AT Everyday life a person most often has to deal with finite quantities. Therefore, it is very difficult to visualize an unrestricted infinity. This concept is shrouded in a halo of mystery and unusualness, which is mixed with reverence for the Universe, the boundaries of which are almost impossible to determine.
The spatial infinity of the world belongs to the most complex and controversial scientific problems. Ancient philosophers and astronomers tried to resolve this issue through the simplest logical constructions. To do this, it was enough to assume that it was possible to reach the supposed edge of the universe. But if you stretch out your hand at this moment, then the border moves back a certain distance. This operation can be repeated countless times, which proves the infinity of the universe.
The infinity of the universe is difficult to imagine, but no less difficult is how a limited world could look like. Even for those who are not very advanced in the study of cosmology, in this case, a natural question arises: what is beyond the boundary of the Universe? However, such reasoning, built on common sense and worldly experience, cannot serve as a solid basis for rigorous scientific conclusions.
Modern ideas about the infinity of the universe
Modern scientists, exploring multiple cosmological paradoxes, have come to the conclusion that the existence of a finite universe, in principle, contradicts the laws of physics. The world outside the planet Earth, apparently, has no boundaries either in space or in time. In this sense, infinity implies that neither the amount of matter contained in the Universe, nor its geometric dimensions can be expressed even by the most a large number(“Evolution of the Universe”, I.D. Novikov, 1983).
Even if we take into account the hypothesis that the Universe was formed about 14 billion years ago as a result of the so-called Big Bang, this may well only mean that in those extremely distant times the world went through another stage of natural transformation. In general, the infinite Universe never appeared during the initial push or inexplicable development of some non-material object. Assumption about infinite universe puts an end to the hypothesis of the Divine creation of the world.
In 2014, American astronomers published the results of the latest research that confirms the hypothesis of the existence of an infinite and flat universe. With high precision, scientists have measured the distance between galaxies located at a distance of several billion light years from each other. It turned out that these colossal space star clusters are located in circles with a constant radius. Built by researchers cosmological model indirectly proves that the Universe is infinite both in space and in time.
Firsov A.
There are only two infinite things: the universe and stupidity. Although I'm not sure about the universe. Albert Einstein
We are accustomed to be aware of the Universe as infinite. Is that so?
Below are some discussions on this issue.
Humanity in three axes of measurements
All his life a person lives in the conditions of gravity, so every moment there is a bottom for him (the direction where he pulls, and up - the direction from which he pulls).
Such a way of life gives a person a clear division of the surrounding space into two parts - that which is below the level of man and that which is above the level of man. What is higher is usually lighter, lighter and safer, respectively, often associated with ease, and peace and a blissful state. What is lower is usually heavier, darker, more dangerous. Accordingly, it is associated in people with heaviness, anxiety, danger and trouble.
Throughout his life, a person moves perpendicular to gravity. Accordingly, two directions are similarly formed for it - to where we are moving (forward) and to where we are moving from, respectively, back. Both directions are almost always perpendicular to gravity. It is easier to move forward, accordingly, everything that a person has in the future is associated with moving forward, and what is in the past is associated with moving backward.
The next directions are the directions perpendicular to motion and gravity - right and left.
Just as the presence of ten fingers on the hands gives rise to a decimal number system for a person (such a system is the most convenient for use in practical life), so the ways of existence form the most convenient idea for a person about the world around him as three-dimensional.
Almost all religions place unpleasant sensations and future troubles below the surface of the earth, and all pleasant sensations and future bliss above the surface of the earth.
Now that science has proven that the earth is spherical. Heaven and hell no longer have a real place of existence, and their synonyms "Heaven" and "Hell" continue to exist already divorced from the specific directions of the top and bottom.
At the same time, the question of when and how the world was created, what size it is, how long it will exist, continues to excite the minds of believers, atheists, and agnostics.
And the question of how far and how long in time it is possible to move in one direction for all sane people has one answer - arbitrarily long and arbitrarily far.
It is difficult for an inexperienced person to imagine that moving up, one could be at the bottom, and moving forward, one could be behind.
But is this true in the real universe? And what does science think about this?
