The American astrophysicist Abraham Loeb, having carried out the corresponding calculations, found out that, in principle, the first life could appear in the Universe as early as 15 million years after the Big Bang. The conditions at that time were such that liquid water could exist on solid planets even when they were outside the habitable zone of their star.
To some, the question of when, in principle, life could appear in our Universe, may seem idle and insignificant. What do we care about at what point in time the conditions of our universe became such that organic molecules the ability to create complex structures? After all, we know for sure that this happened on our planet no later than 3.9 billion years ago (this is the age of the most ancient sedimentary rocks on Earth, in which traces of the vital activity of the first microorganisms were found), and this information, at first glance, may be enough in order to build on this basis all hypotheses about the development of life on Earth.
In fact, this question is much more complex and interesting for earthlings from a practical point of view. Take, for example, the panspermia hypothesis, which is still very popular today, according to which life does not originate on each planet separately, but, having appeared once at the very beginning of the development of the Universe, travels to different galaxies, systems and planets (in the form of the so-called "life disputes"). "- the simplest organisms that are at rest during the journey). However, there is still no reliable evidence for this hypothesis, since living organisms have not yet been found on any planet other than the Earth.
However, if direct evidence cannot be obtained, then scientists can also use indirect evidence - for example, if it is established at least theoretically that life could have originated earlier than 4 billion years ago (recall, the age of our Universe is estimated as 13.830 ± 0.075 billion years, so there was, as you can see, more than enough time for this), then the hypothesis of panspermia from the category of philosophical will already pass into the rank of strictly scientific. It should be noted that one of the most ardent adherents of this theory, academician V. I. Vernadsky generally believed that life is the same fundamental property of the matter of the Universe as, for example, gravity. Thus, it is logical to assume that the appearance of living organisms is quite possible at the earliest stages of the origin of our universe.
Probably, it was precisely such thoughts that prompted Dr. Abraham Loeb from Harvard University (USA) to think about the question of when life could have arisen in the Universe at all and what were the conditions for its existence in the earliest era. He made the appropriate calculations using CMB data and found that this could well have happened when the first star-forming halos appeared inside our Hubble volume (this is the name for the region of the expanding Universe surrounding the observer, outside of which objects move away from the observer at a speed greater than than the speed of light), that is, only after ... 15 million years after big bang.
According to the researcher's calculations, in this early era, the average density of matter in the universe was a million times higher than today, and the temperature of the cosmic microwave background was 273-300 K (0-30 °C). It follows from this: if then there were solid planets, then liquid water on their surface could exist regardless of the degree of their distance from their sun. If we explain this by the example of the objects of our solar system, then the boundless oceans could freely splash on Uranus's satellite Triton, and on Jupiter's moon Europe, and on the famous Saturnian Titan and even on dwarf planets like Pluto and objects from the Oort cloud (provided that the latter have gravity sufficient to hold water masses )!
Thus, it turns out that already 15 million years after the birth of the Universe, there were all the conditions for life to arise on some planets - after all, the presence of water is the main condition for starting the process of formation of complex organic molecules from simple components. True, Dr. Loeb notices that there is one “but” in his constructions. A date 15 million years from the Big Bang corresponds to a redshift parameter z (it determines the amount of displacement relative to the point where the observer is located) with a value of 110. And according to previous calculations, the time of appearance in the Universe heavy elements, without which the formation of solid planets is impossible, corresponds to a z value of 78, and this is already 700 million years after the same Big Bang. In other words, water in liquid form then had nothing to exist on, since there were no solid planets themselves.
However, Abraham Loeb notes, this is exactly the picture that emerges if we admit that the distribution of matter 15 million years after the birth of our universe was Gaussian (that is, normal). However, it is quite possible that it was quite different in those days. And if so, then the likelihood that somewhere in the Universe there were already systems with solid planets is very, very high. Proof of this assumption can serve as objects that astronomers often find in Lately are stars and galaxies whose age is much younger than the end of the reionization epoch (after which the appearance of heavy elements began).
