Goethe-Universität — Press releases

Goethe University PR & Communication Department

Nov 5 2025

11:00

Physicists from Frankfurt and Shanghai compare shadow images of black holes with alternative theories of gravity

Are there different types of black holes? New method puts Einstein to the test

Images of black holes are more than just fascinating visuals: they could serve as a “testing ground” for alternative theories of gravity in the future. An international team led by Prof. Luciano Rezzolla has developed a new method to examine whether black holes operate according to Einstein’s theory of relativity or other, more exotic theories. To that end, the researchers conducted highly complex simulations and derived measurable criteria that can be tested with future, even sharper telescopes. Over the next few years, this method could reveal whether Einstein’s theories hold true even in the most extreme regions of the universe.

Black holes are considered cosmic gluttons, from which not even light can escape. That is also why the images of black holes at the center of the galaxy M87 and our Milky Way, published a few years ago by the Event Horizon Telescope (EHT) collaboration, broke new ground. “What you see on these images is not the black hole itself, but rather the hot matter in its immediate vicinity,” explains Prof. Luciano Rezzolla, who, along with his team at Goethe University Frankfurt, played a key role in the findings. “As long as the matter is still rotating outside the event horizon – before being inevitably pulled in – it can emit final signals of light that we can, in principle, detect.”

The images essentially show the shadow of the black hole. This finding now opens up the opportunity to closely examine the theories behind these extreme cosmic objects. So far, Einstein’s general theory of relativity is considered the gold standard in physics when it comes to the description of space and time. It predicts the existence of black holes as special solutions, along with all their peculiarities. This includes the event horizon, beyond which everything – including light – disappears. “There are, however, also other, still hypothetical theories that likewise predict the existence of black holes. Some of these approaches require the presence of matter with very specific properties or even the violation of the physical laws we currently know,” Rezzolla says.

Together with colleagues from Tsung-Dao Lee Institute Shanghai (China), the Frankfurt-based physicist introduced a new possibility to check such alternative theories in the journal “Nature Astronomy”. Until now, there has been no solid data to enable either the refutation or confirmation of these theories – something the researchers plan to change in the future by using shadow images of supermassive black holes.

“This requires two things,” Rezzolla explains. “On the one hand, high-resolution shadow images of black holes to determine their radius as accurately as possible, and on the other hand, a theoretical description of how strongly the various approaches deviate from Einstein’s theory of relativity.” The scientists have now presented a comprehensive description of how different types of hypothetical black holes diverge from relativity theory and how this is reflected in the shadow images. To investigate this, the team conducted highly complex three-dimensional computer simulations that replicate the behavior of matter and magnetic fields in the curved spacetime surrounding black holes. From these simulations, the researchers then generated synthetic images of the glowing plasma.

“The central question was: How significantly do images of black holes differ across various theories?” explains lead author Akhil Uniyal of the Tsung-Dao Lee Institute. From this, they were able to derive clear criteria that, with future high-resolution measurements, could often allow a decision to be made in favor of a specific theory. While the differences in images are still too small with the current resolution of the EHT, they systematically increase with improved resolution. To address this, the physicists developed a universal characterization of black holes that integrates very different theoretical approaches.

“One of the EHT collaboration’s most important contributions to astrophysics is turning black holes into testable objects,” Rezzolla emphasizes. “Our expectation is that relativity theory will continue to prove itself, just as it has time and again up to now.” So far, the results align with Einstein’s theory. However, the measurement uncertainty is still so high that only a few very exotic possibilities have been ruled out. For instance, the two black holes at the center of M87 and our Milky Way are unlikely to be so-called naked singularities (without an event horizon) or wormholes – just two of the many other theoretical possibilities that need to be checked. “Even the established theory must be continuously tested, especially with extreme objects like black holes,” the physicist adds. It would be groundbreaking if Einstein’s theory were ever proven invalid.

The EHT offers outstanding opportunities for such measurements. This collaboration of several large radio telescopes across the globe achieves a resolution equivalent to a telescope the size of Earth, for the first time enabling a sharp view into the immediate surroundings of black holes. In the future, additional telescopes on Earth are planned to be integrated into the EHT. Scientists are also hoping for a radio telescope in space, which would significantly improve the overall resolution. With such a high-resolution view, it would be possible to subject various theories about black holes to a rigorous test. As the newly presented study shows, this requires angular resolutions of less than one millionth of an arcsecond – comparable to viewing a coin on the Moon from Earth. While this exceeds today’s capabilities, it is expected to be achievable in a few years.

