For most of us, or perhaps all of us, it's impossible to imagine a world consisting of more than three spatial dimensions. Are we correct when we intuit that such a world couldn't exist?

Theoretical physicists point to the idea that there are other dimensions out there, beyond what we can see. And there could be loads of them, as Melissa Hogenboom explains. A film by Melissa ...

But now, some physicists believe they might be more than just cosmic vacuum cleaners—they could be gateways to other dimensions or even alternate universes. Could falling into a black hole ...