Author Archives: Claire Fullarton

Designing the future of gravitational wave astronomy: Choosing the best sites for the next generation of gravitational wave detectors

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Fig 1

A new view of the world map, with the black areas indicating allowable sites for building future generation gravitational wave detectors. The other coloured areas are excluded for various reasons.

Imagine you could time travel to decades after the first detections of gravitational waves by ground-based interferometers: someone has already had the call from Stockholm, a series of amazing gravitational wave discoveries have been reported and the watching world is going wild about gravitational wave astronomy.  Such momentous events would certainly trigger the demand for even more sensitive and powerful gravitational wave detectors to drive forward this exciting new field of observational astronomy. But the immediate question would be: where to put these multi-billion dollar instruments?  Future generations of gravitational wave detectors, like the proposed European Einstein Telescope, would be very expensive to build, so choosing the most favourable sites in which to build them will be a crucial issue. Our work, published in Classical and Quantum Gravity, explores the question of Continue reading →

And now for something completely different…

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Nils Andersson

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 →

Ambitwistor Strings and Soft Theorems

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Arthur Lipstein

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 →

Nominate your student for the Bergmann-Wheeler Thesis Prize for quantum gravity

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Gary Horowitz

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 →