How did our universe? As it turned into seemingly infinite space? And than it will be after many millions and billions of years? These questions plagued (and continue to tear) the minds of philosophers and scientists, it seems, since the beginning of time, thus giving rise to many interesting and sometimes crazy theories. Today, most astronomers and cosmologists have come to a General agreement that the universe as we know it, was the result of a giant explosion that gave birth to not only the main part of matter, but which was the source of fundamental physical laws, according to which there is the space that surrounds us. This is called the Big Bang theory.
The basics of the Big Bang theory is relatively simple. Briefly, according to it all existed and existing now in the Universe of matter came at the same time — about 13,8 billion years ago. At that point in time all matter existed in a very compact abstract of a ball (or point) of infinite density and temperature. This state was called the singularity. Suddenly, the singularity began to expand and gave rise to the Universe as we know it.
It should be noted that the theory of Big Blasting is only one of many proposed hypotheses for its occurrence (for example, there is the theory of a stationary Universe), but it received the widest acceptance and popularity. She not only explains the source of all the known matter, laws of physics, and a large structure of the Universe, it also describes the reasons for the expansion of the Universe and many other aspects and phenomena.
The chronology of events in the Big Bang theory
Based on knowledge about the current state of the Universe, scientists suggest that all was to commence with a single point with infinite density and a finite time, which began to expand. After the initial expansion, according to the theory, the universe underwent a phase of cooling, which allowed for subatomic particles, and later simple atoms. Giant clouds of these elements later ancient gravity began to form stars and galaxies.
All this according to the conjectures of scientists, began around 13.8 billion years ago, and so this starting point is considered the age of the Universe. By examining different theoretical principles, experiments involving particle accelerators and high-energy States, and by conducting astronomical research in the far corners of the Universe scientists have deduced and proposed the chronology of events that began with the Big Bang and the Universe has led eventually to that condition of cosmic evolution, which is the place to be now.
Scientists believe that the earliest times of the origin of the Universe — which lasted from 10-43 to 10-11 second after the Big Bang are still the subject of controversy and discussion. If you consider that the laws of physics, which we now know could not exist at this time, it is very difficult to understand how to regulate the processes in the early Universe. In addition, experiments using the kinds of energies that could be present at the time, still not been carried out. Anyway, many theories about the origin of the Universe ultimately agree that at some time had a starting point from which it started.
The era of the singularity
Also known as the Planck epoch (or Planck era) is regarded as the earliest known periods of the Universe’s evolution. At this time, all matter was contained in a single point of infinite density and temperature. During this period, scientists believe that quantum effects of the gravitational interaction dominated over the individual, and not one of physical strength was not equal to gravity.
The Planck era supposedly lasted from 0 to 10-43 seconds and it was named so because to measure its duration can only be the Planck time. Due to the extreme temperature and infinite density matter state of the Universe in this time period was very unstable. After that came the periods of expansion and cooling that led to the emergence of the fundamental forces of physics.
Approximately in the period from 10-43 to 10-36 seconds the Universe was the process of collision States of transition temperatures. It is believed that at this point the fundamental forces that govern the current Universe started to separate from each other. The first step of this Department has been the emergence of gravitational forces, strong and weak nuclear interactions and electromagnetism.
In the period from about 10-36 to 10-32 seconds after the Big Bang the temperature of the Universe was low enough (1028 K), which led to the separation of electromagnetic forces (the strong interaction) and weak nuclear interactions (the weak interaction).
The era of inflation
With the advent of the first of the fundamental forces in the Universe the era of inflation, which lasted from 10-32 seconds Planck time until an unknown point in time. Most cosmological models assume that the universe during this period was uniformly filled with a high energy density, but an incredibly high temperature and pressure led to its rapid expansion and cooling.
It started at 10-37 seconds, when the phase transition that caused the separation of forces, followed by the expansion of the Universe exponentially. In the same period of time the universe was in a state of baryogenesis, when the temperature was so high that the random motion of particles in space occurred at relativistic speeds.
At this time are formed and immediately destroyed colliding pairs of particles — antiparticles, is believed to have led to the dominance of matter over antimatter in the modern Universe. After the cessation of inflation the universe consisted of a quark-puhovoi plasma and other elementary particles. From that moment on the universe began to cool, began to form and connect matter.
The era of cooling
With the decrease of density and temperature inside the Universe begin to happen and the decrease of energy in every particle. This transitional state will last as long, while the fundamental forces and elementary particles came to its current form. Since the energy of particles dropped to values that can be achieved today within the framework of experiments, the actual possible of this time period makes scientists much less disputes.
