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The Cosmos and Deep Time

Galaxies - James Webb telescope
The galaxy cluster SMACS 0723 at a distance of 4.6 billion light years, with other galaxies in front of and behind the cluster. This field was also imaged by Webb’s Mid-Infrared Instrument (MIRI), which observes mid-infrared light - NASA, ESA, CSA, and STScI - original page


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.


The Origins of the Universe
The Origins of the Universe - image from the Centre for Theoretical Cosmology - original page with link to full-sized image.

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.

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.

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.

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