Picture a spider web in the morning dew. See all those shining beads? Those represent the "volume" of hyperspace underlying galaxies. See those gossamer threads between the beads? Those represent the volume of hyperspace underlying the spaces between the galaxies. See all that empty space? That represents the areas where hyperspace has little or no volume at all.
The dark matter that clumps around and throughought every galaxy spans an area much larger than you'd expect when you look at the starlight a galaxy emitted. This dark matter is principally composed of WIMPs -- "Weakly Interacting Massive Particles." For our Milky Way galaxy this cloud of WIMPs extends over a hundred thousand light-years, or a hundred "kilolights", in every direction from the galactic core. Not coincidentally, this roughly spherical volume is also the volume in which it is possible to teraport.
That said, it is (or at least WAS) possible to teraport to Andromeda. It just requires enormous amounts of power to open the requisite wormholes through the tiny hyperspatial volumes represented by those thin filaments of spiderweb. So much power, in fact, that it hasn't been done other than experimentally.
But I said "WAS." Following the event in the Milky Way's galactic core, several things happened.
- The dewdrop we're living in got shaken loose from the spider web.
- A new spider web, dewdrops and all, began expanding hotly in the middle of our lonely little cut-off universe.
- The spider web as a metaphor got a bit overburdened. Sure, there are spiders who spin webs underwater, but they don't do it "hotly," and they're several times the size of a dewdrop.
So, at the current time, it's possible to teraport right to the hyperspatial borderlands of the Milky Way, but no further. In addition, any sub-light-speed travelling you do from there outward is energetically futile... the rapidly growing "universe of death" behind you will catch up eventually. But hey, you might buy yourself a few minutes if you leave now.
There are two pieces of good news in all this:
- The universe devouring our galaxy will not "jump" back to the spiderweb. The rest of the universe we dropped out of is safe.
- Did I say two pieces of good news? I thought for sure there was something else, but maybe not.