Results of the year: ten major events in science

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Results of the year: ten major events in science
Results of the year: ten major events in science
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The stream of news shows every scientific discovery as extraordinarily important, making it difficult to pick out the most significant ones. Here's our version of the top ten scientific achievements of the year. Let's talk about them in more detail.

The merger of a black hole and a neutron star could be accompanied by quite serious flares, but only gravitational astronomy allows us to detect such an event hundreds of millions of years from us / © mic.com

Snowman asteroid: accident or pattern?

On January 1, 2019, the American space probe New Horizons approached Ultima Thule, a dwarf planet 6.5 billion kilometers from the Sun (43 times farther than the Earth is from the Sun).

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The rapprochement has produced unusual results. It turned out that this object, about 32 by 16 kilometers in size, is a contact double body. This is the name for the bodies stuck together as a result of the collision of two asteroids. This is a very rare class of bodies, and therefore the appearance of Ultima Thule is, in fact, unique: it resembles a cashew nut.

The discovery sparked a tense scientific discussion about how such a strange "contact double" body could have formed. The fact is that in an ordinary, accidental collision of two asteroids, similar to the halves of Ultima Thule, the impact energy would be so huge that both bodies would turn into debris. If they then gathered together by gravity of each other into one whole, then the resulting body would be an ordinary round-shaped asteroid.

The real asteroid Ultima Thule is a "snowman". Such a form could arise only if both asteroids did not collide, but literally touched each other, that is, the speed of their meeting was extremely low.

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One hypothesis (by a group of American scientists) says that these asteroids, for some unclear reason, have been spinning around each other for a long time in a spiral. And then, having lost energy, they touched at low speed.

The second hypothesis, explaining the formation of a mysterious body, belongs to the physicist Nikolai Gorkaviy. According to her, the scenario for the appearance of Ultima Thule is completely different. When an asteroid collides with smaller bodies, they knock debris out of it, forming a ring of debris around the planet. Subsequent impacts on the asteroid quickly increase the mass of the disk: its debris "intercepts" new debris flying from the asteroid. The higher its mass, the more debris knocked out by new asteroids it can capture.

From all new collisions, old debris in the disk lose energy and speed, it becomes easier for them to "stick together" upon impact, without scattering after the collision. This is how a large satellite begins to form in the disk. In the future, it "feeds" on a stream of dust and stones from the surface of the parent body, collisions with such debris slow it down, because of this, the orbit of the asteroid's satellite decreases until it "sits" on the main body, forming a "snowman".

The second hypothesis is good because it describes not some unique set of circumstances, but a universal mechanism for asteroids of different sizes. If it is correct, probes and telescopes of earthlings will discover more than one such "snowman" - perhaps in the coming years.

Unknown incognito ancestor found in humans

New data showed that different types of people easily produced viable hybrids. Previously, scientists have already found out that all Caucasians carry the genes of the Neanderthals, and the Mongoloids (and the indigenous people of America) also carry the genes of the Denisovans.

According to the work of 2019, part of humanity carries in its genes traces of crossing with a fourth type of people - and it is not yet clear who these citizens are, where and when they lived. Geneticists can only say that they are somewhat related to both Denisovans and Neanderthals. Their genes were found in the DNA of the inhabitants of Southeast Asia and Oceania.

Homo crossed the sea in ancient times

The list of anthropological discoveries was supplemented by a whole new species of people - Homo luzonensis (Luzon man). The fragments of his skeleton themselves were found on a large Philippine island back in 2007, but their scientific analysis was completed only now. The new brother in human race was short - about the size of modern African pygmies. His skull was much smaller than ours, although, apparently, he knew how to use stone tools. Its remains are dated more than 50 thousand years ago.

Unusually, in the discovery, Luzon, even during the Ice Age, was separated from the Asian continent by the sea, and by deep sea straits with strong currents. According to modern experiments, they can only be overcome on rafts with oars: swimming to do this for a group of primates is unrealistic.

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It turns out that more than 50 thousand years ago, relatively primitive human ancestors were able to overcome solid water obstacles, make rafts, oars and carry out the simplest navigation at sea. This is evidence of a very high level of mental development.

