Better hearing with widely-spaced ears

The presence of an observatory in Japan, Australia or India would dramatically increase the probability of measuring gravitational waves

Detectors in the US, Germany and Italy are lying in wait to gather evidence that would unveil one of Albert Einstein’s last secrets: gravitational waves. Up to now, it has not been possible to detect these ripples in the curvature of space-time directly. However, if the available detectors were to be distributed differently across the globe, the chance of detecting the gravitational waves would increase more than twofold. This is the conclusion reached in a new study by Bernard F. Schutz, Director at the Max Planck Institute for Gravitational Physics (Albert Einstein Institute) in Golm. A further improvement in the detection process could also be achieved through the construction of additional gravitational wave observatories.

Background information

The direct detection of Einstein's gravitational waves is still one of the most important open questions in modern science. Their direct observation, the scientists hope, will not only underpin the general theory of relativity, especially for extreme gravitational fields around black holes, but also herald the era of gravitational wave astronomy and thus provide completely new insights into our universe: For the first time, it would then be possible to take a look into the very early "nursery" of the universe.

Since previous cosmological observations of the sky have been limited to the electromagnetic spectrum, information about the origin of the universe will only reach us from the period of about 380,000 years after the Big Bang. Development phases further back in time remain hidden from observation because light and matter previously interacted continuously with each other, and the universe only became transparent to electromagnetic radiation after this time. The various theories about the earlier universe have thus not yet been experimentally confirmed. If gravitational waves were measured directly, it would probably be possible to look back to the first quadrillionth of a second after the Big Bang and thus provide completely new insights into our universe.

Gravitational wave research is a worldwide effort, since complete information about many of the gravitational wave sources can only be obtained with several measuring instruments working simultaneously at widely spaced locations. For this reason, scientists around the world have been working closely together for a long time. They share technological research and findings, theoretical advances, and data analysis methods and tools.

The currently active observatories:

• GEO600: The German-British observatory is located near Hanover and is operated by researchers from the Max Planck Institute for Gravitational Physics (Albert Einstein Institute AEI) and Leibniz University Hanover as well as the British universities of Glasgow, Cardiff and Birmingham. The GEO project is funded by the Max Planck Society, the State of Lower Saxony, the Volkswagen Foundation, and the British Science and Technologies Facilities Council (STFC). GEO works closely with the Cluster of Excellence QUEST (Centre for Quantum Engineering and Space-Time Research) in Hannover. Further information: http://www.geo600.de
• Virgo: French-Italian-Dutch project with 3 km long laser arms in Cascina near Pisa. From the beginning, this project also aims at measurements at particularly low frequencies. Virgo is financed by CNRS (Centre national de la recherche scientifique) and INFN (Istituto Nazionale de Fisica Nucleare). Further information: http://www.virgo.infn.it/
• The US LIGO detectors are one 2 km and one 4 km instrument in Hanford, Washington State and one 4 km instrument in Livingston, Louisiana. The LIGO project developed and operated by the California Institute of Technology (CalTech) and the Massachusetts Institute of Technology (MIT) is funded by the National Science Foundation (NSF). Further information: http://www.ligo.caltech.edu/