Who discovered the number Pi? History of computing. What is the number “Pi”, or how do mathematicians swear? The meaning of pi in physics

Math enthusiasts around the world eat a piece of pie every year on the fourteenth of March - after all, it is the day of Pi, the most famous irrational number. This date is directly related to the number whose first digits are 3.14. Pi is the ratio of the circumference of a circle to its diameter. Since it is irrational, it is impossible to write it as a fraction. This is an infinitely long number. It was discovered thousands of years ago and has been constantly studied since then, but does Pi still have any secrets? From ancient origins to an uncertain future, here are some of the most interesting facts about Pi.

Memorizing Pi

The record for memorizing decimal numbers belongs to Rajvir Meena from India, who managed to remember 70,000 digits - he set the record on March 21, 2015. Previously, the record holder was Chao Lu from China, who managed to remember 67,890 digits - this record was set in 2005. The unofficial record holder is Akira Haraguchi, who recorded himself on video repeating 100,000 digits in 2005 and recently published a video where he manages to remember 117,000 digits. The record would become official only if this video was recorded in the presence of a representative of the Guinness Book of Records, and without confirmation it remains only an impressive fact, but is not considered an achievement. Math enthusiasts love to memorize the number Pi. Many people use various mnemonic techniques, for example poetry, where the number of letters in each word matches the digits of Pi. Each language has its own versions of similar phrases that help you remember both the first few numbers and the whole hundred.

There is a Pi language

Mathematicians, passionate about literature, invented a dialect in which the number of letters in all words corresponds to the digits of Pi in exact order. Writer Mike Keith even wrote a book, Not a Wake, which is entirely written in Pi. Enthusiasts of such creativity write their works in full accordance with the number of letters and the meaning of numbers. This has no practical application, but is a fairly common and well-known phenomenon in the circles of enthusiastic scientists.

Exponential growth

Pi is an infinite number, so by definition people will never be able to establish the exact digits of this number. However, the number of decimal places has increased greatly since Pi was first used. The Babylonians also used it, but a fraction of three whole and one eighth was enough for them. The Chinese and the creators of the Old Testament were completely limited to three. By 1665, Sir Isaac Newton had calculated the 16 digits of Pi. By 1719, the French mathematician Tom Fante de Lagny had calculated 127 digits. The advent of computers has radically improved human knowledge of Pi. From 1949 to 1967, the number of digits known to man skyrocketed from 2,037 to 500,000. Not long ago, Peter Trueb, a scientist from Switzerland, was able to calculate 2.24 trillion digits of Pi! It took 105 days. Of course, this is not the limit. It is likely that with the development of technology it will be possible to establish an even more accurate figure - since Pi is infinite, there is simply no limit to accuracy, and only the technical features of computer technology can limit it.

Calculating Pi by hand

If you want to find the number yourself, you can use the old-fashioned technique - you will need a ruler, a jar and some string, or you can use a protractor and a pencil. The downside to using a can is that it needs to be round and accuracy will be determined by how well a person can wrap the rope around it. You can draw a circle with a protractor, but this also requires skill and precision, as an uneven circle can seriously distort your measurements. A more accurate method involves using geometry. Divide the circle into many segments, like a pizza into slices, and then calculate the length of a straight line that would turn each segment into an isosceles triangle. The sum of the sides will give the approximate number Pi. The more segments you use, the more accurate the number will be. Of course, in your calculations you will not be able to come close to the results of a computer, however, these simple experiments allow you to understand in more detail what the number Pi is and how it is used in mathematics.

Discovery of Pi

The ancient Babylonians knew about the existence of the number Pi already four thousand years ago. Babylonian tablets calculate Pi as 3.125, and an Egyptian mathematical papyrus shows the number 3.1605. In the Bible, Pi is given in the obsolete length of cubits, and the Greek mathematician Archimedes used the Pythagorean theorem, a geometric relationship between the length of the sides of a triangle and the area of ​​the figures inside and outside the circles, to describe Pi. Thus, we can say with confidence that Pi is one of the most ancient mathematical concepts, although the exact name of this number appeared relatively recently.

New look at Pi

Even before the number Pi began to be correlated with circles, mathematicians already had many ways to even name this number. For example, in ancient mathematics textbooks one can find a phrase in Latin that can be roughly translated as “the quantity that shows the length when the diameter is multiplied by it.” The irrational number became famous when the Swiss scientist Leonhard Euler used it in his work on trigonometry in 1737. However, the Greek symbol for Pi was still not used - this only happened in a book by a lesser-known mathematician, William Jones. He used it already in 1706, but it went unnoticed for a long time. Over time, scientists adopted this name, and now it is the most famous version of the name, although it was previously also called the Ludolf number.

Is Pi a normal number?

Pi is definitely a strange number, but how much does it follow normal mathematical laws? Scientists have already resolved many questions related to this irrational number, but some mysteries remain. For example, it is not known how often all the numbers are used - the numbers 0 to 9 should be used in equal proportion. However, statistics can be traced from the first trillions of digits, but due to the fact that the number is infinite, it is impossible to prove anything for sure. There are other problems that still elude scientists. It is possible that further development of science will help shed light on them, but at the moment it remains beyond the scope of human intelligence.

