Hopkins scientists pursue origins of the universe

Johns Hopkins University scientists are building a telescope meant to look at space in a way no one has before, hoping to probe the blackness between planets, stars and galaxies, into deep time and the mystery of how it all began.

For decades, scientists have used telescopes to plumb the origins of the universe, but have not applied the scale or precision of the project that will use a four-telescope array called the Cosmology Large-Angular Scale Surveyor, or CLASS, being built now at the university's Bloomberg Center for Physics and Astronomy. Using this instrument, which will stand 24 feet tall on a Chilean desert as soon as this winter, researchers hope to map an infant cosmos as it existed more than 13 billion years ago and help to answer fundamental questions in physics.

"Two things we want to know," said Charles L. Bennett, a Hopkins professor of physics and astronomy, sitting in his office in front of a wall-sized whiteboard spilling over the sides with calculations.

"One, put succinctly: How did the universe begin?" said Bennett, a former NASA scientist who has won some of the most prestigious awards in his field for decades of work in cosmology, the study of the origins, development and future of the universe.

The second question deals with contradictions between the theory of general relativity, which explains gravity, and quantum physics, which explains the behavior of the tiny particles that make up everything. How do these conflicting laws governing how things behave abide in the same universe? Albert Einstein couldn't figure it out; neither has anyone else.

CLASS could help, said Bennett, by studying a microwave remnant of the very earliest moments of the universe, in which one argument says infinitesimal quantum quivers drove the emergence of gravitational forces on a grand scale.

Bennett has devoted years to studying what is called the cosmic microwave background. This encompassing radiation relic carries to this day a faint picture of the universe in its infancy, at roughly 380,000 years old.

As the light of the sun takes eight minutes to reach Earth, meaning we are seeing the sun as it existed eight minutes ago, so the cosmic microwave background — also traveling at the speed of light — shows the universe as it was more than 13 billion years ago.

The imprint from this "cold sea of photons," as one astrophysicist put it, could reveal evidence for a prevalent idea about the origins of the universe known as "inflation," proposed decades ago in hopes of providing missing pieces in the so-called "Big Bang" theory. That notion of a universe that has grown cooler and less dense as it expands — the Big Bang still is going on, at a relatively slow rate of expansion — is accepted widely today, but it hardly answers everything.

Physicist Alan H. Guth, one of the scientists who proposed the "inflation" idea, wrote that the Big Bang "gives not even a clue about what banged, what caused it to bang, or what happened before it banged."

Inflation is the answer, he argued. So many questions about it persist, however, that inflation has not yet gained the status of an established theory, meaning an explanation supported by abundant evidence, such as the theories of gravity, relativity and evolution. Some call inflation a paradigm, or perhaps just an idea.

Inflation proponents claim that expansion unleashed waves of gravity, and these waves imprinted a directional pattern, or polarization, on the cosmic microwave background. Find that polarization pattern, and you find evidence that "inflation" occurred as its proponents claim. Measure the polarization pattern in detail, and you will know which kind of inflation happened.

Led jointly by Bennett and Hopkins professor Tobias Marriage, the Cosmology Large-Angular Scale Surveyor group is one of up to a dozen teams of scientists around the world looking for those waves.

The Hopkins group and three others are supported by the National Science Foundation, which has granted just over $5 million to the CLASS project, expected to cost about $13 million. Jim Ulvestad, the foundation's director of the Division of Astronomical Sciences, said the effort demands more than one approach.

"This is such a fundamental issue on how our universe began," he said. "You want to go after different ways of getting at the answer."

The CLASS instrument consists of two white towers, each with two large telescopes on top to perform a wide-angle study of the cosmic microwave background.

Bennett, Marriage and their crew of students hope to have the first of the four telescopes mounted on a summit of land some 18,000 feet high in the Atacama Desert in Chile by early next year, gaining a view of about 70 percent of the sky. The plan is to have the last of the four working by 2017. CLASS will use four electromagnetic frequencies, scanning more sky with greater sensitivity and with more discerning methods of zeroing in on the target signal than have been pursued before.

The difficulty and significance of discerning the target signal from other signals and interference was highlighted this month in an unfortunate way for scientists at Harvard University, who are also studying the cosmic microwave background, but focusing on a much narrower portion of sky from the South Pole.

In March, they announced that they had found the first evidence of the gravitational waves, a claim that many scientists questioned. This month, the team led by John Kovac of the Harvard-Smithsonian Center for Astrophysics backpedaled a bit. Team members said they were confident about their results, but conceded that dust in the Milky Way galaxy might have interfered with their observations.

A lot can go wrong, Bennett said, but the challenge of helping to solve these fundamental cosmological riddles is irresistible.

"There's nothing more exciting I can think of," he said.


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