries of torrential rain that filled the low-lying basins.

A contributing source was likely the delivery of water by icy asteroids and comets that bombarded the early Earth. Current scientific consensus suggests that water was both native to the Earth’s original formation materials and delivered later by impactors, resulting in the vast, life-sustaining oceans we have today. Evaporating water absorbs carbon dixide from the atmosphere, making it slightly acidic. When it falls as rain, it dissolves sodium from silicate minerals in igneous and metamorphic rocks, causing saline build-up in the oceans.

Atmosphere

Earth’s first atmosphere was a temporary, thin layer of light gases like Hydrogen (H2​) and Helium (He), swept away almost immediately by intense solar winds and the planet’s weak early gravity. As the molten Earth cooled, intense and constant volcanic activity began releasing gases from the planet’s interior—a process called outgassing. This created the stable second atmosphere, composed mainly of Water Vapour (H2​O), Carbon Dioxide (CO2​), and Nitrogen (N2​).

Gemini AI helped me. Its sources included:

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