Big History

Matter, energy, space, and time are created in an instant. The universe is a hot, dense soup of fundamental particles, constantly colliding and interacting. As it expanded and cooled, these particles gradually combined, allowing the first simple atoms (mostly hydrogen and helium) to form. This marked a crucial turning point, laying the foundations for stars, galaxies, and ultimately everything we observe today.

In an extremely brief moment, the universe undergoes exponential expansion, stretching quantum fluctuations across cosmic scales. This process explains why the universe appears so uniform today and seeds the initial structure that will later grow into galaxies.

As the universe cools, energy condenses into quarks, electrons, and neutrinos. Quarks combine to form protons and neutrons, establishing the basic building blocks of all future matter.

Protons and neutrons combine to form the nuclei of hydrogen, helium, and trace lithium. This is the first step toward chemically complex matter in the universe.

After atoms form, no stars yet exist. The universe is mostly invisible hydrogen gas slowly collapsing under gravity. During this long period, the first structures begin forming inside dark matter halos, setting the stage for the first stars.

Dark matter collapses into large-scale halos and filaments. These structures form the invisible “framework” of the cosmic web, guiding where galaxies and stars will later form.

Dense regions of hydrogen collapse inside early dark matter halos to form the first stars. These massive, short-lived stars produce the first heavy elements and begin transforming the chemical makeup of the universe.

Gravity pulls early stars and gas into the first galaxies. These small, irregular systems merge and grow, forming the foundation of all later galactic structures. Most importantly for us, the Milky Way forms through the merging of smaller proto-galaxies. Over billions of years it grows into a large spiral galaxy, becoming the future home of the Solar System.

Radiation from the first stars and galaxies gradually ionises neutral hydrogen. This is not a single event but a long cosmic phase lasting hundreds of millions of years. By its end, the universe becomes fully transparent to UV light.

Around this time, galaxies are forming stars at the highest rate in cosmic history. The universe is filled with bright, active galaxies rapidly producing new stars and enriching space with heavy elements. This era plays a crucial role in shaping the structure and chemistry of the modern universe.

Our Sun forms from a cloud of gas and dust. The remaining 0.1% of matter circles the sun, colliding and accreting into the rocky and gaseous planets of our solar system, including Earth.

Early Earth is a molten, heavily bombarded world. Over time, it cools enough for a solid crust to form, and water begins to accumulate. This sets the stage for the chemical processes that will eventually lead to life.

Volcanic outgassing and comet impacts create Earth’s early atmosphere. Water vapor condenses to form oceans, allowing stable chemical environments.

A Mars-sized body collides with the early Earth, ejecting debris that forms the Moon. This stabilises Earth's rotation and climate, making long-term life possible.

Deep-sea vents or shallow pools provide the perfect conditions for chemistry to become biology. Life begins as single-celled organisms, later evolving photosynthesis, which oxygenates our atmosphere.

Photosynthetic organisms begin releasing oxygen as a byproduct. Over millions of years, oxygen accumulates in the atmosphere, transforming Earth's chemistry and enabling more complex forms of life to evolve.

Eukaryotic cells evolve, containing nuclei and specialised structures. This allows for greater complexity and eventually leads to multicellular life.

Single cells begin forming organised groups, specialising and working together. This marks the beginning of complex organisms.

Earth enters a series of extreme ice ages, with glaciers potentially reaching the equator. This "deep freeze" created a massive evolutionary bottleneck. When the ice finally melted due to volcanic CO2, the resulting nutrient-rich oceans likely triggered the rapid evolution of complex life.

In a relatively short geological period, a huge variety of complex life forms appear. Most major animal groups emerge during this time, filling oceans with diverse ecosystems and setting the foundation for modern life on Earth.

Extinction event triggered by a rapid ice age and falling sea levels, this event wiped out around 85% of marine species. It mainly affected early life in the oceans.

Another extinction event, now caused by ocean oxygen loss and climate instability. Many reef-building organisms disappeared, reshaping marine life and paving the way for later vertebrate evolution.

The Earth's continents collide to form the supercontinent Pangea. This era saw the rise of the first dinosaurs and the largest mass extinction in history (the Permian-Triassic 'Great Dying'), which cleared the ecological stage for the Mesozoic era.

Massive volcanic activity and climate change caused widespread extinctions. Many competing reptile groups died out, allowing the ecologically flexible dinosaurs to become dominant in the Jurassic world.

A massive asteroid impact in the Yucatan Peninsula causes a global extinction event. While tragic for (most) dinosaurs, it allows small, burrowing mammals to thrive and eventually evolve into primates.

Primates evolve with advanced vision and grasping hands. These traits eventually support tool use, intelligence, and human evolution.

The genus Homo emerges in Africa, marking a major evolutionary shift from earlier hominins such as Australopithecus. Early species, including Homo habilis, show increased brain size and begin producing more advanced stone tools. This period represents the beginning of a lineage that would eventually lead to Homo sapiens.

Homo erectus emerges in Africa and represents a significant evolutionary advancement in the human lineage. This species shows more modern body proportions, larger brains, and improved tool use compared to earlier Homo species. It marks the beginning of a lineage that would eventually spread across much of the world.

Homo erectus learn to control fire, enabling cooking, warmth, and protection. This increases energy intake and supports brain development.

Homo sapiens emerge in Africa through gradual evolution from earlier hominin species. Early humans are hunter-gatherers with developing cognitive abilities, tool use, and social structures. Neanderthals in Europe and Denisovans in Asia evolved alongside Homo sapiens. Over time, Homo sapiens eventually replaced and partially interbred with them.

Humans gain the ability to share complex ideas through symbolic language. This means information is no longer lost when an individual dies; it accumulates over generations, accelerating our control over the environment.

As the last Ice Age ends, humans begin domesticating plants and animals. This leads to food surpluses, permanent settlements, and the rise of cities, states, and writing.

The first urban civilisations appear in Mesopotamia (followed by Egypt, the Indus Valley, and China). This organises human societies into cities and states. Writing systems develop, allowing knowledge to be recorded and preserved beyond memory. This marks the beginning of history as we traditionally study it.

Trade routes begin to link the Roman Empire, the Han Dynasty, and the Kushan Empire. For the first time, ideas, religions (like Buddhism), and technologies (like paper and silk) travel across an entire continent, accelerating the pace of collective learning.

Humans begin systematically studying nature through observation and experiment. This leads to rapid advances in physics, astronomy, and biology, fundamentally changing how we understand the universe and our place within it.

Humans tap into the energy stored in fossil fuels. This leads to the Industrial Revolution, a massive population explosion, and global connectivity, but also places immense strain on the Earth's biosphere.

With rockets and satellites, humans begin exploring space. We observe Earth from orbit and expand our understanding of the universe.

Computers and the internet transform communication and knowledge sharing. Information spreads instantly across the globe, reshaping society.

We are now a globally interconnected species. We have the power to explore the stars or destroy our own habitat. The future of the planet and humanity depends on how we manage our collective knowledge today.