South Pole Telescope: Monitoring Cosmic Microwave Background using Superconductors

At the South Pole Telescope, scientists measure Cosmic Microwave Background still traveling across space from the early days of the universe, using superconductors. 

Credit: Daniel Luong-Van, National Science Foundation.

For Argonne physicist Clarence Chang, looking backward in time to the earliest ages of the universe is all in a day's work.

Clarence Chang

Chang helped design and operate part of the South Pole Telescope, a project that aims a giant telescope at the night sky to track tiny bits of radiation that are still traveling across the universe from the period just after it was born.

"Basically, what we're looking at is the afterglow light of the Big Bang," Chang said.

In the wake of the Big Bang, all the matter in the universe was just hot, dense particles and light.

As the universe got older, it began to spread out and cool down over time, and the intense light from that period traveled across space.

It's still traveling, hitting us all the time, and it has a very distinct radiation signature.

"We call this the Cosmic Microwave Background, and it is essentially a snapshot of the universe as it looked about 400,000 years after the Big Bang," Chang said.

There's still a lot we don't know about the makeup of the early universe.

Particularly mysterious are the dark matter and dark energy that appear to make up 95% of the universe, but about which we know very little.

Mapping the Cosmic Microwave Background can shed some light on these dark forms.

The Cosmic Microwave Background photons are absorbed by water, so in order to catch them, you need a very dry, flat and preferably cold space, which narrows it down to just two locations on Earth.

One is the Chilean mountains, where we have a different sky mapping project underway, and the other is the South Pole.

The South Pole telescope is more than 30 feet across; Chang and colleagues at Argonne High Energy Physics Dept. helped build its camera.

At the core of the detector technology is an extremely thin superconducting film. Although superconductors can carry an electrical charge perfectly, they are extremely sensitive to changes in temperature.

When thermal radiation from the Cosmic Microwave Background hits the camera, it heats the material up slightly, which changes the conductivity of the film. This lets physicists record the energy coming from that particular part of the sky.

"So far we've mapped about 2,500 square degrees of the sky," he said, "so there's just 37,500 to go."

BICEP2 telescope at the South Pole

The BICEP2 telescope at the South Pole illuminated during a winter darkness, which lasts for nearly six months straight.

Credit: Robert Schwarz, University of Minnesota

The astrophysics community is abuzz about what may be the first definitive evidence that the very early universe underwent an almost unimaginably fast expansion (The Big Bang), doubling its size sixty times in a sliver of a second.

This sudden growth spurt was first theorized more than three decades ago, yet only last month did data from the U.S. National Science Foundation-funded Background Imaging of Cosmic Extragalactic Polarization (BICEP2) telescope reveal what appears to be "smoking gun" proof.

What is this result and what does it mean for our understanding of the universe?

Earlier this month, The Kavli Foundation hosted a Google Hangout so that four preeminent astrophysicists could discuss this question.

One of many conversations about astrophysics the foundation has hosted and published on its website

A LC-130 aircraft passes the NSF South Pole station during take off. 

Telescopes visible in the background include (left to right) the South Pole Telescope (SPT), the BICEP2 telescope, and the Keck Array telescope.

Credit: Steffen Richter, Harvard University

BICEP2 Post Big Bang Discovery: Evidence spotted for universe's early expansion

In this 2007 photo provided by Steffen Richter, the sun sets behind the BICEP2 telescope, foreground, and the South Pole Telescope in Antarctica. 

In the faint glowing remains of the Big Bang, scientists found "smoking gun" evidence that the universe began with a split-second of astonishingly rapid growth from a seed far smaller than an atom. 

To find a pattern of polarization in the faint light left over from the Big Bang, astronomers scanned about 2 percent of the sky for three years with the BICEP2 at the south pole, chosen for its very dry air to aid in the observations, said the leader of the collaboration, John Kovac of Harvard. 

Credit: AP Photo/Steffen Richter

The universe was born almost 14 billion years ago, exploding into existence in an event called the Big Bang.

Now researchers say they've spotted evidence that a split-second later, the expansion of the cosmos began with a powerful jump-start.

Experts called the discovery a major advance if confirmed by others. Although many scientists already believed that initial, extremely rapid growth spurt happened, finding this evidence has been a key goal in the study of the universe.

Researchers reported Monday that they did it by peering into the faint light that remains from the Big Bang.

