From One to Many Geometries Transcript
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Thales of Miletus Sources and Interpretations Miletli Thales Kaynaklar Ve Yorumlar
Thales of Miletus Sources and Interpretations Miletli Thales Kaynaklar ve Yorumlar David Pierce October , Matematics Department Mimar Sinan Fine Arts University Istanbul http://mat.msgsu.edu.tr/~dpierce/ Preface Here are notes of what I have been able to find or figure out about Thales of Miletus. They may be useful for anybody interested in Thales. They are not an essay, though they may lead to one. I focus mainly on the ancient sources that we have, and on the mathematics of Thales. I began this work in preparation to give one of several - minute talks at the Thales Meeting (Thales Buluşması) at the ruins of Miletus, now Milet, September , . The talks were in Turkish; the audience were from the general popu- lation. I chose for my title “Thales as the originator of the concept of proof” (Kanıt kavramının öncüsü olarak Thales). An English draft is in an appendix. The Thales Meeting was arranged by the Tourism Research Society (Turizm Araştırmaları Derneği, TURAD) and the office of the mayor of Didim. Part of Aydın province, the district of Didim encompasses the ancient cities of Priene and Miletus, along with the temple of Didyma. The temple was linked to Miletus, and Herodotus refers to it under the name of the family of priests, the Branchidae. I first visited Priene, Didyma, and Miletus in , when teaching at the Nesin Mathematics Village in Şirince, Selçuk, İzmir. The district of Selçuk contains also the ruins of Eph- esus, home town of Heraclitus. In , I drafted my Miletus talk in the Math Village. Since then, I have edited and added to these notes. -
Euclid's Error: Non-Euclidean Geometries Present in Nature And
International Journal for Cross-Disciplinary Subjects in Education (IJCDSE), Volume 1, Issue 4, December 2010 Euclid’s Error: Non-Euclidean Geometries Present in Nature and Art, Absent in Non-Higher and Higher Education Cristina Alexandra Sousa Universidade Portucalense Infante D. Henrique, Portugal Abstract This analysis begins with an historical view of surfaces, we are faced with the impossibility of Geometry. One presents the evolution of Geometry solving problems through the same geometry. (commonly known as Euclidean Geometry) since its Unlike what happens with the initial four beginning until Euclid’s Postulates. Next, new postulates of Euclid, the Fifth Postulate, the famous geometric worlds beyond the Fifth Postulate are Parallel Postulate, revealed a lack intuitive appeal, presented, discovered by the forerunners of the Non- and several were the mathematicians who, Euclidean Geometries, as a result of the flaw that throughout history, tried to show it. Many retreated many mathematicians encountered when they before the findings that this would be untrue, some attempted to prove Euclid’s Fifth Postulate (the had the courage and determination to make such a Parallel Postulate). Unlike what happens with the falsehood, thus opening new doors to Geometry. initial four Postulates of Euclid, the Fifth Postulate One puts up, then, two questions. Where can be revealed a lack of intuitive appeal, and several were found the clear concepts of such Geometries? And the mathematicians who, throughout history, tried to how important is the knowledge and study of show it. Geometries, beyond the Euclidean, to a better understanding of the world around us? The study, After this brief perspective, a reflection is made now developed, seeks to answer these questions. -
Sebastian's Space and Forms
GENERAL ARTICLE Sebastian’s Space and Forms Michele eMMer A strong message that mathematics revealed in the late nineteenth and non-Euclidean hyperbolic geometry) “imaginary geometry,” the early twentieth centuries is that geometry and space can be the because it was in such strong contrast with common sense. realm of freedom and imagination, abstraction and rigor. An example For some years non-Euclidean geometry remained marginal of this message lies in the infi nite variety of forms of mathematical AbStrAct inspiration that the Mexican sculptor Sebastian invented, rediscovered to the fi eld, a sort of unusual and curious genre, until it was and used throughout all his artistic activity. incorporated into and became an integral part of mathema- tics through the general ideas of G.F.B. Riemann (1826–1866). Riemann described a global vision of geometry as the study of intellectUAl ScAndAl varieties of any dimension in any kind of space. According to At the beginning of the twentieth century, Robert Musil re- Riemann, geometry had to deal not necessarily with points or fl ected on the role of mathematics in his short essay “Th e space in the traditional sense but with sets of ordered n-ples. Mathematical Man,” writing that mathematics is an ideal in- Th e erlangen Program of Felix Klein (1849–1925) descri- tellectual apparatus whose task is to anticipate every possible bed geometry as the study of the properties of fi gures that case. Only when one looks not toward its possible utility, were invariant with respect to a particular group of transfor- but within mathematics itself one sees the real face of this mations. -