For example, scientists estimate that 10-11 second after the Big Bang, the energy of particles decreased significantly. At about 10-6 seconds quarks and gluons began to form baryons — protons and neutrons. The quarks began to prevail over antiquarii, which in turn led to the predominance of baryons over antibaryons.
As the temperature was not high enough to create new proton-antiproton pairs (or neutron-antineutron pairs), followed by mass destruction of these particles, which resulted in a balance only 1/1010 of the original number of protons and neutrons and the complete disappearance of their antiparticles. A similar process occurred after about 1 second after the Big Bang. Only “victims” this time were the electrons and positrons. After the mass destruction of the remaining protons, neutrons and electrons stopped their random motion, and the energy density of the Universe was filled with photons and to a lesser extent the neutrino.
During the first minutes of expansion of the Universe began a period of nucleosynthesis (the synthesis of chemical elements). Due to the temperature drop up to 1 billion Kelvin and the energy density decrease approximately to the values equivalent to the air density, neutrons and protons began to intermingle and form a first stable isotope of hydrogen (deuterium) and helium atoms. Nevertheless, the majority of protons in the Universe remained as incoherent nuclei of hydrogen atoms.
After about 379 000 years the electrons combined with these nuclei and formed hydrogen atoms (again mostly hydrogen), while the radiation separated from matter and continued to expand almost freely through space. This radiation is called cosmic background radiation, and it is the oldest light source in the Universe.
With the cosmic microwave background radiation is gradually losing its density and energy, and at the moment the temperature is 2,7260 ± with 0.0013 K (-270,424 °C), and energy density of 0.25 eV (or 4,005×10-14 j/m3; 400 to 500 photons/cm3). Microwave radiation extends in all directions and at a distance of around 13.8 billion light years, however, the assessment of its actual distribution says about 46 billion light years from the center of the Universe.
Age structure (hierarchical era)
In the next few billion years, the denser regions of the nearly uniformly distributed matter in the Universe began to be attracted to each other. As a result, they have become even denser, forming gas clouds, stars, galaxies and other astronomical structures that we can observe currently. This period is called the hierarchical era. At this time the universe we see today began to take shape. Matter began to form structures of different sizes — the stars, planets, galaxies, galactic clusters and galactic superclusters, intergalactic separated by ridges, containing only a few galaxies.
The details of this process can be described according to the idea of the number and the type of matter distributed in the Universe, which is presented in the form of cold, warm and hot dark matter and baryonic matter. However, modern standard cosmological Big Bang model is a model Lambda-CDM, in which dark matter particles are moving slower than the speed of light. It was selected because it solves all the contradictions that have appeared in other cosmological models.
According to this model the cold dark matter accounts for about 23 percent of all matter/energy in the Universe. The proportion of baryonic matter is about 4.6%. The lambda-CDM refers to the so-called cosmological constant: theory, proposed by albert Einstein that describes the properties of the vacuum and shows the relationship of balance between mass and energy as a constant static value. In this case, it is connected with dark energy, which serves as an accelerator of expansion of the Universe and supports a giant cosmological structure largely homogeneous.
Long-term predictions about the future of the Universe
A hypothesis concerning the evolution of the Universe has a starting point, a natural way to lead scientists to the possible end point of this process. If the universe began its history from a small point with infinite density that suddenly began to expand, does this mean that it will expand infinitely? Or someday she will end expansive force and will begin a reverse process of compression, the final result of which will be all the same infinitely dense point?
The answers to these questions were the main goal of cosmologists from the outset, disputes about what a cosmological model of the Universe is correct. With the adoption of the Big Bang theory, but for the most part due to the observation of dark energy in the 1990s, scientists came to the agreement on the two most probable scenarios of evolution of the Universe.
The first, dubbed the “great compression”, the universe will reach its maximum size and begin to collapse. Such a scenario would be possible only if the mass density of the Universe becomes larger than the critical density. In other words, if the density of matter reaches a certain value or goes above this value (1-3×10-26 kg of matter per m3), the universe will begin to shrink.
The alternative is another script that says that if the density in the Universe is equal to or below the critical density, its expansion will slow down but never stop completely. According to this hypothesis, called the “heat death of the Universe”, the extension will continue until such time as the star formation will not cease to consume the interstellar gas within each of the surrounding galaxies. That is completely stop the transfer of energy and matter from one object to another. All existing stars in this case will fade and turn into white dwarfs, neutron stars and black holes.
Gradually, the black holes will collide with other black holes, Hello to the formation of more and larger. The average temperature of the Universe will approach absolute zero. Black holes eventually “evaporate” with the release of his latest Hawking radiation. In the end the thermodynamic entropy in the Universe will be maximum. There will come the heat death.