Thus, if Dr. Loeb's calculations are correct, it turns out that life could have arisen on literally every planet in the early universe. Moreover, it turns out that the first planetary systems should be filled with it practically "to the eyeballs", since at least some of these planets have retained their potential suitability for life for a very long time. Well, since no one can still refute the potential possibility of the transfer of living organisms and their spores by meteorite-cometary means, it is logical to assume that in this case, even after the temperature of the cosmic microwave background radiation dropped, these "pioneers of life" could colonize other planetary bodies even before the death of their primary biospheres - after all, the benefit of the distance between planetary systems at that time were a huge number of times less than today.
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What is a hypothesis?
A hypothesis is a statement that is neither true until it has been confirmed, nor false until it has been refuted, but is used as a working version. Hypotheses are most often used in natural sciences, such as physics, and describe the causes natural phenomena. The hypothesis, which was confirmed, becomes the basis for the following assumptions. Hypothesis is the word Greek origin, literally translated as "foundation", "assumption". In the modern sense, not a proven theory or assumption. A hypothesis is put forward on the basis of observations or experiments. Subsequently, the hypothesis can be proven, which indicates the validity of this hypothesis, or refuted, which indicates its fallacy.
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Types of Hypotheses
Scientific hypothesis Metaphysical hypothesis
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Scientific Hypothesis is...
… such a hypothesis that explains all known scientific facts based on the use of a mental abstract model of the objects and phenomena of the real world under study, does not contain internal logical contradictions, and from the analysis of the properties of the model derives consequences that were previously unknown and allow for experimental verification. After checking the predicted consequences, the scientific hypothesis can either be confirmed or refuted by the results of the experiment. With experimental confirmation of the predicted consequences, the hypothesis is recognized as a SCIENTIFIC THEORY.
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scientific hypothesis
The existence of the atomic nucleus Ernest Rutherford
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Scientific Hypothesis
Existence of electromagnetic waves Maxwell
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Scientists
Isaac Newton Einstein
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A metaphysical hypothesis is...
… untestable hypotheses. The impossibility of scientific proof or refutation of a metaphysical hypothesis does not deprive it of the right to exist. To accept or reject such a hypothesis is a matter of a person's belief in its truth or disbelief in it.
This statement can be judged whether it is true or false. It is precisely this that is a necessary link in the development of science.
In this publication, we will define the concept of "hypothesis", as well as talk about some of the shocking hypotheses of the modern world.
Meaning
A hypothesis (from the Greek hypothesis, which means "foundation") is a preliminary assumption that explains a certain phenomenon or group of phenomena; may be associated with the existence of an object or object, its properties, as well as the reasons for its occurrence.
The hypothesis itself is neither true nor false. Only having received confirmation, this statement turns into truth and ceases to exist.
Ushakov's dictionary has another definition of what a hypothesis is. This is a scientific unproven assumption that has a certain probability and explains phenomena that are inexplicable without this assumption.
Vladimir Dal also explains what a hypothesis is in his dictionary. The definition says that this is a guess, a speculative (not based on experience, abstract) position. This interpretation is quite simple and short.
The equally well-known dictionary of Brockhaus and Efron also explains what a hypothesis is. The definition given in it is connected only with the system of natural sciences. According to them, this is an assumption that we make for the interpretation of phenomena. A person comes to such statements when he cannot establish the causes of the phenomenon.
Stages of development
In the process of cognition, which consists in making an assumption, there are 2 stages.
The first, which consists of several stages, is the development of the assumption itself. At the first stage of this stage, the position is advanced. Most often this is a guess, even partially unfounded. At the second stage, with the help of this conjecture, previously known facts and those that were discovered after the appearance of the assumption are explained.
To be must meet certain requirements:
1. It must not contradict itself.
2. The extended position must be verifiable.
3. It cannot contradict those facts that do not belong to the area of the hypothesis.
4. It must comply with the principle of simplicity, that is, it should not contain facts that it does not explain.
5. It must contain new material and have additional content.
At the second stage, the development of knowledge takes place, which a person receives with the help of a hypothesis. Simply put, this is its proof or refutation.