Neutral Geometry
Neutral geometry And then we add Euclid’s parallel postulate Saccheri’s dilemma Options are: Summit angles are right Wants Summit angles are obtuse Was able to rule out, and we’ll see how Summit angles are acute The hypothesis of the acute angle is absolutely false, because it is repugnant to the nature of the straight line! Rule out obtuse angles: If we knew that a quadrilateral can’t have the sum of interior angles bigger than 360, we’d be fine. We’d know that if we knew that a triangle can’t have the sum of interior angles bigger than 180. Hold on! Isn’t the sum of the interior angles of a triangle EXACTLY180? Theorem: Angle sum of any triangle is less than or equal to 180º Suppose there is a triangle with angle sum greater than 180º, say anglfle sum of ABC i s 180º + p, w here p> 0. Goal: Construct a triangle that has the same angle sum, but one of its angles is smaller than p. Why is that enough? We would have that the remaining two angles add up to more than 180º: can that happen? Show that any two angles in a triangle add up to less than 180º. What do we know if we don’t have Para lle l Pos tul at e??? Alternate Interior Angle Theorem: If two lines cut by a transversal have a pair of congruent alternate interior angles, then the two lines are parallel. Converse of AIA Converse of AIA theorem: If two lines are parallel then the aliilblternate interior angles cut by a transversa l are congruent. -
Geometry by Its History
Undergraduate Texts in Mathematics Geometry by Its History Bearbeitet von Alexander Ostermann, Gerhard Wanner 1. Auflage 2012. Buch. xii, 440 S. Hardcover ISBN 978 3 642 29162 3 Format (B x L): 15,5 x 23,5 cm Gewicht: 836 g Weitere Fachgebiete > Mathematik > Geometrie > Elementare Geometrie: Allgemeines Zu Inhaltsverzeichnis schnell und portofrei erhältlich bei Die Online-Fachbuchhandlung beck-shop.de ist spezialisiert auf Fachbücher, insbesondere Recht, Steuern und Wirtschaft. Im Sortiment finden Sie alle Medien (Bücher, Zeitschriften, CDs, eBooks, etc.) aller Verlage. Ergänzt wird das Programm durch Services wie Neuerscheinungsdienst oder Zusammenstellungen von Büchern zu Sonderpreisen. Der Shop führt mehr als 8 Millionen Produkte. 2 The Elements of Euclid “At age eleven, I began Euclid, with my brother as my tutor. This was one of the greatest events of my life, as dazzling as first love. I had not imagined that there was anything as delicious in the world.” (B. Russell, quoted from K. Hoechsmann, Editorial, π in the Sky, Issue 9, Dec. 2005. A few paragraphs later K. H. added: An innocent look at a page of contemporary the- orems is no doubt less likely to evoke feelings of “first love”.) “At the age of 16, Abel’s genius suddenly became apparent. Mr. Holmbo¨e, then professor in his school, gave him private lessons. Having quickly absorbed the Elements, he went through the In- troductio and the Institutiones calculi differentialis and integralis of Euler. From here on, he progressed alone.” (Obituary for Abel by Crelle, J. Reine Angew. Math. 4 (1829) p. 402; transl. from the French) “The year 1868 must be characterised as [Sophus Lie’s] break- through year. -
Euclid Transcript
Euclid Transcript Date: Wednesday, 16 January 2002 - 12:00AM Location: Barnard's Inn Hall Euclid Professor Robin Wilson In this sequence of lectures I want to look at three great mathematicians that may or may not be familiar to you. We all know the story of Isaac Newton and the apple, but why was it so important? What was his major work (the Principia Mathematica) about, what difficulties did it raise, and how were they resolved? Was Newton really the first to discover the calculus, and what else did he do? That is next time a fortnight today and in the third lecture I will be talking about Leonhard Euler, the most prolific mathematician of all time. Well-known to mathematicians, yet largely unknown to anyone else even though he is the mathematical equivalent of the Enlightenment composer Haydn. Today, in the immortal words of Casablanca, here's looking at Euclid author of the Elements, the best-selling mathematics book of all time, having been used for more than 2000 years indeed, it is quite possibly the most printed book ever, apart than the Bible. Who was Euclid, and why did his writings have such influence? What does the Elements contain, and why did one feature of it cause so much difficulty over the years? Much has been written about the Elements. As the philosopher Immanuel Kant observed: There is no book in metaphysics such as we have in mathematics. If you want to know what mathematics is, just look at Euclid's Elements. The Victorian mathematician Augustus De Morgan, of whom I told you last October, said: The thirteen books of Euclid must have been a tremendous advance, probably even greater than that contained in the Principia of Newton. -
Equivalents to the Euclidean Parallel Postulate in This Section We Work
