Perhaps then, I should be checking for a harmonic resonance - several frequencies or even entire chords and octaves resonating at the same time. It would explain it, yes, the dissonance I get when I try only one. However, it would take time for the universe to stabilize to the come and go - a day or even a week before it finds the right resonance to keep everything held together.

[A microwave beeps and Walter scuttles away from his journal, still talking as he goes for his popcorn.]

To aim for a universe crossing would mean having to wait for a stable period and then accounting for each separate resonance in the village. Maybe this is why previous attempts have failed. The number of machines, all vibrating at once to create a portal to travel between this world and each individual's world would be--

[He sits back down at his table, munching on popcorn as his pencil scribbles notes on a different piece of paper.]

-- astronomically difficult to obtain with the level of technology available.