Will the universe expand forever, or will it eventually collapse back into a tiny speck? A study published in June finds that, according to the mainstream theory of physics, infinite expansion is impossible. However, new evidence has emerged that an ever-expanding universe cannot yet be ruled out.

Dark energy and cosmic expansion

Our Universe is riddled with a massive and invisible force that seems to counterbalance gravity. Physicists have called it dark energy. It is believed that it is she who pushes the space out. But the June paper implies that dark energy changes over time. That is, the Universe will not expand for eternity and is capable of collapsing to the size of the Big Bang point.

Physicists immediately found problems in the theory. They believe that the original theory cannot be true, since it does not explain the existence of the Higgs boson, found in the Large Hadron Collider. However, the hypothesis may be viable.

How to explain the existence of everything?

String theory (the theory of everything) is considered a mathematically elegant but experimentally unproven basis for combining Einstein's general theory of relativity with quantum mechanics. String theory suggests that all particles in the universe are not points, but are represented by vibrating one-dimensional strings. Differences in vibrations make it possible to see one particle as a photon and another as an electron.

However, to remain viable, string theory must include dark energy. Imagine the latter as a ball in a landscape of mountains and valleys. If the ball is on top of a mountain, it may remain motionless or roll down at the slightest disturbance, as it is deprived of stability. If it remains unchanged, then it is endowed with low energy and located in a stable universe.

Conservative theorists have long believed that dark energy remains constant and unchanging in the universe. That is, the ball froze between the mountains in the valley and does not roll from the top. However, the June hypothesis suggests that string theory does not take into account the landscape with mountains and valleys above sea level. Rather, it is a slight slope where the ball of dark energy rolls down. As it rolls, the dark energy gets smaller and smaller. Everything can end up with the fact that dark energy will begin to pull the Universe back to the point of the Big Bang.

But there's a problem. Scientists have shown that such unstable mountain peaks must exist, because there is a Higgs boson. It was also experimentally possible to confirm that these particles can be in unstable Universes.

Problems with the stability of the universes

The original hypothesis runs into problems in unstable universes. The revised version indicates the possibility of mountain peaks, but discards stable valleys. That is, the ball should begin to roll down, and the dark energy should change. But if the hypothesis is wrong, then the dark energy will remain constant, we will remain in the valley between the mountains, and the Universe will continue to expand.

The researchers hope that within 10-15 years satellites measuring the expansion of the universe will help to understand the constant or changing nature of the universe.

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From childhood, we memorize elementary truths about the structure of the Universe: all the planets are round, there is nothing in space, the sun burns. Meanwhile, this is not true. No wonder the new Minister of Education and Science Olga Vasilyeva recently announced that it is necessary to return astronomy lessons to school. Editorial medialeaks fully supports this initiative and invites readers to update their understanding of the planets and stars.

1. The earth is a flat ball

The real shape of the Earth is somewhat different from the globe from the store. Many people know that our planet is slightly flattened from the poles. But besides this, different points of the earth's surface are removed from the center of the core at different distances. It's not just the terrain, it's just that the whole Earth is uneven. For clarity, use such a slightly exaggerated illustration.

Closer to the equator, the planet generally has a kind of ledge. Therefore, for example, the most distant point on the earth's surface from the center of the planet is not Everest (8848 m), but the Chimborazo volcano (6268 m) - its peak is 2.5 km further. This is not visible on the pictures from space, since the deviation from the ideal ball is no more than 0.5% of the radius, in addition, the atmosphere smooths out the flaws in the appearance of our beloved planet. The correct name for the shape of the Earth is the geoid.

2. The sun is burning

We are used to thinking that the Sun is a huge fireball, so it seems to us that it is burning, there is a flame on its surface. In fact, combustion is a chemical reaction that requires an oxidizing agent and fuel, and an atmosphere. (By the way, this is why explosions in outer space are almost impossible).

The sun is a huge piece of plasma in a state of thermonuclear reaction, it does not burn, but glows, emitting a stream of photons and charged particles. That is, the Sun is not fire, it is a large and very, very warm light.