New hypotheses
Speaking about the definition of what a hypothesis is, attention should be paid to some of them. Modern world achieved great success in the field of knowledge of the world and scientific discoveries. Many previously put forward hypotheses were refuted and replaced by new ones. Below are some of the most shocking hypotheses:
1. The Universe is not an infinite space, but a material entity created according to a single law. Scientists believe that the universe has an axis around which it rotates.
2. We are all clones! According to Canadian scientists, we are all descendants of cloned creatures, artificially created hybrids grown from a single cell in a test tube.
3. Health problems, with reproductive activity, as well as a decrease in sexual activity are associated with the appearance of synthetic substances in food.
Thus, a hypothesis is not certain knowledge. This is just a prerequisite for its appearance.
In the 19th century paleoclimatic changes were explained by a change in the composition of the atmosphere, in particular, with a change in the content of carbon dioxide in the atmosphere.
As you know, the earth's atmosphere contains about 0.03% carbon dioxide (by volume). This concentration is enough to "warm" the atmosphere, increasing the "greenhouse effect". Increasing the concentration of carbon dioxide can affect the climate, in particular temperature.
On Earth, the average annual temperature is maintained for a long time at 14 ° C with fluctuations of ± 5 ° C.
Calculations show that if there were no carbon dioxide in the atmosphere, then the air temperature on Earth would be 21 o C lower than today and would be equal to -7 o C.
A doubling of the carbon dioxide content, in relation to the current state, would cause an increase in the average annual temperature to +18 o C.
Thus, warm periods in the geological history of the Earth can be associated with a high content of carbon dioxide in the atmosphere, and cold periods, with its low content.
The glaciation, which was supposedly after the Carboniferous period, could be caused by the rapid development of vegetation during this period, which significantly reduced the carbon dioxide content in the atmosphere.
However, if biological or chemical processes unable to absorb the incoming flow (Carbon dioxide can come both from natural sources (volcanic activity, fires, etc.) and from the combustion of fuel as a result of anthropogenic activity) of carbon dioxide, then its concentration increases, this can lead to an increase atmosphere temperature.
It is believed that over the past 100 years, as a result of the combustion of fossil fuels, the global temperature has increased by 0.5 o. A further increase in the concentration of carbon dioxide in the atmosphere may be one of the possible causes climate warming in the 21st century.
What will happen if the concentration of CO 2 doubles?
In the northern mid-latitude regions, summer droughts can reduce the productive potential by 10-30%, which will entail an increase in the average price of world agricultural products by at least 10%. In some areas, the duration of the warm period of the year will increase significantly. This could lead to increased productivity due to agricultural adaptation by introducing late maturing and generally higher yielding varieties. In some parts of the world, the climatic boundaries of the agricultural zone are expected to shift by 200-300 km per degree of warming. May occur a significant shift in the main forest zones, with the shift of forest boundaries in the northern hemisphere may be several hundred kilometers towards the north. Polar deserts, tundra and boreal forests are expected to decrease by about 20%. In the northern regions of the Central Asian part of Russia, the zonal border will move north by 500-600 km. The tundra zone may disappear altogether in the north of Europe. An increase in air temperature by 1-2 ° C, accompanied by a simultaneous decrease in precipitation by 10%, can cause a reduction in the average annual river runoff by 40-70%. An increase in air temperature causes an increase in runoff due to snowmelt from 16 to 81%. At the same time, summer runoff decreases by 30-68% and at the same time soil moisture decreases by 14-36%.
Changes in precipitation and air temperature can radically change the spread of viral diseases, moving the border of their distribution to high latitudes.
