Mathematics in the Modern World GEC 14 Teachers CHAPTER 0 The Nature of Mathematics Mathematics may be undeniably commonplace in everyday life, yet it receives little to no appreciation from most students. Although it is a dreaded subject for many, it is required in university entrance examinations, in IQ tests during job applications and even in qualifying examinations for government service. This shows that aptitude in mathematics is seen as a key skill affecting our capabilities as students, employees or even in nation building. But is mathematics really as how many students would think it is – “Mental Abuse To Humans”? In this preliminary chapter, we wish to re-introduce and re-imagine mathematics in a different light. We will give emphasis on why mathematics is, instead, a useful tool to understand our everyday existence better. More particularly, at the end of this chapter, students are expected to: (1) Identify patterns in nature and regularities in the world; (2) Articulate the importance of mathematics in one’s life; (3) Argue about the nature of mathematics, what it is, how it is expressed, represented and used; and (4) Express appreciation for mathematics as a human endeavor. First Semester page 1 of 23 Mathematics in the Modern World 1 GEC 14 Teachers What is Mathematics? Do you love Mathematics? One can bet this question would most likely receive a big cringe and a loud “NO”. But it is said that “We can only love those which we understand.” Thus, in order to appreciate mathematics more, it is imperative that we understand first its very nature and learn what mathematics really is. If we Google the word mathematics, we can expect over half a billion of results. That is quite daunting to start with. Thus, let us just examine these three descriptions of mathematics: (1) “Mathematics is the science of numbers, quantities and shapes and the relations between them.” (Merriam-Webster Dictionary) (2) “Mathematics, developed by human mind and culture, is a formal system of thought for recognizing, classifying, and exploiting patterns.” (Ian Stewart,) (3) “Mathematics is the alphabet with which God has written the Universe.” (Galileo Galilei) The first description reveals how many of us, especially students, view mathematics – a purely technical and scientific field that only talks about First Semester page 2 of 23 Mathematics in the Modern World GEC 14 Teachers abstract notions such as numbers, measurements, shapes, as well as operations and relationships of these concepts. While it is true that mathematics tackles these notions, there is more to it that we missed to learn or our teacher may have missed to mention inside the classroom. We will see and discuss this in the next two descriptions. Ian Stewart, the author of the book “Nature’s Numbers”, implied that mathematics is invented. Just like the languages that we speak, mathematics is often viewed to be purely a product of human intellect, a means that we developed and consistently use in order to communicate, make sense and understand various phenomena happening around us. Being “manmade”, mathematics can therefore also be regarded as an art. Meanwhile, the great scientist Galileo Galilei believes otherwise. For him, mathematics is already existent in the universe way long before people first attempted to explore into it. That is, mathematics is EVERYWHERE as an integral part of nature and we, mankind, just discovered it. In particular, the patterns that are observable in living and non-living objects are already there even before we have detected and identified it as a regularity. What do you think, is mathematics DISCOVERED or INVENTED? We can sufficiently describe mathematics as follows: First Semester page 3 of 23 Mathematics in the Modern World GEC 14 Teachers (1) Mathematics is the study of patterns. Needless to say, mathematics includes the study of the existence and relationships of patterns in the universe we live in. The discovery of the value of π came from the observations on the ratios of the diameter and circumference of circles. Mathematical formulas such as Einstein’s E = mc2 and Pythagoras’s a2 + b2 = c2 also came about from recurrences in the relationship of energy with mass and speed of light, and of the three sides of right triangles, respectively. In fact, every mathematical formula describes a pattern of relationships governing the elements involved in that formula. We will discuss more of patterns in the succeeding part