Pi sounds divine

Scientists cannot answer some questions about the number Pi, however, every year they understand its essence better and better. Already in the eighteenth century, the irrationality of this number was proven. In addition, the number has been proven to be transcendental. This means that there is no specific formula that allows you to calculate Pi using rational numbers.

Dissatisfaction with the number Pi

Many mathematicians are simply in love with Pi, but there are also those who believe that these numbers are not particularly significant. In addition, they claim that Tau, which is twice the size of Pi, is more convenient to use as an irrational number. Tau shows the relationship between circumference and radius, which some believe represents a more logical method of calculation. However, it is impossible to unambiguously determine anything in this matter, and one and the other number will always have supporters, both methods have the right to life, so this is just an interesting fact, and not a reason to think that you should not use the number Pi.

Doctor of Geological and Mineralogical Sciences, Candidate of Physical and Mathematical Sciences B. GOROBETS.

Graphs of the functions y = arcsin x, the inverse function y = sin x

Graph of the function y = arctan x, the inverse of the function y = tan x.

Normal distribution function (Gaussian distribution). The maximum of its graph corresponds to the most probable value of a random variable (for example, the length of an object measured with a ruler), and the degree of “spreading” of the curve depends on the parameters a and sigma.

The priests of Ancient Babylon calculated that the solar disk fits in the sky 180 times from dawn to sunset and introduced a new unit of measurement - a degree equal to its angular size.

The size of natural formations - sand dunes, hills and mountains - increases with each step by an average of 3.14 times.

Science and life // Illustrations

Science and life // Illustrations

The pendulum, swinging without friction or resistance, maintains a constant amplitude of oscillation. The appearance of resistance leads to exponential attenuation of oscillations.

In a very viscous medium, a deflected pendulum moves exponentially toward its equilibrium position.

The scales of pine cones and the curls of the shells of many mollusks are arranged in logarithmic spirals.

Science and life // Illustrations

Science and life // Illustrations

A logarithmic spiral intersects all rays emanating from point O at the same angles.

Probably, any applicant or student, when asked what numbers and e are, will answer: - this is a number equal to the ratio of the circumference to its diameter, and e is the base of natural logarithms. If asked to define these numbers more strictly and calculate them, students will give formulas:

e = 1 + 1/1! + 1/2! + 1/3! + ... 2.7183…

(remember that factorial n! =1 x 2x 3x… x n);

3(1+ 1/3x 2 3 + 1x 3/4x 5x 2 5 + .....) 3,14159…

(Newton's series is the last one, there are other series).

All this is true, but, as you know, numbers and e are included in many formulas in mathematics, physics, chemistry, biology, and also in economics. This means that they reflect some general laws of nature. Which ones exactly? The definitions of these numbers through series, despite their correctness and rigor, still leave a feeling of dissatisfaction. They are abstract and do not convey the connection of the numbers in question with the outside world through everyday experience. It is not possible to find answers to the question posed in the educational literature.

Meanwhile, it can be argued that the constant e is directly related to the homogeneity of space and time, and to the isotropy of space. Thus, they reflect the laws of conservation: the number e - energy and momentum (momentum), and the number - torque (momentum). Usually such unexpected statements cause surprise, although essentially, from the point of view of theoretical physics, there is nothing new in them. The deep meaning of these world constants remains terra incognita for schoolchildren, students and, apparently, even for the majority of teachers of mathematics and general physics, not to mention other areas of natural science and economics.

In the first year of a university, students can be baffled by, for example, a question: why, when integrating functions of type 1/(x 2 +1), does arctangent appear, and of type arcsine - circular trigonometric functions expressing the magnitude of the arc of a circle? In other words, where do the circles “come from” during integration and where do they then disappear during the inverse action - differentiating the arctangent and arcsine? It is unlikely that the derivation of the corresponding formulas for differentiation and integration will answer the question posed by itself.

Further, in the second year of university, when studying probability theory, the number appears in the formula for the law of normal distribution of random variables (see “Science and Life” No. 2, 1995); from it you can, for example, calculate the probability with which a coin will fall on the coat of arms any number of times with, say, 100 tosses. Where are the circles here? Does the shape of the coin really matter? No, the formula for probability is the same for a square coin. Indeed, these are not easy questions.

But the nature of the number e is useful for students of chemistry and materials science, biologists and economists to know more deeply. This will help them understand the kinetics of the decay of radioactive elements, saturation of solutions, wear and destruction of materials, proliferation of microbes, the effects of signals on the senses, processes of capital accumulation, etc. - an infinite number of phenomena in living and inanimate nature and human activity.

Number and spherical symmetry of space

First, we formulate the first main thesis, and then explain its meaning and consequences.

1. The number reflects the isotropy of the properties of the empty space of our Universe, their sameness in any direction. The law of conservation of torque is associated with the isotropy of space.

This leads to well-known consequences that are studied in high school.

Corollary 1. The length of the arc of a circle along which its radius fits is the natural arc and angular unit radian.

