At the Amundsen–Scott South Pole Station in Antarctica sits a large telescope. Its purpose is to understand the faint hum of microwave light across the Universe, left over from the afterglow of the Big Bang.
Researchers who have just published the results of their work in Physical Review D, haven’t found any physics-breaking results, and they’re delighted – for now Einstein’s theory of relativity will hold.
“We found that the observed lensing patterns in this study are well explained by general relativity,” said Zhaodi Pan, a researcher at the US’s Department of Energy’s Argonne National Laboratory.
“This suggests that our current understanding of gravity holds true for these large scales. The results also strengthen our existing understanding of how structures of matter formed in our universe.”
The telescope was upgraded in 2017 with a new camera called SPT-3G. This camera – which has 16,000 detectors – is measuring the Cosmic Microwave Background (CMB), the afterglow of microwave light left over from the Big Bang.
“The CMB is a treasure map for cosmologists,” said Pan. “It’s minuscule variations in temperature and polarization provide a unique window into the universe’s infancy.”
But there’s another part here too – gravitational lensing. Think of this like staring at a rock through water at the beach – the water distorts and warps the light before it reaches your eyes. In the same way, matter like black holes and large galaxies warps light from the CMB before it reaches the telescopes.
This warping in the fabric of space-time is part of Einstein’s general relativity.
This study is just looking at data from 2018, but so far they found that while looking at a large part of the Southern Sky, the rate of gravitational lensing was close to what general relativity would expect.
“One of the really exciting parts of this study is that the result comes from what’s essentially commissioning data from when we were just beginning observations with the SPT-3G — and the result is already great,” said Amy Bender, a physicist at Argonne.
“We’ve got five more years of data that we’re working on analysing now, so this just hints at what’s to come.”
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