A person invents infinity where he lacks the mind to realize finiteness
To clarify this statement, I'll start with a little parable.
“In the same forest, in a tiny clearing, a tribe of people lived. Around the clearing on all sides was a dense forest. Periodically, tigers came out of the forest and ate people. People were very afraid of tigers. No matter how far people went into the forest, there was only forest everywhere, and almost everywhere one could stumble upon a tiger. The whole Universe for these people consisted only of a clearing in which they live and forests with tigers around. People deified every moving or motionless, but threatening object.
It is not surprising that the people who lived in the clearing reasonably believed that the forest around spreads indefinitely, and that, accordingly, the number of tigers in the forest is also infinite. Because no matter how far you go into the forest, you will either stay in the forest forever or sooner or later, but you will be eaten by a tiger or you will fall into some kind of danger.
Any assumption that either the forest is finite, or the number of tigers or the number of gods, was considered absurd, illogical, contrary to logic and common sense.
However, in the process of life, people needed wood for building houses, making tools and heating. Therefore, the forest around the glade was constantly cut down. Over time, almost the entire forest was cut down.
In the end, it turned out that the size of the forest is limited. The number of tigers in it also turned out to be limited. People have been able to measure both the size of the forest and the number of tigers.”
I cited this parable in order to show that humanity quite easily assumes infinity where there are actually limitations. Human psychology is such that in many cases people invent infinity where, for one reason or another, it is difficult for them to realize finiteness. First of all, this refers to space, time and supernatural forces.
Similarly, it is easier for a person to imagine the immobility of objects associated with him (earth, air, solar system, galaxy) than mobility.
It is this feature human psychology explains the fact that initially the Universe was assumed to be flat and motionless, and the surrounding space and time were assumed to be infinite in all directions.
However, in the process of its development, humanity has changed its understanding of the world around us. At the same time, it should be noted that this change did not always occur without conflict.
Giordano Bruno burned at the stake, preaching in his books both that the Earth is not the center of the Universe, and the infinity of the Universe, and the infinity of the many worlds of the Universe.
Galileo Galilei lived a hard life, supporting the Copernican theory of the rotation of the earth around the sun and around its axis.
How scientific hypotheses develop
"Any new idea goes through three phases. First: what the heck? Second: there is something in it. Third: who does not know this?
It is known that any original idea is first rejected, then subjected to fierce attacks, and, finally, accepted as an axiom. At the end, everything ends with the fourth phase: the idea is not only accepted, but also realized, held in the minds and translated into actions.
Most often new scientific theory begins with the fact that this or that fact is difficult to explain within the framework of the existing theory. Then one or more people appear who, in one way or another, try to explain the discrepancy between the facts. An idea or assumption is born - a hypothesis. Whether this hypothesis is correct or incorrect, further practice shows. If the hypothesis is not confirmed in practice, it is discarded. If the hypothesis has some practical evidence, then it becomes a theory from a hypothesis. They try to test the theory from all sides, until they are convinced of its correctness. Only after that the theory is accepted as a fact, and they begin to use it as a natural and quite understandable phenomenon of the surrounding world.
So, for example, the hypothesis that the earth is convex was put forward by navigators who saw how ships leaving the horizon did not decrease in size to a point, but gradually descended beyond the horizon line.
Later, a theory appeared that claimed that the earth could be round. This theory was tested in practice first by Columbus and then by Magellan. Now it's no secret that the earth is round. Although within the framework of ordinary everyday ideas it is very difficult to imagine and realize.
Something similar happened with the theory that the earth revolves around the sun.
Scientific ideas about the microcosm and the macrocosm
Scientists working both in the field of microparticles and in the field of astrophysics have to work with elements that cannot be touched, considered carefully. Therefore, in these areas of science, people have long figured with such concepts that are more abstract than really tangible or representable: In the microcosm, these are electrons, protons, photons, quarks, electromagnetic waves and fields, antimatter, etc. In the macrocosm, these are galaxies, supernovas, dwarfs, black holes, etc.
All these are quite abstract concepts, poorly represented by an ordinary person.
