Our group hosts M. Rodriguez and O. Varela
Wednesday, July 3, 2013
Our collaborators and friends Maria José and Oscar visited us in Lisbon last week, and each one gave an excellent seminar.
Visit to Belém do Pará
Friday, June 14, 2013
Nami, Hiro, Richard and Vitor visit the gravity group in Belém do Pará,
for the workshop II Amazonian school on gravity.
The picture shows the Guamá bay in the background.
Kerr-Newman black holes are also special
Wednesday, May 29, 2013One of the most amazing predictions of Einstein’s General Relativity is the existence of black holes, regions of the spacetime that are disconnected from the rest of the Universe, as not even light can escape from them. Surprisingly, black holes are extremely simple objects and behave pretty much like elementary particles. Regardless the infinite ways they can be formed, all black holes in the Universe are described by only three physical quantities: mass, spin and electric charge. Black holes with nonvanishing mass, spin and charge are called Kerr-Newman black holes and these solutions were discovered in 1965, after decades of theoretical labour.
Black holes possess characteristic frequencies of vibration, called quasinormal modes. These modes are associated to the emission of gravitational waves, pretty much like the vibrations of a guitar string are associated to acoustic waves. Thus, as the properties of an instrument can be traced back from the sound it produces, by studying the quasinormal modes of black holes one can “hear the sound of spacetime”. In his infamous monograph on black holes, Nobel laureate Subrahmanyan Chandrasekhar forecast that the computation of Kerr-Newman modes would require a major breakthrough.
Now, Paolo Pani and colleagues have developed a new technique to study the vibrations of black holes. Although restricted to slowly-rotating black holes, unexpected features were already uncovered, such as isospectrality between modes, which can have important theoretical implications for gravity and high-energy physics.
For more details read the original article, to appear in Physical Review Letters.
Paolo and Hiro visit PI
Saturday, May 11, 2013
Paolo and Hiro visited the Perimeter Institute for one week, where Paolo presented a summary of his recent work on massive bosonic fields.
Jan visited Térence in Mons
Thursday, April 11, 2013
Jan visited Térence in Mons last week and is looking forward to the workshop in June to have more Belgian beer!