SCIENCE - The Beginning of Everything

"‘Ripples’ of the Big Bang reveal the beginning of the universe" by Rebecca Jacobson, PBS NewsHour 3/18/2014

Excerpt

Scientists believe that almost 14 billion years ago, the universe was a hot, dense place that rapidly expanded after the Big Bang.  The idea that the universe underwent a rapid expansion is called inflation; the universe spread out and cooled down, forming atoms that later made gas, dust, stars and planets.

But what exactly happened at the start of the universe has been unconfirmed until now.  With a radio telescope at the South Pole, scientists followed gravitational waves 13.8 billion years into the past and found the first direct evidence of the universe’s rapid expansion immediately following the Big Bang.  Scientists discussed their findings at a press conference Monday at the Harvard-Smithsonian Center for Astrophysics.

“This is a totally new, independent piece of cosmological evidence that the inflationary picture fits together,” said theoretical physicist Alan Guth of MIT, who proposed the idea of inflation in 1980.

This is the first concrete evidence of gravitational waves, a phenomenon first predicted by Einstein 100 years ago.  After major cosmic events like the merging of black holes or the Big Bang, gravity makes waves in spacetime that travel like ripples on a pond.  These ripples travel at the speed of light, but Einstein thought they would be so feeble, they would be undetectable.

But scientists suspected that these ripples could still be found.  Billions of years later, the waves are too weak to measure directly, so scientists have been looking for imprints left on the “cosmic microwave background”, a soup of elementary particles leftover from the Big Bang.  A U.S.-led team, headed by scientists at the Harvard-Smithsonian Center for Astrophysics, along with the University of Minnesota, Stanford University, the California Institute of Technology and NASA’s Jet Propulsion Laboratory, used a specialized radio telescope called BICEP2 (which stands for Background Imaging of Cosmic Extragalactic Polarization) at the South Pole to hunt for the gravitational waves.  The dry air, thin atmosphere and distance from cell phone and radio towers made the South Pole the ideal wave-hunting location.

The results will be submitted to a scientific journal this week for review and publication, said John Kovac of Harvard, who led the research project.

Theoretical physicist Lawrence Krauss of Arizona State University said if the evidence of gravitational waves is confirmed, the discovery “gives us a window on the universe at the very beginning,” when it was less than one-trillionth of a second old, he told the Associated Press.  He added that the results still need to be confirmed, but this study is the “best hope” of proving the universe’s early growth spurt.

“It’s just amazing,” he said.  “You can see back to the beginning of time.”

SCIENCE - 'Big Bang' Theory Updated?

A timeline of the universe, showing the prevailing theory of how the universe expanded following the Big Bang. (NASA)

"'Big Bang' actually 'Big Chill,' new theory says" by Natalie Wolchover, Fox News 8/22/2012

How did the universe begin? The Big Bang is traditionally envisioned as the moment when an infinitely dense bundle of energy suddenly burst outward, expanding in three spatial directions and gradually cooling down as it did so.

Now, a team of physicists says the Big Bang should be modeled as a phase change: the moment when an amorphous, formless universe analogous to liquid water cooled and suddenly crystallized to form four-dimensional space-time, analogous to ice.

In the new study, lead author James Quach and colleagues at the University of Melbourne in Australia say the hypothesis can be tested by looking for defects that would have formed in the structure of space-time when the universe crystallized. The universe is currently about 13.7 billion years old.

"Think of the early universe as being like a liquid," Quach said in a statement. "Then as the universe cools, it 'crystallises' into the three spatial and one time dimension that we see today. Theorized this way, as the universe cools, we would expect that cracks should form, similar to the way cracks are formed when water freezes into ice.

If they exist, these cracks should be detectable, the researchers said, because light and other particles would bend or reflect off of them as they trek across the cosmos.

The notion that space and time are emergent properties that suddenly materialized out of an amorphous state was first put forth by physicists at Canada's Perimeter Institute in 2006. Called "quantum graphity," the theory holds that the four-dimensional geometry of space-time discovered by Albert Einstein is not fundamental; instead, space-time is more like a lattice constructed of discrete space-time building blocks, just like matter looks continuous, but is actually made of building blocks called atoms.

Originally, at extremely high temperatures, the building blocks were like liquid water: they contained no structure, "representing a state with no space," the researchers wrote in their paper. At the moment of the Big Bang, when the temperature in the universe dropped to the space-time building blocks' "freezing point," they crystallized to form the four-dimensional lattice we observe today.

The math describing the theory checks out, but "the challenge has been that these building blocks of space are very small, and so impossible to see directly," Quach explained. From the human vantage point, space-time looks smooth and continuous.

However, while the building blocks themselves might be too small to detect, the physicists hope to observe the boundaries that would have formed as regions of crystallizing building blocks butted against one another at the time of the Big Bang, creating "cracks" in the universe. More work is needed to predict the average distance between the cracks — it isn't known whether they are microscopic, or light-years apart — in order to characterize their effects on particles.

The research by Quach and his team is detailed in this month's edition of the journal Physical Review D.