Some connection between them by abstract worlds is theoretically given by the theory of relativity, which rather abstractly connects mass, speed of light and energy.
Under such conditions, scientists quite easily operate with theoretical calculations, calculations and assumptions. In those cases when the physical theory and its mathematical calculation does not give the possibility of a solution with infinite distances, masses, velocities, periods of time, but in practice is confirmed by many practical experiments, scientists quite easily admit finiteness and limitation. Such an approach is so captivating that people involved in science begin not only to admit the limitations of some spatial things and the Universe itself, but also, with the help of various assumptions and calculations, try to calculate the size of the Universe.
Einstein's theory of relativity and the limits of speed, mass and energy
In the 20th century, physicists believed that they already understood almost everything in the world around them. One exception was light. It propagated like a wave (bending and refracting) and at the same time interacted with matter much like a particle, for example, exerted pressure.
Attempts to measure the speed of light have baffled physicists. The earth rotates around its axis and moves in space, i.e. Any object on the Earth's surface moves at high speed. However, all attempts to obtain the dependence of the speed of light on the speed of the source or receiver of light ended in failure. The speed of light was constant, regardless of whether it was measured at the light source or at the receiver, whether the light source or the receiver was moving.
The only thing that could be calculated is that the greater the speed with which objects move away from each other, the stronger the shift of their light to the red region.
The paradox with the speed of light was solved mathematically by Albert Einstein. The equations derived by Einstein linked the change in the lengths of material objects and time intervals with changes in the state of motion of material objects, in addition, Einstein developed equations relating the mass of an object to its energy. The connecting factor was the speed of light.
A by-product of Einstein's equations was that it was impossible to achieve a speed greater than the speed of light: It followed from Einstein's equations that no object could move faster than the speed of light.
The impossibility of infinite speed was calmly accepted by physicists.
AT general theory relativity, Einstein connected mass and energy in a single formula.
This, too, was calmly accepted by physicists. However, since the mass of the universe is limited, the logical conclusion from this is that the energy in the universe is limited.
The theory of the expanding universe
The study of light emitted by distant galaxies showed that the farther objects are from each other, the stronger their redshift, i.e. the faster they move away from each other. The farthest objects move away at almost the speed of light.
Based on these observations, the theory of the expanding universe was created. According to this theory, all objects in the universe fly apart from each other at great speeds.
To explain this fact, theories of the big bang and the oscillating (oscillating) universe were invented.
According to the first theory, the Universe flies apart from a certain moment and from a certain point.
According to the second theory, the objects of the Universe either move away from each other, or begin to move towards each other.
The Big Bang Theory
1922 - Soviet mathematician and geophysicist Al. Al. Friedman found non-stationary solutions to Einstein's gravitational equation and predicted the expansion of the universe (a non-stationary cosmological model known as Friedmann's solution). If we extrapolate this situation into the past, we will have to conclude that at the very beginning, all the matter of the Universe was concentrated in a compact area, from which it began to expand. Since explosive processes very often occur in the Universe, Friedman came up with the assumption that at the very beginning of its development there is also an explosive process - the Big Bang.
According to modern concepts, the Universe we are currently observing arose 13.7 ± 0.2 billion years ago from some initial “singular” state with infinite temperature and density, and since then it has been continuously expanding and cooling.
The big bang theory is a logical continuation of the fact of expanding galaxies. We took the expansion speed, calculated the approximate center of expansion, divided the distance by the speed and got the date of the big bang. This is another example of direct logical reasoning based on postulates:
The speed of expansion is constant in time,
The direction of expansion is straight,
In the process of expansion, time is constant and incompressible.
None of these assumptions are proven, so the big bang theory can be assumed within certain limits: not very far forward (into the future) from the present moment and not very far back (into the past).
A consequence of this theory is that the size of the universe is limited by the radius of the expansion of the fragments of the big bang.
CMB radiation
Any body that has a temperature that is not absolutely zero (-273 degrees Celsius) emits a certain type of radiation. The closer to the center of the explosion, the greater must be the temperature of the Universe, and the farther from the point of explosion, the lower it must be. At infinity, the universe must have absolutely zero temperature.
