How and when did the Universe we know begin to exist? Has it always been like now?
Astronomers are mostly convinced that the Universe arose from a great explosion (big Bang), occurred between 13,600 and 13,850 million years before the current moment.
The first indications of this fact were discovered by the American astronomer Edwin Hubble, in the 1920s, when he explained that the Universe is expanding and the clusters of galaxies move away from each other.
The theory of relativity General proposed by the famous physicist and astronomer Albert Einstein also predicts this expansion.
If we take a "picture of the Universe" at any given time, we don't see its current state, but its history. Light travels at 300,000 km. per second. Even when we look at the Moon (the closest celestial object), we see it as it was just over a second ago.
In the following pages we will see how the Universe has been formed and how it evolves. We will also review the materials that form it, the forces that direct it and the movements that originate.
In this chapter:How the Universe was formed: Edwin Hubble discovered that the Universe expands. Albert's theory of general relativity ... Read pageEvolution of the Stars: Stars evolve over millions of years. Actually, they never stop evolving and changing… Read page Materials and radiation: In the Universe there are scattered materials, inside and outside the galaxies. We talk about interstellar matter ... Read pageForces and movements: Gravity is the force of attraction between objects. In the Universe all matter moves because of it and ... Read pageThe expansion of the Universe: The discovery of the expansion of the Universe begins in 1912, with the work of the astronomer ... Read page