Press releases

 

Nov 1 2016
11:46

Maria Roser Valenti is new fellow of the American Physical Society

Distinction for Frankfurt physicist

FRANKFURT. Professor Maria Roser Valenti has been elected as a fellow of the American Physical Society (APS) in the "Division of Computational Physics". She was awarded this high distinction for her contribution to the microscopic understanding of electronically strongly correlated materials, which include high-temperature superconductors. To access these highly complex materials she uses a combination of various theoretical approaches.

Professor Enrico Schleiff, Vice-President of Goethe University Frankfurt: "We congratulate the American Physical Society on this decision as Ms. Valenti is a recognized expert in the field of Theoretical Condensed Matter Physics. She unites all the characteristics of an excellent researcher: she is a constantly driving force for creative ideas, is engaged in international projects at the highest scientific level, devotes herself to her discipline both within and outside the University and is a role model for young academics. She will breathe her own new vigour into the APS, just as she did at Goethe University during her time as vice-president."

Maria Roser Valenti studied Physics at the University of Barcelona and gained her doctorate in 1989. From 1990 to 1991 she was a post-doctoral researcher at the University of Florida in Gainesville. She then became a research associate at TU Dortmund University where in 1997 she began her habilitation with a grant from the German Research Foundation (DFG - Deutsche Forschungsgemeinschaft). In 1999 she moved to Saarland University and completed her habilitation one year later. In 2002 she was awarded one of the prestigious Heisenberg scholarships of the German Research Foundation, which prepares early career researchers for a long-term professorship. In 2003 she became professor at the Institute of Theoretical Physics of Goethe University Frankfurt. From 2009 to 2012, the mother of three children was vice-president of Goethe University. Her research work focuses on the quantum mechanics of materials. She develops theoretical methods to describe unconventional superconductivity, frustrated magnetism, exotic spin liquids or systems with phases with non-trivial topology, among others.

With over 50.000 members worldwide, the APS is the second largest association for physicists. (The largest is the German Physical Society (DPG - Deutsche Physikalische Gesellschaft)). The APS was founded in 1899 with the goal of advancing the knowledge of physics and fostering the next generation of researchers. It is regarded as a great honour to be elected as a fellow. Only those researchers are taken into consideration who have made a significant contribution to basic research or contributed substantially to the development of scientific or technical applications.

 

Oct 21 2016
15:33

Boron compounds extend range of possible chemical synthesis applications

Non-metal catalyst splits hydrogen molecule

Hydrogen (H2) is an extremely simple molecule and yet a valuable raw material which as a result of the development of sophisticated catalysts is becoming more and more important. In industry and commerce, applications range from food and fertilizer manufacture to crude oil cracking to utilization as an energy source in fuel cells. A challenge lies in splitting the strong H-H bond under mild conditions. Chemists at Goethe University have now developed a new catalyst for the activation of hydrogen by introducing boron atoms into a common organic molecule. The process, which was described in the Angewandte Chemie journal, requires only an electron source in addition and should therefore be usable on a broad scale in future.

The high energy content of the hydrogen molecule meets with a particularly stable bonding situation. It was Paul Sabatier who in 1897 detected for the first time that metals are suitable catalysts for splitting the molecule and harnessing elementary hydrogen for chemical reactions. In 1912 he was awarded the Nobel Prize for Chemistry for this important discovery. The hydrogenation catalysts mostly used today contain toxic or expensive heavy metals, such as nickel, palladium or platinum. Only ten years ago non-metal systems based on boron and phosphorous compounds were discovered which allow comparable reactions.

“My doctoral researcher, Esther von Grotthuss, has achieved yet another major simplification of the non-metal strategy which requires only the boron component”, says Professor Matthias Wagner from the Institute of Inorganic and Analytical Chemistry of Goethe University Frankfurt. “What we additionally need is just an electron source. In the laboratory we chose lithium or potassium for this. When put into practice in the field, it should be possible to substitute this with electrical current.”

In order to explain the intricacies of hydrogen activation above and beyond experimental findings, quantum chemical calculations were carried out in cooperation with Professor Max Holthausen (Goethe University Frankfurt). Detailed knowledge of the reaction process is very important for the system’s further expansion. The objective lies not only in replacing transition metals in the long term but also in opening up the possibility for reactions which are not possible with conventional catalysts.

