Cosmic space, definition and study. A-Z index of Cognitio.

The cosmic space is the vacuum that exists between the celestial bodies. It is not completely empty but contains a low particle density, especially hydrogen and helium plasma, electromagnetic radiation, magnetic fields and neutrons. The theory suggests that it also contains Dark matter and dark energy. 

Dark matter, definition and study. A-Z index of Cognitio.

Dark matter

In the 350 BC, the Greek philosopher Aristotle suggested the idea that nature abhors the void, a principle that would become known as a vacant horror. This concept was built on an ontological topic of the fifth century BC. Of the Greek philosopher Parmenides, who denied the possible existence of a void in space. Based on this idea, that vacuum can not exist, in the West, it has been believed for many centuries that space can not be empty. The modern concept of space is based on the Cosmology of the Big Bang, first proposed by the Belgian physicist Georges Lemaître in 1931.

Cosmology, definition and study. A-Z index of Cognitio.


This theory argues that the observable universe originated from a very compact formation, which has since undergone continuous expansion. The matter left behind after its initial expansion has since then been the gravitational collapse, creating stars, galaxies, and other astronomical objects, leaving behind a deep vacuum that forms what is now called space. Since light has a finite speed, this theory also binds the size of the universe directly observable. These leaves open the question of whether the universe is endless or infinite. Space is the natural approximation closest to a perfect vacuum. Contrary to popular belief, a person suddenly exposed to the void would not explode, would not be frozen to death nor die for blood-shedding. However, sudden exposure to low pressure, for example during a rapid decompression, could cause barotrauma, ie the laceration of the lungs, due to the large difference in pressure between the inside and outside of the chest. 

There are no clear boundaries between the Earth’s atmosphere and space, where the density of the atmosphere gradually decreases as the height increases. Certain scientific limits have been identified and more precisely:

The International Aeronautical Federation has defined the Kármán line at a height of 100 km as the boundary between aeronautics and astronautics.

The United States designates as astronauts people traveling over 80km.

In 2009, scientists at the University of Calgary reported specific measurements with an instrument called Supra-Thermal Ion Imager (a tool that measures the direction and velocity of ions) that allowed them to determine that space begins at 118 km above the Land. The theme of spatial exploration – traveling to the cosmic space, going to other planets, and meeting other worlds – has always fascinated the human mind, well before the technology makes the trip possible, and is one of the most popular themes in the planet, Science field. 

Cosmic space, definition and study. A-Z index of Cognitio.



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Cosmic space, definition and study. A-Z index of Cognitio.

Cosmic space