About extradimensional magic verisimilitude...

[Turanil]

When playing D&D and casting spells such as Mordenkainen Magnificent Mansion, or using items such as a Bag of Holding, we simply enjoy the game and don't want to ever think about the blatant implausibility of such concepts.

However, here is something I found on a scientifical website article :

(...) he makes use of another trick from general relativity. The interior volume of a region of space bounded by a closed surface, because of space curvature, can be made much larger than the flat-space volume bounded by its surface. In curved space the inside volume of a sphere of radius R can be much greater than 4/3pR3.

So, your common Bag of Holding is perfectly plausible!

 

[Nifft]

Sure, and every Portable Hole is secretly a Sea of Dirac.

-- N

 

[Zappo]

For example, a warp bubble 100 meters in radius that might contain a space ship of reasonable size would have a net negative energy that was roughly ten times larger in magnitude than the entire (positive) energy of the visible universe.

AAAAAGH! It's an UNDEAD drive! O_O