of this module. (2) Mathematics is a language. Using the layman’s terms and language to describe certain phenomena may be tedious and a bit of a challenge. In watching a Korean TV series, understanding the story will be difficult if there will be no subtitles. Imagine how it would be much easier if we speak Korean! Mathematics also plays the same role as the subtitles or the Korean language itself. We need to understand how equations are written, how operations are executed and applied, and how the observed patterns are analyzed and generalized. Indeed, mathematics is a universal language used to express and communicate our observations about the universe we live in. Later in this module, we will discuss certain rules of expressing mathematical sentences and phrases into symbols and the conventions in using definitions and variables in writing these mathematical expressions. (3) Mathematics is an art. Google defined art as “the expression or application of human creative skill and imagination ... producing works to be appreciated primarily for their beauty or emotional power”. Majority of published works in pure mathematics emanate from this characteristic of mathematics as an art. These outputs are conceptual ideas from the mind of the mathematician and may or may not find application in the physical world. A mathematician has an endless trail First Semester page 4 of 23 Mathematics in the Modern World GEC 14 Teachers of what-ifs, one idea branching out after another. This creative and imaginative feature of mathematics is what makes it all the more beautiful and worthy of appreciation. Also, we are unknowingly making use of mathematics in our aesthetics. The rule of thirds in photography, minimalism in fashion and symmetry in visual arts – all of these are certainly in the scope of mathematics. (4) Mathematics is a set of problem solving tools. We typically reach into our toolboxes whenever we need to fix or build something. Tools are certainly important in solving various problems that we encounter. If we need to make generalizations from a data set obtained from a certain population, we make use of statistical tools. If we need to build something with accuracy and precision, we need our measuring tools. If we need to create a computer program to make a process more convenient, we reach for our logical and computational tools. This role of mathematics as a tool primarily provides the greatest impacts and advantages to the general community. In solving certain problems, mathematics is helpful for organizing ideas, objects and data sets into a more meaningful form, for predicting possible outcomes of certain events that may affect our lives, and for controlling these outcomes so that the effects become more favorable to us. This is why it is very important for all of us to gain, enhance, and master our mathematical skills. (5) Mathematics is a process of thinking. Logical reasoning and critical thinking are characteristics of mathematical thought. They are most useful nowadays in the presence of the internet accompanied by “information explosion”, where contents in social media are quite overflowing, yet some remain unverified or are outright fake. Engaging in mathematics disciplines the mind to think rationally and analytically so as not to readily accept information presented to us without sound bases and irrefutable proofs. First Semester page 5 of 23 Mathematics in the Modern World GEC 14 Teachers Mathematics is indeed everywhere and for everybody. We need not be wary and get anxious in learning about and dealing with the mathematical variables x and y. All we need is to realize first that there is a significant reason why mathematics is inescapable and to see with wider eyes and open minds its importance in our everyday existence. 2 Mathematics: A Study of Patterns Patterns are regular, repeated and recurring forms or designs. When objects and phenomena occur in particular patterns, the observers are able to anticipate what they might see or what happens next as the pattern shows what may have come before. This is proven to be beneficial even to ancient civilizations. The regularity of the flooding of the Nile River enabled the Egyptians to time the planting of their crops. Navigators used the constellations and other astronomical patterns to arrive at their intended destinations. Development in medicine is backed by conducting repeated tests and observing recurring positive results. First Semester page 6 of 23 Mathematics in the Modern World GEC 14 Teachers Hence, patterns are important because they are used to analyze and solve problems, and help individuals in understanding the world better by predicting what comes next, imagining what came before, and estimating outcomes when some variables and conditions are changed. In this section, we will look into different patterns that we will most likely encounter everyday and in our mathematics sessions. 