The Big Bang Timeline
The Milky Way and Andromeda galaxies are expected to collide and merge into a single elliptical galaxy. Despite the dramatic nature of this event, the vast distances between stars mean that direct stellar collisions are unlikely.
Milky Way-Andromeda Collision Read More »
Current scholarship generally places the formation of the Milky Way between 200 and 600 million years after the Big Bang, during the period of early galaxy formation that followed the forging of Population II stars. Some of the oldest stars within the Milky Way belong to this Population II category, with estimates for their formation
Birth of the Milky Way Read More »
Current observations, such as those of GN-z11, suggest that galaxy formation began as early as 400 million years after the Big Bang. This galaxy, observed at a redshift of z=11.09, stands as a testament to the rapidity with which the universe’s first structures began to coalesce from the primordial gas. While the detection of GN-z11
Leaving the highly speculative first second, and skipping to a few minutes later, the Nucleosynthesis period accurred about 3 to 20 minutes after the Big Bang. During this period, the universe had cooled enough for protons and neutrons to come together to form simple nuclei, but not yet atoms, as the universe remained too hot
Nucleosynthesis Period Read More »
We are still within the speculative first second. The Electroweak Era ends around 10−12 seconds after the Big Bang. Following inflation, the universe continued to expand and cool, allowing the electromagnetic and weak nuclear forces to separate. Particles continued to form and annihilate in a hot, dense environment, but as the universe cooled further, the
The Inflationary Epoch was from about 10−36 seconds to 10−32 or so seconds. Notice the duration label change from “era” to “epoch” and from a narrow time to a range. However, also note that we are still within the first millisecond of the Big Bang. This was a period of extremely rapid expansion driven by
Inflationary Epoch Read More »
The speculative Grand Unification Era ends around 10−36 seconds after the Big Bang. During this era, the strong force is believed to have separated from the other three fundamental forces. The universe was still incredibly hot and dense, and it’s during this period that the first subatomic particles, including quarks and leptons, could have begun
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The Plank Era occurred in the first part of the first millisecond after the singularity. Current estimated put it at up to 10−43 seconds after the Big Bang. The term “era” is used for this micro-duration as a sort of tip of the hat to Einstein’s Relativity. It reflects a conceptual approach to time that
The Earth and the other planets formed 4.5 billion years ago from the same cosmic cloud—the primordial material which gave birth to the Sun. The dust and comets—the rocks—were composed largely of hydrogen, ice, carbon, and nitrogen.
Population I stars likely started forming around 8 to 10 billion years ago, with the process continuing to the present day as new star-forming regions develop in galaxies. These third generation stars are composed of the remnants of Population II stars. The majority of the stars adorning the Milky Way today belong to this third
Population I Stars: Like our Sun Read More »
4.6 billion years ago, a cloud of gas and dust collapsed under the force of its own gravity to form our solar system.With the Sun at its center, glowing, the planets had not yet formed. The Sun, a G-type Population 1 star, shines brightly with a surface temperature of about 9,400 degrees, 5,500 Kelvin, and
Legacy: Began enriching the interstellar medium with heavier elements, including carbon, necessary for organic chemistry From the ashes of Population III stars, celestial giants, rose a new generation of stars, the Population II stars. These stars contained a higher proportion of the heavier elements, granting them a longer lifespan, and likely the company of planets.
Population II Stars: Heavy Element Synthesis Read More »
Legacy: First 26 elements of the periodic table of elements. After a few hundred million years, gravity continued to play its part, drawing atoms into an intimate collapse, giving birth to the very first stars and galaxies. These first stars, known as Population III stars, were stellar giants: massive, hot, and short-lived; they burned for
Population III Stars: Heavier Elements Read More »
The image of the early universe that we see in the CMB reveals a time shrouded in darkness. During this era, the 17 known particles first started to combine to form the universe’s first atoms. Electrons, protons, and neutrons came together to create neutral hydrogen atoms, a process that allowed photons—or light—to traverse the cosmos
This supernova was observed by Chinese astronomers in 185 CE. The Chinese kept meticulous astronomical records for centuries, including observations of what modern scientists interpret as supernovae. Chinese astronomical records from 185 AD describe the appearance of a “guest star” in the constellation now known as Circinus. This guest star matches the expected location and
The death of our Sun is estimated to occur in about 5 billion years. Around this point, life on Earth will become uninhabitable. There will likely be life here right up until there’s not. Most humans will have left the planet many millions of years prior to this point. Also, the merging of the Andromeda
A 30 Philosophers touchstone: Chapter 1, “Origin Story.” The universe began as an infinitely dense, unimaginably hot, and minuscule point known as a singularity. In a breathtaking instant, this singularity expanded and cooled, giving rise to the fabric of space, time, and matter, with all the laws of physics taking shape in that moment. The
First DNA Life: From chemical reactions before 4 billion years ago to replicating molecules about 4 billion years ago to DNA based life then to LUCA, the only DNA based branch to survive. Meaning, DNA based life likely started before LUCA, and LUCA is the only branch to survive the test of time. From LUCA
LUCA: Last Universal Common Ancestor Read More »
Around 1.7 billion years ago, a branch of protozoa, an advanced branch of the eukaryote cells, split into animals, plants, and fungi. These three separate lineages are the ancestors of modern plants, fungi and animals. 1.7 billion years ago: Plants diverge from the common protozoa ancestor. 1.5 billion years ago: Fungi and animal branch emerges.
Animals, Plants, and Fungi Split Read More »
The earliest known life on Earth are fossilized microorganisms found in hydrothermal vent precipitates. Currently dated to about 3.42 billion BCE. These microorganisms were prokaryote cells. Single celled organisms with no nucleus and had early simple DNA. More complex DNA in a nucleus evolved about 1.5 billion years later in Eukaryotic cells, circa 2 billion
Oldest Known Fossil-Microorganisms Read More »
