|Microwave radiation from the whole sky captured by the ESA Planck satellite.|
The mottled yellow area is the Cosmic Microwave Background created in the
Big Bang - perhaps when the universe was one dimensional
Theory suggests fourth spatial dimension set to open up as the universe expands
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 next stage? 3D TVs can give the optical illusion of three dimensions to a two dimensional screen. Now scientists believe a fourth dimension could open up
The theory, if valid, would address important conundrums facing particle physicists.
Now, in a new paper in Physical Review Letters, Dr 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 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 Dr Stojkovic reasons that a planned gravitational observatory (LISA) should not detect any gravitational waves emanating from the early universe.
The Laser Interferometer Space Antenna will be a joint project between Nasa and the European Space Agency and is slated to begin work in 2016.
Dr Stojkovic says the theory of evolving dimensions represents a radical shift from the way we think 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.
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.
'What we're proposing here is a shift in paradigm,' Dr Stojkovic said.
'Physicists have struggled with the same problems for 10, 20, 30 years, and straight-forward extensions of extensions of the existing ideas are unlikely to solve them.
'We have to take into account the possibility that something is systematically wrong with our ideas.
'We need something radical and new, and this is something radical and new.'