Alistair Melville says, what does it mean for a dimension to be small or curled up? Aren't dimensions effectively endless in two directions? Is this a concept that falls out of the maths or doesn't yet have any real world evidence? Well, there's no real world evidence. There's still nevertheless big, they're finite in size, but just very, very big, bigger than our observable universe. Yeah, these things are just all completely plausible. They could happen. Jake Cornegay says, a black hole made of elements from a dead star would look different inside the event horizon than a blackhole made of cats and people who happened to fall inside of a black hole