Introduction of Universe

Introduction of Universe

Universe is the name that we use to describe the collection of all the things that exist in space. It is made of many millions of millions of stars and planets and enormous clouds of gas separated by a gigantic empty space.

Astronomers can use telescopes to look at very distant galaxies. This is how they see what the universe looked like a long time ago. This is because the light from distant parts of the universe takes a very long time to reach us. From these observations, it seems the physical laws and constants of the universe have not changed.

Physicists are currently unsure if anything existed before the Big Bang. They are also unsure whether the size of the universe is infinite.

History

Many people in history had ideas to explain the universe. Most early models had the Earth at the centre of the Universe. Some ancient Greeks thought that the Universe has infinite space and has existed forever. They thought it had a set of spheres which corresponded to the fixed stars, the Sun and various planets. The spheres circled about a spherical but unmoving Earth.

Over the centuries, better observations and better ideas of gravity led to Copernicus's Sun-centred model. This was hugely controversial at the time, and was fought long and hard by authorities of the Christian church.

The invention of the telescope in the Netherlands, 1608, was a milestone in astronomy. By the mid-19th century, they were good enough for other galaxies to be distinguished. The modern optical (uses visible light) telescope is still more advanced. Meanwhile, the Newtonian dynamics (equations) showed how the Solar System worked.

The improvement of telescopes led astronomers to realize that the Solar System is in a galaxy made of billions of stars, the Milky Way, and that other galaxies exist outside it, as far as we can see. Careful studies of the distribution of these galaxies and their spectral lines have led to much of modern cosmology. Discovery of the systematic redshift of galaxies led to the conclusion that the Universe is expanding .

Big Bang

The most used scientific model of the Universe is known as the Big bang theory. The Universe expanded from in which all the matter and energy of the Universe was concentrated. Several independent experimental measurements support the expansion of space and, more generally, the Big Bang idea. Recent observations support the idea that this expansion is happening because of. Most of the matter in the Universe may be in a form which cannot be detected by present methods. This has been named dark matter.

Just to be clear, dark matter and energy have not been detected directly (that is why they are called 'dark'). Their existence is from observations which would be difficult to explain otherwise. According to space can get bigger faster than the speed of light, but we can view only part of the universe because of the speed of light. We cannot see space beyond the limitations of light (or any electromagnetic radiation) the diameter of the Universe is at least 93 billion.

It is estimated that the age of the Universe is 13.73 (± 0.12) billion years, and that the diameter of the Universe is at least 93 billion light years, or 8.80 ×1026 meters.

Etymology, synonyms and meaning

The word Universe comes from the Old French word Univers, which comes from the Latin word universum. The Latin word was used by Cicero and later Latin authors in many of the same senses as the modern English word is used.

A different interpretation (way to interpret) of unvorsum is "everything rotated as one" or "everything rotated by one". This refers to an early Greek model of the Universe. In that model, all matter was in rotating spheres centered on the Earth; according to Aristotle, the rotation of the outermost sphere was responsible for the motion and change of everything within. It was natural for the Greeks to assume that the Earth was stationary and that the heavens rotated about the Earth, because careful astronomical and physical measurements (such as the Foucault pendulum) are required to prove otherwise.

The most common term for "Universe" among the ancient Greek philosophers from Pythagoras onwards was το παν (The All), defined as all matter (το ολον) and all space (το κενον).