User:PiRSquared17/Universe
From Wikipedia, the free encyclopedia
The Universe is everything that exists. The word Universe can be used in ways that do not mean the same thing. Examples of this are cosmos, the world, or Nature.
Most of the time, Universe means "the area around everything." But, using a different word meaning, some people have thought that the "Universe" made of getting bigger space-as-we-know-it, is just one of many "universes", which, when put together, are called the multiverse[1]. For example, in the many-worlds hypothesis, new "universes" are created with every quantum measurement[source?]. These universes are usually thought to not be touching our own universe and that makes it not possible for us to find experimentally[who?]. What we have seen of older parts of the universe (which are far away) make it seem that the Universe has had the same physical laws and constants throughout most of its history. However, in bubble universe idea, there may be an infinite amount of types of "universes" created in ways that are not the same, and maybe each with different physical constants.
In recorded history, some cosmologies and cosmogonies have been proposed to make up for sights of the Universe. The most early geocentric models were made by the ancient Greeks, who thought that the Universe has infinite space and has existed forever, but contains a single set of concentric spheres of finite size – relating to the fixed stars, the Sun and various planets – circling about a spherical but not moving Earth. Over the centuries, more precise viewings and better ideas of gravity led to Copernicus's heliocentric model and the Newtonian model of the Solar System. More improvements in astronomy led to people realizing that the Solar System is in a galaxy made of millions of stars, the Milky Way, and that other galaxies exist outside it, as far as machines can reach. Careful studies of the distribution of these galaxies and their spectral lines have led to much of modern cosmology. Discovery of the red shift and cosmic microwave background radiation revealed that the Universe is getting bigger and had a beginning.
According to the most used scientific model of the Universe, known as the Big Bang, the Universe expanded from a very hot, dense phase called the Planck epoch, in which all the matter and energy of the observable universe was concentrated. Since the Planck epoch, the Universe has been getting bigger to its present form, possibly with a brief period (less than 10−32 seconds) of cosmic inflation. Several independent experimental measurements support this theoretical expansion and, more generally, the Big Bang idea. Recent observations show that this expansion is happening because of dark energy, and that most of the matter in the Universe may be in a form which cannot be detected by present computers (and other machines), and so is not accounted for in the present models of the universe; this has been named dark matter.
Current ways of thinking of astronomical observations show that the universe has existed for 13.73 (± 0.12) billion years,[2] and that the diameter of the observable universe is at least 93 billion light years, or 8.80 ×1026 metres.[3] According to general relativity, space can get bigger faster than the speed of light, but we can view only a small part of the universe because of the speed of light. Since we cannot see space beyond the limitations of light (or any electromagnetic radiation), is not completely certain whether the size of the Universe is finite or infinite.