Why is pi special?
20210312
On 14 March every year, the world celebrates the peculiar number pi. Meet the mathematics lecturer JordiLluís Figueras in a conversation about pi and mathematics.
Pi has an infinite number of digits that do not repeat themselves according to any pattern. There are many numbers that have that property, but only pi is designated its own day.
Why is pi so special that it deserves its own day?
“Pi is one of the main constants that appear in mathematics and maybe one of the earliest”, says JordiLluís Figueras, lecturer in mathematics at Uppsala University.
When was pi discovered?
“I suppose, the first time we saw the moon. Every time you see a rounded shape, you see pi. Historically, it was probably the Babylonians, Greeks and Egyptians in between who used pi.”
The first to use an approximation of pi were the Babylonians around 2000 BC. They estimated the pi value to be 3.125 by drawing a hexagon in a circle, calculating the circumference of the hexagon and assuming that the ratio of the circumference of the hexagon to the circle is 24/25. Later on, as the mathematical methods have developed, the approximations of pi have come closer to the real value of pi. But how close to pi can you actually get?
A circle that is 1 cm in diameter has a circumference that is equal to pi. But if we take a measuring tape and measure the circumference, we will get a length that has a finite number of decimals. So not pi. Doesn't this make pi seem a bit unreal?
“Yes and no. Pi is something that lives in the world of mathematics. Now, the question is if what we observe is the same as how we model it. A mathematical triangle is not the same as what we call a triangle in the real world. What we do is that we model the reality by some objects and we take some assumptions that we cannot verify if they are true or not. When we see a rounded object, we say that it’s a circle. And when we say that it’s a circle, we mean that we model this object as a mathematical circle, that is defined by a set of points with the same distance from a given point. But is it true that the real object has the same properties? Can we verify this? I suppose not.
It sounds like it’s impossible to draw a perfect mathematical circle.
“If we take for granted that matter consists of a finite number of particles, your drawn circle will consist of a finite number of particles. So, you’re not drawing a circle, you’re approximating a mathematical circle. In other words, if we suppose that the reality consists of a finite number of particles, then we’ll never be able to measure all the digits of pi.
Thanks to the development of the computer, the number of known digits of pi has increased. According to the Guinness Book of Records, today's record is 50,000,000,000,000,000,000 digits and was set on January 29, 2020 by Timothy Mullican in the United States. The calculation was made using Chudnovsky's algorithm and took eight months. But according to JordiLluís Figueras, the number of known decimals of pi is not so relevant for mathematicians.
“What is important to remember is that pi is an abstract concept that relates very faithfully to physical observations. It enters into a lot of mathematical models that match the reality. By matching, I mean that we experiment and get what the models predict.”
Would it be true to say that the reality is an approximation of mathematics?
“Or the other way around. If I want to model how the population in Uppsala behaves, there are many things that I have to take into account. For instance, Pluto’s gravitation has an marginal effect on us, but in no model you will see Pluto’s orbit as a variable. That’s why you simplify the model and take the most meaningful variables. Otherwise, you are forced to model the whole universe and the model gets so complex that it's out of reach.”
What is your relationship to pi?
“As for any mathematician. Pi appears often and often when we work in mathematics. Sometimes, it shows up naturally, because the computations that you are doing involve some rounded object, like a sphere, so it is expected that pi will be there. And sometimes it appears more mystically. You are computing something where you don’t see any link to a circular object, but pi is there. As a mathematician you reach a certain point where you see that pi always appears. You don’t get super excited when it happens."
How many decimals of pi do you know?
"Eleven. Or twelve. At some point, I decided to learn around ten because I discovered that my students know less. Sometimes, I like to joke with them and ask them how many digits they know. Usually it's four or five. So, to know ten is enough to beat them.
I saw that UNESCO has proclaimed Pi Day to be the International Day of Mathematics, with a different theme each year. This year’s theme is "How can we make the world better with mathematics?". How would you answer that question?
“It’s a big question. There are different aspects of it. One is technological. Take any technological achievement and you’ll se that mathematics is behind it. Another thing that’s a hot topic today, is mathematical modelling of pandemics. Apart from that, there are people who say that if you understand mathematics, you’ll understand logical reasoning, and if you understand logical reasoning, you’ll make better decisions. To that, I am more sceptical. Like anyone else, mathematicians base their support of ideas on emotions.
Are you going to celebrate the Pi Day on Sunday?
“Yes, we always celebrate at home. My wife as a mathematician too.
How will you celebrate?
“With cookies.”
Cookies? Not pie?
“No, we celebrate with pishaped cookies.”
Alma Kirlic
News from the Department of Mathematics

Appreciated alumni event to be repeated next year
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22 million in VR grants
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Arne Beurling's bust moved and reinaugurated
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Geometric puzzles attracted at SciFest
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Beurling visit and G printer opening
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Two laureates of the Frontiers of Science Awards
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On the International Congress of Basic Science in Beijing this summer, newly established prizes in mathematics were awarded. In the category Frontiers of Science Awards the Department of Mathematics at Uppsala University has two laureates, motivated by two different articles. They get the prize for research that is of highest scientific value and originality and that have made an important impact on its area.

Almedalen seminar: Nobody understands AI  what´s the problem?
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Support from KAW's mathematics programme to prominent mathematics researchers
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In order for Sweden to regain an international leading position in the field of mathematics, the Knut and Alice Wallenberg Foundation, together with the Royal Swedish Academy of Sciences, is providing support by giving the best young researchers international experience and recruiting both young and more experienced mathematicians to Sweden. The 2023 award includes four researchers at Uppsala University.