2.1 Geometric Patterns When we talk about patterns, what usually comes to mind first are visual arrangements of points, lines and shapes in space. These are called geometric patterns. A geometric pattern is a motif or design that depicts abstract shapes such as lines, polygons, and circles, and typically repeats like a wallpaper. The following pictures depict geometric patterns in our surroundings: First Semester page 7 of 23 Mathematics in the Modern World 2.1.1 GEC 14 Teachers Symmetry An important element in geometric pattern is symmetry. The word symmetry came from the Greek word symmetria which means “agreement in dimensions, due proportion, arrangement” and aptly so, it refers to “harmony, proportion and balance” when used in layman’s terms. However, symmetry may have specific usage in different fields. In natural sciences, symmetry may mean invariance and lack of change in a given physical system (physics) or may mean regularity in the body shapes of organisms (biology). In geometry, a shape is described as symmetric if the elements in the object are transformed through movements or rearrangements of these elements, but the overall shape remains unchanged. There are several types of symmetries according to the transformation in the object: (1) Reflectional Symmetry – also known as mirror symmetry, exists when we can draw a line separating two portions of the object which are mirror images of each other. First Semester page 8 of 23 Mathematics in the Modern World GEC 14 Teachers (2) Rotational Symmetry – observed when an object can be rotated about a fixed point and the shape of the object remain unchanged. First Semester page 9 of 23 Mathematics in the Modern World GEC 14 Teachers (3) Translational Symmetry – exists if every point of the object can be moved, or translated, on the space without changing its overall shape. (4) Scale Symmetry – also known as dilation, occurs when the object’s shape remain unchanged when it is expanded or contracted. First Semester page 10 of 23 Mathematics in the Modern World GEC 14 Teachers (5) Combined Types of Symmetry – when the object possesses two or more types of symmetries. Helical symmetry – occurs when the object undergoes translation and rotation at the same time; Glide reflection – occurs when a reflection is followed by a translation; and First Semester page 11 of 23 Mathematics in the Modern World GEC 14 Teachers Rotoreflection – occurs when the object undergoes rotation and reflection. Some geometric artworks made use a combination of these symmetric transformations. When an arrangement of shapes are in such a way that they are closely fitted together, especially of polygons in a repeated pattern without gaps or overlapping, what results is a tessellation. Common examples of tessellations can be seen in floor tiles and fabric patterns. First Semester page 12 of 23 Mathematics in the Modern World GEC 14 Teachers Fractals are infinitely complex patterns that are self-similar across different scales. They are created by repeating a simple process over and over in an ongoing feedback loop. It is a characteristic of a fractal that sections in different levels of the object resembles its overall shape; hence, it is sometimes classified under scale symmetry. Read more about tessellations and fractals by exploring the following web addresses: (1) http://www.funmaths.com/fun_math_projects/what_is_a_tessellation.htm (2) https://fractalfoundation.org/resources/what-are-fractals 2.2 Number Patterns In many cases, we can observe some patterns from an array of quantities or numbers. These patterns may be represented as number sequences or through mathematical equations. First Semester page 13 of 23 Mathematics in the Modern World 2.2.1 GEC 14 Teachers Sequences The patterns in numbers are often written as sequences. A number sequence is an infinite progression of numbers following a particular pattern usually called an “nth term formula” as it tells us the “form” of the specific number occupying the nth