The ice of Greenland may completely disappear in the next thousand years, which will lead to a rise in the average level of the World Ocean by six to seven meters. British scientists from the University of Reading came to this conclusion by modeling global climate change. The Greenland glacier is the second largest after the Antarctic - its thickness is about 3 thousand m (2.85 million cubic km of frozen water). Until now, the volume of ice in this area has remained virtually unchanged: melted masses and breakaway icebergs have been compensated by falling snow. If the average temperature in the Greenland region rises by only three degrees Celsius, an intensive process of melting secular ice will begin. Moreover, according to NASA experts, Greenland is already losing about 50 cubic meters. km of frozen water per year.
It is possible to expect the beginning of the melting of the Greenland glacier, as shown by the results of modeling, as early as 2035.
And in the event that the temperature in the area rises by 8 degrees Celsius, the ice will completely disappear within a thousand years.
It is clear that an increase in the average level of the World Ocean will lead to the fact that many islands will be under the water column. A similar fate, in particular, awaits Bangladesh and parts of Florida. It will be possible to solve the problem only if there is a sharp reduction in carbon dioxide emissions into the atmosphere.
Global warming will lead to intensive melting of ice (Greenland, Antarctica, Arctic) and by 2050 an increase in the level of the world ocean by 30-50 cm, and by 2100 up to 1 m. In this case, an increase in surface water temperature by 0.2- 0.5 o C, which will lead to a change in almost all components of the heat balance.
Due to climate warming, the area of productive zones of the World Ocean will decrease by about 7%. At the same time, the primary production of the World Ocean as a whole can decrease by 5-10%.
The melting of glaciers in the archipelagos in the Russian sector of the Arctic may lead to their disappearance in 150-250 years.
Global warming by 2 o C will shift the southern border of the climate zone currently associated with permafrost, in most of Siberia to the northeast, at least 500-700 km.
All this will lead to global restructuring of the world economy and social upheavals. Although the scenario of doubling CO 2 is unlikely, it should be considered.
The above projections show that the use natural resources should focus, on the one hand, on reducing the consumption of organic fuel, and on the other hand, on increasing the productivity of the vegetation cover (increasing the absorption of CO 2 ). To increase the productivity of the natural vegetation cover, it is necessary to take care of forests and swamps, and to increase the productivity of agricultural land, complex reclamation is necessary.
The "greenhouse" or "greenhouse" effect of the atmosphere can also be caused by a change in the content of water vapor in the air. When the moisture content increases, the temperature increases, and when it decreases, it decreases.
Thus, changes in atmospheric parameters can also lead to cooling. For example, halving the moisture content of the air can lower the average temperature earth's surface about 5 o.
Cooling can be caused not only by these reasons, but also as a result of a change in the transparency of the atmosphere due to the release of volcanic dust and ash, nuclear explosions, forest fires, etc.
So, for example, contamination of the atmosphere with volcanic products increases the albedo (reflectivity) of the Earth as a planet and reduces the flow of solar radiation to the earth's surface, and this leads to cooling.
Volcanoes are sources of huge masses of dust and ash. For example, it is estimated that as a result of the eruption of Krakatau volcano (Indonesia) in 1883, 18 km 3 of loose material was thrown into the air, and Katmai volcano (Alaska) in 1912 gave the atmosphere about 21 km 3 of dust and ash.
According to Humphreys, fine dust fractions can remain in the atmosphere for many years. The abundance of solid suspensions emitted into the atmosphere, their rapid distribution throughout the globe and their long-term retention in suspension reduces the arrival of solar short-wave radiation on the earth's surface. This reduces the duration of sunshine.
After the Katmai eruption in 1912, even in Algeria, the radiation intensity was reduced by 20%. In the city of Pavlovsk, near St. Petersburg, after the eruption of this volcano, instead of the normal value of 0.765, the transparency coefficient of the atmosphere decreased to 0.588, and in August to 0.560. On some days, the intensity of solar radiation was only 20% of the normal value. In Moscow, the number of sunshine hours in 1912 was only 75% of that observed in adjacent years. [Alisov B.P., Poltaraus B.P. 1974]
Interesting data on the attenuation of solar radiation by solid impurities in the atmosphere are reported by VB Shostakovich. He reports that in the dry summer of 1915, forest fires covered an area of 1.6 million km 2 in Siberia, and smoke was observed in an area in. 6 million km 2. This area is equal in size to the area of Europe. In this case, solar radiation decreased c. August 1915 to 65%. The fires lasted about 50 days and caused: a delay in the ripening of cereals by 10-15 days.