3. The Earth rotates on its axis in exactly 24 hours.

It often seems that some days go by faster than others. Oddly enough, this is true. A sunny day, that is, the time during which the Sun returns to the same position in the sky, varies within plus or minus about 8 minutes at different times of the year in different parts of the planet. This is due to the fact that the linear velocity of movement and the angular velocity of the Earth's rotation around the Sun are constantly changing as it moves along an elliptical orbit. Days either increase slightly, or decrease slightly.

In addition to solar, there is also a sidereal day - the time during which the Earth makes one revolution around its axis in relation to distant stars. They are more constant, their duration is 23 hours 56 minutes 04 seconds.

4. Complete weightlessness in orbit

It is customary to think that the astronaut on the space station is in a state of complete weightlessness and his weight is zero. Yes, the influence of the Earth's gravity at an altitude of 100-200 km from its surface is less noticeable, but it remains just as powerful: that is why the ISS and the people in it remain in orbit, and do not fly away in a straight line into outer space.

In simple terms, both the station and the astronauts in it are in endless free fall (only they do not fall down, but forward), but the very rotation of the station around the planet maintains the soaring. It would be more correct to call it microgravity. A state close to total weightlessness can only be experienced outside the Earth's gravitational field.

5. Instant death in space without a spacesuit

Oddly enough, for a man who fell out of the hatch of a spaceship without a spacesuit, death is not so inevitable. It will not turn into an icicle: yes, the temperature in outer space is -270 ° C, but heat transfer in a vacuum is impossible, so the body, on the contrary, will begin to heat up. Internal pressure is also not enough to blow up a person from the inside.

The main danger is explosive decompression: gas bubbles in the blood will begin to expand, but theoretically this can be survived. In addition, in space conditions there is not enough pressure to maintain the liquid state of matter, therefore, water will begin to evaporate very quickly from the mucous membranes of the body (tongue, eyes, lungs). In Earth orbit under direct sunlight, instantaneous burns of unprotected skin areas are inevitable (by the way, here the temperature will be like in a sauna - about 100 ° C). All this is very unpleasant, but not fatal. It is very important to be in space on an exhalation (holding air will lead to barotrauma).

As a result, according to NASA scientists, under certain conditions, there is a chance that 30-60 seconds of being in outer space will not cause damage to the human body that is incompatible with life. Death will eventually come from suffocation.

6 The Asteroid Belt Is A Dangerous Place For Starships

Science fiction films have taught us that asteroid clusters are a pile of space debris that fly in close proximity to each other. On maps of the solar system, the asteroid belt also usually looks like a serious obstacle. Yes, there is a very high density of celestial bodies in this place, but only by cosmic standards: half-kilometer blocks fly at a distance of hundreds of thousands of kilometers from each other.

Mankind has launched about a dozen probes that went beyond the orbit of Mars and flew to the orbit of Jupiter without the slightest problem. Impenetrable clumps of space rocks and rocks, like those shown in Star Wars, can result from the collision of two massive celestial bodies. And then - not for long.

7. We see millions of stars

The expression "myriad stars" until recently was nothing more than a rhetorical exaggeration. With the naked eye from the Earth in the clearest weather, you can see no more than 2-3 thousand celestial bodies at the same time. In total, in both hemispheres - about 6 thousand. But in the photographs of modern telescopes, you can really find hundreds of millions, if not billions of stars (no one has counted yet).

A recent Hubble Ultra Deep Field image captured about 10,000 galaxies, the most distant of which are about 13.5 billion light-years away. According to scientists, these ultra-distant star clusters appeared "only" 400-800 million years after the Big Bang.

8. The stars are fixed

It is not the stars that move across the sky, but the Earth rotates - until the 18th century, scientists were sure that, with the exception of planets and comets, most of the celestial bodies remained motionless. However, over time, it was proved that all stars and galaxies without exception are in motion. If we went back several tens of thousands of years ago, we would not recognize the starry sky above our heads (as well as the moral law, by the way).