This unit is dimensionless. To find the number of radians in an arc of a circle, you need to measure its length and divide by the length of the radius of this circle. As we know, along any complete circle its radius is approximately 6.28 times. More precisely, the length of a full arc of a circle is 2 radians, and in any number systems and units of length. When the wheel was invented, it turned out to be the same among the Indians of America, the nomads of Asia, and the blacks of Africa. Only the units of arc measurement were different and conventional. Thus, our angular and arc degrees were introduced by the Babylonian priests, who considered that the disk of the Sun, located almost at the zenith, fits 180 times in the sky from dawn to sunset. 1 degree is 0.0175 rad or 1 rad is 57.3°. It can be argued that hypothetical alien civilizations would easily understand each other by exchanging a message in which the circle is divided into six parts “with a tail”; this would mean that the “negotiating partner” has already at least passed the stage of reinventing the wheel and knows what the number is.

Corollary 2. The purpose of trigonometric functions is to express the relationship between the arc and linear dimensions of objects, as well as between the spatial parameters of processes occurring in spherically symmetrical space.

From the above it is clear that the arguments of trigonometric functions are, in principle, dimensionless, like those of other types of functions, i.e. these are real numbers - points on the number axis that do not need degree notation.

Experience shows that schoolchildren, college and university students have difficulty getting used to dimensionless arguments for sine, tangent, etc. Not every applicant will be able to answer the question without a calculator what cos1 (approximately 0.5) or arctg / 3. The last example is especially confusing. It is often said that this is nonsense: “an arc whose arctangent is 60 o.” If we say this exactly, then the error will be in the unauthorized application of the degree measure to the argument of the function. And the correct answer is: arctg(3.14/3) arctg1 /4 3/4. Unfortunately, quite often applicants and students say that = 180 0, after which they have to correct them: in the decimal number system = 3.14…. But, of course, we can say that a radian is equal to 180 0.

Let us examine another non-trivial situation encountered in probability theory. It concerns the important formula for the probability of a random error (or the normal law of probability distribution), which includes the number. Using this formula, you can, for example, calculate the probability of a coin falling on the coat of arms 50 times with 100 tosses. So, where did the number in it come from? After all, no circles or circles seem to be visible there. But the point is that the coin falls randomly in a spherically symmetrical space, in all directions of which random fluctuations should be equally taken into account. Mathematicians do this by integrating over a circle and calculating the so-called Poisson integral, which is equal to and included in the specified probability formula. A clear illustration of such fluctuations is the example of shooting at a target under constant conditions. The holes on the target are scattered in a circle (!) with the highest density near the center of the target, and the probability of a hit can be calculated using the same formula containing the number .

Is number involved in natural structures?

Let's try to understand the phenomena, the causes of which are far from clear, but which, perhaps, were also not without number.

Domestic geographer V.V. Piotrovsky compared the average characteristic sizes of natural reliefs in the following series: sand riffle on shallows, dunes, hills, mountain systems of the Caucasus, Himalayas, etc. It turned out that the average increase in size is 3.14. A similar pattern seems to have been recently discovered in the topography of the Moon and Mars. Piotrovsky writes: “Tectonic structural forms that form in the earth’s crust and are expressed on its surface in the form of relief forms develop as a result of some general processes occurring in the body of the Earth; they are proportional to the size of the Earth.” Let us clarify - they are proportional to the ratio of its linear and arc dimensions.

The basis of these phenomena may be the so-called law of distribution of maxima of random series, or the “law of triplets”, formulated back in 1927 by E. E. Slutsky.

Statistically, according to the law of threes, sea coastal waves are formed, which the ancient Greeks knew. Every third wave is on average slightly higher than its neighbors. And in the series of these third maxima, every third one, in turn, is higher than its neighbors. This is how the famous ninth wave is formed. He is the peak of the "second rank period". Some scientists suggest that according to the law of triplets, fluctuations in solar, comet and meteorite activities also occur. The intervals between their maxima are nine to twelve years, or approximately 3 2 . According to Doctor of Biological Sciences G. Rosenberg, we can continue constructing time sequences as follows. The period of the third rank 3 3 corresponds to the interval between severe droughts, which averages 27-36 years; period 3 4 - cycle of secular solar activity (81-108 years); period 3 5 - glaciation cycles (243-324 years). The coincidences will become even better if we depart from the law of “pure” triplets and move on to powers of number. By the way, they are very easy to calculate, since 2 is almost equal to 10 (once in India the number was even defined as the root of 10). You can continue to adjust the cycles of geological epochs, periods and eras to whole powers of three (which is what G. Rosenberg does, in particular, in the collection “Eureka-88”, 1988) or the numbers 3.14. And you can always take wishful thinking with varying degrees of accuracy. (In connection with the adjustments, a mathematical joke comes to mind. Let us prove that odd numbers are prime numbers. Take: 1, 3, 5, 7, 9, 11, 13, etc., and 9 here is an experimental error.) And yet the idea of ​​the unobvious role of the number p in many geological and biological phenomena seems to be not entirely empty, and perhaps it will manifest itself in the future.

