Issue No. 07-08/2016 - Monday 15 February 2016 CERN Bulletin More articles at: http://bulletin.cern.ch THE DISCOVERY UNCOVERED Almost exactly one hundred years after the publication of Einstein’s paper on General Relativity, the LIGO and Virgo collaborations have published a paper in which they show a A WORD gravitational signal emitted by the merger of two black holes. The signal has been observed FROM THE DIRECtor-GENERAL with 5-sigma accuracy and is the first direct observation of gravitational waves. CONGRATULATIONS ON THE DIRECT DETECTION OF GRAVITATIONAL WAVES This week saw the announcement of an extraordinary physics result: the first direct detection of gravitational waves by the LIGO Scientific Collaboration, which includes the GEO team, and the Virgo Collaboration, using the twin Laser Interferometer Gravitational- wave Observatory (LIGO) detectors located in Livingston, Louisiana, and Hanford, Washington, USA. (Continued on page 2) On Thursday, 11 February, Barry Clark Barish, one of the fathers of the LIGO experiment, presented the latest results in a packed Auditorium. In this issue Ripples in space-time, the fabric of the Universe: a beautiful, perfectly shaped signal coming this is how we can picture gravitational waves. from the unimaginable collision of two black NEWS In his visionary paper published in June 1916, holes with masses of around 36 and 29 times Einstein predicted that masses deform space- that of the Sun. The discovery uncovered 1 time and, therefore, any change in their position Congratulations on the direct causes a distortion that propagates at the speed The signal was recorded by LIGO’s detection of gravitational waves 1 of light, resulting in gravitational waves. interferometers on 14 September 2015, at the Latest news from the YETS: beginning of the new run following a long on the home straight, handover It wasn’t until 1975, over 60 years later, that upgrade campaign from 2010 to 2015. The first to operations in sight 3 Russell Hulse and Joseph Taylor, who were ever gravitational signal shows a distortion that Augmented reality for improved safety 3 awarded the Nobel Prize in 1993, inferred the becomes more intense and reaches a higher AWAKE’s plasma cell arrives at existence of gravitational waves by observing frequency as the black holes spiral towards the its destination 4 the neutron star binary system PSR1913+16 collision point and fades out again after the When ideas grow up 5 in which the orbital period of the pulsar has collision, when a considerable part of the initial Love science? Tell us about it and win! 5 decreased over the years: the measurement was energy is dissipated in gravitational waves. perfectly in line with the loss of energy through Computer Security 6 gravitational waves predicted by General But don’t imagine a huge explosion! There is no Relativity. However, we have had to wait air out there so no sound (sound is a vibration Official news 7 another 40 years for the first direct observation: or mechanical wave that needs a medium to Learning 7 Take note 8 Seminars 10 (Continued on page 2) Published by: CERN-1211 Geneva 23, Switzerland Tel. + 41 22 767 35 86 Printed by: CERN Printshop © 2016 CERN - ISSN: Printed version: 2077-950X Electronic version: 2077-9518 A word from the director-general (Continued from page 1) LATEST NEWS FROM THE YETS: ON CONGRATULATIONS ON THE DIRECT DETECTION OF THE HOME STRAIGHT, HANDOVER GRAVITATIONAL WAVES TO OPERATIONS IN SIGHT Albert Einstein predicted gravitational travel at the speed of light, this catastrophic was the last missing ingredient of the waves in a paper published 100 years ago event happened more than 1 billion years Standard Model: the quantum theory that in 1916. They are a natural consequence ago. This observation represents another describes fundamental particles and all of being installed for the ATLAS and TOTEM of the theory of general relativity, which crucial milestone in the experimental their interactions, with the exception of With the PS Booster already in its hardware commissioning phase and the PS being handed experiments. describes the workings of gravity and was verification of general relativity, and opens gravity. This week’s discovery paves the over to the operations teams this week, the injector chain is almost ready for the restart of the published a few months earlier. Until now, the door to a new phase of exploration way to significant improvements in our LHC run, planned for the end of March. A list of tests to be carried out in order to they have remained elusive. of the universe: gravitational wave understanding of gravity through future validate all the magnet circuits is being astronomy. measurements of gravitational waves. After an intense maintenance campaign The LHC operators