Bending spacetime – detecting gravity waves

What is a gravity wave?

 

Rippling out from a supermassive collision, for example between two black holes, gravity waves could be detected through the stretching and contracting of space and time

Spacetime

How Ligo and Virgo's detectors work

1

A single laser beam is split and directed down two identical tubes, 4km long

2

Mirrors reflect the twin beams back to a detector

2

Laser beam

Mirror

1

Detector

building

3

Back inside the detector, the laser beams arrive perfectly aligned

4

Recombined, they cancel each other out

3

4

No light is detected

Detecting gravity waves

1

When spacetime is distorted by a gravity wave, the two tubes change length. One tube stretches as the other contracts over and over until the wave has passed

Contraction

Expansion

2

As the distances fluctuate the peaks and troughs of the two returning laser beams move in and out of alignment

3

The recombined waves no longer cancel each other out. Light reaches the detector and the gravity wave can be measured

2

3

Light is detected

What is a gravity wave?

 

Rippling out from a super- massive collision, for example between two black holes, gravity waves could be detected through the stretching and contracting of space and time

Spacetime

How Ligo and Virgo's detectors work

1

A single laser beam is split and directed down two identical tubes, 4km long

2

Mirrors reflect the twin beams back to a detector

3

Back inside the detector, the laser beams arrive perfectly aligned

4

Recombined, they cancel each other out

2

3

Laser beam

Mirror

1

4

No light is detected

Detector

building

How are gravity waves detected?

1

When spacetime is distorted by a gravity wave, the two tubes change length. One tube stretches as the other contracts over and over until the wave has passed

2

As the distances fluctuate the peaks and troughs of the two returning laser beams move in and out of alignment

3

The recombined waves no longer cancel each other out. Light reaches the detector and the gravity wave can be measured

Contraction

2

Expansion

3

Light is detected