The number e and the homogeneity of time and space

Now let's move on to the second great world constant - the number e. The mathematically flawless determination of the number e using the series given above, in essence, does not in any way clarify its connection with physical or other natural phenomena. How to approach this problem? The question is not easy. Let's start, perhaps, with the standard phenomenon of the propagation of electromagnetic waves in a vacuum. (Moreover, we will understand vacuum as classical empty space, without touching on the most complex nature of physical vacuum.)

Everyone knows that a continuous wave in time can be described by a sine wave or the sum of sine and cosine waves. In mathematics, physics, and electrical engineering, such a wave (with an amplitude equal to 1) is described by the exponential function e iβt =cos βt + isin βt, where β is the frequency of harmonic oscillations. One of the most famous mathematical formulas is written here - Euler's formula. It was in honor of the great Leonhard Euler (1707-1783) that the number e was named after the first letter of his last name.

This formula is well known to students, but it needs to be explained to students of non-mathematical schools, because complex numbers are excluded from regular school curricula in our time. The complex number z = x+iy consists of two terms - the real number (x) and the imaginary number, which is the real number y multiplied by the imaginary unit. Real numbers are counted along the real axis O x, and imaginary numbers are counted on the same scale along the imaginary axis O y, the unit of which is i, and the length of this unit segment is the modulus | i | =1. Therefore, a complex number corresponds to a point on the plane with coordinates (x, y). So, the unusual form of the number e with an exponent containing only imaginary units i means the presence of only undamped oscillations described by a cosine and sine wave.

It is clear that an undamped wave demonstrates compliance with the law of conservation of energy for an electromagnetic wave in a vacuum. This situation occurs during the “elastic” interaction of a wave with a medium without loss of its energy. Formally, this can be expressed as follows: if you move the reference point along the time axis, the energy of the wave will be preserved, since the harmonic wave will retain the same amplitude and frequency, that is, energy units, and only its phase, the part of the period distant from the new reference point, will change. But the phase does not affect the energy precisely because of the uniformity of time when the reference point is shifted. So, parallel transfer of the coordinate system (it is called translation) is legal due to the homogeneity of time t. Now, it is probably clear in principle why homogeneity in time leads to the law of conservation of energy.

Next, let's imagine a wave not in time, but in space. A good example of this is a standing wave (oscillations of a string stationary at several nodes) or coastal sand ripples. Mathematically, this wave along the O x axis will be written as e ix = cos x + isin x. It is clear that in this case, translation along x will not change either the cosine or sinusoid if the space is homogeneous along this axis. Again, only their phase will change. It is known from theoretical physics that the homogeneity of space leads to the law of conservation of momentum (momentum), that is, mass multiplied by speed. Let now space be homogeneous in time (and the law of conservation of energy is satisfied), but inhomogeneous in coordinate. Then, at different points of inhomogeneous space, the speed would also be different, since per unit of homogeneous time there would be different values ​​of the length of the segments covered per second by a particle with a given mass (or a wave with a given momentum).

So, we can formulate the second main thesis:

2. The number e as the basis of a function of a complex variable reflects two basic laws of conservation: energy - through the homogeneity of time, momentum - through the homogeneity of space.

And yet, why exactly the number e, and not some other, was included in Euler’s formula and turned out to be at the base of the wave function? Staying within the framework of school courses in mathematics and physics, it is not easy to answer this question. The author discussed this problem with the theorist, Doctor of Physical and Mathematical Sciences V.D. Efros, and we tried to explain the situation as follows.

The most important class of processes - linear and linearized processes - retains its linearity precisely due to the homogeneity of space and time. Mathematically, a linear process is described by a function that serves as a solution to a differential equation with constant coefficients (this type of equations is studied in the first and second years of universities and colleges). And its core is the above Euler formula. So the solution contains a complex function with base e, just like the wave equation. Moreover, it is e, and not another number in the base of the degree! Because only the function ex does not change for any number of differentiations and integrations. And therefore, after substitution into the original equation, only the solution with the base e will give an identity, as a correct solution should.

Now let’s write down the solution to the differential equation with constant coefficients, which describes the propagation of a harmonic wave in a medium, taking into account the inelastic interaction with it, leading to the dissipation of energy or the acquisition of energy from external sources:

f(t) = e (α+ib)t = e αt (cos βt + isin βt).

We see that Euler's formula is multiplied by a real variable e αt, which is the amplitude of the wave changing over time. Above, for simplicity, we assumed it to be constant and equal to 1. This can be done in the case of undamped harmonic oscillations, with α = 0. In the general case of any wave, the behavior of the amplitude depends on the sign of the coefficient a with the variable t (time): if α > 0, the amplitude of oscillations increases if α< 0, затухает по экспоненте.

Perhaps the last paragraph is difficult for graduates of many ordinary schools. It, however, should be understandable to students of universities and colleges who thoroughly study differential equations with constant coefficients.

Now let’s set β = 0, that is, we will destroy the oscillatory factor with number i in the solution containing Euler’s formula. From the former oscillations, only the “amplitude” that decays (or grows) exponentially will remain.

To illustrate both cases, imagine a pendulum. In empty space it oscillates without damping. In space with a resistive medium, oscillations occur with exponential decay in amplitude. If you deflect a not too massive pendulum in a sufficiently viscous medium, then it will smoothly move towards the equilibrium position, slowing down more and more.

