A public lecture in the Living Reviews in Relativity Anniversary Lectures Series. We are celebrating our 10th year online with a number of colloquia by distinguished authors in the Berlin/Potsdam area.

Date:
March 11, 2009 – 14:00

Place:
Max Planck Institute for Gravitational Physics (Albert Einstein Institute), Lecture Hall, Am Mühlenberg 1, 14476 Potsdam-Golm (map)

Abstract:
It is well known that the description of the non-gravitational interactions (electromagnetism, weak and strong nuclear forces) relies on finite-dimensional Lie groups and algebras (e.g., SU(3)X SU(2)X U(1)). Recently, it has been argued by many research teams that the description of the gravitational interaction should involve infinite-dimensional Lie algebras of hyperbolic Kac-Moody type, such as E(10). The talk will provide a brief, pedagogical introduction to these mathematical structures and present some of the evidence for their relevance to gravity.

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LRR Lecture Series

A public lecture in the Living Reviews in Relativity Anniversary Lectures Series. We are celebrating our 10th year online with a number of colloquia by distinguished authors in the Berlin/Potsdam area.

Date:
November 13, 2008 – 18:00

Place:
Brandenburgische Akademie der Wissenschaften (BBAW), Akademiegebäude am Gendarmenmarkt, Einstein-Saal, Jägerstraße 22/23, 10117 Berlin (map)

Abstract:
In general relativity, it is meaningless to ask what happened before the big bang because this is the moment when time itself came into existence. How the initial state arose that set up the expanding universe, or what exactly happened at that initial time are questions which cannot be answered by general relativity. In this theory, the big bang appears as a mathematical singularity: a time when the dynamical equations for a changing universe break down. Only by extending the theory by equations which do not break down can we reliably see what the earliest stages of the universe may have looked like. A commonly expected extension is to combine general relativity with quantum features. Cosmological models analyzed in this context show the emergence of repulsive forces in a small and dense universe, which prevent the formation of a singularity. Instead, the universe did have a pre-history prior to the big bang where the universe collapsed before bouncing into the expanding phase we see now. Detailed mathematical derivations combined with sensitive observations may some day allow us to obtain glimpses of our universe at and before the big bang.

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LRR Lecture Series

A public lecture in the Living Reviews in Relativity Anniversary Lectures Series. We are celebrating our 10th year online with a number of colloquia by distinguished authors in the Berlin/Potsdam area.

Date:
November 6, 2008 – 17:30

Place:
Universität Potsdam, Campus Golm, Institut für Physik und Astronomie (Haus 28), Raum 0.104 (map)

Abstract:
Gravitational waves are a firm prediction of Einstein’s general relativity theory. Ripples of the fabric of space-time propagating with the speed of light, they have already been indirectly verified in astronomy by observing the motion of the binary pulsar PSR 1913+16 around its companion. Detailed analysis show that this system is losing energy at exactly the right amount as predicted for gravitational radiation.

A huge world-wide experimental effort is currently aiming at detecting gravitational waves directly on Earth (ground-based detectors LIGO, VIRGO and GEO, and space-based one LISA). The most powerful waves are expected to be produced by systems of neutron stars or black holes when they collide together and merge. Gravitational waves should also be produced in the early Universe. A wealth of astrophysical information concerning the sources of these waves will be contained in the gravitational wave signals. Even cosmological information on the expansion and constituents of the Universe at large scales could be obtained from observations by all these detectors.

However, to be able to extract all this potential information, theorists must work hard to predict the details of gravitational wave signals with high precision. Approximation methods in general relativity have been developed that go deep inside Einstein’s gravity by including new effects impossible to detect by means other than gravitational waves. Numerical relativity too has succeeded in providing excellent predictions for the signals. Gravitational wave experiments and theory go hand in hand to probe the gravitational Universe and also to test Einstein’s gravity theory.

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A public lecture in the Living Reviews in Relativity Anniversary Lectures Series. We are celebrating our 10th year online with a number of colloquia by distinguished authors in the Berlin/Potsdam area.

Date: July 7, 2008 – 19:00

Place: Humboldt-Universität zu Berlin, Unter den Linden 6, 10117 Berlin, Hauptgebäude Hörsaal 3075 (map)

Abstract: How has the most important scientific theory of the 20th century held up under the exacting scrutiny of planetary probes, radio telescopes, and atomic clocks? After almost 100 years, is Einstein still right? In this lecture we will relate the story of testing relativity, from the 1919 measurements of the bending of light to modern measurements of decaying double-neutron-star systems that reveal the action of gravity waves, to a 2004 space experiment to test whether spacetime “does the twist”. We will show that future observations using gravitational wave detectors and other astronomical tools will test Einstein’s theory in new regimes, and may prove once and for all whether black holes really exist.

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A public lecture in the Living Reviews in Relativity Anniversary Lectures Series. We are celebrating our 10th year online with a number of colloquia by distinguished authors in the Berlin/Potsdam area.

Date: June 3, 2008 – 19:00

Place: Humboldt-Universität zu Berlin, Unter den Linden 6, 10117 Berlin, Hauptgebäude Hörsaal 2097 (map)

Abstract: Black holes have proved to be a treasure trove for fundamental physics. As is widely appreciated, they vividly bring out the powerful interplay between gravity and geometry. However, their properties have also provided deep and totally unexpected clues on the relation between the three pillars of modern physics — general relativity, quantum field theory and statistical mechanics. And they continue to baffle, vex and amaze the experts. The goal of this colloquium is to tell this fascinating story to non-experts, emphasizing recent conceptual advances.

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