We tend not to think that we exist in three dimensions. Forward-backward, left-right, up-down; these are the axis by which we navigate the world. When we try to imagine something else, it usually conjures up images of the wildest science fiction – from portals to space-time and parallel worlds.
However, serious physicists have long been puzzled additional measures. For all their intangibility, they promise to solve many big questions about the deepest workings of the universe. Moreover, they cannot be dismissed because they are difficult to imagine and even more difficult to observe. “There’s no reason it has to be three,” he says Georges Obied at the University of Oxford. “It could have been two; it could have been four or 10.”
However, there comes a point where any self-respecting physicist wants hard evidence. That’s why it’s so exciting that, in recent years, researchers have developed very few techniques that can demonstrate extra dimensions. You may still see them flowing to gravity, for example. We can see their subtle traces in black holes or find their traces in particle accelerators.
But now, in an unexpected twist, Obied and others are pushing for another extra dimension we’ve only guessed before. This “dark dimension” would hide particles from the beginning of time that could solve the mystery dark matterwhose gravitational pull is believed to have shaped the cosmos. Crucially, it should be enough…
