Alan Guth was one of the first physicists to hypothesize the
existence of inflation, which explains how the universe expanded
so uniformly and so quickly in the instant after the Big Bang 13.8
billion years ago.Rick Friedman for The New York Times
CAMBRIDGE, Mass. — One night late in 1979, an itinerant young
physicist named Alan Guth, with a new son and a year’s appointment
at Stanford, stayed up late with his notebook and equations,
venturing far beyond the world of known physics.
He was trying to understand why there was no trace of some exotic
particles that should have been created in the Big Bang. Instead he
discovered what might have made the universe bang to begin with. A
potential hitch in the presumed course of cosmic evolution could
have infused space itself with a special energy that exerted a
repulsive force, causing the universe to swell faster than the speed
of light for a prodigiously violent instant.
Confirming inflation would mean that the universe we see, extending
14 billion light-years in space with its hundreds of billions of
galaxies, is only an infinitesimal patch in a larger cosmos whose
extent, architecture and fate are unknowable. Moreover, beyond our
own universe there might be an endless number of other universes
bubbling into frothy eternity, like a pot of pasta water boiling
over.
‘As Big as It Gets’
Reaching back across 13.8 billion years to
the first sliver of cosmic time
with telescopes at the South Pole, a team of astronomers led by John
M. Kovac of the Harvard-Smithsonian Center for Astrophysics detected
ripples in the fabric of space-time — so-called
gravitational waves
— the signature of a universe being wrenched violently apart when it
was roughly a trillionth of a trillionth of a trillionth of a second
old. They are the long-sought smoking-gun evidence of inflation,
proof, Dr. Kovac and his colleagues say, that Dr. Guth was correct.
Inflation has been the workhorse of cosmology for 35 years, though
many, including Dr. Guth, wondered whether it could ever be proved.
Confirming inflation would mean that the universe we see, extending 14
billion light-years in space with its hundreds of billions of
galaxies, is only an infinitesimal patch in a larger cosmos whose
extent, architecture and fate are unknowable. Moreover, beyond our own
universe there might be an endless number of other universes bubbling
into frothy eternity, like a pot of pasta water boiling over.
The Theory of Inflation
Astronomers have found evidence to support the theory of inflation,
which explains how the universe expanded so uniformly and so quickly
in the instant after the Big Bang 13.8 billion years ago.
THE UNIVERSE is just under 14
billion years old. From our position in the Milky Way galaxy, we
can observe a sphere that is now about 92 billion light-years
across. But there's a mystery. Wherever we look, the universe
has an even temperature.
NOT ENOUGH TIME The universe is
not old enough for light to have traveled the vast distance from
one side of the universe to the other, and there has not been
enough time for scattered patches of hot and cold to mix into an
even temperature.
DISTANT COFFEE At a smaller
scale, imagine using a telescope to look a mile in one
direction. You see a coffee cup, and from the amount of steam,
you can estimate its temperature and how much it has cooled.
COFFEE EVERYWHERE Now turn around
and look a mile in the other direction. You see a similar coffee
cup, at exactly the same temperature. Coincidence? Maybe. But if
you see a similar cup in every direction, you might want to look
for another explanation.
STILL NOT ENOUGH TIME There has
not been enough time to carry coffee cups from place to place
before they get cold. But if all the coffee cups were somehow
filled from a single coffee pot, all at the same time, that
might explain their even temperature.
INFLATION solves this problem.
The theory proposes that, less than a trillionth of a second
after the Big Bang, the universe expanded faster than the speed
of light. Tiny ripples in the violently expanding energy field
eventually grew into the large-scale structures of the universe.
FLUCTUATION Astronomers have now
detected evidence of these ancient fluctuations in swirls of
polarized light in the cosmic background radiation, which is
energy left over from the early universe. These are
gravitational waves predicted by Einstein.
EXPANSION Returning to our
coffee, imagine a single, central pot expanding faster than
light and cooling to an even temperature as it expands. That is
something like inflation. And the structure of the universe
mirrors the froth and foam of the original pot.
By LARRY BUCHANAN and JONATHAN CORUM
Andrei Linde of Stanford, a prolific theorist who first described the
most popular variant of inflation, known as chaotic inflation, in
1983, was about to go on vacation in the Caribbean last week when
Chao-Lin Kuo, a Stanford colleague and a member of Dr. Kovac’s team,
knocked on his door with a bottle of Champagne
to tell him the news.
Stanford Professor Andrei Linde celebrates physics breakthrough
video by StanfordUniversity
In 2002, he was part of a team that discovered that the microwave
radiation was polarized, meaning the light waves had a slight
preference to vibrate in one direction rather than another.
This was a step toward the ultimate goal of detecting the
gravitational waves from inflation. Such waves, squeezing space in one
direction and stretching it in another as they go by, would twist the
direction of polarization of the microwaves, theorists said. As a
result, maps of the polarization in the sky should have little arrows
going in spirals.
The Bicep2 telescope, in the foreground, was used to detect the
faint spiraling gravity patterns — the signature of a universe
being wrenched violently apart at its birth. Steffen Richter/Associated Press
This was a step toward the ultimate goal of detecting the
gravitational waves from inflation. Such waves, squeezing space in one
direction and stretching it in another as they go by, would twist the
direction of polarization of the microwaves, theorists said. As a
result, maps of the polarization in the sky should have little arrows
going in spirals.
“If you trace your cosmic roots,” said Abraham Loeb, a
Harvard-Smithsonian astronomer who was not part of the team, “you wind
up at inflation.”
A version of this article appears in print on March 18, 2014,
Section A, Page 1 of the New York edition with the headline: Space
Ripples Reveal Big Bang’s Smoking Gun.
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