So, from thesis 2 we can deduce the following corollary:

Corollary 1. In the absence of an imaginary, purely vibrational part of the function f(t), at β = 0 (that is, at zero frequency), the real part of the exponential function describes many natural processes that proceed in accordance with the fundamental principle: the increase in value is proportional to the value itself .

The formulated principle mathematically looks like this: ∆I ~ I∆t, where, let’s say, I is a signal, and ∆t is a small time interval during which the signal ∆I increases. Dividing both sides of the equality by I and integrating, we obtain lnI ~ kt. Or: I ~ e kt - the law of exponential increase or decrease of the signal (depending on the sign of k). Thus, the law of proportionality of the increase in a value to the value itself leads to a natural logarithm and thereby to the number e. (And here this is shown in a form accessible to high school students who know the elements of integration.)

Many processes proceed exponentially with a valid argument, without hesitation, in physics, chemistry, biology, ecology, economics, etc. We especially note the universal psychophysical law of Weber - Fechner (for some reason ignored in the educational programs of schools and universities). It reads: “The strength of sensation is proportional to the logarithm of the strength of stimulation.”

Vision, hearing, smell, touch, taste, emotions, and memory are subject to this law (naturally, until physiological processes abruptly turn into pathological ones, when the receptors have undergone modification or destruction). According to the law: 1) a small increase in the irritation signal in any interval corresponds to a linear increase (with a plus or minus) in the strength of sensation; 2) in the area of ​​weak irritation signals, the increase in the strength of sensation is much steeper than in the area of ​​strong signals. Let's take tea as an example: a glass of tea with two pieces of sugar is perceived as twice as sweet as tea with one piece of sugar; but tea with 20 pieces of sugar is unlikely to seem noticeably sweeter than with 10 pieces. The dynamic range of biological receptors is colossal: signals received by the eye can vary in strength by ~ 10 10 , and by the ear - by ~ 10 12 times. Wildlife has adapted to such ranges. It protects itself by taking a logarithm (by biological limitation) of incoming stimuli, otherwise the receptors would die. The widely used logarithmic (decibel) sound intensity scale is based on the Weber-Fechner law, in accordance with which the volume controls of audio equipment operate: their displacement is proportional to the perceived volume, but not to the sound intensity! (The sensation is proportional to lg/ 0. The threshold of audibility is taken to be p 0 = 10 -12 J/m 2 s. At the threshold we have lg1 = 0. An increase in the strength (pressure) of sound by 10 times corresponds approximately to the sensation of a whisper, which is 1 bel above the threshold on a logarithmic scale. Sound amplification a million times from a whisper to a scream (up to 10 -5 J/m 2 s) on a logarithmic scale is an increase of 6 orders of magnitude or 6 Bel.)

Probably, such a principle is optimally economical for the development of many organisms. This can be clearly observed in the formation of logarithmic spirals in mollusk shells, rows of seeds in a sunflower basket, and scales in cones. The distance from the center increases according to the law r = ae kj. At each moment, the growth rate is linearly proportional to this distance itself (which is easy to see if we take the derivative of the written function). The profiles of rotating knives and cutters are made in a logarithmic spiral.

Corollary 2. The presence of only the imaginary part of the function at α = 0, β 0 in the solution of differential equations with constant coefficients describes a variety of linear and linearized processes in which undamped harmonic oscillations take place.

This corollary brings us back to the model already discussed above.

Corollary 3. When implementing Corollary 2, there is a “closing” in a single formula of numbers and e through Euler’s historical formula in its original form e i = -1.

In this form, Euler first published his exponent with an imaginary exponent. It is not difficult to express it through the cosine and sine on the left side. Then the geometric model of this formula will be motion in a circle with a speed constant in absolute value, which is the sum of two harmonic oscillations. According to the physical essence, the formula and its model reflect all three fundamental properties of space-time - their homogeneity and isotropy, and thereby all three conservation laws.

Conclusion

The thesis about the connection of conservation laws with the homogeneity of time and space is undoubtedly correct for Euclidean space in classical physics and for the pseudo-Euclidean Minkowski space in the General Theory of Relativity (GR, where time is the fourth coordinate). But within the framework of general relativity, a natural question arises: what is the situation in regions of huge gravitational fields, near singularities, in particular, near black holes? Physicists have differing opinions here: most believe that these fundamental principles remain true under these extreme conditions. However, there are other points of view of authoritative researchers. Both are working on creating a new theory of quantum gravity.

To briefly imagine what problems arise here, let us quote the words of theoretical physicist Academician A. A. Logunov: “It (Minkowski space. - Auto.) reflects properties common to all forms of matter. This ensures the existence of unified physical characteristics - energy, momentum, angular momentum, laws of conservation of energy, momentum. But Einstein argued that this is possible only under one condition - in the absence of gravity<...>. From this statement of Einstein it followed that space-time becomes not pseudo-Euclidean, but much more complex in its geometry - Riemannian. The latter is no longer homogeneous. It changes from point to point. The property of space curvature appears. The exact formulation of conservation laws, as they were accepted in classical physics, also disappears in it.<...>Strictly speaking, in general relativity, in principle, it is impossible to introduce the laws of conservation of energy-momentum; they cannot be formulated" (see "Science and Life" No. 2, 3, 1987).

