Did the early universe have just one spatial dimension? That’s the mind-boggling question at the heart of a theory scientists say they are on the brink of solving.
The theory was first proposed by physicist Dejan Stojkovic and colleagues from the University of Buffalo in 2010. They suggested that the early universe – which exploded from a single point and was tiny at first – was one-dimensional (like a straight line) before expanding to include two dimensions (like a plane) and then three, which is the world in which we live today. The theory, if valid, would address important conundrums facing particle physicists.
Now, in a new paper in Physical Review Letters, Stojkovic and colleagues have come up with 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 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 reasons that a planned gravitational observatory (LISA) should not detect any gravitational waves emanating from the early universe.
Stojkovic says the theory of evolving dimensions represents a radical shift from the way we think about how our universe came to be. The theory also suggests that space has fewer dimensions at very high energies of the kind associated with the early, post-big bang universe.
If correct it may help to address the incompatibility between quantum mechanics (used to describe the universe of the very small) and general relativity (good at describing the universe on a large scale.) It could also explain why the expansion of the universe is speeding up with the addition of a fourth dimension.