The first shot of the silhouette of a black hole

2019 also brought us the first snapshot of the silhouette of a black hole. Unfortunately, many media outlets have described it as a "snapshot of a black hole," which is technically incorrect.

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The black hole M87, the surroundings of which astronomers filmed, lies too far from us to be able to talk about getting a picture of it. It is located in another galaxy, and the light from its vicinity went to the Earth for 55 million years. In addition, it completely absorbs all photons falling on it, which makes it difficult to see it. Therefore, we cannot yet take a photo of her, just as we cannot take a photo of a black kitten in a completely dark room.

In fact, the Event Horizon Telescope - a group of 11 coordinated radio telescopes scattered from Antarctica (the South Pole Telescope at the polar station) to the Northern Hemisphere - captured the silhouette of a black hole in front of its red-hot lunch.

The gravity of the black hole "pulls" gas and dust from the surrounding space to it, but this matter cannot immediately fall into the black hole. It forms an accretion disk in which gas and dust rotate, braking against each other, after which the speed of their particles is reduced enough for them to fall into the black hole. This disk is incandescent to at least thousands of degrees, so it emits - and it is this radiation that the Event Horizon Telescope caught.

The black hole, due to its powerful gravity, distorts the light of the accretion disk. Therefore, half of the "ring" around the black hole in the famous picture is dimmer, and half is brighter. The gravity of M87 slowed down half of the photons from a donut of hot matter around this very black hole, which makes half of this seem dim to us.

M87 rotates at 90% of the maximum possible for any object (limiting the speed of light for the outer parts of the object), and this is quite unusual. Obviously, a black hole with a mass of 6.5 billion Suns absorbs a lot of matter.

A snapshot of her silhouette - as well as other similar objects - can be of great importance for the study of black holes in general. And this topic is very important for science. Judging by the data of recent years, each galaxy is forming around its own supermassive black hole in the center, similar to the hole M87. Meanwhile, without galaxies, the formation of stellar systems would not have taken place, in one of which we live. It is worthwhile to better study the bodies to which we, in fact, owe our existence.

Did humans defeat the Neanderthals with bow and arrow?

In the fall of 2019, Nature Ecology & Evolution published an article about the discovery of the first tips of throwing weapons in Europe. Most likely, they were used to equip arrows for a bow - only the age of this part of the arrow, found in the Horsehead Cave in Italy, was 40-45 thousand years. It was then that a modern-type man came to Europe, where in a matter of thousands of years he ousted the Neanderthals.

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It should be noted that the Neanderthals have no trace of a bow.Yes, some finds of their weapons are similar to javelin throwers for javelins, but the "firing" speed of such weapons is much lower than that of a bow. New finds show that Homo sapiens, who arrived in Europe 45 thousand years ago, in a military-technical sense, could have noticeable advantages over the local population. It is possible that this explains the subsequent rapid decline of the Neanderthals.

You can read more about how the appearance of a bow in the hands of Homo sapiens could have influenced his victory over other species of people in the material Naked Science.

Bow and arrow: how advanced technology allowed blacks to take over Europe

The first interstellar comet in history - and possibly the last major discovery by amateur astronomers

Rarely enough, the largest discoveries of the year come from Russia. But in 2019 it happened. Amateur astronomer Gennady Borisov, an engineer at the Crimean Astrophysical Observatory, discovered comet 2I / Borisov in August, the first interstellar comet recorded in the history of astronomy. Interestingly, he made the discovery with a 65-centimeter telescope that he built himself. This is a unique case in the history of modern astronomy: never before has such a major discovery been made by an amateur, using a telescope assembled by him.

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To understand that this is not one of the comets of the solar system, its orbit and direction of movement helped. The speed of 2I / Borisov relative to the Sun is about 30 km / s, that is, much more than the speed of leaving the solar system (the third cosmic speed). Therefore, our interstellar guest will not stay for a long time. On December 7, it has already passed the point of closest approach to our star and is now moving away from it.

