We Heard Spacetime Ripple: How LIGO Detects Colliding Black Holes

On 14 September 2015, two detectors in the United States moved by less than one ten-thousandth of the width of a proton. That tiny tremble was a gravitational wave from two black holes that collided 1.3 billion years ago. In this video: what gravitational waves are, how LIGO's 4 km laser interferometers measure them, why it takes two detectors, how scientists pull a signal out of the noise with matched filtering, and what it sounds like. Chapters 0:00 Intro: 14 September 2015 0:24 Gravity is geometry 1:08 Stretch and squeeze 1:39 The source 2:27 The instrument 3:20 Two detectors 4:05 Finding the signal 4:49 A new sense Quiz answer: Livingston heard it first, about 7 ms before Hanford. What should we explain next? Neutron stars, black hole images, or dark matter? Tell us in the comments. Learn more: LIGO Caltech (ligo.caltech.edu) · LIGO Open Science Center data (gwosc.org) #LIGO #GravitationalWaves #BlackHoles #Physics #Astrophysics #Einstein #Science