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The Cosmos and Deep Time

Introduction

The cosmos refers to the physical universe, including all matter and energy, as well as the laws that govern it. The study of the cosmos, or cosmology, seeks to explain how the universe came into existence and how it has evolved over time.

The universe is estimated to be around 13.8 billion years old, and its early history can be divided into several key stages. The initial expansion of the universe, known as the Big Bang, was followed by a period of rapid cooling and the formation of the first stars and galaxies. These early galaxies then merged and formed larger structures, eventually leading to the formation of the Milky Way and other present-day galaxies.

In addition to the formation of galaxies, the evolution of the cosmos has been shaped by several key processes, including the formation of stars, supernovae explosions, and the eventual formation of heavier elements such as iron. These elements have gone on to form the building blocks of planets, and have played a critical role in the evolution of life on Earth.

Deep Time

In order to understand the history of universe, of life on Earth, and human history in perspective, it is necessary to understand Deep Time.

Deep Time, the idea that the Earth and the universe are not merely thousands, but millions, or even billions, of years old, was only discovered in the Western world with the birth of the science of geology through figures such as Hutton and Lyell, although even more radical ideas of a literally beginningless universe have been standard to Eastern philosophy (Jainism, Buddhism, and Hinduism) for several millennia. Of course, even today there are religious fundamentalists who cannot understand science, these are called Young Earth Creationists. It’s worth noting though that many proponents of Deep Time and Big History are actually Christians. These include evolutionary theologian Pierre Teilhard de Chardin and paleontologist Robert T Bakker.

Both Western geological, and Eastern, ideas were however uniformitarian; the past was assumed to be just like the present. Lyell for example resisted contemporary ideas of transformation of life. It was only with Darwin's great revolutionary insight of evolutionary naturalism that we had not only deep time but the idea of change and evolution as well.

Cosmological time

Cosmological time goes beyond even deep time. It is logarithmic; it begins with the postulated unimaginably short moments of, and immediately following, the Big Bang, then becomes more sedate as the universe expands and things slow down. Finally it settles down to a leisurely rate of billions of years. Scientists have even postulated trillions upon trillions of future years in which all the stars slowly go out, a rather bleak prospect which does not take into account various other factors such as alternative cosmologies and possible future space-time engineering technology. Here, Cosmic Time is defined as the period from the origin of the known universe (the "Big Bang") to the present, a period of some 13.7 billion years (or 137 geons), and is considered to extend an indefinite but finite number of gigayears into the future.

Timeline

This timeline gives a rough overview of the early universe and its development, with the focus on the formation of our solar system and the Earth. Some of this is taken from Wikipedia.

The whole cosmology is physically deterministic, a result of the initial conditions of the Big Bang. Early dates represent compressed time (including nanoseconds and less). A number of cosmic evolutionary / big history thresholds are passed in a brief period of time. As the universe expands, physical transitions slow, and time is measured in millions and finally billions of years, represented here as Gya - Billions of years ago (“G” = gigayear).

This period is divided into two eras, the Primordial and the Stelliferous

Primordial Era. On a logarithmic scale, the Primordial Era is defined as "−50 < n < 5". In this era, the Big Bang, the subsequent inflation, and Big Bang nucleosynthesis are thought to have taken place. Toward the end of this age, the recombination of electrons with nuclei made the universe transparent for the first time - Wikipedia - The Five Ages of the Universe.

• 13.8 billion years ago (13.8 Gya): The Big Bang, the beginning of the universe. The universe expands rapidly from an infinitely dense and hot state. Threshold, the Radiant Era, the radiation-filled early universe.
• 10^-33 to 10^32 seconds: The universe undergoes a phase of exponential expansion known as inflation, which smoothed out the universe and formed the seeds for the formation of galaxies and stars. An alternative hypothesis called “Eternal Inflation” (see this article by physicist Ethan Siegal) does away with the Big Bang singularity and pre-inflation epochs like Planck epoch and Grand unification.
• 10^-12 seconds: Quark epoch. The universe is filled with a hot, dense soup of particles, including quarks and gluons, which later formed protons and neutrons.
• 10^-6 seconds: Hadron epoch. Quarks combine to form protons and neutrons, and the universe was filled with a plasma of particles.
• 1 second: Lepton epoch. The universe cools to 10^9 kelvin. Hadrons and anti-hadrons annihilate each other, leaving behind leptons and antileptons
• 10 seconds: Photon epoch begins: Most of the leptons and antileptons annihilate each other. A small number of unmatched electrons are left over. Universe dominated by photons (radiation). Dark matter particles start building non-linear structures as dark matter halos. Because charged electrons and protons hinder the emission of light, the universe becomes a super-hot glowing fog.
• 3 minutes: Primordial nucleosynthesis: The universe has cooled down enough to allow protons and neutrons to combine and form the first atomic nuclei, mainly hydrogen and helium.
• 370,000 years after the Big Bang: The universe becomes cool enough for electrons and protons to combine into hydrogen atoms. The universe becomes transparent to light.

Stelliferous Era. On a logarithmic scale, the The Stelliferous Era, is defined as, "6 < n < 14". This is the current era, in which matter is arranged in the form of stars, galaxies, and galaxy clusters, and most energy is produced in stars. Stars will be the most dominant objects of the universe in this era. Massive stars use up their fuel very rapidly, in as little as a few million years. - Wikipedia - The Five Ages of the Universe.

• 13.8 Gya - One million years after the Big Bang: The Stelliferous Era begins
• 13.2 Gya - 600 million years after the Big Bang: Threshold, the Celestial Era / Stars, galaxies, and chemical elements. The first stars begin to glow; stars and galaxies begin to form, marking the end of the Dark Ages. Nuclear fusion begins, producing more complex elements such as carbon, oxygen, and nitrogen. These heavier elements would later form the building blocks of life
• 12 Gya, about 2 billion years after the Big Bang: Galaxies continue to form and evolve, including the Milky Way.
• 9 Gya, about 5 billion years after the Big Bang. The thin disk of our galaxy began to form
• 5.1 Gya, about 8.7 billion years after the Big Bang: The Milky Way merges with another galaxy to become the spiral galaxy we see today.
• 5 Gya, about 8.8 billion years after the Big Bang. Dark energy and matter are balanced. After this, the dark energy dominated era begins and the expansion of the universe begins to accelerate
• 4.6 Gya, the Sun and Solar System formed formed from a cloud of gas and dust
• 4 Gya: The Earth begins to cool, oceans form
• 3.5 Gya. The earliest traces of life on Earth.
• 0.5 Gya. Complex life on Earth.
• 0.0003 Gya. First anatomically modern humans.
• 0.000005 Gya. History begins.

For the future equivalent, see The Very Far Distant Future. Eventually, the only luminous stars remaining will be white dwarf stars. By the end of the Stelliferous era, bright stars as we know them will be gone, their nuclear fuel exhausted, and only white dwarfs, brown dwarfs, neutron stars and black holes will remain; see the Five Eras.

Page by M Alan Kazlev, 2023