A hole in an elastic sponge closes on its own. To keep it open, you need a brace that pushes from the inside with negative effort — effectively pulling the walls inward rather than pushing them apart. Ordinary matter can't do this: it only attracts, causing the hole to collapse faster. Such is a wormhole — a tunnel in curved spacetime. It requires exotic matter with negative energy.

Adding dark energy, the very vacuum that stretches the Universe, and its energy exchange with matter does not change the picture. As shown by John Wheeler and Kip Thorne, the throat opens only when pressure exceeds energy density. A new theorem proves that quantum fluctuations and tricks with redshift won't save you. Gravity will mercilessly collapse the tunnel.

This conclusion is important for searching for wormhole traces in gravitational waves at LIGO and Virgo. And for science fiction: time dilation at the throat is such that even light won't slip through. Nature doesn't need shortcuts — known physics won't allow them.