For the first time, scientists have found direct evidence of the
expansion of the universe, a previously theoretical event that
took place a fraction of a second after the Big Bang explosion
nearly 14 billion years ago.
We all know that the universe is big. Really big. But just how
large is it?
The clue is encoded in the primordial cosmic microwave
background radiation that continues to spread through space to
Scientists found and measured a key polarisation, or
orientation, of the microwaves caused by gravitational waves,
which are miniature ripples in the fabric of space.
Scientists at the Dark Sector Lab at the South Pole discover one
of the Holy Grails of astronomy, ripples in the fabric of
space-time which echo the expansion of the cosmos just after the
Steffen Richter/Harvard University)
Gravitational waves, proposed by Albert
Einstein's General Theory of Relativity nearly 100 years ago but
never before proven, are believed to have originated in the Big
Bang explosion and then been amplified by the universe's
"This detection is cosmology's missing link,"
says physicist Marc Kamionkowski, of Johns
"It's something that we thought should be there,
but we weren't really sure. It has been eagerly sought now for
close to two decades," says Kamionkowski.
Because gravitational waves squeeze space as they
travel, they imprint a specific pattern in the cosmic microwave
background. Like light waves, gravitational waves have
"handedness" that correlates to left- and right-skewed
Using the Dark Sector Laboratory at the South
Pole, scientists not only detected gravitational waves in the
universe's fossil radiation; they also found that the telltale
polarisation signals are much stronger than expected.
"This has been like looking for a needle in a
haystack, but instead we found a crowbar," says team co-leader
Clem Pryke, of the University
In addition to providing the first direct
evidence of the universe's inflation, the measurements can be
used to date the process and determine how much energy it took.
"This is not something that's just a home run,
but a grand slam. It's the smoking gun for inflation. It hints
at unification of the fundamental forces at energies 10
trillions of times higher than those accessible at the Large
Hadron Collider at CERN," says Kamionkowski.
Computer models indicate that the universe
expanded by 100 trillion trillion times in
.0000000000000000000000000000000001 (10 to the minus-34) seconds
after the Big Bang explosion 13.8 billion years ago.
The telescope used to detect the gravitational
waves is called Bicep, short for Background Imaging of Cosmic
"These results are as extraordinary as they get,
and they will require the most extraordinary scrutiny," says
"If these results hold up … then we've learned
only that inflation has sent us a telegram, encoded on
gravitational waves and transcribed on the cosmic microwave
background sky. It will be essential in the years to come to
follow through with more detailed and precise measurements to
infer fully what this telegram is telling us," he adds.
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