Publication: Akhil Uniyal, Indu K. Dihingia, Yosuke Mizuno, Luciano Rezzolla: The future ability to test theories of gravity with black-hole shadows, Nature Astronomy (2025). https://doi.org/10.1038/s41550-025-02695-4

Images for download:
https://www.uni-frankfurt.de/179886970

Caption: At the current resolution of telescopes, black holes predicted by different theories of gravity still look very similar. Future telescopes will make the differences more visible, making it possible to distinguish Einstein's black holes from others. (L. Rezzolla / Goethe University)

Further Information
Prof. Dr. Luciano Rezzolla
Institute for Theoretical Physics
Goethe University Frankfurt
Tel: +49 (69) 798-47871
rezzolla@itp.uni-frankfurt.de
https://astro.uni-frankfurt.de/rezzolla/

Oct 31 2025

11:36

“Identification of membrane targets for lipid species containing esterified EETs (ELS)” – New Koselleck Project at Goethe University Frankfurt explores unresolved research question

The Role of Lipids in Cardiovascular Diseases

Lipids are not just energy sources and structural components of cell membranes – they also act as molecules that transmit signals within and between cells. A new Koselleck Project at the Institute of Pharmaceutical Chemistry at Goethe University Frankfurt and the Max Planck Institute for Heart and Lung Research focuses on certain products derived from arachidonic acid. These products exhibit beneficial effects in cardiovascular diseases as well as in Alzheimer's dementia and chronic pain.

FRANKFURT. Some products of arachidonic acid have already been well studied: the prostanoids formed by cyclooxygenases are central mediators of inflammation, fever, and pain. Their synthesis is inhibited by drugs such as acetylsalicylic acid (aspirin). Likewise, the effects and mechanisms of leukotrienes, which are formed by lipoxygenases from arachidonic acid and serve as targets for asthma medications, are well known.

Less well understood, however, is a third group of lipids – the epoxyeicosatrienoic acids (EETs), which are produced from arachidonic acid by cytochrome P450 epoxygenases. It has been known for almost 40 years that EETs can trigger a range of beneficial biological effects: they lower blood pressure, have anti-inflammatory properties, and are neuroprotective. Yet even after decades of intensive research, the molecular pathways through which these effects are mediated remain unclear. As a result, no pharmacological targets are currently known that could be used to mimic the therapeutic potential of EETs.

A new research project funded by the German Research Foundation (DFG) under its Koselleck Program – led by Prof. Eugen Proschak and Prof. Stefan Offermanns – aims to shed light on this question through novel experimental approaches. Evidence suggests that cell membrane receptors may be involved, which could be activated either directly by EETs or after their incorporation into membrane lipids. The project, titled “Identification of membrane targets for lipid species containing esterified EETs (ELS)", will systematically search for transmembrane proteins that bind to EETs and mediate their effects. In addition, the researchers will test the hypothesis that EETs act not as free lipids but in a more complex form – that is, after being integrated into more complex membrane lipids.

“We know these effects exist, but we still don't understand how they come about. Yet to develop an entirely new class of drugs, we urgently need this basic knowledge," explains Prof. Eugen Proschak. A particular focus will be on endothelial cells – structures of the vascular system – and thus on diseases of the cardiovascular system.

The project brings together two research groups with complementary expertise: Prof. Proschak's group at the Institute of Pharmaceutical Chemistry, specializing in medicinal chemistry and the synthesis of pharmacological tools, and Prof. Offermanns' group at the Institute of Molecular Medicine, which uses classical and molecular pharmacological methods both in vitro and in vivo. Prof. Offermanns is also Director of the Max Planck Institute for Heart and Lung Research in Bad Nauheim.

Divided into four subprojects, the research combines chemical, pharmacological, and proteomic approaches – the latter encompassing the entirety of proteins present in a cell. With this innovative concept, the researchers hope to uncover the molecular mechanisms through which EETs exert their biological effects. A total of €1.25 million is available for this work until 2030.

Established in 2008, the Koselleck Program is named after Reinhart Koselleck (1923–2006), one of Germany's most important 20th-century historians and a co-founder of modern social history. Koselleck projects are awarded to “researchers distinguished by outstanding scientific achievements." Funding is reserved for particularly innovative and high-risk research approaches.

The project by Eugen Proschak and Stefan Offermanns exemplifies these criteria in an exceptional way: until now, all attempts to elucidate EETs' mechanism of action have failed. If this endeavor succeeds, the resulting insights could be groundbreaking – not least for the potential development of entirely new classes of drugs that specifically mimic the beneficial effects of EETs.

Further Information
Prof. Dr. Eugen Proschak
Institute of Pharmaceutical Chemistry / Faculty of Biochemistry, Chemistry and Pharmacy
Goethe University Frankfurt
proschak@pharmchem.uni-frankfurt.de

Prof. Dr. Stefan Offermanns
Max Planck Institute for Heart and Lung Research
stefan.offermanns@mpi-bn.mpg.de

Oct 30 2025

11:15

Frobenius Institute Research Award goes to Maren Jordan

Why fewer children are being born in Oman

Each year, the Frobenius Institute presents the Frobenius Research Award for outstanding ethnological dissertations in German-speaking countries. This year, the €3,000 prize was awarded to Maren Jordan for her dissertation “Temporalities of Reproduction: Fertility Transformations across Generations in the Sultanate of Oman."

