From 29 June till 3 July the University of Tartu Institute of Physics (UTIP) is hosting an international conference “Geometric Foundations of Gravity and eXtensions”, where gravity theorists, cosmologists, particle physicists and mathematicians gather to discuss what kind of solutions to contemporary problems in fundamental physics could be found by exploring less studied possibilities in the geometric description of spacetime structure.
This is the 10th anniversary edition of the series of conferences held in Tartu, where the gravity theory research group has become a trailblazer in the subject. "In recent years, researchers have been puzzled by some statistically significant tensions between the observational data of the Universe and the standard model of cosmology. These discrepancies may indicate the need to extend the theoretical framework of Einstein's general theory of relativity, which is the basis of modern gravitation and cosmology. On the other hand, it turns out that the recently developed more complete geometric formulation of general relativity is able to resolve some deep conceptual problems, which theorists have been struggling with for over a hundred years since Einstein," explains Tomi Koivisto, visiting professor of UTIP, highlighting some of the hot topics of the conference.
A special focal point of the current conference is doing research in the age of AI. “There are great expectations within the scientific community about how artifical intelligence may transform the way we do science. For theoretical physicists, the AI revolution has arrived not without controversy, but also as a powerful ally: it became a strong support for accelerating our tasks of computations and generating new ideas. This is why, during the conference, we plan to hold a debate with all participants on the role of AI in theoretical physics: what can it genuinely do, what are its limitations, and what ethical questions and potential risks raise with it,” outlines the topic Dr. María José Guzmán, associate professor of UTIP an convener of the AI discussion panel at the conference.
Although the present conference is already tenth gravity meeting in Tartu in a row, and despite a rather specialised subject, the international interest is growing. About 80 participants from 20 countries have registered to come to Tartu which is more than in the earlier years, notes UTIP associate professor in theoretical physics, head of the Laboratory of Theoretical Physics Dr. Laur Järv. The cutting edge research performed in Tartu and communicated at the conferences have contributed to propel UTIP among the top 1% of the world’s most highly cited research institutions in the field of physics.
General public who finds the future of science interesting, can satisfy the curiosity at the conference public lecture held in the Tartu Old Observatory on Tuesday, 30 June at 18:15. Ginevra Braga from Gran Sasso Science Institute (Italy) who has pioneered research exploring how AI-assisted methods can support theoretical investigations in gravity, will speak on the topic “From Questions to Discoveries: How AI Can Support Scientific Research."
See more information on the conference homepage.
From 30 June till 4 July the University of Tartu Institute of Physics (UTIP) is hosting an international conference “Geometric Foundations of Gravity 2025”, where gravity theorists, cosmologists, particle physicists and mathematicians gather to discuss what kind of solutions to the contemporary problems in fundamental physics could be found by exploring the less studied possibilities in the geometric description of the spacetime structure.
This is the latest edition of the series of conferences held in Tartu, where the gravity theory research group has become a trailblazer in the subject. "In recent years, researchers have been puzzled by some statistically significant tensions between the observational data of the Universe and the standard model of cosmology. These discrepancies may indicate the need to expand the theoretical framework of Einstein's general theory of relativity, which is the basis of modern gravitation and cosmology. On the other hand, it turns out that the recently developed more complete geometric formulation of general relativity is able to resolve some deep conceptual problems, which theorists have been struggling with for over a hundred years since Einstein," explains Tomi Koivisto, visiting professor of UTIP, highlighting some of the hot topics of the conference.
"Geometry has played a pivotal role in the development of modern physics, and Einstein was perhaps the first to lead the way through his geometrization of gravity in terms of Riemannian differential geometry," continues Dr. Sotirios Karamitsos, a postdoctoral fellow in the gravity group. "However, the notions of geodesic motion and curvature, inextricably linked through the metric in Einstein's original formulation, can be conceptually decoupled from one another, leading to the much more general class of metric-affine theories. In this framework, matter can interact with spacetime through not only energy density and momentum, but also hypermomentum (dilation, shear, and spin), leading to torsion and non-metricity, more sophisticated geometrical effects that are not present in the original Riemannian formulation. These effects represent a physical, tangible departure from general relativity, and their signatures can be seen and measured across the cosmos, from subtle alterations to properties of stars, black holes, and gravitational waves, to the cosmological evolution of the Universe itself," elaborates Dr. Karamitsos further.
