Story URL: http://news.medill.northwestern.edu/chicago/news.aspx?id=185596
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LISA, an orbital antenna, could provide valuable gravitational wave readings and shed  light on how the early universe developed.


Did the early universe drop some dimensions?

by Brian Warmoth
April 28, 2011


Hollywood hopes to rev up more ticket sales for 3-D movies right away. But a new theory in the world of particle physics could make us all start envisioning the universe in only one or two dimensions.

Quantum mechanics works well explaining how physics works at the subatomic level. By contrast, general relativity as Albert Einstein conceived of physics on large, cosmic scales.

University of Buffalo physicist Dejan Stojkovic and his colleague, Loyola Marymount University physicist Jonas Mureika, have now published a potential bridge between the two in the journal Physical Review Letters.

They believe that, soon after the Big Bang, the universe may have expanded from a single point known as a singularity into a one-dimensional string and then a two-dimensional plane before expanding to have depth.

Recent budget cuts at NASA cut off funding U.S. for an international project called the Laser Interferometer Space Antenna (LISA). Those changes will likely delay important tests related to the 2-D proposition, but researchers remain hopeful.

“It would simplify everything,” said Stojkovic.

Scientists have already observed cosmic rays aligned along a two-dimensional plane, indicating that they may have come from a 2-D point of origin. Cosmic rays are also commonly believed to emanate from high-energy explosions in events such as supernovae.

The Large Hadron Collider, the atom smasher at CERN in Europe, may also provide support for the 2-D theory as results emerge from particle studies there.

“If our theory is correct, then the LHC must see planary events,” Stojkovic said.

Those events would include energy readings that correspond to lower-dimensional spaces.

LISA, meanwhile, would also be able to provide Stojkovic and Mureika with valuable information from gravitational waves at the cosmic scale.

Since gravitational waves cannot exist in 1-D or 2-D spaces, LISA could determine whether or not dramatic changes in frequency—indicative of a dimensional expansion—left behind perceivable evidence in older parts of the universe.

The European Space Agency will continue to fund the orbital observatory, but without NASA’s $1.5 billion contribution, the two physicists believe it could take many more years before the tests they would like to see can be performed.

If the LHC and LISA corroborate Stojkovic and Mureika’s theory, a newer, even more intriguing conversation may take hold, since dimensional expansion could indicate that a fourth physical dimension is on its way—or already in existence around the observable universe.

Mureika describes the differences between 1-D and 2-D spaces and the evolution of 3-D space to a potential 4-D universe in terms of what an ant living on a single sheet of newspaper might experience compared to a human being capable of moving around with clear notions of length, width and depth.

And the idea that the universe as it is currently understood could feed into a higher-dimensional context excites him.

“[Our universe] might itself be a lattice on a larger scale,” he suggested.