We take part in the Nordic Congress of Mathematicians
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On July 37, the 29th Nordic Congress of Mathematicians will take place in Aalborg, Denmark. The congress is usually held every four years. Researchers from the Department of Mathematics at Uppsala University are involved in arranging two of the congress's special sessions.

UTN's pedagogical award to Anna Sakovich
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UTN's pedagogical award for 2022 was awarded to Anna Sakovich for her pedagogical efforts in the Single Variable Calculus course! Thanks to Anna's drive, dedication and interest in the students' learning, she makes the students enjoy the studies.

Starting grant enables research on random graphs
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Over 20 million in VR grants
20221107
The Swedish Research Council (VR) has awarded five project grants and one starting grant totaling almost 22 million SEK to researchers at the Department of Mathematics at Uppsala University. VR rewards research of the highest scientific quality in national competition. In the same call, VR distributed a total of approximately SEK 94 million for research in mathematics.

Entertaining mathematician gets prize
20220913
David Sumpter, professor of applied mathematics, receives this year's Disapris for his popular science books on mathematics. David Sumpter has been a professor in the Department of Mathematics but is now active in the Department of Information Technology.”

International collaboration between mathematics and physics
20210903
Michele Del Zotto at Uppsala University has been appointed a principal investigator within the Simons Collaboration on Global Categorical Symmetries. This collaboration brings together world leading theoretical physicists and mathematicians from several different universities and gives Uppsala University a financial support of around 500,000 USD during four years.

Seidon Alsaody receives the University's pedagogical award
20210526
Seidon Alsaody is the 2021 pedagogical laureate at Uppsala University in the field of mathematics, science and technology. He was notified at the mathematics department's staff meeting by the Deputy ViceChancellor Coco Norén, who made an unexpected visit.

Johan Asplund is looking forward to mathematical conversations
20210326
Johan Asplund, who will soon defend his doctoral thesis in symplectic geometry, has received a postdoctoral position at Columbia University in New York, funded by the Knut and Alice Wallenberg Foundation. He is looking forward to exciting mathematical conversations and to finding himself as a mathematician.

What does this year's Abel Prize mean for mathematics?
20210324
This year's Abel Prize has gone to László Lovász and Avi Wigderson for their basic contributions to discrete mathematics and theoretical computer science. Stephan Wagner and Svante Janson, who both conduct research in discrete mathematics, tell about what the prize means for their field.

Why is pi special?
20210312
On 14 March every year, the world celebrates the peculiar number pi. Meet the mathematics lecturer JordiLluís Figueras in a conversation about pi and mathematics.

Seidon Alsaody receives pedagogical award from student union
20210226
Last year's pedagogical award from the Uppsala Union of Technology and Science Students (UTN) goes to the mathematics lecturer Seidon Alsaody, because he has "through his teaching method succeeded to inspire, support and motivate his students in a way that few teachers have managed to do".
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Wallenberg prize 2020 goes to Thomas Kragh
20200415
Thomas Kragh receives the 2020 year's Wallenberg Prize "for his work in sympathetic geometry and topology, especially for his important contribution to Floers homotope theory and Lagrange topology."

Will AI take over the world?
20181010
Fake news don't affect people's worldview as much as we might think, said David Sumpter in a lecture he held as part of a symposium organised by Uppsala University in collaboration with Tokyo Tech.

Summer math camp – success continues
20181010
In August, the department organized the fifth round of the Summer Math Camp. The camp is aimed at students who want to try mathematical research. In this year's edition, under the theme finite fields and their applications, four students participated: Mikolaj CuszynskiKruk, Sara Freyland, Johannes Granér and Einar Waara. We've asked the students about their thoughts on the camp.

Julian Külshammer receives algebra prize
20180820
The new Uppsala mathematician Julian Külshammer has received the algebra prize ICRA 2018

Uppsala mathematician awarded The Moore Prize for Applications of Interval Analysis
20180712
Uppsala mathematicians JordiLluís Figueras and Alejandro Luque are awarded The Moore Prize for Applications of Interval Analysis for the article "Rigorous Computer Assisted Application of KAM Theory: A Modern Approach", which they written with Alex Haro. Thus, Uppsala University is the only one that has recieved the Moore Prize twice. The first time the award went to a matemathematician from Uppsala was in 2002, when the prize went to Warwick Tucker.

Hania UsckaWehlou receives two teaching awards
20180621
The students have rewarded Hania UsckaWehlou with no less than two awards, the Electrotechnical Educational Prize 2018 and the FTeacher Award 2018.

Student from Uppsala participates in a project about the number Pi at Sorbonne
20180621
Uppsala student Nima Akbarian knows 3141 decimals of pi. He has demonstrated this skill at an event that took place in early June at the Sorbonne Université in Paris.

Research grant to Samuel Edwards from Uppsala
20180404
Knut och Alice Wallenberg foundation continues to invest in mathematics. According to the chair Peter Wallenberg jr, mathematics is important for handling the huge amounts of data that we are exposed to today. Therefore, the foundation is investing in development of basic research in mathematics and awarding grants to fourteen mathematicians. One of the researchers to receive a grant is Samuel Edwards, who will defend his doctoral thesis at the department of mathematics in Uppsala on June 8.

Math for social activism
20180307
From Facebook to job evaluations, mathematics now plays an important part in every aspect of our social lives. And, increasingly, mathematicians are actively using their skills to improve society. The Centre for Interdisciplinary Mathematics will thus run a theme around "Maths for social activism" culminating in a workshop on June 4th and 5th.