Why is space three-dimensional? © Getty Images

Why is space three-dimensional?

The big bang might be to blame for our 3-D Universe.

Asked by: Nathaniel Hey, Jersey

Advertisement

In principle, it’s possible for the Universe to have many more space dimensions; some attempts to explain the fundamental forces of nature assume no fewer than six extra ones.

Yet for reasons still unclear, any additional dimensions that may have existed at the Big Bang somehow failed to take part in the cosmic expansion and remained far smaller than the three dimensions we inhabit. What is certain is that, had they grown in size, the Universe would be a very different place.

Theoreticians have shown that any extra dimensions would make atoms unstable, while any fewer would eliminate the force of gravity. Max Tegmark, a cosmologist at the Massachusetts Institute of Technology, has gone further, arguing that the very fact we exist to ask about extra dimensions of space proves they don’t exist.


Advertisement

Subscribe to BBC Focus magazine for fascinating new Q&As every month and follow @sciencefocusQA on Twitter for your daily dose of fun science facts.