FRANKFURT. Maren Jordan studied ethnology and Islamic studies at the University of Hamburg. After completing her master's degree, she worked in teaching. Her doctoral thesis was written as part of the German Research Foundation (DFG)-funded project “Fertility Transformation in the Sultanate of Oman," under the supervision of Prof. Julia Pauli and Prof. Laila Prager. Since 2022, she has served as academic coordinator for the Collaborative Research Center (CRC) 1475 “Metaphors of Religion: Religious Meaning-Making in Language Use" at the Center for Religious Studies (CERES) at the University of Bochum.

Between 2016 and 2017, Jordan conducted twelve months of ethnographic research in the central Omani oasis town of al-Hamra. Her work focused on a demographic development observed in Oman since the 1970s: the significant decline in birth rates, often referred to as a “reproductive revolution." Jordan's research challenges the assessment that this phenomenon constitutes a revolution tied to notions of a new “modernity." Instead, she examines changing marriage practices, gender roles, and shifting norms and values surrounding birth control and family planning, offering a nuanced perspective. Her study spans several generations, from the 1970s to the present, and is based on 70 systematically collected birth and marriage histories of women, extensive interview material, as well as supplementary quantitative data and source analyses.

According to the Frobenius Institute, the dissertation impressively demonstrates how ethnology can engage productively with other disciplines. It builds a bridge to demography while maintaining its ethnological identity, the Institute said, adding that by using quantitative data to deepen qualitative findings – and ethnographic depth to interpret statistical trends — the work is highly relevant not only to ethnology but also to sociology, demography, and gender studies.

Further Information
Frobenius Institute for Research in Cultural Anthropology
Apl. Prof. Dr. Susanne Fehlings
fehlings@uni-frankfurt.de
www.frobenius-institut.de/en

Oct 17 2025

06:34

With its launch at Goethe University Frankfurt, Germany joins Instruct-ERIC to make cutting-edge technologies freely available to researchers across Europe.

Instruct-DE Strengthens Europe’s Structural Biology Research Infrastructure

FRANKFURT. Today, October 17, 2025, the German Instruct Center Instruct-DE officially begins its work at Goethe University. Instruct-ERIC (European Research Infrastructure Consortium) is a pan-European distributed research infrastructure specialized in high-end technologies and methods in structural biology, which is recognized by the European Union. The consortium’s goal is to make cutting-edge technologies and methods from 17 partner countries accessible to researchers across Europe. Following a multi-year exploratory process, Germany was accepted as a partner country in Instruct-ERIC in 2024. In addition to providing German researchers with access to technologies in European partner countries, it also opens access to excellent German infrastructures for researchers from all over Europe.

The new German center is organized in a decentral manner and coordinated by Goethe University Frankfurt. Partner institutions include Helmholtz Munich, Helmholtz-Zentrum Berlin, DESY Hamburg, Hamburg-based European XFEL, University of Hamburg’s Center for Structural Systems Biology (CSSB), and Forschungszentrum Jülich. Instruct-DE also has four other institutions joining as national associated partners: Helmholtz Centre for Infection Research (HZI) Braunschweig, University of Bayreuth, Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP) Berlin, and Charité – Universitätsmedizin Berlin.

With the establishment of Instruct-DE, Germany’s advanced technologies become part of the freely accessible European Instruct Technology Catalog, which researchers from all partner countries can use at no cost, as explained by its spokesperson, Prof. Dr. Clemens Glaubitz. “The previously highly successful mutual use of research infrastructures is taking a decisive leap forward with Germany’s participation through Instruct-DE,” emphasizes Prof. Dr. Harald Schwalbe, Director of Instruct-ERIC, adding that, “Structural biology in Germany is conducted at the highest level. Instruct-DE not only strengthens European research but also opens up new opportunities for German researchers to engage in European collaborations.”

Contact:
Prof. Dr. Clemens Glaubitz
Instruct-DE Spokesperson
Institute of Biophysical Chemistry
Goethe University Frankfurt
Tel. +49 (0)69 798 29927
E-Mail: glaubitz@em.uni-frankfurt.de

Oct 13 2025

13:09

Global Tipping Points Report 2025 shows: It will take immense effort now to prevent the die-off of many coral reefs.