Lawrence Krauss

If verified, the discovery "gives us a window on the universe at the very beginning," when it was far less than one-trillionth of a second old, said theoretical physicist Lawrence Krauss of Arizona State University, who was not involved in the work.

"It's just amazing," he said. "You can see back to the beginning of time."

Alan Guth

Another outside expert, physicist Alan Guth of the Massachusetts Institute of Technology (MIT), said the finding already suggests that some ideas about the rapid expansion of the universe can be ruled out.

Right after the Big Bang, the universe was a hot soup of particles.

It took about 380,000 years to cool enough that the particles could form atoms, then stars and galaxies.

Billions of years later, planets formed from gas and dust that were orbiting stars. The universe has continued to spread out.

This image provided by the BICEP2 Collaboration shows slight temperature fluctuations, indicated by variations in colour, of the Cosmic Microwave Background (CMB) of a small patch of sky and the orientation of its polarisation, shown as short black lines.

Researchers say since the CMB is a form of light, it exhibits all the properties of light, including polarisation. 

The changes in a particular type of polarisation, indicated here, are theorised to be caused by gravitational waves. 

These waves are signals of an extremely rapid inflation of the universe in its first moments. 

Credit: AP Photo/BICEP2 Collaboration

Krauss said he thinks the new finding could rank with the greatest discoveries about the universe over the last 25 years, such as the Nobel prize-winning discovery that the universe's expansion is accelerating.

The new results were announced by a collaboration that includes researchers from the Harvard-Smithsonian Center for Astrophysics (CfA), the University of Minnesota, Stanford University, the California Institute of Technology (CalTech) and NASA's Jet Propulsion Laboratory.

The team plans to submit its results to a scientific journal this week, said its leader, John Kovac of Harvard.

Read the full article here

Rumours that Gravitational waves have been detected

This detailed map of the Cosmic Microwave Background (CMB) is created from seven years worth of data. 

The colour variations correspond to temperature variations in the young universe: the seeds for stars and galaxies observed today. 

Credit: NASA

Last week the Harvard-Smithsonian Center for Astrophysics (CfA) stated rather nonchalantly that they will be hosting a press conference on Monday, March 17th, to announce a "major discovery."

Without a potential topic for journalists to muse on, this was as melodramatic as it got but then the Guardian posted an article on the subject and the rumours went into overdrive.

The speculation is this: a U.S. team is on the verge of confirming they have detected primordial gravitational waves—ripples in the fabric of spacetime that carry echoes of the big bang nearly 14 billion years ago.

If there is evidence for gravitational waves, it will be a landmark discovery, ultimately changing the face of physics.

Not only are gravitational waves the last untested prediction of Albert Einstein's General Theory of Relativity, but primordial gravitational waves will allow astronomers to glimpse the universe in its infancy.

"It's been called the Holy Grail of cosmology," Hiranya Peiris, a cosmologist from University College London, told reporters.

"It would be a real major, major, major discovery." Any convincing evidence would almost certainly lead to a Nobel prize.

The signal is rumoured to have been found by a telescope known as BICEP (Background Imaging of Cosmic Extragalactic Polarization), which scans the sky from the south pole, looking for a subtle effect in the Cosmic Microwave Background (CMB): the radiation released 380,000 years after the big bang when space became transparent to light and photons were allowed to travel freely across the universe.

The South Pole Telescope (left) and BICEP (right). Credit: Dana Hrubes

While the CMB has been mapped in exquisite detail, astronomers think that hidden within the map is a second fingerprint, which would reveal gravitational waves.

Its radiation was scattered toward us from the universe's earliest atoms, similar to the way blue light is scattered toward us from the atoms in the sky and just as the sky is slightly polarized, the waves have a preferred orientation, so is the CMB (on the level of a few percent).

Cosmologists are digging through the data, searching for a subtle twist in the polarized light, known as B-modes.

If a gravitational wave moves through the fabric of spacetime, it will squeeze spacetime in one direction (the universe will look a little hotter) and stretch it in another (the universe will look a little cooler).

The photons will scatter with a preferred direction, leaving a slightly polarized imprint on the CMB, due to the passing gravitational wave.

Andrew Jaffe

"If a detection has been made, it is extraordinarily exciting," Andrew Jaffe, a cosmologist from Imperial College, London, told reporters.

"This is the real big tick-box that we have been waiting for. It will tell us something incredibly fundamental about what was happening when the universe was only 10-34 seconds old."