In many areas meets term Universe, but each of them with a different meaning. Even in astronomy there are several interpretations. The first and simplest definition they give astronomers as: The universe represents everything we see. It would be observable universe, containing all the stars and galaxies, the closest to the most distant, which can be detected directly by receiving radiation they emit.
But observable universe is not far delineated. Its dimensions are growing, as the progress of science improves the working tools of astronomy telescopes, radio telescopes, satellites – observatories, space probes.
In another definition, the Universe would be all that is observable plus whatever might exist. This is the whole universe, forming more subject to mathematical and philosophical studies, which are known by extrapolating data from observable universe.
The third definition would encompass the whole universe is described by the known laws of physics. This is the physical universe, a slight extension of the observable Universe, including areas that he not be observed directly, but whose presence can be inferred through its effects on some observable entities.
The universe would have existed for about 15 billion years after Stephen Hawking.
The universe has in its composition visible matter galaxies, stars, planets, asteroids, dust which represents about 10% of its total mass and dark matter and dark energy which would represent about 90% of the universe.
Physical universe and cosmology
The physical universe is the subject of cosmology. One of the main problems in cosmology is seeking to respond to the delimitation of the universe because there really a limit? Or the universe is infinite? One of the limits of the universe is known: it is the one imposed by the tools of observation, such as limited observation optical telescopes.
Every time more distant objects have been detected, the observations are great circle, and hence is great and observable universe.
For now we have not reached what might be called the end of the universe, although the strength to penetrate increasingly deeper into the universe grows continuously. In terms of cosmic dust clogging distant objects, it proved very weak, so apparently the dust is not so dense as to hinder the observations made so far.
But there is a limit of Knowledge Universe, a much larger share. It’s the speed limit. It is about the idea of the Universe expanding, which means that all objects in the universe moving away from us at speeds increasingly larger.
They removed these signals can arrive only by the critical situation in which a cell phone tracker is moving away from us with a speed almost equal to the speed of light.
The limits of the observable Universe would be 15 billion light-years distant galaxies because it moves at the speed of light 85-90%, which means that what’s beyond them / they not physically see.
So we see with the most advanced telescopes or cosmological horizon is universal. For us, at least for now, there are traces the limits of the universe.