The body of the comet is covered with a coma, particles that evaporate from its surface under the influence of solar radiation. Therefore, the size of the nucleus of this comet is difficult to establish: it can have a diameter of two to 16 kilometers. Unfortunately, the comet is moving too fast, it will not be possible to study it with a probe - the existing terrestrial carriers will not allow it to quickly pick up the same speed as that of an interstellar comet.

Today, the parameters of a guest from another planetary system seem to be close to those of "ordinary" comets. Its spectrum contains traces of monocyanine (CN, formed on comets during the decay of hydrocyanic acid under the influence of solar ultraviolet radiation), as well as water vapor. These are compounds typical of comets.

Nevertheless, even the absence of unusualness in a body of such an unusual origin is already significant, from a scientific point of view, information. If comets of other systems are similar to ours, then the mechanisms of formation of cometary components of systems in different stars are generally similar. This is not the most trivial conclusion, given that the planets of other stars, as it became clear in the last ten years, often do not look like those that we see in the solar system.

Ebola vaccine confirmed to be effective

For the first time ever, an Ebola vaccine has been officially approved. This is one of the most dangerous viral diseases of our time. During the 2014-2015 outbreak alone, 11,323 people died from it. In July 2019, the World Health Organization declared another outbreak of Ebola, on a smaller scale, in the Congo as an international emergency.

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It is doubly difficult to create a vaccine against it. The causative agent itself, the Ebola virus, is difficult to obtain in a weakened form, therefore it is necessary to "train" immunity against it with some other virus.

To succeed, Canadian scientists took the vesicular stomatitis virus, a disease of livestock that is harmless to humans. They replaced one of the virus's genes, P03522, with the P87666 gene, taken from the Ebola virus. This gene encodes a protein in the outer envelope of the virus. Genetically modified vesicular stomatitis viruses have become the hallmark of the Ebola virus. When vaccinated, the stomatitis virus tried to attack the human body, but, being unadapted to it, it always lost.But the cells of the vaccinated immune system learned to recognize and attack the Ebola viruses.

However, the creation of this vaccine (called Ervebo) was only the beginning of the journey. It takes extensive experimentation for someone to allow it to be used on humans. It is ethically impossible to conduct them: no one will allow people to infect people with the most dangerous virus for the sake of testing a vaccine. Therefore, it had to be tested during the outbreak in the Kivu region (Congo) for everyone. Due to the fact that the chances of dying after being infected with the virus are 50%, there were many who wanted to.

As a result, in the fall of 2019, the European Medical Agency finally recommended that the Ervebo vaccine be accepted as officially approved for Ebola vaccination. Now it can be used to combat the disease not experimentally, but on the widest scale. Yes, it has drawbacks: in 2.5% of cases, it does not work yet, does not form a sufficiently powerful immunity, that is, it does not prevent infection of vaccinated people. As with many other vaccines, it produces mild side effects in the first days after vaccination. However, it is the first vaccine adopted against a disease that previously lacked effective prophylaxis and treatment.

First merger of a neutron star and a black hole

In August 2019, scientists working with the LIGO gravitational interferometer announced the registration of gravitational waves from an unusual event. To generate strong gravitational waves, two compact objects of large mass need to move quickly relative to each other. This time, the researchers found a merger of bodies of about 5.0 and about 2.5 solar masses. The first compact object can only be a black hole: an ordinary star is not compact enough to generate such a signal, and a neutron star simply cannot have such a large mass.

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But the second body in this merger, with a mass of about 2.5 solar, is almost certainly a neutron star, an object 25 kilometers in diameter. For comparison, the Sun is 1.4 million kilometers in diameter, that is, the density of a neutron star by earthly standards is simply fantastic.

The event happened very far from us: gravitational waves traveled from it to the Earth for 900 million years. This distance is so huge that the usual methods of fixing celestial bodies such as a neutron star and a black hole would simply not work there. LIGO has shown once again that observations of gravitational waves are capable of delivering data, in principle, not available from other sources.

Mars: a sea four kilometers deep?

On November 26, 2018, the Insight non-self-propelled lander successfully landed on the surface of Mars.

