2. WHAT IS GRAVITATIONAL WAVES ??
• Gravitational waves are 'ripples' in space-time caused by some of the most violent and
energetic processes in the Universe.
• Albert Einstein predicted the existence of gravitational waves in 1916 in his general theory of
relativity.
• These cosmic ripples would travel at the speed of light, carrying with them information
about their origins, as well as clues to the nature of gravity itself.
• The strongest gravitational waves are produced by cataclysmic events such as colliding black
holes, supernovae (massive stars exploding at the end of their lifetimes), and colliding
neutron stars.
• These waves squeeze and stretch anything in their path as they pass by.
• Scientists call these ripples of space gravitational waves.
5. WHAT IS LIGO??
LIGO-Laser Interferometer Gravitational Wave Observatory
In 2015, scientists detected gravitational waves for the very first time. They used a
very sensitive instrument called LIGO (Laser Interferometer Gravitational-Wave
Observatory). These first gravitational waves happened when two black holes
crashed into one another. The collision happened 1.3 billion years ago. But, the
ripples didn’t make it to Earth until 2015!
LIGO is made up of two observatories: one in Louisiana and one in Washington. Each
observatory has two long “arms” that are each more than 2 miles (4 kilometers) long.
Credit: Caltech/MIT/LIGO Lab
7. How are gravitational waves detected?
When a gravitational wave passes by Earth, it squeezes and stretches space. LIGO can detect this
squeezing and stretching. Each LIGO observatory has two “arms” that are each more than 2 miles (4
kilometers) long. A passing gravitational wave causes the length of the arms to change slightly. The
observatory uses lasers, mirrors, and extremely sensitive instruments to detect these tiny changes.