However, practical attempts to measure the temperature of the Universe have shown that it is not equal to zero. It turned out that from almost all directions the temperature of the universe is about 3.5 degrees Celsius.
In practice, this means that the energy released during the so-called "Big Bang" did not dissipate without limit, but heated the Universe to a certain temperature in all places.
In other words, one can say that, or
1. The amount of energy released during the "Big Bang" immediately turned out to be infinite and was distributed evenly throughout the Universe, or what
2. The heat capacity of the Universe turned out to be finite.
And the first contradicts the theory of relativity (heat could not reach the entire universe in a limited time). The second means that the Universe is limited in heat capacity, which practically means that the Universe is finite.
Moreover, the temperature is unevenly distributed throughout the Universe, on some sides the Universe is heated more strongly, and on others - weaker. Scientists call this distribution of temperature throughout the Universe - fluctuations of the cosmic microwave background radiation.
Now the astronomer is interested in measuring the fluctuations of the background radiation, since it can shed light on the processes that took place in the Universe at the initial stages of its development. The fact that the temperature of the boundaries of the Universe is not zero is an established fact, while the fluctuations are unevenly distributed.
Size of the Universe
In fact, based on the rate of expansion of the universe and the presence of the CMB, it turns out that our universe is relatively small - about 70 billion light years across with a number of stars equal to 10 to the nineteenth power.
How can a sane person understand that the universe is finite?
It is very difficult for a sane person to believe that the Universe can be finite. Only the experience of understanding other moments of the macrocosm can help here, which at first glance contradict common sense, but in fact are proven facts:
The earth is not flat, but round.
The sun is much larger than the earth
The sun does not revolve around the earth, but the earth revolves around the sun,
The earth rotates on its axis,
The speed of any object cannot be the speed of light,
Mass can be converted into energy and vice versa,
Light is both a wave and a particle at the same time, etc.
These things do not fit well in the mind ordinary person. But they were proposed by scientists, tested experimentally and are already being used by mankind in its practical life.
The limited nature of the Universe is only assumed by scientists and is being tested in research. But, perhaps, someday, humanity will test it experimentally, and will be able to use this fact in practical life.
What does the end of the universe mean in practice?
If the Universe is finite, then this does not mean that a person will sooner or later run into a wall. The Universe has no edge as such.
This can only mean one more closure. This means a return after some time to the starting point. So a signal or an object sent in a certain direction, and moving in a straight line, will move for a very long time until one day it returns to its starting point from the side opposite to where it went. And a ray of light, propagating in space, must return to its starting point after a certain (large) period of time.
We see the starry sky all the time. Space seems mysterious and immense, and we are only a tiny part of it. vast world, mysterious and silent.
Throughout life, mankind asks different questions. What is out there, outside our galaxy? Is there something outside of space? And does space have a border? Even scientists have been pondering these questions for a long time. Is space infinite? This article provides information that scientists currently have.
The borders of the infinite
It is believed that our solar system formed as a result of the Big Bang. It occurred due to the strong compression of matter and tore it apart, scattering gases into different sides. This explosion gave life to galaxies and solar systems. The Milky Way was previously thought to be 4.5 billion years old. However, in 2013, the Planck telescope allowed scientists to recalculate the age of the solar system. Now it is estimated at 13.82 billion years.
The most modern technology cannot cover the entire cosmos. Although the latest devices are able to catch the light of stars that are 15 billion light years away from our planet! They may even be stars that have already died, but their light is still traveling through space.
Our solar system is just a small part of a huge galaxy called Milky Way. The Universe itself contains thousands of such galaxies. And whether space is infinite is unknown ...
The fact that the Universe is constantly expanding, forming more and more new cosmic bodies, is scientific fact. Probably her appearance is constantly changing, so millions of years ago, as some scientists are sure, it looked completely different than today. And if the universe is growing, then it definitely has boundaries? How many universes exist behind it? Alas, no one knows this.
