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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

Media: Sunday Times
2006-05-20

Sunday Times, 4 June 2006

True leadership may mean admitting disunity
 

In this edited extract from the inaugural King Moshoeshoe Memorial Lecture at the University of the Free State, Professor Njabulo S Ndebele explores the leadership challenges facing South Africa

RECENT events have created a sense that we are undergoing a serious crisis of leadership in our new democracy. An increasing number of highly intelligent, sensitive and committed South Africans, across class, racial and cultural spectrums, confess to feeling uncertain and vulnerable as never before since 1994.

When indomitable optimists confess to having a sense of things unhinging, the misery of anxiety spreads. We have the sense that events are spiralling out of control and that no one among the leadership of the country seems to have a definitive handle on things.

There can be nothing more debilitating than a generalised and undefined sense of anxiety in the body politic. It breeds conspiracies and fear.

There is an impression that a very complex society has developed, in the last few years, a rather simple, centralised governance mechanism in the hope that delivery can be better and more quickly driven. The complexity of governance then gets located within a single structure of authority rather than in the devolved structures envisaged in the Constitution, which should interact with one another continuously, and in response to their specific settings, to achieve defined goals. Collapse in a single structure of authority, because there is no robust backup, can be catastrophic.

The autonomy of devolved structures presents itself as an impediment only when visionary cohesion collapses. Where such cohesion is strong, the impediment is only illusory, particularly when it encourages healthy competition, for example, among the provinces, or where a province develops a character that is not necessarily autonomous politically but rather distinctive and a special source of regional pride. Such competition brings vibrancy to the country. It does not necessarily challenge the centre.

Devolved autonomy is vital in the interests of sustainable governance. The failure of various structures to actualise their constitutionally defined roles should not be attributed to the failure of the prescribed governance mechanism. It is too early to say that what we have has not worked. The only viable corrective will be in our ability to be robust in identifying the problems and dealing with them concertedly.

We have never had social cohesion in South Africa — certainly not since the Natives’ Land Act of 1913. What we definitely have had over the decades is a mobilising vision. Could it be that the mobilising vision, mistaken for social cohesion, is cracking under the weight of the reality and extent of social reconstruction, and that the legitimate framework for debating these problems is collapsing? If that is so, are we witnessing a cumulative failure of leadership?

I am making a descriptive rather than an evaluative inquiry. I do not believe that there is any single entity to be blamed. It is simply that we may be a country in search of another line of approach. What will it be?

I would like to suggest two avenues of approach — an inclusive model and a counter-intuitive model of leadership.

In an inclusive approach, leadership is exercised not only by those who have been put in some position of power to steer an organisation or institution. Leadership is what all of us do when we express, sincerely, our deepest feelings and thoughts; when we do our work, whatever it is, with passion and integrity.

Counter-intuitive leadership lies in the ability of leaders to read a problematic situation, assess probable outcomes and then recognise that those outcomes will only compound the problem. Genuine leadership, in this sense, requires going against probability in seeking unexpected outcomes. That’s what happened when we avoided a civil war and ended up with an “unexpected” democracy.

Right now, we may very well hear desperate calls for unity, when the counter-intuitive imperative would be to acknowledge disunity. A declaration of unity where it manifestly does not appear to exist will fail to reassure.

Many within the “broad alliance” might have the view that the mobilising vision of old may have transformed into a strategy of executive steering with a disposition towards an expectation of compliance. No matter how compelling the reasons for that tendency, it may be seen as part of a cumulative process in which popular notions of democratic governance are apparently undermined and devalued; and where public uncertainty in the midst of seeming crisis induces fear which could freeze public thinking at a time when more voices ought to be heard.

Could it be that part of the problem is that we are unable to deal with the notion of opposition? We are horrified that any of us could be seen to have become “the opposition”. The word has been demonised. In reality, it is time we began to anticipate the arrival of a moment when there is no longer a single, overwhelmingly dominant political force as is currently the case. Such is the course of history. The measure of the maturity of the current political environment will be in how it can create conditions that anticipate that moment rather than seek to prevent it. We see here once more the essential creativity of the counter-intuitive imperative.

This is the formidable challenge of a popular post-apartheid political movement. Can it conceptually anticipate a future when it is no longer overwhelmingly in control, in the form in which it is currently, and resist, counter-intuitively, the temptation to prevent such an eventuality? Successfully resisting such an option would enable its current vision and its ultimate legacy to our country to manifest in different articulations, which then contend for social influence. In this way, the vision never really dies; it simply evolves into higher, more complex forms of itself. Consider the metaphor of flying ants replicating the ant community by establishing new ones.

We may certainly experience the meaning of comradeship differently, where we will now have “comrades on the other side”.

Any political movement that imagines itself as a perpetual entity should look at the compelling evidence of history. Few movements have survived those defining moments when they should have been more elastic, and that because they were not, did not live to see the next day.

I believe we may have reached a moment not fundamentally different from the sobering, yet uplifting and vision-making, nation-building realities that led to Kempton Park in the early ’90s. The difference between then and now is that the black majority is not facing white compatriots across the negotiating table. Rather, it is facing itself: perhaps really for the first time since 1994. Could we apply to ourselves the same degree of inventiveness and rigorous negotiation we displayed leading up to the adoption or our Constitution?

This is not a time for repeating old platitudes. It is the time, once more, for vision.

In the total scheme of things, the outcome could be as disastrous as it could be formative and uplifting, setting in place the conditions for a true renaissance that could be sustained for generations to come.

Ndebele is Vice-Chancellor of the University of Cape Town and author of the novel The Cry of Winnie Mandela

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