World Surpasses Its First Climate Tipping Point

In a report released today, October 13, 2025, international climate researchers conclude that the death of numerous tropical coral reefs caused by rising ocean temperatures can now only be prevented with the utmost effort. Parts of the polar ice sheets may have already passed their tipping points. Their continued melting could lead to an irreversible sea level rise of several meters.

Among the lead authors of the Global Tipping Points Report 2025 (GTPR 2025) is Nico Wunderling, Professor of Computational Earth System Sciences at Goethe University's Center for Critical Computational Studies | C3S and researcher at the Senckenberg Research Institute Frankfurt, who, together with other lead authors, headed the chapter on “Earth System Tipping Points and Risks." Wunderling says: “The devastating consequences that arise when climate tipping points are crossed pose a massive threat to our societies. There is even a risk of the tipping of one climate system potentially triggering or accelerating the tipping of others. This risk increases significantly once the 1.5°C threshold is exceeded."

Some two dozen subsystems of the climate system are known to have tipping points. According to the report, the first of these – that of tropical coral reefs – has now been reached. The study further assumes that the global average temperature will increase by 1.5°C above pre-industrial levels within the next few years. This means the world is entering a phase in which the crossing of further climate tipping points is at risk, potentially leading to far-reaching consequences such as sea level rise from melting ice sheets or global temperature changes in the event of a collapse of the Atlantic Ocean circulation. The report also proposes measures to counter further temperature increases.

Coordinating lead author of the GTPR 2025 is Tim Lenton, Professor at the University of Exeter's (UK) Global Systems Institute. More than 100 scientists from over 20 countries contributed to the report, published just in time for the 30th World Climate Conference, which begins on November 10, 2025, in Belém, Brazil. The Global Tipping Points Report, first published in 2023 and already widely noted at the time, is regarded as an authoritative publication in the field of assessing both the risks and opportunities of negative and positive tipping points in the Earth system and in human societies.

Climate tipping points have started receiving greater attention within climate sciences for only about 20 years. The authors of the report define a climate-induced tipping point in Earth systems – such as coral reefs, the Amazon rainforest, or large-scale ocean currents – as the level of warming beyond which these systems undergo self-reinforcing and often irreversible changes. For example, many tropical coral reefs would die off after exceeding their tipping point, even if humanity were to limit further global warming. The scientists predict that it is quite possible that additional tipping points will be crossed in the coming decades, especially as some may already lie at around 1.5°C of global warming – including those of the Amazon rainforest (leading to savannization), the ice sheets of Greenland and West Antarctica (causing several meters of sea level rise), and the Atlantic Ocean circulation (causing a sharp cooling of the European continent).

The GTPR also features a series of case studies on various tipping elements of the climate system, including the following:

Coral Reefs: Worldwide, coral reefs in tropical regions are suffering unprecedented mortality due to repeated mass bleaching events. The current global warming of about 1.4°C already exceeds their thermal tipping point, which scientists estimate at about 1.2°C. Even in the unrealistic case that warming could be stabilized at 1.5°C, there is a very high probability that the reefs will tip. Many will be permanently lost unless global temperatures drop again to 1°C above pre-industrial levels or less. The longer and the further this threshold is exceeded, the less likely recovery becomes.
Amazon Rainforest: Climate warming combined with partial deforestation is already exposing the Amazon rainforest to the risk of large-scale savannization at 1.5–2°C of global warming. This in turn could further amplify climate change.
AMOC (Atlantic Meridional Overturning Circulation): The collapse of the AMOC, which includes the Gulf Stream, could already occur at less than 2°C of global warming. This would lead to much colder winters in northwestern Europe, disrupt global monsoon systems, and reduce agricultural yields in large parts of the world.

The GTPR's authors emphasize that, alongside these negative tipping points in the climate system, there also exist positive tipping points in our societies. Crossing these can trigger rapid transformations toward more climate-friendly behavior. Some examples:

Renewable energies are already cheaper than fossil fuels in most parts of the world, and electric vehicles are replacing gasoline and diesel cars on the roads. This trend could prove to be both irreversible and self-reinforcing.
The gradual introduction and promotion of climate-friendly technologies by policymakers can accelerate the emergence of positive tipping points, including in the adoption of sustainable heating systems or in freight transport.
“Social contagion" mechanisms can cause a majority of people to adopt behavioral changes initiated by a minority – such as reducing meat consumption or altering mobility habits.

Global Tipping Points Report: https://global-tipping-points.org/

Further Information / Contact:
Prof. Dr. Nico Wunderling
Professor for Computational Earth System Sciences
Center for Critical Computational Studies (C3S)
Goethe University Frankfurt and Senckenberg Research Institute Frankfurt
wunderling@c3s.uni-frankfurt.de
Thilo Körkel, Research Assistant
Center for Critical Computational Studies (C3S)
koerkel@c3s.uni-frankfurt.de

Press releases – 2025