The chemists in Frankfurt consider that especially substitution reactions are highly promising which permit easy access to compounds of hydrogen with other elements. Expensive and potentially hazardous processes are still mostly used for such syntheses. For example, the simplified production of silicon-hydrogen compounds would be extremely attractive for the semiconductor industry.

Image for download: www.uni-frankfurt.de/63671511

Information: Prof. Matthias Wagner, Institute of Anorganic and Analytical Chemistry, Phone +49 (0)69 798-29156, Matthias.Wagner@chemie.uni-frankfurt.de

 

Oct 21 2016
10:42

Theoretical phyiscists model the sound of gravitational waves

Did LIGO detect black holes or gravastars?

The idea of black holes has been around for a long time. From the original "dark stars" suggested by John Michell and Pierre Laplace 200 years ago, to ubiquitous sci-fi movies and TV series like Star Trek, the black hole (whose name was coined by John Wheeler in the 1960's) has become a familiar concept, albeit not so well understood.

And that also goes for physicists and astrophysicists working with them. Some of the strange mathematical properties of black holes, coming from Karl Schwarzschild's first solution of the Einstein field equations of general relativity in 1915, still puzzle the scientists. The existence of an event horizon and a central singularity, leading to conundrums like the information paradox, have inspired some researchers to propose alternative theories.

One of the alternative models is the gravastar (a gravitational vacuum condensate star) proposed by Pawel Mazur and Emil Mottola in 2001. A gravastar would be made of a core of exotic matter similar to dark energy, that prevents the collapse of a matter shell surrounding it, made of the normal matter that once made up a star. When the star started to collapse at the end of its life, a phase transition would happen that could create this exotic matter before the event horizon could be formed. This speculative object would be almost as compact as a black hole, but the tiny difference between them would be enough to prevent the formation of the event horizon and the conceptual questioning that comes with it.

How, then, could we tell a gravastar from a black hole? It would be almost impossible to "see" a gravastar, because of the same effect that makes a black hole "black": any light would be so deflected by the gravitational field that it would never reach us. However, where photons would fail, gravitational waves can succeed! It has long since been known that when black holes are perturbed, they "vibrate" emitting gravitational waves. Indeed, they behave as "bells", that is with a signal that progressively fades away, or "ringsdown". The tone and fading of these waves depends on the only two properties of the black hole: its mass and spin. Gravastars also emit gravitational waves when they are perturbed, but, interestingly, the tones and fading of these waves are different from those of black holes. This is a fact that was alreadyknown soon after gravastars were proposed.

After the first direct detection of gravitational waves that was announced last February by the LIGO Scientific Collaboration and made news all over the world, Luciano Rezzolla (Goethe University Frankfurt, Germany) and Cecilia Chirenti (Federal University of ABC in Santo André, Brazil) set out to test whether the observed signal could have been a gravastar or not.

When considering the strongest of the signals detected so far, i.e. GW150914, the LIGO team has shown convincingly that the signal was consistent with the a collision of two black holes that formed a bigger black hole. The last part of the signal, which is indeed the ringdown, is the fingerprint that could identify the result of the collision. "The frequencies in the ringdown are the signature of the source of gravitational waves, like different bells ring with different sound", explains Professor Chirenti.

After modelling the expected sound from a gravastar that would have the same characteristics of the final black hole, the two researchers have concluded that it would be very hard to explain the frequencies observed in the ringdown of GW150914 with a gravastar. To use the same language introduced before, although the gravitational-wave signals from gravastars are very similar to those of black holes, the tones and fadings are different. Just like two keys in a piano emit different notes, the "notes" measured with GW150914 simply do not match those that can be produced by gravastars. Hence, the signal measured cannot have been produced by two gravastars merging into another and larger gravastars. This result was recently resented in a paper published on Physical Review D.

"As a theoretical physicist I'm always open to new ideas no matter how exotic; at the same time, progress in physics takes place when theories are confronted with experiments. In this case, the idea of gravastars simply does not seem to match the observations", says Professor Rezzolla.

Publikation:
Cecilia Chirenti, Luciano Rezzolla: "Did GW150914 produce a rotating gravastar?", in Physical Review D 94, 084016 (2016). https://doi.org/10.1103/PhysRevD.94.084016.

Image for download: www.uni-frankfurt.de/63684192

Image caption: Gravitational wave signal from GW150914 as measured in the two detectors at Livingston and Hanford (top panel); artistic rendering of a gravastar (lower panel).