position (called the nth term) in the sequence. A number sequence may be represented by writing its first few terms separated by commas and followed by an ellipsis (...) when the pattern is quite obvious and is often denoted as a1 , a2 , a3 , ... where a1 is the first term, a2 is the second term and so on, or by writing its nth term formula inside a pair of braces usually denoted as { an }. Example 1. Consider the sequence 1, 4, 9, 16, 25, .... We can immediately detect that the first five terms of the sequence are squares of the numbers 1, 2, 3, 4 and 5, respectively. That is, a1 = 1 = 12 , a2 = 4 = 22 , a3 = 9 = 32 and so on. Thus, we can predict that the sixth term is a6 = 62 = 36. This pattern is equivalent to {n2 } in terms of its nth term formula. Example 2. In the sequence { n 2 +n 2 }, the first term a1 is obtained by having 12 + 1 n = 1. That is, a1 = 2 = 1. In the same manner, the 34th term of this 2 sequence is a34 = 34 2+34 = 595. First Semester page 14 of 23 Mathematics in the Modern World GEC 14 Teachers In some sequences, we need to determine first the preceding terms before we can compute for the next term. If the terms of the sequence depend on the values of the initial terms, this sequence is a recursively defined sequence. Take a look at the following example: Example 3. If { an } is the sequence where a1 = 1 and an = 2an−1 + 3, we will see that: a2 = 2a1 + 3 = 2(1) + 3 = 5, a3 = 2a2 + 3 = 2(5) + 3 = 13, a4 = 2a3 + 3 = 2(13) + 3 = 29, and so on. Here, we cannot determine a5 unless we compute for the value of a4 ;hence, this sequence is a recursively defined sequence. 2.2.2 Mathematical Formulas A mathematical formula is a generalization of relationships existing between different quantities. It is simply a fact or a sort of a rule that is typically represented using mathematical variables like x and y, and reR lational or operational symbols like =, ×, and . The previously given equations E = mc2 and a2 + b2 = c2 are some known examples introduced to us while learning physics and mathematics. But there are more examples of mathematical formulas that are used everyday even by common people (even those who say they hate maths!). Take a look at some of them in Example 4 and see if you can add more. First Semester page 15 of 23 Mathematics in the Modern World GEC 14 Teachers Example 4. Here are some mathematical formulas we use regularly (sometimes, unknowingly) in real-life situations: (1) I = Prt, where I is the simple interest for a loaned or invested amount, P is the principal amount, r is the interest rate and t is the duration of the loan or investment; (2) W = ( R p − R0 )C, where W is the amount of the monthly water bill, R p is the present month’s water meter reading, R0 is the previous month’s water meter reading and C is the cost of water per cubic meter; and m, d ≤ 4 km F (d) = , where F (d) is the amount m + add − 4 kme d > 4 km} in pesos of jeepney fare for a distance travelled d in kilometers, m is the minimum fare for the first four kilometers and a is the added amount per kilometer in excess of the 4 kilometers travelled. The function d x e is called the ceiling function, which returns the value of x if x is a whole number, and returns the next higher integer of x whenever x contains a decimal. In this case d4e = 4 and d4.2e = 5. Hence, if the minimum fare is Php 7.00 for the first four kilometers with additional Php 2.00 for every succeeding kilometer, and you travelled 6.3 km, then your fare will be computed as follows: First Semester page 16 of 23 Mathematics in the Modern World GEC 14 Teachers F (6.5 km) = Php7.00 + Php2.00(d6.3 − 4e) = Php7.00 + Php2.00(d2.3e) = Php7.00 + Php2.00 (3) = Php7.00 + Php6.00 = Php13.00. We must realize that even though numbers and mathematical formulas are abstract concepts, their applications extend to our day-to-day activities. In the next section, we will dig deeper into a more subtle but extremely delightful interconnection of mathematics and the patterns in nature. 