Equivalents to the Euclidean Parallel Postulate In this section we work within neutral geometry to prove that a number of different statements are equivalent to the Euclidean Parallel Postulate (EPP). This has historical importance. We noted before that Euclid’s Fifth Postulate was quite different in tone and complexity from his first four postulates, and that Euclid himself put off using the fifth postulate for as long as possible in his development of geometry. The history of mathematics is rife with efforts to either prove the fifth postulate from the first four, or to find a simpler postulate from which the fifth postulate could be proved. These efforts gave rise to a number of candidates that, in the end, proved to be no simpler than the fifth postulate and in fact turned out to be logically equivalent, at least in the context of neutral geometry. Euclid’s fifth postulate indeed captured something fundamental about geometry. We begin with the converse of the Alternate Interior Angles Theorem, as follows: If two parallel lines n and m are cut by a transversal l , then alternate interior angles are congruent. We noted earlier that this statement was equivalent to the Euclidean Parallel Postulate. We now prove that. Theorem: The converse of the Alternate Interior Angles Theorem is equivalent to the Euclidean Parallel Postulate. ~ We first assume the converse of the Alternate Interior Angles Theorem and prove that through a given line l and a point P not on the line, there is exactly one line through P parallel to l. We have already proved that one such line must exist: Drop a perpendicular from P to l; call the foot of that perpendicular Q. -
The Independence of the Parallel Postulate and the Acute Angles Hypothesis on a Two Right-Angled Isosceles Quadrilateral
The independence of the parallel postulate and the acute angles hypothesis on a two right-angled isosceles quadrilateral Christos Filippidis1, Prodromos Filippidis We trace the development of arguments for the consistency of non-Euclidean geometries and for the independence of the parallel postulate, showing how the arguments become more rigorous as a formal conception of geometry is introduced. We use these philosophical views to explain why the certainty of Euclidean geometry was threatened by the development of what we regard as alternatives to it. Finally, we provide a model that creates the basis for proof and demonstration using natural language in order to study the acute angles hypothesis on a two right-angled isosceles quadrilateral, with a rectilinear summit side. Keywords: parallel postulate; Hilbert axioms; consistency; Saccheri quadrilateral; function theory; The independence of the parallel postulate and development of consistency proofs Euclid’s parallel postulate states: ”If a straight line falling on two straight lines makes the interior angles on the same side less than two right angles, the two straight lines if produced indefinitely meet on that side on which are the angles less than two right angles.” The earliest commentators found fault with this statement as being not self-evident ‘Lewis [1920]’. Euclid uses terms such as “indefinitely” and makes logical assumptions that had not been proven or stated. Thus the parallel postulate seemed less obvious than the others.According to Lambert, Euclid overcomes doubt by means of 1 [email protected] 1 postulates. Euclid’s theory thus owes its justification not to the existence of the surfaces that satisfy it, but to the postulates according to which these “models” are constructed ‘ Dunlop [2009]’. -
The Fifth Postulate and Non-Euclidean Geometry a Timeline by Ederson Moreira Dos Santos
The fifth postulate and non-Euclidean Geometry A timeline by Ederson Moreira dos Santos 300 B. C. Euclid’s Elements were published. The fifth postulate is not self-evident, and in virtue of its relative complexity and scant intuitive appeal, in the sense that it could be proved, many mathematicians tried to present a proof of it. 300 B.C Aristoteles linked the problem of parallels lines to the question of the sum of the angles of a triangle in his Prior Analytics. 100 B.C Diodorus, and Anthiniatus proved many different prepositions about the fifth postulate. 410-485 Proclus described an attempt to prove the parallel postulate due to Ptolemy. Ptolemy gave a false demonstration of if two parallel lines are cut by a transversal, then the interior angles on the same side add up to two right angles, which is an assertion equivalent to the fifth postulate. Proclus also gave his own (erroneous) proof, because he assumed that the distance between two parallel lines is bounded, which is also equivalent to the fifth postulate. 500’s Agh_n_s (Byzantine scholar) proved the existence of a quadrilateral with four right angles, which lead to a proof of the fifth postulate, and this was the key point of most medieval proofs of the parallel postulate, but his proof is based on an assertion equivalent to the fifth postulate. 900’s Ab_ ‘Al_ ibn S_n_ (980-1037) defined parallel straight lines as equidistant lines, which is an equivalent proposition to the fifth postulate. The Egyptian physicist Abu ‘Al_ Ibn al-Haytham (965-1041) presented a false proof for the fifth postulate, using the same idea of equidistant lines, to define parallel lines. -
