SKY_July2014.pdf

20 July 2014 sky & telescope

Big Bang Breakthrough

The observatory’s historic Phillips Auditorium was

packed with scientists, reporters, and TV crews. As the

BICEP project’s co-leaders ended more than two hours of

presentations, MIT cosmologist Max Tegmark (who was

not involved in the project) couldn’t contain himself. “This

is one of the greatest discoveries of all time,” he declared.

Marc Kamionkowski, a cosmologist at Johns Hopkins Uni-

versity, assured the media that the fi nding “is as Nobel-

Prize-worthy as it gets.” Alan Guth and Andrei Linde, who

originated and developed infl ation physics more than 30

years ago, basked for reporters in what appeared to be the

triumphant confi rmation of their life work.

The polarization patterns had turned out to be unex-

pectedly strong. Their strength, and their average angular

size on the sky, pin down for the fi rst time when infl ation

occurred and at what temperature: at 10–38 second after

the theoretical time zero and at 2 × 1029 °°C, meaning an

energy of 2 × 1016 GeV — a few trillion times more energy

per particle than the Large Hadron Collider can achieve.

That’s a little earlier and hotter than theorists expected.

The signal’s strength means that other teams will have

an easier time following up than anyone hoped. It also

means opportunities for studying it in fi ner detail. In

this new kind of astronomy, we peer back through what

we normally call the Big Bang into a truly alien time of

extreme physics beyond anything otherwise possible to

test experimentally — perhaps getting a glance into much

wider realms that exist before and outside of our universe.

Nearly a dozen groups were hoping to get there fi rst,

operating receivers in Antarctica, the Chilean Andes, the

upper atmosphere, and in space (S&T: Oct. 2013, p. 22).

Several should soon confi rm or contradict BICEP’s fi nd-

ings. The science team for the European Space Agency’s

Planck probe plans to announce results from its full-sky

cosmic-background polarization maps in October or

November. The South Pole Telescope, located next to the

BICEP installation, should also have something to say by

the end of 2014. The Atacama B-Mode Search in Chile,

which covers three times BICEP2’s sky area, should “be

able to weigh in on the matter within the year,” says its

leader Suzanne Staggs of Princeton. The BICEP team, for

its part, is now running a new, fi ve-times-faster instru-

ment called the Keck Array and is preparing BICEP3.

And a much wider, more sensitive, much sharper-

seeing polarization mapper that U.S. astronomers were

already planning out — the next generation of this new

astronomy — now seems sure to be funded and built.

Pulling Up the Picture

All these projects are designed to tease out subtle,

second-level features of the Big Bang’s dim microwave

afterglow that wallpapers the sky. The microwave back-

ground comes from long after the cosmic-origin process:

380,000 years after the Big Bang. But its subtle patterns

of warm and cool spots carry rich statistical information

about the universe in its earlier phases. Ever-improving

measurements of these patterns for the last 22 years have

been the foundation of modern precision cosmology.

The new wave of experiments goes further to extract

not patterns of temperature, but polarization. Like the

light blocked by polarizing sunglasses, microwaves can

have their electric-fi eld components oriented a particular

PROUD PARENTS Alan

Guth (left) came up with the

infl ation theory in 1979. Andrei

Linde developed its fi rst eter-

nal version in 1982.

GRAVITONS BEHIND THE SKY Top: This sky map of the cos-

mic B-mode polarization patterns was drawn from three years of

BICEP2 data. Each black dash shows the strength and direction of

the B-mode polarization at a point on the sky. Orange highlights

the clockwise curls, blue the counterclockwise ones. Above: A

constellation map shows the same area of sky. Your fi st held at

arm’s length (10°) is about 2 / 3 the height of each map.

S&T:

CAMILLE CARLISLE

Right ascension

Declination

2 h 1 h 0 h 23 h 22 h

−65°

−60°

−55°

−50°

_

_

_ `

r ¡

c

a

c –55°

–50°

–60°

–65°

1 h 0 h 23 h

TUCANA

GRUS

ERI PHOENIX

HYI

Achenar

BICEP2 COLLABORATION