In the links below Carl Sagan and TED-Ed described about higher dimension: and here's a description of Brian Greene: Carl Sagan and TED-Ed explained, we can not see the higher dimensions because we are limited to perceive only three dimensions. They didn't say a dimension can be small or big. These explanations completely makes sense. But Brian Greene explains, higher dimensions can be tiny and curled up. Isn't every dimension perpendicular to each of the other dimensions? If so, then how can a dimension be tiny or big? I want to know, which is the right way to imagine higher dimensions?