Washington: Astronomers announced yesterday that they had discovered what many consider the Holy Grail of their field: ripples in the fabric of space-time that are echoes of the massive expansion of the universe that took place just after the Big Bang.

The beginning of the universe: An illustration explaining the Big Bang theory and the beginning of the universe. Pic/Thinkstock Images

Predicted by Albert Einstein nearly a century ago, the discovery of gravitational waves would be the final piece in one of the greatest achievements of the human intellect. It would help scientists understand how the universe began and evolved into the cornucopia of galaxies and stars, nebulae and vast stretches of nearly empty space that constitute the known universe.

“Detecting this signal is one of the most important goals in cosmology today,” John Kovac of the Harvard-Smithsonian Center for Astrophysics, who led the research, said in a statement.

The gravitational waves were detected by a telescope at the South Pole called BICEP2. The instrument, which scans the sky from the South Pole, examines what is called the cosmic microwave background, which is the extremely weak radiation that pervades the universe. Its discovery in 1964 by astronomers at Bell Labs in New Jersey, was hailed as the best evidence to date that the universe began in an immensely hot explosion.

The microwave background radiation, which has been bathing the universe since 3,80,000 years after the Big Bang, is a mere 3° above absolute zero, having cooled to near non-existence from the immeasurably hot plasma that was the universe in the first fractions of a second of its existence. The team not only found the pattern, but also discovered it was considerably stronger than expected.