Primordial weirdness: Did the early universe have one dimension?

A new theory by UB physicist Dejan Stojkovic and colleagues proposes that the early universe had just one dimension and a fourth dimension may be opening up as the universe expands. Did the early universe have just one spatial dimension?

That's the mind-boggling concept at the heart of a theory that University at Buffalo physicist Dejan Stojkovic and colleagues proposed in 2010.

They suggested that the early universe - which exploded from a single point and was very, very small at first - was onedimensional (like a straight line) before expanding to include two dimensions (like a plane) and then three (like the world in which we live today).

The theory, if valid, would address important problems in particle physics.

Now, in a new paper in Physical Review Letters, Stojkovic and Loyola Marymount University physicist Jonas Mureika describe a test that could prove or disprove the "vanishing dimensions" hypothesis.

Because it takes time for light and other waves to travel to Earth, telescopes peering out into space can, essentially, look back into time as they probe the universe's outer reaches.

Gravitational waves can't exist in one or two-dimensional space. So Stojkovic and Mureika have reasoned that the Laser Interferometer Space Antenna (LISA), a planned international gravitational observatory, should not detect any gravitational waves emanating from the lower-dimensional eras of the early universe.

Stojkovic, an assistant professor of physics at UB, says the theory of evolving dimensions represents a radical shift from the way we think about the cosmos - about how our universe came to be.

The core idea is that the dimensionality of space depends on the size of the space we're observing, with smaller spaces associated with fewer dimensions. That means that a fourth dimension will open up - if it hasn't already - as the universe continues to expand.

The theory also suggests that space has fewer dimensions at very high energies of the kind associated with the early, post-big bang universe.

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