Primordial inflation data may provide a clue to a unified quantum gravity.
The BICEP telescope and some of the data it has generated.
Not so long ago, our very own Matthew Francis attended the press conference
in which results were announced from Antarctic observatory BICEP 2.
Researchers claimed that the instruments there had located the
unmistakable signature of gravitational waves during primordial
inflation—a period of time during which the Universe expanded at a
But our initial article also hinted at trouble to come.
The BICEP 2 experiment measures the ratio between light scattered by
gravitational waves and light scattered by everything else, which shows
up in the polarization of the cosmic microwave background (CMB)
radiation. BICEP 2, however, is not the only instrument that can measure
the properties of the CMB. Scientists have used the Planck satellite to
measure the same ratio of light scatters—and guess what? The value
obtained from BICEP 2 data doesn't agree with the value obtained from
the Planck data.
Under these circumstances, we're faced with two possibilities: either
one set of experimental data has not been interpreted properly or the
Universe plays by unexpected rules. These possibilities are not mutually
exclusive, providing lots of room for an interesting range of
explanations. Under these circumstances, theoretical physicists tend to
get a bit wild around the eyes and start stocking up on food, water,
paper, and pencils. Once they are in their safe place, they let their
imaginations run wild...
A group of Chinese and Canadian physicists asked themselves if a bouncing Universe might explain both the BICEP 2 and Planck results. A bouncing Universe is a consequence of loop quantum gravity,
an attempt to unify quantum mechanics and relativity. One neat feature
of loop quantum gravity is that, when the Universe is dense, gravity
becomes repulsive. This means that inflation occurs naturally and
doesn't require additional physics.