引力波英语演讲精要.pptx

Imagine that space is a giant sheet of rubber. Things that have mass cause that rubber sheet to bend, like a bowling ball on a trampoline（蹦床）. The more mass, the more that space gets bent and distorted by gravity. For example, the reason the Earth goes around the Sun is that the Sun is very massive, causing a big distortion（形变） of the space around it. If you just try to move in a straight line around such a big distortion, you will find yourself actually moving in a circle. That’s how orbits work: there’s no actual force pulling the planets around, just a bending of the space. In?Einsteins?theory of?general relativity,?gravity?is treated as a phenomenon resulting from the curvature of?space-time. This curvature is caused by the presence of?mass. Generally, the more mass that is contained within a given volume of space, the greater the curvature of space-time will be at the boundary of its volume.?As objects with mass move around in space-time, the curvature changes to reflect the changed locations of those objects. In certain circumstances, accelerating objects generate changes in this curvature, which propagate outwards at the?speed of light?in a wave-like manner. These propagating phenomena are known as gravitational waves Gravitational Waves 引力波 On 11 February 2016, the LIGO and?Virgo?collaborations announced the?first observation of a gravitational wave.?The signal was named GW150914.?The waveform showed up on 14 September 2015, within just two days of when the Advanced LIGO detectors started collecting data after their upgrade.?It matched the?predictions of general relativity?for the inward spiral and?merger?of a?pair?of?black holes?and subsequent ringdown of the resulting single black hole. The observations demonstrated the existence of binary stellar-mass black hole systems and the first observation of a binary black hole merger. According to general relativity, a pair of black holes orbiting around each other lose energy through the emission of gravitation