The fundamental constants of our world, the nature of which we talked about, are known not only to physicists, but also to lyricists. Thus, the irrational number equal to 3.14159265358979323846... inspired the outstanding Polish poet of the twentieth century, Nobel Prize winner in 1996 Wisława Szymborska, to create the poem “Pi,” with a quote from which we will end these notes:

A number worthy of admiration:
Three comma one four one.
Each number gives a feeling
start - five nine two,
because you will never reach the end.
You can’t grasp all the numbers at a glance -
six five three five.
Arithmetic operations -
eight nine -
is no longer enough, and it’s hard to believe -
seven nine -
that you can’t get away with it - three two three
eight -
nor an equation that does not exist,
not a joking comparison -
you can't count them.
Let's move on: four six...
(Translation from Polish - B. G.)

What is Pi equal to? we know and remember from school. It is equal to 3.1415926 and so on... It is enough for an ordinary person to know that this number is obtained by dividing the circumference of a circle by its diameter. But many people know that the number Pi appears in unexpected areas not only of mathematics and geometry, but also in physics. Well, if you delve into the details of the nature of this number, you will notice many surprising things among the endless series of numbers. Is it possible that Pi is hiding the deepest secrets of the universe?

Infinite number

The number Pi itself appears in our world as the length of a circle whose diameter is equal to one. But, despite the fact that the segment equal to Pi is quite finite, the number Pi begins as 3.1415926 and goes to infinity in rows of numbers that are never repeated. The first surprising fact is that this number, used in geometry, cannot be expressed as a fraction of whole numbers. In other words, you cannot write it as the ratio of two numbers a/b. In addition, the number Pi is transcendental. This means that there is no equation (polynomial) with integer coefficients whose solution would be the number Pi.

The fact that the number Pi is transcendental was proved in 1882 by the German mathematician von Lindemann. It was this proof that became the answer to the question of whether it is possible, using a compass and a ruler, to draw a square whose area is equal to the area of ​​a given circle. This problem is known as the search for squaring a circle, which has worried humanity since ancient times. It seemed that this problem had a simple solution and was about to be solved. But it was precisely the incomprehensible property of the number Pi that showed that there was no solution to the problem of squaring the circle.

For at least four and a half millennia, humanity has been trying to obtain an increasingly accurate value for Pi. For example, in the Bible in the Third Book of Kings (7:23), the number Pi is taken to be 3.

The Pi value of remarkable accuracy can be found in the Giza pyramids: the ratio of the perimeter and height of the pyramids is 22/7. This fraction gives an approximate value of Pi equal to 3.142... Unless, of course, the Egyptians set this ratio by accident. The same value was already obtained in relation to the calculation of the number Pi in the 3rd century BC by the great Archimedes.

In the Papyrus of Ahmes, an ancient Egyptian mathematics textbook that dates back to 1650 BC, Pi is calculated as 3.160493827.

In ancient Indian texts around the 9th century BC, the most accurate value was expressed by the number 339/108, which was equal to 3.1388...

For almost two thousand years after Archimedes, people tried to find ways to calculate Pi. Among them were both famous and unknown mathematicians. For example, the Roman architect Marcus Vitruvius Pollio, the Egyptian astronomer Claudius Ptolemy, the Chinese mathematician Liu Hui, the Indian sage Aryabhata, the medieval mathematician Leonardo of Pisa, known as Fibonacci, the Arab scientist Al-Khwarizmi, from whose name the word “algorithm” appeared. All of them and many other people were looking for the most accurate methods for calculating Pi, but until the 15th century they never got more than 10 decimal places due to the complexity of the calculations.

Finally, in 1400, the Indian mathematician Madhava from Sangamagram calculated Pi with an accuracy of 13 digits (although he was still mistaken in the last two).

Number of signs

In the 17th century, Leibniz and Newton discovered the analysis of infinitesimal quantities, which made it possible to calculate Pi more progressively - through power series and integrals. Newton himself calculated 16 decimal places, but did not mention it in his books - this became known after his death. Newton claimed that he calculated Pi purely out of boredom.

Around the same time, other lesser-known mathematicians also came forward and proposed new formulas for calculating the number Pi through trigonometric functions.

For example, this is the formula used to calculate Pi by astronomy teacher John Machin in 1706: PI / 4 = 4arctg(1/5) – arctg(1/239). Using analytical methods, Machin derived the number Pi to one hundred decimal places from this formula.

By the way, in the same 1706, the number Pi received an official designation in the form of a Greek letter: William Jones used it in his work on mathematics, taking the first letter of the Greek word “periphery,” which means “circle.” The great Leonhard Euler, born in 1707, popularized this designation, now known to any schoolchild.

Before the era of computers, mathematicians focused on calculating as many signs as possible. In this regard, sometimes funny things arose. Amateur mathematician W. Shanks calculated 707 digits of Pi in 1875. These seven hundred signs were immortalized on the wall of the Palais des Discoverys in Paris in 1937. However, nine years later, observant mathematicians discovered that only the first 527 characters were correctly calculated. The museum had to incur significant expenses to correct the error - now all the figures are correct.