Modern observations, taking into account the presence of dark energy and its impact on the expansion of the cosmos, leading the researchers to conclude that over time, more and more of space of the Universe will pass beyond our event horizon and will become invisible to us. The final and logical result, scientists are not yet known, but “heat death” may well be the endpoint of such events.
There are other hypotheses regarding the distribution of dark energy, or rather, its possible species (such as phantom energy). According to them, galactic clusters, stars, planets, atoms, nuclei and matter itself will be torn apart as a result of its endless expansion. This scenario of evolution is called “big break”. The cause of death of the Universe in this scenario is the extension itself.
The history of the Big Bang theory
The earliest mention of the Big Bang refers to the beginning of the 20th century with the observations of the cosmos. In 1912, the American astronomer Slipher Vesto conducted a series of observations of spiral galaxies (which initially seemed nebulae) and measured their Doppler redshift. In almost all cases, observations show that spiral galaxies are moving away from our milky Way.
In 1922, the prominent Russian mathematician and cosmologist Alexander Friedman deduced from Einstein’s equations for General relativity the so-called Friedmann equations. Despite the promotion of Einstein’s theory in favor of the existence of the cosmological constant, Friedmann’s work showed, rather, that the universe is expanding.
In 1924, Edwin Hubble measure the distance to the nearest spiral nebulae showed that these systems actually are really other galaxies. At the same time, Hubble has begun to develop a series of indicators for deduction of the distances, using the 2.5-meter hooker telescope at the Observatory mount Wilson. By 1929 Hubble discovered a relationship between the distance and the speed of removal of galaxies that later became the Hubble law.
In 1927, the Belgian mathematician, physicist and Catholic priest Georges Lemaitre independently came to the same results, which showed the equation of Friedman, and was the first to formulate the dependence between the distance and speed of galaxies, suggesting the first evaluation of the coefficient of this dependence. Lemaitre believed that at some time in the past all the mass of the Universe was concentrated in one point (atom).
These findings and assumptions caused a lot of controversy between physicists in the 20-ies and 30-ies, most of which believed that the universe is in a stationary state. It is well-established in the time model, new matter is created along with infinite expansion of the Universe uniformly and equally distributed density throughout its length. Among the scientists that support it, the idea of the Big Bang seemed to be more theological than scientific. To the Lemaitre sound critical about bias on the basis of religious prejudice.
It should be noted that at the same time there were other theories. For example, the Milne model of the Universe and the cyclic model. Both were based on the postulates of the General theory of relativity and subsequently received the support of the scientist. According to these models the universe exists in an endless stream of recurring cycles of expansions and collapses.
After the Second world war between the supporters of the stationary Universe model (which actually has been described by the astronomer and physicist Fred Hoyle) and supporters of the Big Bang theory, fast gaining popularity among the scientific community, sparked heated debate. Ironically, Hoyle brought the phrase “big Bang”, which later became the name of the new theory. It happened in March 1949 on the British radio BBC.
In the end, further research and observation more and more spoke in favor of the Big Bang theory, and increasingly questioned the model of a stationary Universe. Detection and confirmation of cosmic microwave background radiation in 1965 finally strengthened the Big Bang as the best theory of the origin and evolution of the Universe. Since the late 60-ies and up until the 1990s astronomers and cosmologists have carried out more research into the Big Bang and find solutions for many of the theoretical problems standing in the way of this theory.
Among these solutions, for example, the work of Stephen Hawking and other physicists who proved that the singularity was undeniable initial state of General relativity and cosmological models of the Big Bang. In 1981, physicist Alan Guth brought the theory describing the period of rapid cosmic expansion (inflation era), who has solved numerous previously unsolved theoretical issues and problems.
In the 1990s observed increased interest in dark energy, which is considered as the key to solving the many unsolved questions of cosmology. In addition to the desire to find an answer to the question of why the universe loses its weight along with the dark mothers (hypothesis was proposed in 1932 by Jan Aorta), it was also necessary to find an explanation for why the universe is still accelerating.
Further progress of the study required the creation of more advanced telescopes, satellites and computer models, which have enabled astronomers and cosmologists to look further into the Universe and better understand its true age. The development of space telescopes and the appearance such as, for example, Cosmic Background Explorer (or COBE), the Hubble space telescope, Wilkinson Microwave box Probe (WMAP) and Planck space Observatory, also made an invaluable contribution to the study.
Today cosmologists can with rather high accuracy measurements of various parameters and characteristics of the model of the Big Bang theory, not to mention more accurate calculations of the age of the surrounding space. And it all began with a simple observation of massive space objects that are located many light years from us and slowly continue to move away from us. And despite the fact that we have no idea how it all will end, to find out, by cosmological standards, it will take not so much time.