Of course, this happens slowly, but individual stars change their position in outer space in such a way that it becomes noticeable after just a few years of observations. Bernard's star "flies" the fastest - its speed is 110 km / s. Galaxies are also moving.

For example, the Andromeda Nebula, visible to the naked eye from Earth, is approaching the Milky Way at a speed of about 140 km/s. In about 5 billion years, we will collide.

9. The moon has a dark side

The Moon always faces the Earth on one side, because its rotation around its own axis and around our planet is synchronized. However, this does not mean that the rays of the Sun never fall on the half invisible to us.

On a new moon, when the side facing the Earth is completely in shadow, the reverse is completely illuminated. However, on the natural satellite of the Earth, the day changes at night somewhat more slowly. A full lunar day lasts approximately two weeks.

10 Mercury Is The Hottest Planet In The Solar System

It is quite logical to assume that the planet closest to the Sun is also the hottest in our system. Also not true. The maximum temperature on the surface of Mercury is 427 °C. This is less than on Venus, where an indicator of 477 ° C is recorded. The second planet is almost 50 million km farther from the Sun than the first, but Venus has a dense atmosphere of carbon dioxide, which, due to the greenhouse effect, retains and accumulates temperature, while Mercury has practically no atmosphere.

There is one more moment. Mercury completes a full revolution around its axis in 58 Earth days. A two-month night cools the surface to -173 °C, which means that the average temperature at the equator of Mercury is about 300 °C. And at the poles of the planet, which always remain in the shadows, there is even ice.

11. The solar system is made up of nine planets.

Since childhood, we have been accustomed to thinking that the solar system has nine planets. Pluto was discovered in 1930, and for more than 70 years he remained a full member of the planetary pantheon. However, after much discussion, in 2006 Pluto was downgraded to the rank of the largest dwarf planet in our system. The fact is that this celestial body does not correspond to one of the three definitions of a planet, according to which such an object must clear the neighborhood of its orbit with its mass. Pluto's mass is only 7% of the combined mass of all Kuiper belt objects. For example, another planetoid from this region, Eris, is only 40 km smaller than Pluto in diameter, but noticeably heavier. For comparison, the mass of the Earth is 1.7 million times greater than that of all other bodies in the vicinity of its orbit. That is, there are still eight full-fledged planets in the solar system.

12 Exoplanets Are Like Earth

Almost every month, astronomers delight us with reports that they have discovered another exoplanet on which life could theoretically exist. Imagination immediately draws a green-blue ball somewhere near Proxima Centauri, where it will be possible to dump when our Earth finally breaks. In fact, scientists have no idea what exoplanets look like and what conditions they have. The fact is that they are so far away that we cannot yet calculate their actual size, composition of the atmosphere and temperature on the surface with modern methods.

As a rule, only the estimated distance between such a planet and its star is known. Of the hundreds of exoplanets found that are inside the habitable zone, potentially suitable for supporting Earth-like life, only a few could potentially be similar to our home planet.

13. Jupiter and Saturn - balls of gas

We all know that the largest planets in the solar system are gas giants, but this does not mean at all that once in the gravitational zone of these planets, the body will fall through them until it reaches the solid core.

Jupiter and Saturn are mostly made up of hydrogen and helium. Under the clouds, at a depth of several thousand kilometers, a layer begins in which hydrogen, under the influence of monstrous pressure, gradually passes from gaseous to the state of liquid boiling metal. The temperature of this substance reaches 6 thousand ° C. Interestingly, Saturn radiates into space 2.5 times more energy that the planet receives from the Sun, while it is not entirely clear why.

14. In the solar system, life can only exist on Earth

If something similar to terrestrial life existed somewhere else in the solar system, we would notice it ... Right? For example, the first organics appeared on Earth more than 4 billion years ago, but for hundreds of millions of years not a single external observer would have seen any clear signs of life, and the first multicellular organisms appeared only after 3 billion years. In fact, in addition to Mars, there are at least two other places in our system where life could well exist: these are the satellites of Saturn - Titan and Enceladus.

