Cel mai mare proiect referitor la cercetarea undelor gravitationale (nedescoperite inca de nimeni)
este programat sa inceapa abia in anul 2034 si se numeste
LISA - Laser Interferometer Space Antenna
Pentru detalii accesati -
http://en.wikipedia.org/wiki/Laser_I..._Space_Antenna
LISA will be the first dedicated space-based gravitational wave detector. It will measure gravitational waves directly by using laser interferometry. The LISA concept has a constellation three spacecraft, arranged in an equilateral triangle with million kilometre arms (5 million km for classic LISA, 1 million km for eLISA) flying along an Earth-like heliocentric orbit. The distance between the satellites is monitored to detect a passing gravitational wave.
A LISA-like mission is designed to directly observe gravitational waves, which are distortions of space-time travelling at the speed of light. Passing gravitational waves alternately squeeze and stretch objects by a tiny amount. Gravitational waves are caused by energetic events in the universe and, unlike any other radiation, can pass unhindered by intervening mass. Launching eLISA will add a new sense to scientists' perception of the universe and enable them to listen to a world that is invisible with light
Gravitational-wave astronomy seeks use direct measurements of gravitational waves to study astrophysical systems and to test Einstein's theory of gravity. The existence of gravitational waves has been confirmed from observations of the decreasing orbital periods of several binary pulsars, such as the famous Hulse–Taylor binary pulsar. However, gravitational waves have not yet been directly detected on Earth because of their extremely small effect on matter.
Un alt experiment care studiaza undele gravitationale are loc in Italia si este numit VIRGO
Pentru detalii accesati -
http://en.wikipedia.org/wiki/VIRGO
The VIRGO is a gravitational wave detector in Italy, which started operating in 2007.
It is one of a handful of the world's major experiments working towards the observation of gravitational waves. VIRGO is located within the site of EGO (European Gravitational Observatory) at Cascina, Italy.
VIRGO is a massive Michelson laser interferometer made of two orthogonal arms, each three kilometers long. Due to the multiple reflections between mirrors located at the extremities of each arm, the effective optical length of each arm is extended up to 100 kilometers.
The gravitational wave frequency range sensitivity of VIRGO extends from 10 hertz to 10,000 hertz. This range, as well as the very high sensitivity, should allow detection of gravitational radiation produced by supernovae and the coalescence of binary systems in the Milky Way and in outer galaxies.
In order to reach the extreme sensitivity required, the whole interferometer must remain as optically perfect as possible and is extremely well isolated from seismic disturbances[3] in order to be only sensitive to the gravitational waves. To achieve this, Italian and French project scientists have developed many of the current leading techniques in the fields of high power ultrastable lasers, high reflectivity mirrors, seismic isolation and position and alignment control. To avoid spurious motions of the optical components due to seismic noise; each component is isolated by a 10 m high, very elaborate system of compound pendulums.
Regarding optics, VIRGO uses a new generation of ultrastable lasers and one of the most stable oscillators ever built.[2] A specific optical coating facility was built to produce extremely high quality mirrors combining reflectivity over 99.999%, with nanometer surface control.
Because the presence of any residual gas would disturb the measurements, the light beam must propagate under an ultra high vacuum. Indeed, the two tubes, 3 km long and 1.2 m diameter are the largest ultra high vacuum vessels in Europe and the second largest in the world.
Au masurat ce au masurat dar nu au descoperit nimic ...
Un alt experiment care studiaza undele gravitationale are loc in Germania si se numeste GEO 600
Pentru detalii accesati -
http://en.wikipedia.org/wiki/GEO_600
GEO 600 is a gravitational wave detector located near Sarstedt in the South of Hanover, Germany. This instrument, and its sister interferometric detectors, when operational, are some of the most sensitive gravitational wave detectors ever designed. They are designed to detect relative changes in distance of the order of one part in 10−21, about the size of a single atom compared to the distance from the Sun to the Earth. GEO 600 is capable of detecting gravitational waves in the frequency range 50 Hz to 1.5 kHz.
GEO600 is a Michelson interferometer. It consists of two 600 meter long arms, which the laser beam passes twice, so that the effective optical arm length is 1200 m. The major optical components are located in an ultra-high vacuum system. The pressure is in the range of 10−8 mbar.
In November 2005, it was announced that the LIGO and GEO instruments have begun an extended joint science run. The three instruments (LIGO's instruments are located near Livingston, Louisiana and on the Hanford Site, Washington in the U.S.) will collect data for more than a year, with breaks for tuning and updates. This will be the fifth science run of GEO 600. No signals were detected on previous runs, but the sensitivity of the instruments (and the quality of the data analysis) is continually improving, and once the data from the current run are analyzed, it is hoped that they will perhaps reveal the arrival at Earth of two unambiguous bursts of gravitational waves.
Au masurat ce au masurat dar nu au descoperit nimic ...
Un alt experiment care studiaza undele gravitationale are loc in Japonia si se numeste TAMA 300
Pentru detalii accesati -
http://en.wikipedia.org/wiki/TAMA_300
TAMA 300 is a gravitational wave detector located at the Mitaka campus of the National Astronomical Observatory of Japan. It is a project of the gravitational wave studies group at the Institute for Cosmic Ray Research (ICRR) of the University of Tokyo.
The TAMA project started in 1995. It adopts a Fabry Perot Michelson Interferometer (FPMI) with power recycling. It is officially known as the 300m Laser Interferometer Gravitational Wave Antenna.
The goal of the project is to develop advanced techniques needed for a future kilometer sized interferometer and to detect gravitational waves that may occur by chance within our local group of galaxies.
Au masurat ce au masurat dar nu au descoperit nimic ...
Dupa cum ati observat a fost folosita cea mai avansata tehnologie si totusi undele gravitationale nu au fost detectate. Devine din ce in ce mai evident faptul ca modelul matematic al gravitatiei propus de Einstein este gresit si trebuie inlocuit de o noua teorie ...
In ultima vreme,
Erick Verlinde, fizician si matematician celebru, care si-a legat deja numele de "teoria stringurilor" (supersimetria universurilor paralele), agita lumea academica din Statele Unite printr-o serie de conferinte
in care face bucati teoria gravitatiei. Viziunea lui Erik Verlinde arunca o lumina noua asupra unora dintre marile teme ale fizicii contemporane: asa-numita "dark energy" (energia obscura), un soi de anti-gravitatie care pare a accelera expansiunea universului, sau "materia obscura", care ipotetic tine galaxiile unite intre ele.