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The main mission of the apparatus - drilling five meters deep - has failed so far (already at 35 centimeters the drill "got stuck"), like all attempts to drill on Mars deeper than 7.5 centimeters.

At the same time, Insight received a large consolation prize. According to preliminary data leaked to the press, he discovered with magnetometric instruments under the surface of Mars, in the landing area, a layer of electrically conductive material four kilometers thick. The red planet does not have active geology, and the only candidate for such an electrically conductive layer proposed today is water with dissolved salts in it.

If the data is confirmed, then Insight has discovered a fairly deep subsurface sea. This is the name deserves a body of water with a water column of four kilometers. Such places have long been considered one of the best candidates for the simplest life. Similar large lakes in Antarctica (Lake Vostok) contain microorganisms, despite the fact that these reservoirs themselves have been hidden under the ice for many millions of years.

Martian Oxygen: Life or an Unknown Chemical Process?

But this is not the only major "Martian" news. Scientists working for NASA have found that the amount of oxygen near the surface of the Red Planet changes markedly throughout the year. In spring, its level rises sharply and remains so throughout the summer.In winter, on the contrary, it drops sharply.

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There are no ready-made explanations for this fact. Today, there are no known inorganic chemical processes that would allow - in anhydrous conditions - to sharply increase the oxygen level in the warm season and lower it in the cold. Scientists are trying to suggest hypothetical paths for such processes, but the work is not easy. Usually, when heated, oxygen is not released, but, on the contrary, binds more efficiently, oxidizing the substances in contact with it.

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In theory, life can also be an explanation for what is happening. Yes, there is no terrestrial vegetation on Mars, but this does not mean that living organisms - if they are there - cannot be a source of oxygen fluctuations in the atmosphere.

There are two groups of microorganisms on Earth that are capable of producing small amounts of oxygen without photosynthesis. First, there are bacteria that can break down perchlorates for energy. There is quite a lot of perchlorate in the Martian soil (by earthly standards, there is a record amount of it there), and, in principle, their decomposition is an accessible source of O2.

Secondly, not so long ago, methanotrophic bacteria were discovered on Earth, capable of decomposing methane to obtain the energy they need. As you know from the Curiosity data, there is a source of methane of unknown origin on Mars (a biological version cannot be ruled out there, too). It can be assumed that in order to oxidize methane with oxygen in an oxygen-poor environment, such bacteria produce their own oxygen from nitrogen oxides (these are also found in the Martian soil).

A positive difference in the biological explanation of fluctuations in the level of oxygen in the Martian atmosphere is that it is easy to explain seasonal fluctuations in the amount of this gas. Both bacteria that decompose perchlorates and bacteria that decompose methane with their "own" oxygen need a relatively high temperature, that is, in the warm season they are naturally much more active than in the cold one.

As of today, there are no final conclusions - and they are unlikely to be made in the foreseeable future. It is not easy to find both "perchlorate" and methane-oxidizing microbes: even on Earth, both of these groups were discovered quite recently, already in the 21st century, since they live in hard-to-reach conditions. On Mars, microorganisms cannot inhabit the surface, where it is too cold and dry. The depth they need to survive starts from one to two meters. If they are there, only deep drilling can find them.

As we already wrote, the deepest drilling on Mars so far has taken 35 centimeters. In addition, an ordinary automaton simply does not have the ability to detect such "well-hidden" life forms. Therefore, before the study of Mars in the course of manned expeditions, an unambiguous solution to the riddle of Martian oxygen is unlikely.

The list of ten really interesting discoveries of the year reflects some of the obvious trends in modern science. It develops most rapidly where it has recently acquired new instruments and methods - that is, in the field of astronomy, exploration of space and other planets by probes, as well as in areas related to genetics. The surge in anthropological news this year is more a reflection of the luck of specific anthropologists who described the remains of a new species, as well as the tips of throwing weapons.

Unfortunately, other branches of science have not shown such striking results this year - neither particle physics, nor the search for dark matter, nor a number of other areas. Perhaps they will be lucky next year?

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