Starmus 2014: Hawking states that “surprising” BICEP2 results always “needed to be followed up by Planck”
The Planck satellite brings BICEP2’s Big Bang discovery into further question
The South Pole BICEP2 telescope, which hit the headlines earlier this year with claims of obtaining the first evidence for the violent inflation at the beginning of the universe, has been brought into further question with data from the defunct Planck satellite, which ended its mission in 2013.
“The universe expanded by a factor of a million, trillion, trillion in a tiny fraction of a second,” said Stephen Hawking at the Starmus astronomy festival in Tenerife this week. “It was an important thing that gave us the universe that we observe today.”
The BICEP2 team believe that they have witnessed this rapid expansion of the universe in the form of the gravitational waves it left behind, which are imprinted on the primordial cosmic microwave background (CMB) – the radiation from the cosmos’ earliest point in time. On the face of it, this would seemingly confirm the theory of cosmic inflation. Even more excitingly, and if correct, the observations would be the first detection of gravitational waves and provide extra backing for the Big Bang theory.
“Cosmic inflation produces a universe that looks the same everywhere in every direction,” stated Hawking.
However, Hawking admits that European Space Agency scientists working with the Planck data must follow up to “confirm if the BICEP2 results are correct” to ensure that a mistake had not been made – the error being dust within our own galaxy getting in the way. Since the polarisation of a gravitational wave is similar to the way that dust polarises light, it might be that BICEP2 has got its results muddled.
“BICEP2 concluded that the scalar-to-tensor ratio [that is, the ratio between the size of the gravitational waves and the density fluctuations in the sea of matter in the early universe] was 20 per cent, much higher than Planck, and much higher than anyone expected,” said Hawking. “This apparent discrepancy in gravitational waves really was surprising news.”
“Personally, I think the measurement should be at least five per cent,” said Hawking. “I hope this is confirmed by future observations.”
Sadly, data from the defunct satellite might have spelt bad news for the BICEP2 team. Planck has revealed that the south pole telescope is likely to have detected galactic dust, rather than the cosmological signal we had all hoped for.
Granted, the BICEP2 team admitted that the effects of galactic dust could have caused an error, and have acknowledged this after their results were attacked by other cosmologists within days of being released. On the plus side, it now looks as if both teams – that of BICEP2 and Planck will be collaborating to build a dust map of our galaxy.
Fondly recalling his trip to Antarctica back in 1997, Hawking said of the BICEP2 team: “I can only admire their dedication to science out in the middle of nowhere.”
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