When computers appeared, the number of digits of Pi began to be calculated in completely unimaginable orders.

One of the first electronic computers, ENIAC, created in 1946, was enormous in size and generated so much heat that the room warmed up to 50 degrees Celsius, calculated the first 2037 digits of Pi. This calculation took the machine 70 hours.

As computers improved, our knowledge of Pi moved further and further into infinity. In 1958, 10 thousand digits of the number were calculated. In 1987, the Japanese calculated 10,013,395 characters. In 2011, Japanese researcher Shigeru Hondo exceeded the 10 trillion character mark.

Where else can you meet Pi?

So, often our knowledge about the number Pi remains at the school level, and we know for sure that this number is irreplaceable primarily in geometry.

In addition to formulas for the length and area of ​​a circle, the number Pi is used in formulas for ellipses, spheres, cones, cylinders, ellipsoids, and so on: in some places the formulas are simple and easy to remember, but in others they contain very complex integrals.

Then we can meet the number Pi in mathematical formulas, where, at first glance, geometry is not visible. For example, the indefinite integral of 1/(1-x^2) is equal to Pi.

Pi is often used in series analysis. For example, here is a simple series that converges to Pi:

1/1 – 1/3 + 1/5 – 1/7 + 1/9 – …. = PI/4

Among the series, Pi appears most unexpectedly in the famous Riemann zeta function. It’s impossible to talk about it in a nutshell, let’s just say that someday the number Pi will help find a formula for calculating prime numbers.

And absolutely surprisingly: Pi appears in two of the most beautiful “royal” formulas of mathematics - Stirling’s formula (which helps to find the approximate value of the factorial and gamma function) and Euler’s formula (which connects as many as five mathematical constants).

However, the most unexpected discovery awaited mathematicians in probability theory. The number Pi is also there.

For example, the probability that two numbers will be relatively prime is 6/PI^2.

Pi appears in Buffon's needle-throwing problem, formulated in the 18th century: what is the probability that a needle thrown onto a lined piece of paper will cross one of the lines. If the length of the needle is L, and the distance between the lines is L, and r > L, then we can approximately calculate the value of Pi using the probability formula 2L/rPI. Just imagine - we can get Pi from random events. And by the way, Pi is present in the normal probability distribution, appears in the equation of the famous Gaussian curve. Does this mean that Pi is even more fundamental than simply the ratio of circumference to diameter?

We can also meet Pi in physics. Pi appears in Coulomb's law, which describes the force of interaction between two charges, in Kepler's third law, which shows the period of revolution of a planet around the Sun, and even appears in the arrangement of the electron orbitals of the hydrogen atom. And what is again most incredible is that the number Pi is hidden in the formula of the Heisenberg uncertainty principle - the fundamental law of quantum physics.

Secrets of Pi

In Carl Sagan's novel Contact, on which the film of the same name is based, aliens tell the heroine that among the signs of Pi there is a secret message from God. From a certain position, the numbers in the number cease to be random and represent a code in which all the secrets of the Universe are written.

This novel actually reflected a mystery that has occupied the minds of mathematicians all over the world: is Pi a normal number in which the digits are scattered with equal frequency, or is there something wrong with this number? And although scientists are inclined to the first option (but cannot prove it), the number Pi looks very mysterious. A Japanese man once calculated how many times the numbers 0 to 9 occur in the first trillion digits of Pi. And I saw that the numbers 2, 4 and 8 were more common than the others. This may be one of the hints that Pi is not entirely normal, and the numbers in it are indeed not random.

Let's remember everything we read above and ask ourselves, what other irrational and transcendental number is so often found in the real world?

And there are more oddities in store. For example, the sum of the first twenty digits of Pi is 20, and the sum of the first 144 digits is equal to the “number of the beast” 666.

The main character of the American TV series “Suspect,” Professor Finch, told students that due to the infinity of the number Pi, any combination of numbers can be found in it, ranging from the numbers of your date of birth to more complex numbers. For example, at position 762 there is a sequence of six nines. This position is called the Feynman point after the famous physicist who noticed this interesting combination.

We also know that the number Pi contains the sequence 0123456789, but it is located at the 17,387,594,880th digit.

All this means that in the infinity of the number Pi one can find not only interesting combinations of numbers, but also the encoded text of “War and Peace”, the Bible and even the Main Secret of the Universe, if such exists.

By the way, about the Bible. The famous popularizer of mathematics, Martin Gardner, stated in 1966 that the millionth digit of Pi (at that time still unknown) would be the number 5. He explained his calculations by the fact that in the English version of the Bible, in the 3rd book, 14th chapter, 16 verse (3-14-16) the seventh word contains five letters. The millionth figure was reached eight years later. It was the number five.

Is it worth asserting after this that the number Pi is random?

For many centuries and even, oddly enough, millennia, people have understood the importance and value for science of a mathematical constant equal to the ratio of the circumference of a circle to its diameter. the number Pi is still unknown, but the best mathematicians throughout our history have been involved with it. Most of them wanted to express it as a rational number.

