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Explore the revolutionary detection of violent cosmic events using gravitational waves, from colliding black holes to the Big Bang's echoes. Learn about the challenges and breakthroughs in detecting these waves and unveiling the secrets of the cosmos. Join the international effort with Virgo, LIGO, and other detectors to open a new window on the mysteries of the universe.
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Observing the Most Violent Events in the UniverseVirgoBarry BarishDirector, LIGOVirgo Inauguration23-July-03 Cascina 2003
Michelangelo“The Battle of Cascina” Unfinished Full Size Drawing of the Violence of War
VirgoGravitational Waves Detecting Violent Events in the Cosmos like Colliding Black HolesCredit:: National Center for Supercomputing Applications (NCSA)
A Conceptual Problem is solved ! Newton’s Theory “instantaneous action at a distance” Gmn= 8pTmn Einstein’s Theory information carried by gravitational radiation at the speed of light
Einstein’s Theory of Gravitation • a necessary consequence of Special Relativity with its finite speed for information transfer • gravitational waves come from the acceleration of masses and propagate away from their sources as a space-time warpage at the speed of light gravitational radiation binary inspiral of compact objects
Detectionof Gravitational Waves Gravitational Wave Astrophysical Source Terrestrial detectors Virgo, LIGO, TAMA, GEO Detectors in space LISA
International Network on Earth simultaneously detect signal LIGO Virgo GEO TAMA AIGO detection confidence locate the sources decompose the polarization of gravitational waves
The effect … Leonardo da Vinci’s Vitruvian man Stretch and squash in perpendicular directions at the frequency of the gravitational waves
Detecting a passing wave …. Free masses
Detecting a passing wave …. Interferometer
The challenge …. I have greatly exaggerated the effect!! If the Vitruvian man was 4.5 light years high, he would grow by only a ‘hairs width’ Interferometer Concept
As a wave passes, the arm lengths change in different ways…. Interferometer Concept • Arms in Virgo are 3km • Measure difference in length to one part in 1021 or 10-18 meters • Laser used to measure relative lengths of two orthogonal arms …causing the interference pattern to change at the photodiode Suspended Masses
One meter ~ 40 inches Human hair ~ 100 microns Wavelength of light ~ 1 micron Atomic diameter 10-10 m Nuclear diameter 10-15 m Virgo sensitivity 10-18 m How Small is 10-18 Meter?
The Search has Begun … • Virgo joins the international effort to detect gravitational waves and to open a new window on the Universe • On behalf of LIGO and the rest of the international community, I welcome Virgo into this exciting adventure Congratulations !!!
Astrophysical Sourcessignatures • Compact binary inspiral: “chirps” • NS-NS waveforms are well described • BH-BH need better waveforms • search technique: matched templates • Supernovae / GRBs: “bursts” • burst signals in coincidence with signals in electromagnetic radiation • prompt alarm (~ one hour) with neutrino detectors • Pulsars in our galaxy: “periodic” • search for observed neutron stars (frequency, doppler shift) • all sky search (computing challenge) • r-modes • Cosmological Signal “stochastic background”
Early Universe: “correlated noise” ‘Murmurs’ from the Big Bang Cosmic Microwave background WMAP 2003
International NetworkLIGO Hanford Observatory MIT Caltech Livingston Observatory
What Limits LIGO Sensitivity? • Seismic noise limits low frequencies • Thermal Noise limits middle frequencies • Quantum nature of light (Shot Noise) limits high frequencies • Technical issues - alignment, electronics, acoustics, etc limit us before we reach these design goals
LIGO Sensitivity Livingston 4km Interferometer May 01 First Science Run 17 days - Sept 02 Jan 03 Second Science Run 59 days - April 03
Signals from the Early Universe • Strength specified by ratio of energy density in GWs to total energy density needed to close the universe: • Detect by cross-correlating output of two GW detectors: First LIGO Science Data Hanford - Livingston
Gravitational Waves from the Early Universe E7 results projected S1 S2 LIGO Adv LIGO
Gravitational Waves A New Window on the Universe Virgoand its international partners will provide a new way to view the dynamics of the Universe