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TED Talks about rainbows

18 April 2022 | Story Leonie Bolleurs | Photo Stephen Collett

“A rainbow is a natural phenomenon, the result of the refraction and reflection of the sun’s rays in drops of rain. As far as mankind is concerned, it’s a perfectly useless object and won’t make anyone money. Yet the poet who said, My heart leaps up when I behold a rainbow in the sky, only put into word the feeling of wonder and excitement we all have when we see a rainbow.”

“Every day I see a rainbow in my work; I do not need to wait to see one in the sky,” says Prof Ted Kroon, Professor in the Department of Physics at the University of the Free State (UFS), who used this phenomenon to introduce the topic of his inaugural lecture: What’s the use of a rainbow.

“Far from being only a colourful spectacle with no practical value, rainbows are useful – and lead to useful things,” he believes.

According to Prof Kroon, one can find examples of real rainbows and rainbow analogies used not only in everyday life, but also in physics. “Besides it being familiar devices in literature, culture, and even marketing, studies of rainbows can yield practical engineering information and may even help us to find new habitable planets,” he says.

Inspired by the many uses of a rainbow

In his lecture, he discussed the basic features of natural rainbows and how they come about. He also explored how the rainbow gives meaning to colour, and how this relates to the temperature of objects. He looked at an array of instances where the rainbow is used; from depicting the life of a star to indicating that we are sick (a thermometer) or when we need to refill a gas cylinder.

Moreover, Prof Kroon pointed out that rainbows are used in computer chips, stress identification, and to transmit internet data through underwater cables of glass fibre. He also referred to how the rainbow was harnessed as an engineering tool to measure refractive index and characterise fine droplet sprays used in industry.

He continues, “Remarkably, the science developed to understand the natural rainbow can be redirected and applied to the optical properties of metallic nanoparticles, allowing the development of nanotechnology. Knowing how the natural rainbow works and its limitations, better systems have been developed to produce rainbows. Such rainbows have been used to discover new elements and to determine the age of the universe.”

As a member of an international community of phosphor researchers who are privileged to work with rainbows every day, he has used them to study the light-emitting properties of materials doped with bismuth. With this project – an initiative with the African Laser Centre taking place between 2016 and 2021 – he collaborated with the University of Khartoum in Sudan and trained a number of its postgraduate students. “My role included the guidance of students and the measurement and interpretation of the light-emitting properties of the materials. Our research during this time, considering more than a dozen materials, was summarised in 34 scientific publications that contributed to a greater understanding of bismuth ions as light-emitting materials,” he explains.

Developing new materials, efficient in emitting blue light

He has been developing luminescent materials since 2006, primarily for general lighting (fluorescent tubes and LEDs) and displays (television, computer, and cellphone screens), as well as niche applications in medical and forensic science.

As part of his current research, he is examining the effect of plasmonic metal nanoparticles on phosphor light emission. He is also exploring materials that absorb infrared light but emit visible light. “For this, I would like to consider the long-term stability of such materials and develop new materials that are more efficient in emitting particularly blue light,” he says.

Prof Kroon holds a C2 rating from the National Research Foundation and has published more than 150 articles and book chapters, obtaining a Scopus h-index of 26.

News Archive

UFS can lead SA in race relations - Ramphele

2010-08-06

Pictured are: Dr Boesak and Dr Ramphele
Photo: Mangaliso Radebe

The University of the Free State (UFS) could well be a perfect model of excellence in race relations that the whole of South Africa could emulate.

This was said by Dr Mamphela Ramphele, the first African to be a Managing Director of the World Bank, during the Anti-Racism Network in Higher Education (ARNHE) Colloquium held at the UFS recently.

“Healing circles need to be constructed on this campus to address issues raised by the Reitz incident,” she said.

“You might yet be the pioneer of what needs to happen on a nation-wide level.

“Can we confidently commit today to go on this quest for a true humanity and walk together as fellow citizens and strive for a more human face for our society? That is our challenge. That is what the UFS is called to give leadership to.”

“It is this human face which has the power to liberate us from the body of death and strengthen us in our struggle for meaningful life together in South Africa,” added one of the main speakers, Dr Allan Boesak, a cleric and former anti-apartheid activist.

However, said Dr Ramphele, this could only be achieved if all South Africans, black and white, abandoned the fear for each other that was hindering, if not stalling, progress in this regard.

“Fear of each other is the most important impediment to the sustainability of our journey into a society united in our diversity,” she said.

“People in this country are afraid to stand up and be counted, including many vice-chancellors and clerics. They are afraid of being seen to be difficult, and that is a major problem. Fear is the most destructive emotion that you can have because it makes you really incompetent and unable to respond to challenges.”

She said the biggest impediment, though, to ending racism was denial. “White people deny vehemently that they are or have ever been racist,” she said.

“We need to go through a process of acknowledging our wounds and scars from our racist past and present missteps in public policy.”

“Instead of saying they are sorry, those who are conscious of their whiteness should rather say what they are sorry for,” said another main speaker, Prof. Dennis Francis, the Dean of the Faculty of Education at the UFS.

On the other hand, according to Dr Boesak, blacks were and still are, to a large extent, also to blame for their own ongoing oppression. “The key here was the acknowledgement of our sheepish timidity, our complicity,” he said.

The Chairperson of ARNHE, Prof. Norman Duncan, had this to say: “If we are to confront and eradicate racism in higher education institutions, we should not do so to create comfort zones for ourselves.”

The theme of this ARNHE Colloquium was Black consciousness and those conscious of their whiteness. It was presented by the International Institute for Studies in Race, Reconciliation and Social Justice at the UFS.

Media Release:
Mangaliso Radebe
Assistant Director: Media Liaison
Tel: 051 401 2828
Cell: 078 460 3320
E-mail: radebemt@ufs.ac.za
6 August 2010

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