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18 April 2022 | Story Leonie Bolleurs | Photo Stephen Collett
Prof Ted Kroon
Prof Ted Kroon from the Department of Physics recently delivered his inaugural lecture on the topic What’s the use of a rainbow on the UFS Bloemfontein Campus.

“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

“To forgive is not an obligation. It’s a choice.” – Prof Minow during Reconciliation Lecture
2014-03-05

“To forgive is not an obligation. It’s a choice.” – Prof Minow during the Third Annual Reconciliation Lecture entitled Forgiveness, Law and Justice.
Photo: Johan Roux

No one could have anticipated the atmosphere in which Prof Martha Minow would visit the Bloemfontein Campus. And no one could have predicted how apt the timing of her message would be. As this formidable Dean of Harvard University’s Law School stepped behind the podium, a latent tension edged through the crowded audience.

“The issue of getting along after conflict is urgent.”

With these few words, Prof Minow exposed the essence of not only her lecture, but also the central concern of the entire university community.

As an expert on issues surrounding racial justice, Prof Minow has worked across the globe in post-conflict societies. How can we prevent atrocities from happening? she asked. Her answer was an honest, “I don’t know.” What she is certain of, on the other hand, is that the usual practice of either silence or retribution does not work. “I think that silence produces rage – understandably – and retribution produces the cycle of violence. Rather than ignoring what happens, rather than retribution, it would be good to reach for something more.” This is where reconciliation comes in.

Prof Minow put forward the idea that forgiveness should accompany reconciliation efforts. She defined forgiveness as a conscious, deliberate decision to forego rightful grounds of resentment towards those who have committed a wrong. “To forgive then, in this definition, is not an obligation. It’s a choice. And it’s held by the one who was harmed,” she explained.

Letting go of resentment cannot be forced – not even by the law. What the law can do, though, is either to encourage or discourage forgiveness. Prof Minow showed how the law can construct adversarial processes that render forgiveness less likely, when indeed its intention was the opposite. “Or, law can give people chances to meet together in spaces where they may apologise and they may forgive,” she continued. This point introduced some surprising revelations about our Truth and Reconciliation Commission (TRC).

Indeed, studies do report ambivalence, disappointment and mixed views about the TRC. Whatever our views are on its success, Prof Minow reported that people across the world wonder how South African did it. “It may not work entirely inside the country; outside the country it’s had a huge effect. It’s a touchstone for transitional justice.”

The TRC “seems to have coincided with, and maybe contributed to, the relatively peaceful political transition to democracy that is, frankly, an absolute miracle.” What came as a surprise to many is this: the fact that the TRC has affected transitional justice efforts in forty jurisdictions, including Rwanda, Sierra Leone, Cambodia and Liberia. It has even inspired the creation of a TRC in Greensborough, North Carolina, in the United States.

There are no blueprints for solving conflict, though. “But the possibility of something other than criminal trials, something other than war, something other than silence – that’s why the TRC, I think, has been such an exemplar to the world,” she commended.

Court decision cannot rebuild a society, though. Only individuals can forgive. Only individuals can start with purposeful, daily decisions to forgive and forge a common future. Forgiveness is rather like kindness, she suggested. It’s a resource without limits. It’s not scarce like water or money. It’s within our reach. But if it’s forced, it’s not forgiveness.

“It is good,” Prof Minow warned, “to be cautious about the use of law to deliberately shape or manipulate the feelings of any individual. But it is no less important to admit that law does affect human beings, not just in its results, but in its process.” And then we must take responsibility for how we use that law.

“A government can judge, but only people can forgive.” As Prof Minow’s words lingered, the air suddenly seemed a bit more buoyant.

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