The current event this year is already the ninth international gravity meeting in a row, tells UTIP associate professor in theoretical physics, head of the Laboratory of Theoretical Physics Dr. Laur Järv. This year is made special by the computer algebra workshop held as a part of the conference, focusing on the application of free software packages Cadabra and SymPy in complicated symbol calculations. More than 60 participants from over a dozen countries will come to Tartu, about the same number of researchers have registered interest to follow the talks online. Thanks to the support of the University of Tartu Asia Centre, one of the conference plenary speakers will be Dr. Che-Yu Chen from RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences, a national scientific research institute of Japan.
General public who finds the fundamental issues of the cosmos interesting, can satisfy the curiosity at the conference public lecture held in the Tartu Old Observatory on Tuesday, 1 July at 18:15. Dr. Aneta Wojnar, associate professor at Wroclaw University and the leader of the EU funded "Fundamental Physics and Seismology" research network will speak on the topic “From stars and seismic waves to the fundamentals of gravity”.
See more information on the conference homepage.
From 17 till 21 June the University of Tartu Institute of Physics (UTIP) is hosting an international conference “Metric-Affine Frameworks for Gravity 2024”, where gravity theorists, cosmologists, particle physicists and mathematicians gather to discuss what kind of solutions to the contemporary problems in fundamental physics could be found by exploring the less studied possibilities in the geometric description of the spacetime structure.
This is the latest edition of the series of conferences held in Tartu, where the gravity theory research group has become a trailblazer in the subject. "In recent years, researchers have been puzzled by some statistically significant tensions between the observational data of the Universe and the standard model of cosmology. These discrepancies may indicate the need to expand the theoretical framework of Einstein's general theory of relativity, which is the basis of modern gravitation and cosmology. On the other hand, it turns out that the recently developed more complete geometric formulation of general relativity is able to resolve some deep conceptual problems, which theorists have been struggling with for over a hundred years since Einstein," explains Tomi Koivisto, visiting professor of UTIP, highlighting some of the hot topics of the conference.
"Following the spirit Einstein's geometrization of gravity, contemporary theoretical research is interested in the various modifications and extensions that go beyond the usual Riemannian framework," continues Dr. Damianos Iosifidis, also a postdoctoral fellow in the gravity group. "Such extended geometric arenas may be related to the the other properties of matter besides energy and momentum. For instance in the metric-affine theories, the micro-properties of matter (like spin, dilation, and shear) can also play a role and produce additional non-Riemannian effects of spacetime torsion and non-metricity. These features will have an influence on the gravitational phenomena in a non-trivial way and consequently can modify the cosmological evolution or the universe, or alter the subtle properties of stars, black holes, and gravitational waves," elaborates Dr. Iosifidis further.
The current event this year is already the eighth international gravity meeting in a row, tells UTIP associate professor in theoretical physics, head of the Laboratory of Theoretical Physics Dr. Laur Järv. While the recent conferences had to be conducted basically online or in a heavily hybrid format, in this year the conference puts focus on in-person participation. More than 50 participants from over a dozen countries will come to Tartu, while over 30 more researchers have registered interest to follow the talks online.
General public who finds the fundamental issues of the cosmos interesting, can satisfy the curiosity at the conference public lecture held in the Tartu Old Observatory on Tuesday, 18 June at 18:15. Dr. Christian Pfeifer, a researcher at the Center of Applied Space Technology and Microgravity in Bremen will speak on the topic “Gravity: The Final Frontier? The search for quantum gravity on largest and smallest scales” aiming at unraveling the mysteries of our universe and highlighting the need for a theory that will encompass quantum mechanics and general relativity.
From 19 till 22 June the University of Tartu Institute of Physics (UTIP) is hosting an international conference “Geometric Foundations of Gravity 2023”, where gravity theorists, cosmologists, particle physicists and mathematicians gather to discuss what kind of solutions to the contemporary problems in fundamental physics could be found by exploring the less studied possibilities in the geometric description of the spacetime structure.
This is the latest edition of the series of conferences held in Tartu, where in the recent years the gravity theory research group has become a trailblazer in the subject. "Currently, the way science describes the gravitational phenomena ranging from planetary motions to black holes and universe as a whole is based on Einstein's theory of general relativity. It relies on the mathematics of Riemannian geometry, and stipulates how the energy and momentum of matter generate the curvature of spacetime. The theory has proven to be really successful during the last century as it explains many observations and experiments. Yet there are several major open questions concerning the structure of the universe and its origin. In this conference, we have gathered experts from different areas of theoretical physics and mathematics with the aim of exploring new geometrical features that might allow us to address these open questions," explains Dr. Alejandro Jiménez, a postdoctoral fellow in the gravity group.
