A much-publicized "discovery" last year of gravitational waves said to be an "echo" of the Big Bang got it wrong, a new study by scientists involved in the original finding suggests.
The signal scientists thought they detected using sensitive detectors on an Antarctic telescope, in an experiment dubbed BICEP2, was created instead by lights emissions from dust in our own Milky Way galaxy, the study concluded.
For some 35 years astrophysicists have been looking for evidence to support a theory that the universe experienced a brief but ultra-fast expansion in a tiny fraction of a second after the initial Big Bang.
Scientists with the BICEP2 project announced last year they had detected polarized patterns -- dubbed primordial B-waves -- in the cosmic microwave background, the light reaching the Earth from the very edge of the observable Universe.
Those patterns, they announced, could be evidence of primordial gravitational waves, anticipated ripples in the fabric of space-time created by that ultra-fast expansion.
However, there was doubt about the findings expressed by many scientists almost as soon as the March 214 announcement of the historic "discovery" was made.
Now, a second team of astronomers, which was operating a European Space Agency space telescope also seeking the same expansion pattern, says what BICEP2 saw was not true evidence of the expansion.
Mapping the microwave radiation at many more frequencies than BICEP2, the Planck space telescope identified the confusing role of dust in our own galaxy, capable of producing the shifts in the polarization in the cosmic background radiation researchers thought would be evidence of gravitational waves and the universe's expansion.
Combining the original BICEP2 data with the Planck data and subsequent additional data from another telescope in Antarctica known as the Keck Array, the new study suggests that whatever signal BICEP2 may have detected, it cannot be separated from the spoiling effects of dust.
In other words, the study authors say, the original observations are equally compatible with effects that could exist without primordial gravitational waves.
"This joint work has shown that the detection of primordial B-modes is no longer robust once the emission from galactic dust is removed," Jean-Loup Puget, principal investigator of Planck's high frequency instrument, said in a statement from the ESA.
"So, unfortunately, we have not been able to confirm that the signal is an imprint of cosmic inflation."
However, that doesn't rule out inflation, and the signal might still be in the BICEP2 data, just swamped by the effect of galactic dust, says scientists.
"The gravitational wave signal could still be there, and the search is definitely on," says Brendan Crill from NASA's Jet Propulsion Laboratory in Pasadena, Calif., who is a member of the Planck and BICEP2 teams.
