Sebastian Fischetti (left) is a graduate student of Professor Don Marolf (middle) at UCSB. Aron Wall (right) is a member of the School of Natural Sciences at the Institute for Advanced Study.
One of the most useful features of gauge/gravity duality is that it converts difficult problems in certain types of gauge theories into (relatively) simple geometric problems in gravity in one higher dimension. For example, the Hubeny-Rangamani-Takayagani (HRT) conjecture says that Continue reading
Interstellar‘s accretion disc, with and without Doppler shift. Figure 15 a, c from “Gravitational lensing by spinning black holes in astrophysics, and in the movie Interstellar” Oliver James et al 2015 Class. Quantum Grav. 32 065001
New insights into the effects of black holes from the team responsible for the Oscar®-winning visual effects of Interstellar.
Depicting a super-massive black hole in the movie Interstellar presented a new challenge to our visual effects team at Double Negative. Luckily the Executive Producer was theoretical physicist Kip Thorne who ended up working closely with us to create a new computer code, DNGR: Double Negative Gravitational Renderer. This code traces the path of light past a spinning black hole (Kerr metric) whose immense gravity warps space and time in its vicinity. A hot disk of gas orbiting the hole appears to Continue reading
Nils Andersson is Head of the Southampton University Gravity group. He is mainly focussed on problems involving the modelling of neutron stars and understanding various related astrophysical phenomena, from pulsar glitches to magnetar giant flares. Away from the office, he writes science-inspired books for kids and occasionally blows his own trumpet in public.
Each and every trade has its favourite tools, some more powerful than others. A plumber would not get by without a good wrench, a carpenter needs a hammer, a mechanic a screwdriver and so on. Theoretical physicists prefer action principles.
This preference is natural given that many of the phenomena we are interested in are associated with deviations from some minimum energy equilibrium state. It is well known that, once you understand a problem from the variational point-of-view, you have a very powerful tool at your hands. However, it is also generally accepted that this approach is restricted to conservative systems.
Our recent paper in Classical and Quantum Gravity challenges this consensus view. Working in the framework of classical general relativity (no extra dimensions and fancy stuff here!), we develop Continue reading
Geoffrey Lovelace is an Assistant Professor of Physics at California State University, Fullerton. As member of Fullerton’s Gravitational-Wave Physics and Astronomy Center and the Simulating eXtreme Spacetimes collaboration, his research interests focus on using computer simulations to model colliding black holes and neutron stars and the gravitational waves they emit.
A single black hole’s size limits its spin. Do colliding black holes obey this limit?
In our recent paper, published in Classical and Quantum Gravity, we take a first look at how supercomputer simulations can help reveal the answer.
A black hole is an object whose gravity is so strong that nothing, even light, can escape from inside its horizon. An isolated, uncharged black hole can be completely described by just two numbers: its spin and its horizon surface area. All of the black hole’s properties then follow from Kerr’s solution of Einstein’s equations.
Kerr’s solution implies that a single black hole can spin no faster than its horizon area times a constant: spinning any faster would destroy the horizon. Astronomers have found evidence that some black holes spin very close to the limit (but still below it). Mathematical relativists have proven that this spin limit is obeyed not only by Continue reading
Arthur Lipstein is a Postdoctoral Research Associate at University of Hamburg/DESY.
Ambitwistor string theories are a family of chiral (holomorphic) string theories whose target space is the space of complexified null geodesics in a general space-time. Like conventional strings, they are critical in 10 dimensions and describe supergravity, but unlike conventional strings, they do not admit a tower of higher massive modes (and are correspondingly not thought to be ultraviolet finite). They provide a natural generalization of the twistor-strings of Witten, Berkovits and Skinner to arbitrary dimension and their correlators give rise to the beautiful formulae for gravitational and Yang-Mills scattering amplitudes in all dimensions recently discovered by Cachazo, He and Yuan (CHY). Ambitwistor strings were also used to obtain new formulae in four dimensions by the authors of this article.
In a recent series of papers, Strominger and Continue reading
Guillaume Faye is Chargé de Recherche (researcher)
The gravitational-wave observatory Advanced LIGO is now in its commissioning stage and preparing for its first scientific runs in early 2015. It will be soon followed by the Advanced Virgo detector. Being reasonably optimistic, one can expect the first detections to occur by 2018. The most likely sources to be observed are coalescences of two compact objects. As both detection and
parameter estimation rely on matched filtering techniques, several programs to compute accurate waveform models using various approximation techniques are being pursued. Notably, the post-Newtonian perturbative approach, where all quantities of interest are expanded in powers of Continue reading
Gary Horowitz is President of the ISGRG
In 2008, the International Society on General Relativity and Gravitation instituted a Thesis Prize in memory of two great pioneers of quantum gravity: Professors Peter Bergmann (1915–2002) and John Wheeler (1911–2008). This prize is sponsored by Classical and Quantum Gravity and is awarded for the best PhD thesis in the broad area encompassing all approaches to quantum gravity. The winner of the next iteration of the prize will receive a cheque for $1800 and a certificate.
The primary criteria for selection will be the high quality of scientific results, creativity and originality, and the significance of results to the broad area of the prize. The winner for this prize will be chosen by a committee of leading international experts in the field approximately six months before presentation of the prize at Continue reading
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