The cosmos is still unknown, and the more we immerse ourselves in its secrets, the more questions we get. Let's note 7 main mysteries of space that science has faced.
The origin of the universe
This is a riddle of riddles, over which humanity will struggle for a long time. One of the very first scientific hypotheses - the theory of the "Big Bang" put forward by the Soviet geophysicist A. A. Fridman in 1922 and today is the most popular in explaining the origin of the universe.
According to the hypothesis, at the beginning, all matter was compressed into one point, which is a homogeneous medium with an extremely high energy density. As soon as the critical level of compression was overcome, the Big Bang occurred, after which the Universe began its constant expansion.
But scientists are interested in what happened before the Big Bang? According to one of the hypotheses - nothing, according to the other - everything. The Big Bang is just another stage in an endless cycle of space expansion and contraction.
However, the Big Bang theory also has vulnerabilities. According to some physicists, the expansion of the Universe after the Big Bang would be accompanied by a chaotic distribution of matter, but on the contrary, it would be ordered.
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The boundaries of the universe
The universe is constantly growing, and this is an established fact. Back in 1924, American astronomer Edwin Hubble discovered fuzzy nebulae using a 100-inch telescope. These were the same galaxies as ours. A few years later, he proved that galaxies move away from each other obeying a certain pattern: the further a galaxy is, the faster it moves.
With the help of powerful modern telescopes, astronomers plunging into the depths of the Universe simultaneously transport us to the past - to the era of the formation of galaxies.
Astronomers have calculated its age from the light coming from the far reaches of the Universe - about 13.7 billion years. The size of our Milky Way galaxy was also determined - about 100 thousand light years and the diameter of the entire Universe - 156 billion light years.
However, American astrophysicist Neil Cornish draws attention to one paradox: if the motion of galaxies continues to accelerate uniformly, then over time their speed will exceed the speed of light. In his opinion, in the future it will no longer be possible to “see so many galaxies”, because the superluminal signal is impossible.
And what is outside the designated boundaries of the universe? There is no answer to this question yet.
Black holes
Despite the fact that the existence of black holes was known even before the creation of Einstein's theory of relativity, evidence of their presence in space has been obtained relatively recently.
The black hole itself cannot be seen, but astrophysicists have paid attention to the movement of interstellar gas in the center of each of the galaxies, including ours. The peculiarities of the behavior of matter made scientists understand that the object attracting it has a "monstrous" gravity.
The power of the black hole is so great that the space-time surrounding it simply collapses. Any object, including light, falling beyond the so-called "event horizon" is forever drawn into a black hole. In the center of the Milky Way, according to scientists, is one of the most massive black holes - millions of times heavier than our Sun.
British physicist Stephen Hawking suggested that there are also ultra-small black holes in the Universe, which can be compared with the mass of a mountain, compressed to the size of a proton. Perhaps the study of this phenomenon will be accessible to science.
Supernova
When a star dies, it illuminates outer space with the brightest flash, capable of surpassing the glow of the galaxy in power. This is a supernova. Despite the fact that, according to astronomers, supernovae appear regularly, science has complete data only on the outbursts recorded in 1572 by Tycho Brahe and in 1604 by Johannes Kepler.
According to scientists, the duration of the supernova's maximum brightness is about 2 Earth days, but the consequences of the explosion are observed after thousands of years. So, it is believed that one of the most amazing sights in the Universe - the Crab Nebula - is the creation of a supernova.
The theory of supernovae is still far from complete, but already now science claims that this phenomenon can occur both during gravitational collapse and during a thermonuclear explosion. Some astronomers hypothesize that the chemical composition of supernovae is the building block of galaxies.
Space time
Time is a relative quantity. Einstein believed that if one of the twin brothers was sent into space at the speed of light, then on return he would be much younger than his brother who remained on Earth. The "twins paradox" is explained by the theory that the faster a person moves in space, the slower his time flows.
However, there is another theory: the stronger the gravity, the more time slows down. According to her, time on the surface of the Earth will flow more slowly than in orbit. This theory is also confirmed by the clock installed on the GPS spacecraft, which, on average, is ahead of Earth's time by 38700 ns / day.
However, the researchers say that for six months in orbit, astronauts, on the contrary, gain about 0.007 seconds. It all depends on the speed of the spacecraft. To test the theory of relativity in practice, in March 2015, NASA experts are going to send American astronaut Scott Kelly on a one-year expedition to the ISS, while his twin brother Mark will remain on Earth.
Kuiper Belt
The asteroid belt (Kuiper belt) discovered at the end of the 20th century beyond the orbit of Neptune has changed the usual picture of the solar system. In particular, he predetermined the fate of Pluto, which migrated from the family of planets to the cohort of planetoids.
Part of the gases trapped during the formation of the solar system in the most remote and coldest region turned into ice, forming many planetoids. Now there are more than 10,000 of them. It is interesting that just recently a new object was discovered - the UB313 planetoid, which is larger than Pluto. Some astronomers are already predicting the find in the place of the disappearing 9th planet.
Kuiper belt located at a distance of 47 AU. That is, from the Sun, it would seem to have outlined the final boundaries for objects in the solar system, but scientists continue to find more and more new, much more distant and mysterious planetoids. In particular, astrophysicists have suggested that a number of Kuiper belt objects "have nothing to do with the solar system and contain matter of a system alien to us."
Inhabited worlds
According to Stephen Hawking, the physical laws of the Universe are the same everywhere, therefore the laws of life must also be universal. The scientist admits the possibility of the existence of life like the earthly one and in other galaxies.
A relatively young science, astrobiology, is engaged in assessing the viability of planets based on their similarity to Earth. While the main efforts of astrobiologists are directed to the planets of the solar system, but the results of their studies are not comforting for those who hope to find organic life near the Earth. In particular, scientists argue that there is no life on Mars and could not be, since the planet's gravity is too small to hold a sufficiently dense atmosphere. Moreover, the bowels of planets like Mars are rapidly cooling, which leads to the cessation of geological activity that supports organic life.
The only hope of scientists is exoplanets of other stellar systems, where conditions can be comparable to those on Earth. For these purposes, the Kepler spacecraft was launched in 2009, which over several years of operation discovered more than 1000 candidates for habitable planets. The size of 68 planets turned out to be the same as that of Earth, but to the nearest of them at least 500 light years. So the search for life in such distant worlds is not a very near future question.