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“An unbelievably big gift. Two doctoral candidates!” They are still a bit dazed, but also extremely happy: “I think it’s very special that we’ve received funding from a private individual to conduct fundamental research”, says Henk Stoof, Professor of Theoretical Physics and leader of the focus area Complex Systems Studies. “The government has actually cut back the funding available for fundamental research.” Thanks to a gift from Dr. Peter Koeze, who earned his PhD. in Physics in 1968, the focus area can now appoint two PhD candidates to conduct fundamental research.

The first PhD candidate, Joris Broere, has already begun to work. Under the guidance of Henk Stoof and Vincent Buskens, Professor of Theoretical Sociology, he will study how the models used in the field of theoretical physics can provide more insight into the functioning of social networks. This is an excellent example of interdisciplinary cooperation within the focus area.

Success with applying physics

Peter Koeze earned his PhD. in Physics at Utrecht ľ�ϸ���Ӱ�� in 1968, and went on to complete a Bachelor’s in Psychology in 1980. After his studies, Koeze worked for employers such as Shell and the Nederlandsche Bank. “I was able to successfully apply my knowledge, insights and techniques learned in my study of physics to an economic problem: investing in the stock market. I expect that there are also other areas in the social sciences where physics knowledge can be successfully utilised, as has already been done in the fields of medicine and biology.”

Over the past few years Koeze has come to the realisation that he wanted to devote part of his fortune to a good cause while he was still alive: “That way, you can enjoy the results and you can provide additional information about your ideas, vision and wishes. Plus, the fiscal benefits are only attainable during your lifetime. That way, everyone profits from it.”

He placed a high value on using the gift for unorthodox, “and in that sense, risky” research, and he is confident that the gift will be spent wisely by Utrecht ľ�ϸ���Ӱ��: “Most other charities do not report on how they spend their legacies, or only when they are urged to do so. The years that I spent on my doctoral research in Utrecht were one big party, both in my research and in other areas of life. The atmosphere and the culture at Utrecht ľ�ϸ���Ӱ�� is extremely motivating.”

Fundamental and relevant to society

Koeze requested his gift should be used to conduct research in which mathematical and physics models can be applied to socially relevant issues. That is precisely the subject studied in the focus area Complex Systems Studies, which was founded last year.

From a scientific standpoint, a surprising number of phenomena in daily life are complex systems, such as the economy, the weather, the development of the nervous system and the creation of a traffic jam. “But although we come across many different forms of complex systems, they often follow the same basic mathematical and physical laws,” explains Henk Stoof, the driving force behind the focus area. Stoof conducts research into solids and liquids that are governed by the laws of quantum mechanics. These laws can be observed in superconductive materials, for example.

Small changes, large effects

One of the more difficult characteristics of complex systems is that they are not linear: small changes can have very large and unexpected effects. When you heat water, no changes are observed for a relatively long time until it apparently suddenly begins to boil. Such sudden transitions are also observable in many social and economic phenomena, such as stock market crashes.

“We now know that water will begin to evaporate based on a rise in temperature. Economists would also like to have such an observable early warning signal for phenomena such as stock market crashes”, Stoof explains. In the field of sociology and other social sciences, the application of mathematical models is also undergoing a strong development.

Physics models for social developments

Vincent Buskens graduated as a mathematician and earned his PhD. on the construction of mathematical models for sociology. He studies the influence of social networks on cooperation within networks. “Some networks facilitate cooperation better than others. I try to explain what exactly makes one network better than the other. For example, in our ‘participation society’, it is interesting to know which characteristics are common in social networks in the neighbourhoods where people are more likely to help one another.”

Joris Broere, the first PhD candidate who has been appointed thanks to Koeze’s gift will study which physical models most resemble the social network models that have already been developed within the field of sociology. “This can help us to better analyse the social model or adjust it in order to better correspond to the real conditions prevalent in society”, explains Buskens.

Counter-intuitive

As an example, he mentions the social segregation model, which describes how different social groups settle within a city. To the surprise of American sociologists, the increased tolerance of Afro-Americans by white Americans after the 1960s has led to little or no racial mixing in residential neighbourhoods. “This is counter-intuitive. You would expect that a gradual increase in tolerance would also lead to a gradual increase in racial mixing. The fact that this hasn’t happened indicates that there are other factors that play a role in addition to tolerance or that the relation between tolerance and segregation is non-linear”, according to Buskens.

“The social segregation model strongly resembles the Ising model used in physics; a simple theoretical model for magnetic materials. That is useful for sociologists to know, because the standard segregation model is based on two groups, but a city can consist of many different social groups, which makes the model much more complex. In that case, a physicist would switch to the Potts model, which is a generalisation of the Ising model. That may also be useful for a social segregation model with more than two groups.”

In order to evaluate that, a physicist must first understand the degree to which the interactions between social groups are comparable to interactions between electron spins. “Because in the final analysis, it’s not about just having a more elegant model”, says Buskens. “It’s about understanding the complex reality of our society, so that we can prevent undesirable developments and encourage desirable ones.”