"Following the spirit Einstein's geometrization of gravity, contemporary theoretical research is interested in the various modifications and extensions that go beyond the usual Riemannian framework," continues Dr. Damianos Iosifidis, also a postdoctoral fellow in the gravity group. "Such extended geometric arenas may be related to the the other properties of matter besides energy and momentum. For instance in the metric-affine theories, the micro-properties of matter (like spin, dilation, and shear) can also play a role and produce additional non-Riemannian effects of spacetime torsion and non-metricity. These features will have an influence on the gravitational phenomena in a non-trivial way and consequently can modify the cosmological evolution or the universe, or alter the subtle properties of stars, black holes, and gravitational waves," elaborates Dr. Iosifidis further.
The current event this year is already the seventh international gravity meeting in a row, tells UTIP associate professor in theoretical physics, head of the Laboratory of Theoretical Physics Dr. Laur Järv. While the recent conferences had to be conducted basically online or in a heavily hybrid format, in this year the conference puts focus on in-person participation. More than 70 participants from 20 countries will come to Tartu, while over 40 more researchers have registered interest to follow the talks online.
General public who finds the fundamental issues of the cosmos interesting, can satisfy the curiosity at the conference public lecture held in the Tartu Old Observatory on Tuesday, 20 June at 18:15. The current President-Elect of the European Physical Society Prof. Mairi Sakellariadou form King's College London will speak on the topic Early Universe Cosmology: a primer, aiming at unraveling the mysteries of our universe and highlighting the need for a theory that will encompass quantum mechanics and general relativity.
See more information on the conference homepage.
From 27 June to 1 July the University of Tartu Institute of Physics (UTIP) is hosting an international conference “Metric-Affine Frameworks for Gravity 2022”, where gravity theorists, cosmologists, particle physicists and mathematicians gather to discuss what kind of solutions to the contemporary problems in fundamental physics could be found by exploring the less studied possibilities in the geometric description of the spacetime structure.
According to one of the conference organizers, UTIP research fellow in theoretical physics Dr. Jorge G. Valcárcel the metric-affine framework offers a modern approach to gravity which attempts to unify the effects of the main fundamental properties of matter, such as the energy, momentum, and spin, into a single geometrical description. Although the mathematical undepinnings of this class of theories date back to the works of Élie Cartan, Hermann Weyl, and Albert Einstein a century ago, a systematic analysis and application of these models in cosmological and astrophysical settings has only become feasible relatively recently with a heavy use of computer algebra to aid the calculations.
Among the different variants in this family of theories, in the last years many research efforts in Tartu have focused and contributed to the development of teleparallel gravity. Also at the conference almost half of the presentations touch the various aspects of these particular kinds of models. As the conference organizer UTIP research fellow in theoretical physics Dr. María José Guzmán explains, teleparallel gravity is interesting because it provides a new landscape for exploring theories that supersede general relativity, for it uses the concept of torsion instead of curvature to describe spacetime. Thereby uncharted avenues open up to understand the observed features of the Universe, along with possible mathematical pitfalls that might render the theory unviable.
The MaffGrav conference belongs to a series of international gravity meetings held in Tartu, the current event this year is already the sixth in a row, tells UTIP associate professor in theoretical physics, head of the Laboratory of Theoretical Physics Dr. Laur Järv. While the last two conferences had to be conducted basically online, this year the conference takes place in a truly hybrid form. Despite the lingering Covid-19 pandemic and potentially threatening security situation, among the almost 120 conference participants roughly half will attend the meeting in-person.
General public who finds the fundamental issues of the cosmos interesting, can satisfy the curiosity at the conference public lecture held in the Tartu Old Observatory on Tuesday, 28 June at 18:15. Prof. Davi Rodrigues will speak on the topic Why galaxies rotate? aiming to explain what are the reasons to postulate the existence of dark matter and whether there are any viable alternatives.
See more information on the conference homepage.
Tartu international gravity conference was held for the fifth year, this time in a hybrid format
From 28 June to 2 July 2021 the conference "Geometric Foundations of Gravity", organized by the University of Tartu, Institute of Physics, Laboratory of Theoretical Physics, had over 160 registered online participants from 42 countries. Despite the uncertainties related to travel during the lingering pandemic, some researchers still found the opportunity to arrive in Tartu and the conference was held in hybrid form.
While black holes and gravitational waves have provided interesting new observational data in the past few years, in this year the crisis in cosmology in determining the so-called Hubble-Lemaitre parameter H0 started to excite researchers. Comparing the decrease in brightness of distant supernovae with accurate data on background radiation from the early universe, we obtain two predictions for the relative rate of universe expansion that differ far more than the measurement error limits would allow. Thus, it seems that the standard model of cosmology or ΛCDM, whereby the universe is described by general relativity with a cosmological constant and dark matter, does not really hold. Celia Escamilla Rivera, Professor at the Autonomous University of Mexico, gave a conference public lecture on just this topic.