Space expansion
Today, scientists say that the cosmos is expanding very rapidly. Faster than they previously thought. Due to the expansion of the Universe, exoplanets and galaxies are moving away from us at different speeds. But at the same time, its growth rate is the same and uniform. It's just that these bodies are at different distances from us. So, the star closest to the Sun "runs away" from our Earth at a speed of 9 cm / s.
Now scientists are looking for an answer to another question. What causes the universe to expand?
Dark matter and dark energy
Dark matter is a hypothetical substance. It does not produce energy and light, but occupies 80% of the space. The presence of this elusive substance in space, scientists guessed back in the 50s of the last century. Although there was no direct evidence of its existence, there were more and more supporters of this theory every day. Perhaps it contains substances unknown to us.
How did the dark matter theory come about? The fact is that galactic clusters would have collapsed long ago if their mass consisted only of materials visible to us. As a result, it turns out that most of our world is represented by an elusive, yet unknown to us substance.
In 1990, the so-called dark energy was discovered. After all, before physicists thought that the force of gravity works to slow down, one day the expansion of the Universe will stop. But both teams that took up the study of this theory, unexpectedly revealed an acceleration of expansion. Imagine that you are tossing an apple into the air and waiting for it to fall, but instead it starts moving away from you. This suggests that the expansion is influenced by a certain force, which has been called dark energy.
Today, scientists are tired of arguing about whether the cosmos is infinite or not. They are trying to understand what the universe looked like before the Big Bang. However, this question does not make sense. After all, time and space themselves are also infinite. So, let's consider several theories of scientists about space and its boundaries.
Infinity is...
Such a concept as "infinity" is one of the most surprising and relative concepts. It has long been of interest to scientists. AT real world in which we live, everything has an end, including life. Therefore, infinity attracts with its mystery and even some mysticism. Infinity is hard to imagine. But it exists. After all, it is with its help that many problems are solved, and not only mathematical ones.
infinity and zero
Many scientists are confident in the theory of infinity. However, the Israeli mathematician Doron Zelberger does not share their opinion. He claims that there is a huge number and if you add one to it, the end result will be zero. However given number lies so far beyond human understanding that its existence will never be proven. It is on this fact that the mathematical philosophy called "Ultra-infinity" is based.
Infinite space
Is there a chance that adding two identical numbers together will result in the same number? At first glance, this seems absolutely impossible, but if we are talking about the Universe... According to the calculations of scientists, subtracting one from infinity results in infinity. When two infinities are added together, infinity comes out again. But if you subtract infinity from infinity, most likely, you get one.
Ancient scientists also wondered if there was a limit to the cosmos. Their logic was simple and brilliant at the same time. Their theory is expressed as follows. Imagine that you have reached the edge of the universe. They stretched out their hand beyond its borders. However, the boundaries of the world have moved apart. And so endlessly. It is very difficult to imagine this. But it is even more difficult to imagine what exists beyond its borders, if it really exists.
Thousand worlds
This theory says that the cosmos is infinite. It probably has millions, billions of other galaxies that contain billions of other stars. After all, if you think broadly, everything in our life begins again and again - films follow one after another, life, ending in one person, begins in another.
In world science today, the concept of a multicomponent Universe is considered generally accepted. But how many universes are there? None of us know this. Other galaxies may contain very different celestial bodies. These worlds are dominated by completely different laws of physics. But how to prove their presence experimentally?
This can be done only by discovering the interaction between our universe and others. This interaction occurs through certain wormholes. But how to find them? One of the latest assumptions of scientists says that there is such a hole right in the center of our solar system.
Scientists suggest that in the event that the cosmos is infinite, somewhere in its expanses there is a twin of our planet, and, possibly, of the entire solar system.
Another dimension
Another theory says that the size of the cosmos has limits. The thing is that we see the nearest one as it was a million years ago. Even further means even earlier. Space is not expanding, space is expanding. If we can exceed the speed of light, go beyond the boundaries of space, then we will fall into the past state of the Universe.
And what lies beyond this notorious border? Perhaps another dimension, without space and time, which only our consciousness can imagine.
Regarding the boundaries of the cosmos and the infinity of the universe, I will allow myself the audacity to refer to one of my previous answers.
