The universe

When I was a child I wanted to be an astronaut so one of my favorite topics is the Universe.

The universe is the totality of space and time, all forms of matter, energy and momentum, laws and physical constants that govern them.

Astronomical observations indicate that the universe has an age between 13 730 and 13 810 million years and at least 93 000 million light years extension. According to the most accepted theory, the event that started the universe is called the Big Bang. Also this theory states that after the Big Bang, the universe began to expand to reach its current condition and continues.

Because, according to special relativity, matter can’t move at a speed greater than the speed of light, it may seem paradoxical that two objects in the universe may have been separated 93 billion light years in time only 13 billion years; however, this separation does not conflict with the theory of general relativity, because it only affects the motion in space, but not the space itself, which can be extended at a higher rate, not limited by the speed of light. Therefore, two galaxies can be separated from one another faster than the speed of light if the space between them which expands.

Recent observations have shown that the expansion of Universe is accelerating, and most of the matter and energy in the universe are so-called dark matter and dark energy, ordinary matter only represent just over 5% of total.

Experiments suggest that the universe has been governed by the same physical laws and constants throughout its extent and history. It is homogeneous and isotropic. The dominant force at cosmological distances is gravity, and general relativity is currently the most accurate way to describe it. The universe has at least three dimensions of space and one of time, although experimentally not be ruled extra dimensions. The space-time appears to be connected easily, and space has a very small or even zero mean curvature.

Based on observations of the observable universe, physicists attempt to describe the space-time in which we, along with all matter and energy existing in it. Their study, in the largest scales, is the subject of cosmology based on astronomy and physics, which describes all aspects of this universe with its phenomena discipline.

The currently most accepted on the formation of the universe theory was theorized by the Belgian Lemaître canon, from Albert Einstein's equations. Lemaitre concluded (as opposed to what Einstein thought) that the universe was not stationary, that the universe had an origin. It is the Big Bang model, which describes the expansion of space-time from a spacetime singularity. The universe underwent a rapid period of cosmic inflation that swept all initial irregularities. Thereafter the universe expanded and became stable, cooler and less dense.

As for its final destination, current evidence seems to support the theory of the permanent expansion of the universe (Big Freeze or Big Rip), which indicates that the expansion of space itself, cause there will come a point where the atoms they will separate into subatomic particles. Other possible futures that were considered, speculated that the dark matter could exert force severe enough to stop the spread and make all matter is compressed again;

something scientists call the Big Crunch or the Big Crunch, but recent observations go in the direction of the Big Rip.

https://en.wikipedia.org/wiki/Universe