Titan has a dense atmosphere, as well as seas, lakes and rivers - though not from water, but from liquid methane. But in 2010, NASA scientists said they found signs of the possible existence of the simplest life forms on this satellite of Saturn, using methane and hydrogen instead of water and oxygen.

Enceladus is covered with a thick layer of ice, it would seem, what kind of life is there? However, under the surface at a depth of 30-40 km, as planetologists are sure, there is an ocean of liquid water about 10 km thick. The core of Enceladus is hot, and in this ocean there may be hydrothermal vents like the terrestrial "black smokers". According to one hypothesis, life on Earth appeared precisely due to this phenomenon, so why not the same thing happen on Enceladus. By the way, water breaks through the ice in some places and erupts outward in fountains up to 250 km high. Recent data confirm that this water contains organic compounds.

15. Space - empty

There is nothing in interplanetary and interstellar space, many have been sure since childhood. In fact, the vacuum of space is not absolute: there are atoms and molecules in microscopic quantities, the cosmic microwave background radiation that remains from the Big Bang, and cosmic rays, which contain ionized atomic nuclei and various subatomic particles.

Moreover, scientists have recently suggested that the cosmic void is actually composed of matter that we cannot yet detect. Physicists have called this hypothetical phenomenon dark energy and dark matter. Presumably, our Universe is 76% dark energy, 22% dark matter, 3.6% interstellar gas. Our usual baryonic matter: stars, planets, and so on - is only 0.4% of the total mass of the universe.

There is an assumption that it is the increase in the amount of dark energy that causes the Universe to expand. Sooner or later, this alternative entity, in theory, will tear the atoms of our reality into pieces of individual bosons and quarks. However, by that time, neither Olga Vasilyeva, nor the lessons of astronomy, nor mankind, nor the Earth, nor the Sun will exist for several billion years.

Space is fraught with many mysteries, and we have only begun to study it. And one of the problems to be solved in the future is gravity.

What's wrong with her, you ask? And she is not! Or rather, not so. Gravity is always there, we experience it from the Earth, the Moon, the Sun, other stars and even the center of our galaxy. But the force of gravity that suits us is only on Earth. And when we fly to other planets or surf space, what about gravity? You have to create it artificially.

Why do we need a certain gravitational force?

On Earth, all organisms have adapted to an attractive force of 9.8 m/s^2. If it is more, then the plants will not be able to grow up, and we will constantly experience pressure, because of which our bones will break and our organs will collapse. And if it is less, then we will have problems with the delivery of nutrients in the blood, muscle growth, etc.

When we develop colonies on Mars and the Moon, we will face the problem of reduced gravity. Our muscles partially atrophy, having adapted to the local force of gravity. But upon returning to Earth, we will have problems with walking, dragging objects, and even breathing. That's how it all depends on gravity.

And we already have an example of how this happens - the International Space Station.

Astronauts on the ISS and why there is no gravity

Those who visit the ISS must train on treadmills and machines every day. This is because during their stay, their muscles lose their “grip”. In conditions of weightlessness, you do not need to lift your body, you can relax. This is how the body thinks. There is no gravity on the ISS, not because it is in space.

The distance from it to the Earth is only 400 kilometers, and the force of gravity at such a distance is only slightly less than on the surface of the planet. But the ISS does not stand still - it rotates in the earth's orbit. It literally constantly falls to the Earth, but its speed is so high that it does not allow it to fall.

That is why astronauts are in a state of weightlessness. But still. Why can't gravity be created on the ISS? This would make the life of astronauts much easier. After all, they are forced to spend several hours a day on physical exercises just to keep fit.

How to create artificial gravity?

In science fiction, the concept of such a spaceship has long been created. This is a huge ring that must constantly rotate around its axis. As a result of this, the centrifugal force "pushes" the astronaut away from the center of rotation, and he will perceive this as gravity. But problems arise when we face it in practice.