3 Fibonacci Sequence and the Golden Ratio One of the most famous number sequences in mathematics is the Fibonacci sequence, named after the famous Italian mathematician Fibonacci, who was also known as Leonardo of Pisa. In this module, we adopt the special notation { Fn } for the Fibonacci sequence, where F1 = 1, F2 = 1 = Fn−1 + Fn−2 F3 = F2 + F1 = 1 + 1 = 2 F4 = F3 + F2 = 2 + 1 = 3 F5 = F4 + F3 = 3 + 2 = 5 .. . and Fn for n ≥ 3. That is, In this form, the Fibonacci sequence is recursively defined where first ten terms of the sequence are 1, 1, 2, 3, 5, 8, 13, 21, 34,and 55. Where can we observe this sequence? First Semester page 17 of 23 Mathematics in the Modern World 3.1 GEC 14 Teachers The Golden Spiral We will now observe the Fibonacci sequence in terms of squares. Take a square of side 1 unit (F1 ) and from this, extend a second square of side 1 unit (F2 ). Then, from the combined sides of the two squares, extend a third square of side 2 units (F3 ). It would look like this: From the combined sides of the second and third squares, extend another square of side 3 units (F4 ). Continuing in this manner, we can obtain a sequence of squares, called the Fibonacci squares, whose sides correspond to the terms of the Fibonacci sequence as can be seen in the following image: Now, in each square, draw an arc from one vertex to another using the side as the radius as follows: First Semester page 18 of 23 Mathematics in the Modern World GEC 14 Teachers This beautiful curve is called the golden spiral. This spiral can be observed aplenty in nature – in the minuteness of shells and fingerprints, in arrangement of petals and whorls of vines, and even up to the formation of typhoons and of galaxies. This apparent pattern speak of the handiwork shown in the masterpiece First Semester page 19 of 23 Mathematics in the Modern World GEC 14 Teachers of one perfect Divine Creator. 3.2 The Golden Ratio One important number derived from the Fibonacci sequence is the golden ratio. Recall the first few terms of the sequence { Fn }which are 1, 1, 2, 3, 5, 8, 13, 21, 34 and 55. Observe that if we divide compute for the ratio Fn /Fn−1 of two succeeding terms, we will get the following values: F2 /F1 = 1/1 = 1 F7 /F6 = 13/8 = 1.625 F3 /F2 = 2/1 = 2 F8 /F7 = 21/13 = 1.6153 F4 /F3 = 3/2 = 1.5 F9 /F8 = 34/21 = 1.6190 F5 /F4 = 5/3 = 1.6667 F10 /F9 = 55/34 = 1.6176 F6 /F5 = 8/5 = 1.6 F11 /F10 = 89/55 =1.6182 Continuing this process as n gets larger and larger, we will see that this ratio gets closer and closer to the value ϕ = 1.6180339887.... This value is known as the golden ratio. This constant exists when a line is divided into two parts A and B and then the longer part A when divided by the smaller part B is equal to the quotient when A + B is divided by A. This only happens when both of the ratios A/B and ( A + B)/A is equal to ϕ = 1.6180339887.... By using intermediate mathematical calculations, √ the value of ϕ is exactly given by ϕ = 1+ 5 2 . How then is this inconspic- uous number so significant and even more wondrous? The golden ratio is much prevalent in design and aesthetics. Artists and designers use this proportion to place objects into their design, although some may be unaware while they are doing so. Many famous ancient works of art contain this design element such as Leonardo da Vinci’s Mona Lisa and the Parthenon. Product logos are also deliberately crafted using the golden ratio. Women groom their eyebrows with this divine proportion in mind. First Semester page 20 of 23 Mathematics in the Modern World GEC 14 Teachers We need not look far to spot the existence of the golden ratio. The lengths of the bones in our arms seem to satisfy this proportion as well – from the phalanges, the carpals, up to the radius and ulna. First Semester page 21 of 23 Mathematics in the Modern World GEC 14 Teachers To learn more of the Fibonacci sequence, watch the videos found in the following web addresses: (1) Nature by Numbers by Cristobal Vila, https://www.youtube.com/watch?v=kkG (2) Gods Fingerprint – The Fibonacci Sequence - Golden Ratio and The Fractal Nature of Reality, https://www.youtube.com/watch?v=4VrcO6JaMrM (3) The Golden Ratio and Fibonacci Sequence in Music (feat. It’s Okay to be Smart), https://www.youtube.com/watch?v=9mozmHgg9Sk With this apparent link of mathematics and nature in the form of patterns, one cannot deny that mathematics is part of us, whether we like it or not. Opening our eyes to this exquisite interrelationship may be a good start to fully embrace and appreciate the significance of mathematics in our daily lives. It is therefore the goal – and the hope – of this course, GEC 14 Mathematics in the Modern World, to build up our understanding about the nature of mathematics and, at the same time, to make more vivid the presence of mathematics in nature in order to harness the full advantageous potential of mathematics into our existence. First Semester page 22 of 23