A series of talks at the conference presented the latest advances in extensions and alternatives to Einstein's theory of general relativity, covering not only cosmology and black holes but also models of stars. "Especially when studying theories where other geometric quantities such as torsion or nonmetricity are involved in describing gravity instead of spacetime curvature, Tartu has become in several directions an international pioneer and a center of attraction for scientific thought," explained María José Guzmán, a young researcher from Chile who recently got a postdoc grant in Tartu. Another notable circle of presentations and discussions concerned the quantum effects of gravity and the possibilities for their manifestation in astrophysical observations, where the basic ideas of theorists offer an input into the planning of new observation missions.
"Geometry is beautiful. It is even more beautiful when you realize that it suits to describe the laws of nature. However, there are still blank spots in this particular description, and this is why we are here: to discover," concluded Aneta Wojnar, a University of Tartu research fellow in theoretical physics, one of the conference organizers.
University of Tartu physicists organise a teleconference on teleparallel gravity
On 15–19 June 2020, the University of Tartu Institute of Physics will host an international online conference on teleparallel theories of gravity, where about 100 theoretical physicists and mathematicians from all continents have registered their interest to attend.
In mathematical terms Einstein's 1915 theory of general relativity describes the force of gravity by spacetime curvature. This explains many astronomical phenomena, and has recently received remarkable confirmation by the observations of gravitational waves as well as the black hole image. Yet the unresolved puzzles of dark matter and dark energy invite the researchers to think beyond general relativity. In fact, Einstein himself in his later years played with the alternative geometric notions of torsion and nonmetricity to model gravity. Such theories where the spacetime has no curvature are called "teleparallel" in the mathematical language.
These early ideas did not receive too much attention, as general relativity seemed to work well, but were later picked up and developed further by other researchers. "Currently we know several alternative formulations leading to the equivalent classical dynamics. The question arises whether the geometry of spacetime can be decided by experiments, or whether it is merely a matter of convention," Tomi Koivisto, Senior Research Fellow of Theoretical Physics at the University of Tartu and one of the conference organisers, explained the crux of the problem.
The conference is already the fourth consecutive international scientific meeting dedicated to the geometric foundations of gravity, organised by the University of Tartu Institute of Physics as a part of the activities of the Centre of Excellence The Dark Side of the Universe. "This conference was initially planned as a relatively small and specialised workshop to discuss some recent results and ponder the open problems, but as the travel restrictions forced the event to go online, the participation numbers tripled," said Laur Järv, Senior Research Fellow of Theoretical Physics and Assistant Director of the institute.
The conference talks and discussions are scheduled to take place in a narrow time frame from 12 to 18, to better accommodate participants from the distant time zones of Asia and America. The welcome event is replaced by a TeleQuiz, and instead of the conference excursion, the participants are invited to visit the virtual exhibition hall of the University of Tartu Museum.
On Tuesday, 16 June at 18, Professor Emmanuel Saridakis of the National Technical University of Athens and Hefei University of Technology, and Lead Researcher at the National Observatory of Athens, delivers a popular lecture describing the most recent insights and discoveries from the cosmos, "Black holes and gravitational waves: a new window to look at the universe". The lecture is held in English and is accessible online for free.
More details are available on the conference webpage.
Gravity conference delves into the geometric foundations of the universe
On 17-21 June 2019 University of Tartu, Institute of Physics will host the 2nd international conference "Geometric Foundations of Gravity", attended by over 60 theoretical physicists and mathematicians from 20 countries.
Einstein's general relativity, which mathematicallly describes the force of gravity by spacetime curvature, explains well many astronomical phenomena, and has recenty acquired remarkable confirmation by the observations of gravitational waves as well as the black hole image. Yet, the unresolved problems of dark matter and dark energy raise the possibility that general relativity is just a limiting case of a more broad theory, that engenders significant effects only on the behaviour of the universe at very large scales. "Fitting together the standard models of particle physics, cosmology, and gravity for a comprehensive description of the universe does not give a fully consistent picture. This motivates the researchers to revisit the geometric foundations and systematically consider all possible alternatives in the formulation of the theory," explains the topic UT IP senior research fellow in theoretical physics Manuel Hohmann, one of the conference organizers.
