Gravitational Wave Evidence of the 'Big Bang' May Not Hold Up with Analysis

In March of last year, scientists announced that they had observed the portion of cosmic background radiation, which is the fossil radiation from the Big Bang, generated by gravitational waves. In other words, they'd made the first observation of the cosmological effects of this phenomenon predicted by Einstein's theory of General Relativity. Now, though, new evidence is calling this discovery into question.

"Basically, what we conclude is that no investigation of this kind can escape a systematic study of contaminating sources," said Carlo Baccigalupi, SISSA cosmologists and one of the authors of the new paper, in a news release. "And it can only be systematic if several instruments are used at the same time."

In this case, the researchers wanted to make sure that the observed signal was genuine and not the effect of contaminants due to the polarized emission of our Milky Way Galaxy. In the March paper, the researchers stated that current knowledge indicates that contaminating radiation is small compared to the observed signal. That said, Planck's response was that the data have shown that polarized galactic radiation is not negligible.

In this case, further research showed that the Planck view is the correct one. With more in-depth analysis, the scientists confirmed that the galactic contaminants are sufficiently intense to preclude any definite statement concerning the presence or absence of gravitational waves.

"Our work isn't over," said Baccigalupi. "Current experiments (including BICEP2) and future projects (a new satellite, a 'descendent of Panck called CORE+ has just been proposed to the European Space Agency) have understood the message of Planck and BICEP2 very well, and are planning to equip themselves with technology capable of observing the Galaxy with very sharp eyes, to be able to distinguish it from the signal of the Big Bang, if indeed it did emit gravitational waves."

The findings are published in the journal Physical Review Letters.

For more great science stories and general news, please visit our sister site, Headlines and Global News (HNGN).