A similar effect of the huge forest fires in 1950, Wexler describes. He reports that due to the smoke, the daily amount of solar radiation intensity on cloudless days in Washington was 52% of the norm for a cloudless day. A similar situation could be observed in 1972 and 2002 in Russia.
Brooks is a supporter of the effect of clouding of the atmosphere on climate. According to him, all cold years, starting from 1700, followed major eruptions volcanoes. Cold 1784 - 1786 - after the eruption of the volcano Asama (Japan) in 1783. Cold 1816 ("year without summer") - for the eruption of Tomboro (Sumbawa Island) in 1815. Cold 1884 - 1886 - after the eruption of Krakatoa in 1883. Cold 1912-1913 -- for the eruption of Katmai (Alaska) in 1912 (see Figure 5.5).
An active supporter of the hypothesis of volcanic causality, which explains the fluctuations and changes in climate, is one of the largest climatologists in Russia - M. I. Budyko. He showed that after a volcanic eruption, with an average decrease in direct radiation by 10%, the average annual temperature northern hemisphere decreases by about 2 - 3 o C.
MI Budyko's calculations, moreover, prove that as a result of atmospheric pollution by volcanic dust, the total radiation is more significantly weakened in the polar region and less so in tropical latitudes. In this case, the decrease in temperature should be more significant at high latitudes and relatively small at low latitudes.
Over the past half century, the Earth has become significantly darker. This conclusion was made by scientists at the Goddard Institute. space research at NASA. Global measurements show that from the late 1950s to the early 1990s, the amount of sunlight reaching the earth's surface decreased by 10%. In some regions, such as Asia, the United States and Europe, the light has become even smaller. In Xianggang (Hong Kong), for example, it "darkened" by 37%. Researchers attribute it to pollution environment, although the dynamics of "global dimming" is not completely clear. Scientists have long known that particles of substances that pollute the atmosphere, to some extent, reflect sunlight, preventing it from reaching the earth. The process has been going on for a long time and does not come as a surprise, said Dr. Hansen, but "its consequences are enormous." Experts do not predict the imminent onset of eternal night. Moreover, some are optimistic, pointing out that as a result of the fight against environmental pollution, the air over some areas of the planet has become cleaner. And yet the phenomenon of "global dimming" needs to be studied in depth.
It follows from the above facts that mechanical impurities emitted into the atmosphere by volcanoes and formed as a result of anthropogenic activity can have a significant impact on the climate.
For complete glaciation the globe it is enough to reduce the influx of total solar radiation by only 2%.
The hypothesis of the influence of atmospheric pollution on climate was adopted in modeling the consequences nuclear war, which was performed by scientists of the Computing Center of the Russian Academy of Sciences under the guidance of Acad. N.N. Moiseeva. They showed that as a result of nuclear explosions, dust clouds are formed, weakening the intensity of the flow sun rays. This leads to a significant cooling on the entire territory of the planet and to the death of the biosphere during the “nuclear winter”.
The need for high precision maintenance natural conditions on Earth and the inadmissibility of their change is evidenced by the statements of many scientists.
For example, Cressy Morrison, the former president of the New York Academy of Sciences, in his book "Man is not alone" says that people are now at the dawn of the scientific era, and each new discovery reveals the fact that "the universe was conceived and created by a great constructive Mind. The presence of living organisms on our planet presupposes such an incredible number of conditions for their existence that the coincidence of all these conditions cannot be a matter of chance. The earth is exactly the distance from the sun that the sun's rays heat us enough, but not too much. The earth has an elliptical tilt of twenty-three degrees, which causes the different seasons; without this tilt, water vapor evaporating from the surface of the ocean would move along a north-south line, heaping ice on our continents.
