Master Timeline
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 »
Galaxies formed early in cosmic history, within a few hundred million years of the Big Bang.
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 »
In the first fraction of a second, the universe cooled enough for the electromagnetic and weak forces to split, setting the stage for stable particles.
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
When we trace the universe backward, our equations point to an unimaginably hot, dense beginning — not a confirmed object, but the mysterious edge where current physics breaks down.
Hourglasses, also known as sandglasses or sand timers, were first used in the 14th century, although it is unclear exactly when they were invented. The earliest written reference to an hourglass dates back to the early 14th century in Europe, but they may have been used earlier in other parts of the world. Hourglasses were
A good legal system slows judgment so claims can be tested fairly. Think well by asking not just what was ruled, but how the claim was tested.
Law of the Twelve Tables Read More »
The appendix is an example of a Phenotype Variation — a trait that varies among individuals. In fact, something like 1 in 100,000 people are born without an appendix.
The first known postal system goes back to the Pharoah’s of Egypt circa 2400 BCE. Pharaohs used couriers to send out decrees throughout the Egyptian territory. The earliest surviving piece of mail dates back to 255 BCE and is also Egyptian.
First Mail, First Postal System Read More »