are eager to restart the prepared by teams in the Technology Gravitational waves are tiny ripples Results such as these two come along only over the last few weeks, the PS is now being physics run around the end of March. For department. New Electrical Quality Assurance in space-time produced by violent The importance of this result for physics very rarely, and it is a privilege to be able cleaned and prepared for commissioning. the time being, all maintenance operations (ELQA) tests have also been added to the list gravitational phenomena. Because the is huge. Much of what we take for granted to see them. They also spur us on to the are progressing according to schedule. of jobs to be completed before powering. fractional change in the space-time in modern society rests on two pillars, greatest challenge of our time in physics: At the SPS, the last access for YETS activities In particular, all the repairs involving the The Departmental Safety Officer (DSO) test geometry can be at the level of 10-21 or theoretical frameworks that emerged at the reconciliation of general relativity and is planned for Friday, 19 February. More than cryogenic equipment have been completed will trigger the handover of the LHC to the smaller, extremely sophisticated, high- around the same time. General relativity quantum mechanics. 560 interventions have taken place over the but inspections are still under way to identify operations teams. sensitivity instruments are needed to is one. Quantum mechanics is the other. past eight weeks. Since the beginning of and fix any possible leaks. Wherever new detect them. Recently, the Advanced LIGO GPS positioning systems would not work Congratulations to the LIGO and Virgo the technical stop, 14 magnets have been hardware (in particular for the LHC beam Antonella Del Rosso detector increased its sensitivity by almost without general relativity, while much of Collaborations for this extraordinary changed and three more will be replaced absorber for injection, the so-called TDI) has a factor of four, which was crucial for the the electronics industry is built on quantum contribution to fundamental physics! before commissioning starts. The campaign been installed, the final position has been reported observation. mechanics. Yet the two theories seem to be for identifying obsolete cables is progressing validated using X-ray technology. The cabling incompatible. well and will be completed on schedule. campaign is continuing, with new cables The by-now familiar GW150914 signal, recorded on 14 September 2015, is Four years ago at CERN, we dotted the “i”s To learn more about this new discovery, attributed to the merger of two massive and crossed the “t”s of the Standard Model read the article “The discovery uncovered” black holes - 30-40 solar masses each - of particle physics with the discovery of on page 1. occurring at a distance of about 400 the Higgs boson, the messenger of the Megaparsecs. Since gravitational waves Brout-Englert-Higgs mechanism. This Fabiola Gianotti AUGMENTED REALITY FOR IMPROVED SAFETY (Continued from page 1) THE DISCOVERY UNCOVERED Sometimes, CERN experts have to operate in low visibility conditions or in the presence of environment that is not fully predictable, possible hazards. Minimising the duration of the operation and reducing the risk of errors is frequently with bad and changing lighting. “We try to provide accuracy in the range therefore crucial to ensuring the safety of personnel. The EDUSAFE project integrates different of millimetres without losing speed and propagate) and nothing but gravitational waves perturbation it causes. In other words, we paper reports that it occurred at about 1000 technologies to create a wearable personnel safety system based on augmented reality. flexibility,” says Giulio Aielli from the University can escape from a black hole, not even light, so now have a very powerful instrument to study million light-years from the Earth. Nothing to of Rome Tor Vergata, who coordinates the AR from our vantage point, everything happened previously invisible events in the Universe. And worry about, then, but a huge discovery for technology development team. “Since this is in darkness and silence. Indeed, such an event you don’t have to worry about this catastrophic humankind. around is difficult. The EDUSAFE Marie Curie something not yet achieved by the AR systems can only be “seen” through the gravitational event happening anywhere near you: the Antonella Del Rosso Innovative Training Network project (see box) uses augmented reality (AR) to reduce the currently available, we are developing our duration of the operation and to enhance the own solution: the Weighting Resistive Matrix safety of the worker by decreasing the room technology.” Originally