Building a human-sized wormhole, for example, would require harnessing vast amounts of peculiar quantum field energy and deploying gravitational stabilizing technology that would need the resources of a cosmic super-civilization.
But whereas a black hole represents a one-way journey to nowhere -- jump in and you can never get out -- a wormhole has an exit as well as an entrance.
The Large Hadron Collider -- the giant accelerating machine that created the Higgs boson -- might just make a tiny wormhole for long enough that its time-bending effects could be glimpsed.
The ball may disintegrate into a powder, or break in half, or hit up against its earlier self at just such an angle so as to enter the wormhole in just such a way that even more peculiar events occur.