Astronomy Picture of the Day

Explanation: Does our universe have higher but unusual spatial dimensions? This idea has been gaining popularity to help explain why vastly separated parts of our universe appear so similar, and why the geometry of our universe does not seem to result naturally from the amounts of matter it seems to contain. In a new incarnation of an old extra-dimensional idea, some astrophysicists hypothesize that we live in a universe dubbed Ekpyrotic, where our four dimensions (three spatial plus one time) resulted from the fiery collision of two four-dimensional spaces (branes) in a five-dimensional universe. This big-bang hypothesis is meant to compete with another big-bang hypothesis that our universe underwent a superluminal inflation event in the distant past, and does make distinct testable predictions. Above, a dynamic three-dimensional drawing (two spatial plus one time) of a four-dimensional depiction of a five-dimensional cube (a hypercube with four spatial dimensions is also known as a tesseract) is shown. Donning red-blue glasses will give the best multi-dimensional perspective.