Models in Geometry and Logic: 1870-1920 ∗
Models in Geometry and Logic: 1870-1920 ∗ Patricia Blanchette University of Notre Dame 1 Abstract Questions concerning the consistency of theories, and of the independence of axioms and theorems one from another, have been at the heart of logical investigation since the beginning of logic. It is well known that our own contemporary methods for proving independence and consistency owe a good deal to developments in geometry in the middle of the nineteenth century, and especially to the role of models in estab- lishing the consistency of non-Euclidean geometries. What is less well understood, and is the topic of this essay, is the extent to which the concepts of consistency and of independence that we take for granted today, and for which we have clear techniques of proof, have been shaped in the intervening years by the gradual de- velopment of those techniques. It is argued here that this technical development has brought about significant conceptual change, and that the kinds of consistency- and independence-questions we can decisively answer today are not those that first motivated metatheoretical work. The purpose of this investigation is to help clarify what it is, and importantly what it is not, that we can claim to have shown with a modern demonstration of consistency or independence.1 ∗This is the nearly-final version of the paper whose official version appears in Logic, Methodology, and Philosophy of Science - proceedings of the 15th International Congress, edited by Niiniluoto, Sepp¨al¨a,Sober; College Publications 2017, pp 41-61 1Many thanks to the organizers of CLMPS 2015 in Helsinki, and also to audience members for helpful comments. -
The Continuous Transition of Hamiltonian Vector Fields Through Manifolds of Constant Curvature
THE CONTINUOUS TRANSITION OF HAMILTONIAN VECTOR FIELDS THROUGH MANIFOLDS OF CONSTANT CURVATURE Florin Diacu, Slim Ibrahim, and Je˛drzej Śniatycki Pacific Institute for the Mathematical Sciences and Department of Mathematics and Statistics University of Victoria P.O. Box 1700 STN CSC Victoria, BC, Canada, V8W 2Y2 [email protected], [email protected], [email protected] September 6, 2018 Abstract. We ask whether Hamiltonian vector fields defined on spaces of constant Gaussian curvature κ (spheres, for κ> 0, and hyperbolic spheres, for κ < 0), pass continuously through the value κ = 0 if the potential functions Uκ,κ ∈ R, that define them satisfy the property limκ→0 Uκ = U0, where U0 corresponds to the Euclidean case. We prove that the answer to this question is positive, both in the 2- and 3-dimensional cases, which are of physical interest, and then apply our conclusions to the gravitational N-body problem. 1. Introduction The attempts to extend classical equations of mathematical physics from Eu- clidean space to more general manifolds is not new. This challenging trend started in the 1830s with the work of János Bolyai and Nikolai Lobachevsky, who tried to generalize the 2-body problem of celestial mechanics to hyperbolic space, [2], [14]. This particular topic is much researched today in the context of the N-body problem in spaces of constant curvature, [4], [5], [6], [7], [10], [11], [12]. But ex- arXiv:1510.06327v1 [math.DS] 21 Oct 2015 tensions to various manifolds have also been pursued for PDEs, even beyond the boundaries of classical mechanics, such as for Schrödinger’s equation [1], [3], [13], and the Vlasov-Poisson system, [9], to mention just a couple. -
Lobachevsky, Nikolai
NIKOLAI LOBACHEVSKY ( December 1, 1792 – February 24, 1856) by HEINZ KLAUS STRICK, Germany NIKOLAI IVANOVICH LOBACHEVSKY was born in Nizhny Novgorod. When his father died in 1799, his mother moved to Kazan on the central Volga. There he began studying medicine at the newly founded university at the age of 15, but switched to mathematics a year later. His professor was MARTIN BARTELS, a friend of CARL FRIEDRICH GAUSS. He had previously worked as a teacher in Germany and was now appointed as a mathematics professor in Kazan. LOBACHEVSKY finished his mathematics studies at the age of 19 and at the age of 24 he was appointed professor at the University of Kazan. Later he became the dean and rector of the university. At the age of 22 he was already concerned with the question of the meaning of the so-called axiom of parallels, that is, the fifth postulate of EUCLID's geometry. Many mathematicians had been concerned with this postulate since antiquity, but it was only LOBACHEVSKY, GAUSS and JANOS BOLYAI who achieved decisive new insights almost simultaneously. However, they were not recognised during their lifetime. LOBACHEVSKY himself also received high honours, such as elevation to the hereditary nobility; however, this was not because of his discovery / invention of a new geometry. His Geometric Investigations of the Theory of Parallels, published in 1840, was viewed by most as the crazy ideas of an otherwise deserving scientist. EUCLID had around 300 BC in the first volume of his Elements proposed a system of five postulates from which all geometrical propositions should be derived: (1) Two points can always be connected by a line.