Gravitational waves, Einstein’s ripples in space-time, spotted for 2nd time

In its first four months, the Advanced LIGO detectors have already detected two signals of gravitational waves, produced by the collision of two very different binary black hole systems.

On December 25, 2015, at 10:38 p.m. EST (7:38 p.m. PST), the scientists observed gravitational waves for the second time.

“This has cemented the age of gravitational wave astronomy”, says Professor Susan Scott from the ANU Research School of Physics and Engineering. The paper about the second burst has been accepted for publication in Physical Review Letters, reports Gizmodo.

The black holes collided approximately 1.4 billion years ago, forming a single black hole an astonishing 21 times the size of our sun.

Today’s announcement is the second set of gravitational wave ripples detected by LIGO, following the historic first detection announced in February of this year.

The first detection of gravitational waves was a milestone in physics and astronomy, confirming a major prediction of Albert Einstein’s 1915 general theory of relativity.

The first detection of the waves, the possible existence of which has been one of the biggest mysteries of the past 100 years, happened on September 14, 2015 and was announced in February.

“Once again, the collaborative work of hundreds of scientists and engineers has allowed us to pull the curtains and peek into the new window of the universe that was opened last September”, said Laura Cadonati, Georgia Tech professor and chair of LIGO’s data analysis council. The waves were measured 1.1 milliseconds apart by two LIGO detectors, and therefore provide only little hints about the direction.

The second event was expected, since LIGO proved itself capable of detecting gravitational waves, though no one could have predicted when it would take place.

“We can now think seriously about gravitational waves as a new way to learn about the universe”, University of Florida physicist Clifford Will, who wasn’t part of the team, said in an email.

After travelling an unimaginable distance across space, the waves were “captured” by the twin Ligo (Laser Interferometer Gravitational-wave Observatory) detectors located in Livingston, Louisiana, and Hanford, Washington, US.

The Ligo Scientific Collaboration consists of more than 1,000 scientists from 17 countries, including researchers from 10 United Kingdom universities – Glasgow, Birmingham, Cardiff, Strathclyde, West of Scotland, Sheffield, Edinburgh, Cambridge, King’s College London and Southampton.

While gravitational waves are not sound waves, the researchers converted the gravitational wave’s oscillation and frequency to a sound wave with the same frequency.

Dr Somak Roychoudhury, director, IUCAA, said detection of another binary black hole merger, coming barely two months after the first one was detected, will put an end to scepticism in scientific circles.

“I am thrilled to have been given the opportunity to work directly on the Hanford detector with the LIGO scientists and engineers in Washington and look forward to further exciting results from the detectors as they are made even more sensitive to these ripples in space-time”. Scientists said yesterday that they have spotted them for a second time.

LIGO’s next data-taking run will begin in the fall.

“We are starting to get a glimpse of the kind of new astrophysical information that can only come from gravitational-wave detectors”, said Massachusetts Institute of Technology researcher David Shoemaker. Until these LIGO observations, scientists have been making sense of the Universe based on electromagnetic observations that our instruments can detect, such as visible light emissions, radio waves, and X-rays.