The conference is run by the UT IP Laboratory of Theoretical Physics, and it is a part of the activities of the Center of Excellence "The Dark Side of the Universe", supported by the European Regional Development Fund. The invited speakers of the conference include Professors Fawad Hassan (Stockholm), Lavinia Heisenberg (ETH Zürich), Jutta Kunz (Oldenburg) and Derek Wise (Concordia, St. Paul). "Tartu has become and internationally recognized hub of gravity theory and it is a pleasure to see that after two years many seasoned experts as well as young researchers in the field have found a possibility to delve with us into the puzzles of universe," rejoices the UTIP assistant director Laur Järv, also a conference organizer.
On the popular level the gravity related topics are explained at a public lecture on Tuesday, 18 June at 6 p.m. at Tartu Old Observatory (on Toomemägi). Professor Lavinia Heisenberg will speak in English under the title "Our Dark Universe".
More details are available on the conference webpage.
On June 25-29, 2018, the Institute of Physics of the University of Tartu will host a conference on teleparallel gravity, where a few dozen theoretical physicists from ten countries have gathered to mathematically understand the deep structures of the universe.
The history of teleparallel gravity goes back to Einstein's 1928 articles, where he tried to construct a theory unifying all forces. While Einstein's general theory of relativity, postulated in 1915, describes the gravitational field through the curvature of space-time, while the torsion and non-metricity of space-time are taken to be zero, teleparallel theories assume that the curvature of space-time is zero and gravity is described by either torsion or non-metricity. The curvature of space means that when geometric objects are moved, they change their orientation, while the absence of curvature allows objects to remain parallel to themselves when moved, hence the name teleparallelism. The theories in question are constructed in such a way that in terms of physical predictions they are equivalent to the general theory of relativity, but the interpretation of mathematical quantities is different and the structure of the teleparallel theory begins to resemble other theories describing fundamental interactions. If the theory is extended or generalized, for example, with a view to describing dark energy or dark matter, then the models based on teleparallelism begin to differ from analogous extensions of the general theory of relativity, hence the growing interest of researchers in them.
As a side event of the conference, a public lecture will be held on Tuesday, June 26 at 18:15 in the old Tartu Observatory, where Salvatore Capozziello, professor of astronomy and astrophysics at the University of Naples "Federico II" and president of the Italian Society for General Relativity and Gravitation, will speak on the topic of time travel, black holes and wormholes. The lecture will be in English, all interested parties are welcome!
Gravitational theorists gather in Tartu to think beyond Einstein
From August 28 to September 1, the Institute of Physics of the University of Tartu will host an international conference “Geometric Foundations of Gravity”, bringing together over 60 theoretical physicists and mathematicians from more than 20 countries.
Einstein’s general theory of relativity, which describes gravitational phenomena mathematically through the curvature of space-time, is in good agreement with many astronomical observations and recently received brilliant confirmation in the form of the discovery of gravitational waves. However, the still unsolved problems of dark matter and dark energy in cosmology raise the possibility that general relativity is only a limit case of some more general theory, the observational effects of which only manifest themselves in the behavior of the universe at extremely large scales. “This encourages scientists to consider the geometric foundations of gravity and the possibilities of a coherent extension of the general theory of relativity. Thus, in the last decade, in addition to new observational data, many interesting developments have also been added to the field of gravitational theory,” explains Laur Järv, one of the organizers of the thematic conference.
Among the speakers invited to the conference are, for example, professors Salvatore Capozziello (Naples), Friedrich Hehl (Cologne), Claus Lämmerzahl (Bremen) and Sergei Odintsov (Barcelona). Scientists from Brazil, Chile, Canada, Japan, South Korea and China are represented from more distant countries.
The conference is organized by the Theoretical Physics Laboratory of the Institute of Physics of the University of Tartu and is part of the activities of the “Dark Universe” Center of Excellence, which is funded by the European Regional Development Fund. The organization of the conference is also supported by the University of Tartu and the Tartu City Government.
Gravity and the universe have a long history in Tartu. Professor Sven Dimberg of the Swedish Academy Gustavo-Carolina was one of the first in the world to introduce Newton's theory of gravity in a university course. Research on Einstein's general theory of relativity began in Tartu in the late 1930s under the initiative of the later academician Harald Keres and continued after the war. In 1963, an all-Union gravity summer school was held here, where internationally renowned theorists Vladimir Fok, Aleksei Petrov, Dmitri Ivanenko and others were lecturers. In the following decades, the Tartu working group had close ties both east and west: it participated in conferences and seminars and organized them itself as much as it could. Several major international conferences on theoretical and mathematical physics have been held in Tartu in the past, but now, for the first time, the focus is clearly on gravity.
At a popular science level, anyone interested can gain an idea of the issues related to gravity at a public lecture at the Old Observatory in Tartu, which will take place on Tuesday, August 29 at 6:15 PM and will be given by Professor Emeritus of Lancaster University, Robin Tucker (in English).
