Space-time ripples left over from the Big Bang have been picked up for the first time by Harvard scientists.
Astrophysicists have been hunting for ‘primordial gravitational waves’ since they were predicted by Albert Einstein’s theory of general relativity in 1916.
Today, after days of rumour and speculation, scientists from the Harvard-Smithsonian Centre announced they had recorded the first direct evidence of gravitational waves rippling through the infant universe.
"The implications for this detection stagger the mind,” said project leader Jamie Bock. “We are measuring a signal that comes from the dawn of time.”
Our universe burst into existence 13.8 billion years ago. Fractions of a second later, space and time were created, expanding exponentially in an episode known as 'inflation'.
It was theorized that inflation should also produce gravitational waves - ripples in space-time which spread throughout the universe.
"Think of the ripples you see when you throw a stone into a pond," said Professor Martin Hendry of the department of Physics and Astronomy at the Univesity of Glasgow.
"But these aren't ripples on the surface of the water, they are gravitational waves emitted billions of years ago, rippling through the fabric of space and time itself, in the universe's earliest moments.
"We always suspected they were still washing about but we haven't been able to detect them.
"Think of a cocktail party where a great many voices are speaking all at once. It's hard to distinguish any individual voice but suddenly you hear someone with a high pitched voice, or someone a bit more excitable. That's what we have been looking for."
The signal was found using a specialised telescope called Bicep (Background Imaging of Cosmic Extragalactic Polarization) at the South Pole.
It scans the sky at microwave frequencies, where it picks up light energy from slightly after the Big Bang - around 380,000 years later. Scientists have been searching for tiny ripples in this light which would show it is being slightly stretched by gravitational waves.
The effect of gravitational waves causes a distinct twisting pattern known as a 'curl' or 'b-mode' in the cosmic microwave background radiation.
"The swirly B-mode pattern of polarization is a unique signature of gravitational waves," say Chao-Lin Kuo of Stanford University.
"This is the first direct image of gravitational waves across the primordial sky."
Gravitational waves cause the cosmic radiation (light emitted shortly after the Big Bang) - to swirl
The team travelled to the South Pole scan the sky because it is the clearest place on Earth for stargazing.
"The South Pole is the closest you can get to space and still be on the ground," says John Kovac of the Harvard-Smithsonian Center for Astrophysics, project co-leader and BICEP2 principal investigator.
"It's one of the driest and clearest locations on Earth, perfect for observing the faint microwaves from the Big Bang."
Dr Joanna Dunkley, a lecturer in astrophysics at Oxford University, said the finding would give the most 'direct view' possible of the Big Bang and tell scientists what was happening right at the beginning of the universe.
“These gravitational waves are space itself shrinking and stretching," she said.
"They were put in, we think, by this model called 'inflation' where we think space expanded faster than the speed of light during the first trillionth of a second of the universe.
“It’s kind of a snapshot of the universe as early as we can possibly see it."
The breakthrough could show just how 'big' the Big Bang really was
Dr Chris Lintott, astrophysicist at the University of Oxford, said the finding was the 'most significant cosmological discovery in nearly two decades.'
“It’s like all our Christmases at once - I doubt many cosmologists will get much sleep tonight.”
Professor John Womersley, Chief Executive of the Science and Technology Facilities Council (STFC) which funds UK research into cosmology, said: "Inflation is the very rapid expansion of the very early universe that is one of the pillars of our understanding of cosmology. Without inflation we would not be here.
"With the recent confirmation of the existence of the Higgs boson and now the first direct evidence for inflation, these are very exciting times to be a physicist.”