What was terrifying about their passage in Chapter 4?

Meg suddenly feels her self transported into what feels like another dimension. Charles Wallace and Calvin disappear from around her and all “light and sound” vanished. She feels as though she is moving through a “horrifying void.”

It is terrifying because Meg feels as if she is being blown into nothingness and whisked away into a black void of nothingness. This could be connecting to Buddhism, as they say that there is no hell but the one you make for yourself, as she felt that the void of nothing was a hell, or she could've thought of it that way.