 

Sep 28 2016
14:43

Renowned scientists from Germany and abroad discuss the location of religious topics in modern science

Religious education: Where the debate is taking place

FRANKFURT.Professional mobility and immigration have changed society permanently, and homogenous religious landscapes in Germany belong to the past. The impact of this development on religious upbringing and education will be discussed at a conference held by the Faculty of Protestant Theology at Frankfurt's Goethe University on the 12th and 13th October 2016. All interested are welcome to attend.

In Germany, the teaching of religious studies in state schools is anchored in the constitution, and training for the required teachers takes place at universities. Until the 1960s, this was also reflected in teacher training publications, just as all other areas of education have their place in general educational science today. However, discussions about the role of religious education in modern societies have been moved out of educational and into theological faculties since Germany's student movement of 1968.

Changes in society due to increasing mobility and migratory movements also indicate a changing view of religious upbringing, education, and socialisation. The growing percentage of Muslims in the population and the request for Islamic religious studies also sheds new light on Christian religious education. However, in which field of science should the debate about this take place? Has religion been neglected in educational research until now? Or should educational research have more weight in the field of theology?

The conference "Religion and Educational Research. National Traditions and Transnational Perspectives", initiated by Prof. David Käbisch, scholar in the field of Protestant religious education, will question the significance of religion-related research in educational science, especially when compared internationally. Renowned scientists from different countries have been invited to participate, including Prof. Deirdre Raftery (Dublin, Ireland), Prof. Daniel Lindmark (Umeå, Sweden), Dr. Ezequiel Gomez Caride (Buenos Aires, Argentina), and Prof. Mette Buchardt (Aalborg, Denmark).

Against the backdrop of topical discussions about state schools as a location for Islamic religious education and the current dynamic of political conflicts in France, Turkey, the Levant, and North Africa, the conference will hear from speakers whose research projects have a special focus on Islam. Frankfurt education researcher Prof. Harry Harun Behr will speak about “Islamic Education-Research in Germany”, and Islamic studies researcher Prof. Armina Omerika will discuss "Transnationalizing the History of Islam and Islamic Education" in the case of Bosnia-Herzegovina. The main topic of the conference is one that will become more important in the future, especially in the Rhine-Main region due to its dynamic population. At the same time, it will promote the international networking of religion-related research at Frankfurt University.

 

 

Sep 21 2016
14:44

Mergers expert Schweizer: Hostile takeovers are always particularly risky / Cultural differences should not be underestimated

Monsanto takeover a “major challenge” for Bayer

Lars Schweizer, Professor for Strategic Management at Goethe University Frankfurt, calls the planned takeover of Monsanto by German pharmaceuticals giant Bayer a major challenge. Apart from cultural differences and the strategic repositioning of Bayer which will become necessary as a result of the takeover, Schweizer especially points out that the move originally began as a hostile takeover. “That means that so far Bayer has only been able to look at Monsanto from the outside. They know neither the exact figures nor anything about internal affairs, but instead simply made an offer on the basis of the market price.” According to Schweizer, Bayer will discover little by little whether this price is indeed justified. On average, half of all takeovers fail (see interview with Schweizer from December 2015).

With regard to cultural distance, Lars Schweizer reminds of the example of Daimler-Chrysler. “The cultural differences between Germany and the USA are not to be underestimated.” The alliance between German car manufacturer Daimler and the US-American Chrysler group in 1997, which was extolled at first as a “marriage made in heaven”, was annulled in 2007 when the targeted goals proved impossible to achieve and the value of both parts of the company dropped umpteen billion euro.

Schweizer also points out that the takeover of Monsanto will mean a shift in weights within the Bayer group and hence make strategic repositioning necessary. “Such realignment always raises the question of whether workforce and clientele will go along with it.” Monsanto’s rather poor reputation and above all its controversial glyphosate weedkiller are certainly not particularly conducive here.

Then there is the substantial purchase price which Bayer must first of all finance. Schweizer emphasizes in this context that the sum is not based on any meticulous audit, but instead ultimately on the market value of the US-American firm alone. “A takeover which originated as a hostile offer thus always involves a greater risk than mergers already are.” In Schweizer’s view, the planned takeover of Monsanto is hence a major challenge overall for the Leverkusen-based firm and only after many years will it be possible to judge accurately its success or failure.