If the moon were only fifty thousand miles away, instead of about two hundred and forty thousand miles away, our ocean tides would be so huge that they would flood our earth twice a day...
If our atmosphere were more rarefied, burning meteorites (which burn by the millions in space) would strike our earth from different directions every day, producing fires...
These examples and many others show that there is not a single chance in a million for life on our planet to be an accident” (quoted from materials by A.D. Shakhovsky).
Conclusions to the fifth chapter
Climatic conditions are decisive for many processes on which the existence of the biosphere on Earth depends.
Climate change as a result of anthropogenic activities is dangerous if it occurs on a global scale.
A significant change in climatic conditions is possible with an increase in the content of "greenhouse" gases in the atmosphere (carbon dioxide, water vapor, etc.)
To compensate for the greenhouse effect, it is necessary to increase the productivity of natural and artificial cenoses.
A significant change in climatic conditions is also possible when the atmosphere is polluted with mechanical impurities.
The use of natural resources should be focused, on the one hand, on reducing the consumption of fossil fuels, and on the other hand, on increasing the productivity of the vegetation cover (increasing CO 2 absorption).
Observation- a method of studying objects and phenomena of objective reality in the form in which they exist in nature. An observable is any physical quantity whose value can be found experimentally (measured).
Hypothesis- a probable assumption about the cause of any phenomena, the reliability of which state of the art science cannot be tested and proven.
Experiment- the study of a particular phenomenon under precisely taken into account conditions, when it is possible to monitor the course of a change in a phenomenon, to actively influence it.
Theory- generalization of experience, practice, scientific activity, revealing the main patterns of the process or phenomenon under study.
Experience- a set of accumulated knowledge.
Mechanics- a science that studies mechanical movements, i.e. moving bodies relative to each other or changing body shapes.
Material point- a physical body, the size and shape of which can be neglected.
translational movement- a movement in which any straight line, rigidly connected with the body, moves parallel to itself.
Instant speed (speed)– characterizes the rate of change of the displacement radius vector r at time t.
Acceleration- characterizes the rate of change of speed at time t.
Tangential acceleration characterizes the change in speed modulo.
Normal acceleration- towards.
Angular velocity is the vector value of the derivative of the elementary angular displacement with respect to time.
Angular acceleration is a vector quantity equal to the first derivative of the angular velocity with respect to time.
Pulse- vector measure of quantity mechanical movement, which can be transferred from one body to another, provided that the movement does not change its form.
mechanical system- a set of bodies allocated for consideration.
internal forces are the forces with which the bodies that are part of the system under consideration interact with each other.
Outside forces- act from the side of bodies that do not belong to the system.
System called closed or isolated if there are no external forces
Direct problem of mechanics– knowing the forces, find the motion (functions r(t), V(t)).
Inverse problem of mechanics- knowing the motion of the body, find the forces acting on it.
Mass (additive value):
1. Measure of inertia in the translational motion of the body (inertial mass)
2. A measure of the amount of a substance in the volume of a body
3. Measure of the gravitational properties of the bodies involved in gravitational interactions(gravitational mass)
4. Measure of energy
Inertia manifests itself:
1. In the ability of the body to maintain a state of motion
2. In the ability of a body under the influence of other bodies to change the state not in jumps, but continuously.
3. Resist a change in the state of your movement.
reference systems, in relation to which the free b.m. is in a state of relative rest or uniform rectilinear motion, are called inertial(in them, Newton's I law is fulfilled).
INewton's law: If the frame of reference moves relative to the inertial one with acceleration, then it is called non-inertial.
IINewton's law: In the inertial system, the rate of change of momentum b.m. equal to the resulting force acting on it and coincides with it in direction.
IIINewton's law: The forces with which interacting bodies act on each other are equal in magnitude and opposite in direction.
Absolute Speed– b.w. speed with respect to a fixed frame of reference.
Relative speed– b.w. speed relative to the moving frame of reference.
Carrying speed is the speed of the moving frame relative to