As for the visible part of the universe, it's a little trickier there. Due to the expansion of the universe, the light from those parts of it that fly away from us faster speed light will never reach us. However, the light of those objects that are already beyond this boundary reaches us, still reaches us, but with a shifted wavelength - one of the manifestations of the Doppler effect. Read more here.
If we now talk about what is beyond the boundaries of the visible part of the universe, then speaking roughly, "now" there is most likely the same universe as the whole as the part that surrounds us. More precisely, in terms special theory In relativity, if we go to some distant point in the universe at sublight speed, then by the time we arrive, according to our clock, the universe at that point will visibly resemble ours in general terms.
Finally, the very redshift effect, due to which light from the far ends of the visible universe comes to us with a longer wavelength - and therefore, for the most part, is no longer visible to our eye - and allows us to conclude that the universe is expanding. Expansion is what makes the sky appear dark at night—in an infinite or large finite universe, it should appear almost uniformly bright.
The reasons for the expansion of the universe are still not clear, so far the concept of "dark energy" has been introduced in physics, due to which the universe is expanding. Its nature is not yet clear, it is not yet possible to observe its carriers directly - that is why this hypothetical object is called "dark" energy.
Still, it’s not entirely accurate, the Hubble sphere is not yet an event horizon, and light from objects that move faster than the speed of light precisely due to the acceleration of the expansion of the universe will someday fall inside the Hubble sphere and reach us. With an event horizon (not particles) - more tricky, we can see light from certain objects and will see it in the future, but we will not see how, for example, those stars will go out (even if they have already gone out), in general, events after a certain date / time.
There are two options: either the universe is finite and has a size, or it is infinite and stretches forever. Both options are thought provoking. How big is our universe? It all depends on the answer to the above questions. Have astronomers tried to understand this? Of course they tried. It can be said that they are obsessed with finding answers to these questions, and thanks to their search, we are building sensitive space telescopes and satellites. Astronomers peer into the cosmic microwave background, the CMB left over from the Big Bang. How can you test this idea just by looking at the sky?
Scientists have been trying to find evidence that features at one end of the sky are related to features at the other, like the way the edges of a bottle wrap fit together. So far, no evidence has been found that the edges of the sky can be connected.
In human terms, this means that for 13.8 billion light-years in all directions, the universe does not repeat itself. Light travels back and forth across all 13.8 billion light years before leaving the universe. The expansion of the universe has pushed back the boundaries of light leaving the universe by 47.5 billion years. We can say that our universe is 93 billion light-years across. And this is the minimum. Perhaps this number is 100 billion light years, or even a trillion. We do not know. Perhaps we won't know. Also, the universe may well be infinite.
If the universe is really infinite, then we will get an extremely interesting result that will make you seriously rack your brains.
So imagine. In one cubic meter (just spread your arms wider) there is finite number particles that can exist in this region, and these particles can have a finite number of configurations, taking into account their spin, charge, position, speed, etc.
Tony Padilla of Numberphile calculated that the number should be ten to the tenth to the seventieth power. It's so big number that it cannot be written with all the pencils in the universe. Assuming, of course, that other lifeforms haven't invented perpetual pencils, or that there isn't an extra dimension filled entirely with pencils. And still, probably not enough pencils.
There are only 10^80 particles in the observable universe. And this is much less than the possible configurations of matter in one cubic meter. If the Universe is really infinite, then moving away from the Earth you will eventually find a place with an exact duplicate of our cubic meter of space. And the further, the more duplicates.
Think, you say. One cloud of hydrogen looks the same as the other. But you should know that as you go through places that will look more and more familiar, you will eventually get to the place where you find yourself. And finding a copy of yourself is perhaps the strangest thing that can happen in an infinite universe.
As you continue, you will discover entire duplicates of the observable universe, with exact and inaccurate copies of you. What's next? Possibly an infinite number of duplicates of observable universes. You don't even have to drag in the multiverse to find them. These are repeating universes within our own infinite universe.
It is extremely important to answer the question whether the Universe is finite or infinite, because any of the answers will be mind-blowing. While astronomers do not know the answer. But do not lose hope.
