#134: 'Hum' in universe | Gravitational Waves

SnT Notes for UPSC

Universe is humming low frequency gravitational waves/ripples in fabric of spacetime created by huge objects moving around, colliding and merging with each other.

First time the evidences of large-scale motion of everything in universe are found

This was predicted by Albert Einstein 100+ years ago

- He proposed that gravitations attraction was result of 'bending' of the fabric of spacetime by heavy objects (like earth, moon, stars etc)
- This curvature formation created ripples in spacetime (like moving boat in water)
- As heavy objects move, the curvature around them moves too
- These ripples are gravitational waves

- First detected in 2015 by LIGO (high frequency)

- These can be seen as distortions in the universe

Newton was first to recommend gravitational theory where he said:

Every celestial body exerts attractive force on other.

- This force is directly proportional to Mass of the two bodies

- Inversely proportional to square of the distance between them

Fault: WHY are two bodies attracted to the other (This was answered by Einstein with curvature's motion)

Importance of Gravitational waves

- Almost all that we know of faraway objects has come through detection of Electromagnetic waves (EMW)

- The visible light is part of these EMW

- 95% of the universe is dark matter and dark energy and does not emit any form of EMW

- Gravitational waves solve for this offering tool for scientists to study the universe as GWs carry characteristic information from their source, just like EMWs

Hum detection

- Radio astronomers of 5 countries worked together using 6 large telescopes

- Study conducted on objects called pulsars

- Pulsar: Rapidly rotating neutron stars emitting pulses of radiation which look like bright flashes from earth

- These bursts take place at precise time intervals and thus called cosmic clocks

- 25 pulsars examined over 15 years to find some signals arriving earlier than others

- This millionth of second time difference gave away hum sound presence

Importance of detection

- Help scientists expand knowledge about nature and evolution of universe

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