1. Researchers and true fans of the number Pi have organized a club, to join which you need to know by heart a fairly large number of its signs.

2. Since 1988, “Pi Day” has been celebrated, which falls on March 14th. They prepare salads, cakes, cookies, and pastries with his image.

3. The number Pi has already been set to music, and it sounds quite good. A monument was even erected to him in Seattle, America, in front of the city Museum of Art.

At that distant time, they tried to calculate the number Pi using geometry. The fact that this number is constant for a wide variety of circles was known by geometers in Ancient Egypt, Babylon, India and Ancient Greece, who stated in their works that it was only a little more than three.

In one of the sacred books of Jainism (an ancient Indian religion that arose in the 6th century BC) it is mentioned that then the number Pi was considered equal to the square root of ten, which ultimately gives 3.162... .

Ancient Greek mathematicians measured a circle by constructing a segment, but in order to measure a circle, they had to construct an equal square, that is, a figure equal in area to it.

When decimal fractions were not yet known, the great Archimedes found the value of Pi with an accuracy of 99.9%. He discovered a method that became the basis for many subsequent calculations, inscribing regular polygons in a circle and describing it around it. As a result, Archimedes calculated the value of Pi as the ratio 22 / 7 ≈ 3.142857142857143.

In China, mathematician and court astronomer, Zu Chongzhi in the 5th century BC. e. designated a more precise value for Pi, calculating it to seven decimal places and determined its value between the numbers 3, 1415926 and 3.1415927. It took scientists more than 900 years to continue this digital series.

Middle Ages

The famous Indian scientist Madhava, who lived at the turn of the 14th - 15th centuries and became the founder of the Kerala school of astronomy and mathematics, for the first time in history began to work on the expansion of trigonometric functions into series. True, only two of his works have survived, and only references and quotes from his students are known for others. The scientific treatise "Mahajyanayana", which is attributed to Madhava, states that the number Pi is 3.14159265359. And in the treatise “Sadratnamala” a number is given with even more exact decimal places: 3.14159265358979324. In the given numbers, the last digits do not correspond to the correct value.

In the 15th century, the Samarkand mathematician and astronomer Al-Kashi calculated the number Pi with sixteen decimal places. His result was considered the most accurate for the next 250 years.

W. Johnson, a mathematician from England, was one of the first to denote the ratio of the circumference of a circle to its diameter by the letter π. Pi is the first letter of the Greek word "περιφέρεια" - circle. But this designation managed to become generally accepted only after it was used in 1736 by the more famous scientist L. Euler.

Conclusion

Modern scientists continue to work on further calculations of the values ​​of Pi. Supercomputers are already used for this. In 2011, a scientist from Shigeru Kondo, collaborating with an American student Alexander Yi, correctly calculated a sequence of 10 trillion digits. But it is still unclear who discovered the number Pi, who first thought about this problem and made the first calculations of this truly mystical number.

Studying Pi numbers begins in the elementary grades when students learn about the circle, circumference, and the value of Pi. Since the value of Pi is a constant meaning the ratio of the length of the circle itself to the length of the diameter of a given circle. For example, if we take a circle whose diameter is equal to one, then its length is equal to Pi number. This value of Pi is infinite in mathematical continuation, but there is also a generally accepted designation. It comes from a simplified spelling of the value of Pi, it looks like 3.14.

The Historical Birth of Pi

The number Pi supposedly got its roots in Ancient Egypt. Since ancient Egyptian scientists calculated the area of ​​a circle using diameter D, which took the value D - D/92. Which corresponded to 16/92, or 256/81, which means Pi is 3.160.
India in the sixth century BC also touched on the number Pi, in the religion of Jainism, records were found that stated that the number Pi is equal to 10 in the square root, which means 3.162.

Archimedes' teachings on the measurement of the circle in the third century BC led him to the following conclusions:

Later, he substantiated his conclusions by a sequence of calculations using examples of correctly inscribed or described polygonal shapes with doubling the number of sides of these figures. In precise calculations, Archimedes concluded the ratio of diameter and circumference in numbers between 3 * 10/71 and 3 * 1/7, therefore the value of Pi is 3.1419... Since we have already talked about the infinite form of this value, it looks like 3, 1415927... And this is not the limit, because the mathematician Kashi in the fifteenth century calculated the value of Pi as a sixteen-digit value.
English mathematician Johnson W. in 1706, began to use the symbol pi for the symbol? (from Greek it is the first letter in the word circle).

Mysterious meaning.

The value of Pi is irrational and cannot be expressed in fraction form because fractions use whole values. It cannot be a root in the equation, which is why it also turns out to be transcendental; it is found by considering any processes, being refined due to the large number of considered steps of a given process. There have been many attempts to calculate the largest number of decimal places in Pi, which have resulted in tens of trillions of digits of a given decimal value.

Interesting fact: Oddly enough, the value of Pi has its own holiday. It is called International Pi Day. It is celebrated on March 14th. The date appeared thanks to the very value of Pi 3.14 (mm.yy) and the physicist Larry Shaw, who was the first to celebrate this holiday in 1987.

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