Evolution of the universe: Origin, materials and radiation, forces and movements, Expansion

Evolution of the universe

Astronomers are convinced the majority that the universe arose from a huge explosion (Big Bang), between 13,700 and 13.900 million years before the present time.
The first signs of this fact were discovered by the American astronomer Edwin Hubble, in the 1920's, when it stated that the universe is expanding and clusters of galaxies away from each other. The theory of general relativity proposed by Albert Einstein also predicts this expansion.
If we make a "picture of the universe" at a given moment, we don't see their current status, but its history. Light travels at 300,000 km. per second. Even when looking at the Moon (the nearest celestial object), we see as it was more than one second ago.
In this chapter we will see how it is formed the universe and how it evolves. We will also give a review materials that form it, the forces that direct it and the movements that originate.

Origin of the universe

Edwin Hubble discovered that the universe is expanding. The theory of general relativity by Albert Einstein had already planned it.


It was found that galaxies move away, still today, the one from the other. If we spend the film backward, where we arrive?
Scientists try to explain the origin of the universe with different theories, supported by observations and a few coherent mathematical calculations. The most accepted are the and the Big Bang theory Inflacionaria, complemented among if.

The Big Bang theory

The theory of the Big Bang or big bang, supposedly, makes between 13,700 and 13.900 million of years, all the matter in the universe was concentrated in an extremely small area of space, a single point, and exploded. Matter was driven with great energy in all directions.
The shocks that inevitably from sprodujeron and a certain disorder did that matter are banded and to focus more on certain places in space, and the first stars and galaxies first formed. Since then, the universe continues in constant movement and evolution.
This theory about the origin of the universe is based on rigorous observations and is mathematically correct from a first moment after the explosion, but does not have an explanation for the time zero of the origin of the universe, called "singularity".

Inflationary theory

Alan Guth's inflationary theory attempts to explain the origin and the first moments of the universe. Based on studies of strong gravitational fields, and that there are close to a black hole.
Inflationary theory assumes that a single force was divided into the four that we now know, producing the rise to the universe.
The initial thrust lasted practically invaluable time, but the explosion was so violent that, while the attraction of gravity slows the galaxies, the universe still grows, expands.
Time Event
Big Bang Infinite density and zero volume.
10 e-43 secs. Undifferentiated forces
10 e-34 secs. Soup of elementary particles
10 e-10 secs. Protons and neutrons are formed
1 sec. 10,000,000,000 degrees. Universe size Sun
3 minutes 1,000,000,000 second. Nuclei of atoms
30 minutes 300,000,000 °. Plasma
300,000 years Atoms. Transparent universe
1,000,000 years Germs of galaxies
100 million years First galaxies
billion years Star. The rest, cools
5 billion years Formation of the milky way
10,000 million years Solar system and Earth

No one should imagine the Big Bang as the explosion of a point of matter in a vacuum, because at this point, all matter, energy, space and time were concentrated. There was no 'out' or 'before'. The space and time are also expanded with the universe.

Materials and radiation

In the universe there are scattered materials, inside and outside galaxies. We talked about the interstellar matter, light, background radiation, and dark matter.

Interstellar matter

The gas and dust between the stars and galaxies is. Most is not visible, but can be detected through its gravitational effects and its electromagnetic emissions.
It consists, mainly, of hydrogen, but there are also small amounts of helium, nitrogen, oxygen, carbon and simple molecules of water, alcohols and ammonia.


An atom of hydrogen and one of oxygen can be combined to form a group o (hidroxilico), very active, capable of joining with almost any material. If you are with a hydrogen atom, form a molecule of water.
More complex molecules, formed by dozens of atoms were located from the 1970s.
Some could, under favourable conditions, forming organic matter, which is the basis of living organisms.

Light, waves or particles?

Light waves, such as X rays, can not be issued one by one, but only in packets called "how many". The science that studies it is quantum mechanics.
These types of high-frequency radiation, depending on how you look, behave like particles and, at the same time, as waves. The particles of light are photons. They have no mass and travel at about 300,000 km/s.

