Washington: Astronomers used telescope in Antarctica and ESA`s Herschel space observatory to detect a subtle twist in the relic radiation from the Big Bang, which could reveal the first moments of the Universe`s existence.
The elusive signal was found in the way the first light in the Universe has been deflected during its journey to Earth by intervening galaxy clusters and dark matter, an invisible substance that is detected only indirectly through its gravitational influence.
The relic radiation from the Big Bang - the Cosmic Microwave Background, or CMB - was imprinted on the sky when the Universe was just 380,000 years old.
Today, some 13.8 billion years later, we see it as a sky filled with radio waves at a temperature of just 2.7 degrees above absolute zero.
Tiny variations in this temperature - around a few tens of millionths of a degree - reveal density fluctuations in the early Universe corresponding to the seeds of galaxies and stars we see today.
The CMB contains a wealth of other information. A small fraction of the light is polarised, like the light we can see using polarised glasses. This polarised light has two distinct patterns: E-modes and B-modes.
They can arise in two ways. The first involves adding a twist to the light as it crosses the Universe and is deflected by galaxies and dark matter - a phenomenon known as gravitational lensing.
The second has its roots buried deep in the mechanics of a very rapid phase of enormous expansion of the Universe, which cosmologists believe happened just a tiny fraction of a second after the Big Bang - `inflation`.
Scientists believe that during inflation, violent collisions between clumps of matter and between matter and radiation, should have created a sea of gravitational waves.
Finding such a signal would yield crucial information about the very early Universe, well before the time when the CMB itself was generated.