2次元筒君がぐぐってマウント取りたがってたからM2の定義をwikiから引っ張ってきてあげた

https://en.wikipedia.org/wiki/M2-brane
>In theoretical physics, an M2-brane, is a spatially extended mathematical object (brane)
>that appears in string theory and in related theories (e.g. M-theory, F-theory).
>In particular, it is a solution of eleven-dimensional supergravity
>which possesses a three-dimensional world volume.

何次元のオブジェクトかって言われたら3次元って言うのが普通なんよね
2次元筒ってｗ