# National Science Week: twisting somersaults public lecture & maths workshops

To celebrate National Science Week in 2023, a range of mathematical activities took place across Australia over 12–20 August.

## Photo gallery: Dr Karl and friends, Sydney Town Hall, 17 August 2023

All photographs by Jayne Ion.

SMRI organised three public events at the University of Sydney for all ages and levels of mathematics over 15–17 August: see descriptions below.

Find more National Science Week events in Sydney. Plus, catch SMRI Director Geordie Williamson on stage with Dr Karl and friends for “Innovation and Beyond” (details below).

## “The mathematics of twisting somersaults” public lecture and reception: Tuesday 15 August, 18:00**–**20:00, New Law Building Annex (Lecture Theatre 101)

What do a space station, a falling cat, and a springboard diver have in common?

They are in free fall. But in contrast to a falling rock, they all have the ability to reorient themselves whilst they are falling.

In this talk, we’ll explore the principles behind this phenomenon. The mathematics underpinning the reorientation uses beautiful symmetries to explain the conservation laws of dynamical systems. In mathematics, this refers to systems where a function describes a point in space that is dependent on time, e.g. the swinging of a clock pendulum, or water flowing in a pipe.

Our understanding of the theory behind twisting somersaults (backed up by numerical simulations) has led to the discovery of a new dive called 513XD, which is awaiting performance at one of the next Olympics!

**About the speaker**: Holger Dullin is a Professor of Applied Mathematics at the University of Sydney. His research in dynamical systems employs geometric ideas to better understand a variety of problems ranging from (non-) rigid body dynamics to the gravitational n-body problem, quantum mechanics and spectral theory. He currently holds two ARC grants.

Holger received his PhD in theoretical physics from the University of Bremen in Germany in 1994. He was a researcher in Boulder, Colorado, and a lecturer in Loughborough, UK before coming to Sydney in 2008. When not doing mathematics, he can be found bushwalking with his wife and son.

## Infinity Mathematics workshop: Wednesday 16 August, 16:30**–**18:00, Susan Wakil Health Building

In this workshop, we will have a deeper look into counting to infinity and try to figure out if all infinities are equal or one thing can be more infinite than another one. We will explore the mathematics of infinity through discussion and solving problems.

This event will be presented by University of Sydney mathematician, Milena Radnovic.

The workshop is for high-school students in Sydney who are studying maths. Considering taking higher level mathematics in your senior years or at University? Come along!

Register via Eventbrite by 14 August (now closed).

## Twist and Turn workshop: Thursday 17 August, 16:30**–**18:00, Susan Wakil Health Building

In this activity, we take a mathematical spin on tangling and untangling! We will consider a situation where we have two ropes and apply two possible operations: a twist and a turn. In this simple setup, we can create deceivingly complex tangles, but can we untangle them using the same two operations? We will answer this question by exploring the mathematics behind these tangles in a combination of hands-on activities and discussions.

This event will be presented by University of Sydney mathematician, Andy Tran.

The workshop is for high-school students in Sydney who are studying maths. Considering taking higher level mathematics in your senior years or at University? Come along!

Register via Eventbrite by 14 August (now closed).

## Dr Karl and Friends: Innovation and Beyond Thursday 17 August, 18:30**–**20:00, Sydney Town Hall

There’s a buzz this National Science Week as Dr Karl Kruszelnicki and friends join forces, live on stage at Sydney Town Hall.

Take a ride with Dr Karl through the past 100 years of the greatest scientific discoveries and innovations that changed our lives forever.

Today’s thinkers will do the same, but how? Dr Karl will talk to four future-focused researchers poised to blast our futures into the stratosphere: Professor Anita Ho-Baillie, Professor Emma Johnston, Associate Professor Michael Bowen and SMRI Director Professor Geordie Williamson. This event will be hosted by Associate Professor Alice Motion and is supported by the City of Sydney.

Register free on the Sydney Science event page (now closed).

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