First, you need to take into account the Coriolis force - the force that occurs when moving in a circle. Without this, our astronaut will be constantly motion sick, and this is not very fun. In this case, you need to speed up the rotation of the ring on the ship to 2 revolutions per second, and this is a lot, the astronaut will be very unwell. To solve this problem, you need to increase the radius of the ring to 224 meters.

A ship the size of half a kilometer! We are close to Star Wars. Instead of creating terrestrial gravity, first we will create a ship with reduced gravity, in which the simulators will remain. And only then will we build ships with huge rings to preserve gravity. By the way, they are just going to build modules for creating gravity on the ISS.

Today, scientists from Roscosmos and NASA are preparing to send centrifuges to the ISS, necessary to create artificial gravity there. Astronauts no longer have to spend a lot of time on physical exercises!

The problem with gravity at high accelerations

If we want to fly to the stars, it takes 4.2 years to travel to the nearest Alpha Centauri A at 99% the speed of light. But in order to accelerate to this speed, a huge acceleration is required. And that means huge overloads, about 1000-4000 thousand times more than the earth's gravity. No one can withstand this, and a spaceship with a rotating ring must be simply gigantic, hundreds of kilometers away. You can build this, but is it necessary?

Unfortunately, we still don't fully understand how gravity works. And so far they have not figured out how to avoid the effect of such overloads. We will explore, test, study.

The big bang invariably grabs our attention more than any other scientific theory: the majestic explosion in which our universe was born. But what happened after the Big Bang?

For about 100 million years, the universe was plunged into darkness.

When the very first stars finally lit up in space, they were larger and brighter than the stars of all subsequent generations. They radiated in the ultraviolet range so intensely that they turned the atoms of the gas around them into ions. The cosmic dawn - starting with the appearance of the first stars and continuing until the completion of this "cosmic reionization" - took a total of about one billion years.

Where did these stars come from? How did they evolve into galaxies - forming a universe filled with radiation and plasma - that we see today? These are the key questions for us,” said Professor Michael Norman, director of the San Diego Supercomputing Center, USA, and lead author of the new study.

Norman's team solves mathematical equations in a cubic virtual universe.

"We've spent over 20 years perfecting this computer code to better understand Cosmic Dawn."

This model calculates the formation of the first stars in the universe. The equations of the model describe the motion and chemical reactions inside the gas clouds that existed in the Universe before the moment when it became transparent to light, as well as the powerful gravitational influence from invisible dark matter.

The very first heavy elements were formed in the Universe as a result of the explosions of the first stars, which consisted almost exclusively of hydrogen and helium. The model contains equations describing the enrichment of the Universe with heavy elements.

“The transition was swift: within 30 million years, all the stars became enriched in metals. New generation stars forming in galaxies were smaller and much more numerous than primary stars as chemical reactions became possible between metals,” explained Norman.

The increased number of reactions in the gas clouds allowed them to fragment and form a large number of stars located inside the "filaments" with a lower gas density, where the combining elements radiate energy into the surrounding space - instead of transferring it to each other.

“At this stage, we are observing the first objects in the universe that can rightfully be called galaxies: a combination of dark matter, metal-rich gas and stars,” notes Norman.

Most people can only judge this from frames from science fiction films, so they are subject to an implausible myth.

What will actually happen to a man in outer space?

There are many theories about what will happen to a person who gets into outer space without a spacesuit. Most of them are based on fiction. Someone believes that the body will freeze in a few moments, others say that it will be incinerated by cosmic radiation, there is even a theory about boiling liquid inside the human body. Consider the most popular myths about what will happen to a man without a spacesuit in outer space.

The body will immediately freeze

Scientists are ready to answer with accuracy that this will not happen. It is very cold in space, but its density is too low. In such a minimum density, the human body will not be able to transfer its heat to the environment, there is emptiness around it, and there is no one to take away this heat. One of the main difficulties in the work of the ISS is the removal of heat from the station, not at all protection from space cold.