The cosmic background radiation

The "tangible" proof of the Big Bang was found in 1965. Checking a very sensitive microwave detector, two scientists discovered a radiation strange derived equally from all points of space.
Other theorists had already predicted that we should observe, coming from all over the universe, a "glow" testimony of the Big Bang, and that this light, due to the expansion of the universe, would be presented in the form of microwave.

Dark matter

It is believed that the dark matter is a material that does not emit any electromagnetic radiation. Its existence is based on theoretical considerations and is, by far, one of the main problems facing the Astrophysics.
Studying the forces in the universe, it is estimated that total matter is much more than the detected by our instruments. As we know nothing of it, it is called dark matter.

Forces and movements

Gravity is the force of attraction between objects.
In the universe all matter moves because of this and other forces.
The severity depends on the mass of the objects and the distance that separates them. How much more mass they have and are closer, greater is the force. When separate double, the force is reduced to a quarter.
Gravity acts as if all the mass of a body to focus on a single point, the center of gravity. The spherical area around a body acts where its gravity is the gravitational field.
The law of universal gravitation was formulated by British physicist Isaac Newton in the year 1684.
If we stopped two bodies with mass and at rest, unless you act any other force except in their attraction, inevitably, they would collide. But in the universe there are many "gravities", they act other forces and bodies are in motion.


A gravitational collapse is when a body becomes smaller as a result of its own gravity, for example, a cloud of gas to form a star, or a star to form a black hole. Atoms are broken and the building collapses.
Atoms are empty boxes where a force maintains the structure. But if gravity exceeds this force, the central structure will not hold and matter starts a chain reaction.
The density increases (the body is small without losing mass), the gravitational field intensifies and the collapse occurs.

Fundamental forces of the universe

There are four fundamental forces that determine all forms of interaction of matter:
-strong nuclear interactions,
-weak nuclear interactions,
-electromagnetism and
Gravity is the weakest of the four and the only one that only works in one direction. The scientists speculate about whether the supplementary.


Stars, galaxies and the universe move. Another thing is to detect the movement of some bodies, especially in the most distant.
The movement of many objects in the universe has been measured. So we know that, to move a distance apparent equal to the diameter of the Moon, the star nearest Alpha Centaur, need 506 years. Arthur need 815; Syrian, 1.410; Altair, 2.830; Capella, 4270 and Fomalhaut, more than 5,000.
Orbit called the trajectory of an object which revolves around another. The orbital period is the time that the object takes to complete an orbit. It seems that all objects in space, orbiting around others with more mass.

The expansion of the universe

The discovery of the expansion of the universe began in 1912, with the works of the American astronomer Vesto M. Slipher. While studying the spectra of galaxies observed that, except in the nearest, spectrum lines are displaced toward the red.
This means that the majority of galaxies move away from the milky way since correcting this effect in the spectra of galaxies, demonstrates that the stars that comprise them are composed of known chemical elements. This shift to the Red is due to the Doppler effect.
If we measure the redshift in the spectrum of a star, we can know if it approaches or moves away from us. Mostly this shift is towards the red, which indicates that the focus of the radiation away. This is interpreted as a confirmation of the expansion of the universe.
At first it seems that galaxies move away from the milky way in all directions, giving the feeling that our Galaxy is the center of the universe. This effect is a consequence of the way in which the universe expands. It is as if the milky way and other galaxies were points on the surface of a balloon. Inflating the balloon, all points move away from us. If we were to change our position to any of the other points and perform the same operation, we would observe exactly the same.

The Hubble Law

The American astronomer Edwin Powell Hubble related, in 1929, the shift towards red observed in the spectra of galaxies with the expansion of the universe. He suggested that this shift toward red, called the cosmological red shifting, is caused by the Doppler effect, and therefore indicates the speed of receding galaxies.
Hubble also noted that the speed of recession of the galaxies was larger and farther away were. This discovery led him to enunciate his law of the speed of recession of galaxies, known as the "Hubble's law", which States that the speed of a Galaxy is proportional to their distance.
The Hubble or proportionality constant is the ratio between the distance of a Galaxy to the Earth and the speed with which moves away from it. It is estimated that this constant is between 50 and 100 Km/s per megaparsec.
Published for educational purposes authorized by: Astronomía: Tierra, Sistema Solar y Universo

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