Man will be incinerated by cosmic radiation

Radiation in space reaches large values, it is very dangerous. Radioactive charged particles permeate the human body, causing radiation sickness. But in order to die from this radiation, it is necessary to receive a very large dose, and this will take a long time. During this time, a living being will have time to die under the influence of other factors. In order to get protection from space burns, you do not need a spacesuit, ordinary clothes will cope with this task. If we assume that a person decided to go out into outer space completely naked, then the consequences of this exit for him will be very bad.

The blood in the vessels of a person boils from low pressure

Another of the theories, allegedly from low pressure, the blood in the body boils and breaks its vessels. Indeed, there is very low pressure in space, it will help to reduce the temperature at which liquids boil. However, the blood in the human body will be under its own pressure, for boiling, its temperature must reach 46 degrees, which cannot be in living organisms. If a person in outer space opens his mouth and sticks out his tongue, he will feel his saliva boil, but he will not get burned, the saliva will boil at a very low temperature.

The body will break the pressure difference

Pressure in space is very dangerous, but it works differently. The pressure difference can double the volume of the internal organs of a person, his body will swell twice. But a spectacular explosion with scattering of the insides in all directions will not occur, the human skin is very elastic, it can withstand such pressure, and if a person wears tight-fitting clothes, then the volume of his body will remain unchanged.

The person will be unable to breathe.

This is true, but the situation is not as many of us imagine it to be. A huge danger to the human respiratory system in space is pressure. There is no oxygen in space, so a person's life expectancy without a space suit will depend on how much he can hold his breath. Being under water, people hold their breath and try to float to the surface, in space this will not work. Holding one's breath in space causes the lungs to rupture under the influence of vacuum, in such a situation it will be impossible to save a person. There is only one way to prolong life in outer space, you need to allow all the gases to rapidly exit your body, this process can be accompanied by unpleasant consequences in the form of emptying the stomach or intestines. After the oxygen leaves the respiratory system, the person will have approximately 14 seconds until oxygenated blood continues to feed the brain, after which the person will lose consciousness. However, and this does not mean imminent death, the human body is not as fragile as it might seem at first glance, it is able to withstand the hostile environment of space. Scientists suggest that if a person, after a one and a half minute stay in outer space, is delivered to a safe environment for him, then he will not only survive, but will also be able to fully recover after such a test.

To confirm this assumption, experiments were carried out on monkeys.
Studies have shown that a chimpanzee, after a three-minute stay in a vacuum, returns to normal after a few hours.

During the experiment, all the symptoms that were described above were observed - an increase in the body in volume and loss of consciousness due to oxygen starvation. Similar experiments were carried out with dogs, dogs tolerate vacuum conditions worse, the survival limit for them was only two minutes.

The human body reacts to changes in the environment in a different way than the body of an animal, so you cannot fully rely on these experiences. It is clear that no one will specifically conduct such experiments on people, but there are several demonstrative accidents with astronauts in history. Space engineer Jim Leblanc in 1965 checked the tightness of a spacesuit designed for lunar expeditions in a special chamber. During one of the stages of the test, the pressure in the chamber was as close as possible to space pressure, the pressure suit unexpectedly depressurized, and the technician in it lost consciousness after 14 seconds. Normally, it took about half an hour to restore normal earth pressure in the chamber, but in view of the emergency of the situation, the process was accelerated to one and a half minutes. Jim Leblanc regained consciousness when the pressure in the chamber became the same as on Earth at an altitude of 4.5 km above sea level.

Another example is the accident on the Soyuz-11 spacecraft. When the device descended to the ground, there was a depressurization. This accident entered the history of astronautics forever, since the cause of death of three astronauts was an accidentally opened ventilation valve with a diameter of one and a half centimeters.

According to information received from the recording equipment, all three lost consciousness 22 seconds after the complete depressurization, and death occurred 2 minutes later. The total time spent under near vacuum conditions was 11.5 minutes. After the spacecraft landed on earth, it was unfortunately too late to save the astronauts.