CON-3: The Krasnikov tube

The L2 scheme that accepts the bootstrap, and it still pays the ENE-3 bill and the CAU-3 bill.

Kind: constraint · Family: CON (Control) · Last reviewed: 2026-09-12

The result

The Krasnikov tube: a metric laid down along the outbound sublight journey that makes an arbitrarily long round trip take an arbitrarily short time by the traveller's clock and the home clock alike. Everett and Roman show the tube, like warp bubbles and traversable wormholes, needs unphysically thin layers of negative energy density and large total negative energies, and that a time machine can be built from two non-overlapping tubes

What it forbids or costs

The L2 scheme that accepts the bootstrap, and it still pays the ENE-3 bill and the CAU-3 bill

Escape hatches

None beyond those of ENE-3

Who it bites

Physics proposals

• SATISFIES: Everett and Roman 1997: the superluminal subway. This paper is the entry: arbitrarily short round trips, Planck-thin negative-energy layers, large total negative energies and the two-tube time machine, all verified against the text.
• SATISFIES: Krasnikov 1998: the tube laid on the way out. This paper is the entry's first citation; the round trip is arbitrarily short by home and traveller clocks alike, and the paper accepts the ENE-3 and CAU-3 costs the entry lists.

Fictional drives

• SILENT: Star Trek: transwarp, quantum slipstream and the other beyond-warp drives. A transwarp conduit is a Krasnikov tube in shape, a route pre-laid along which later travel is fast; the episodes never price its energy or its two-tube time machine.

Sources

• Krasnikov, Phys. Rev. D 57, 4760 (1998); Everett and Roman, "A superluminal subway: The Krasnikov tube", Phys. Rev. D 56, 2100 (1997), arXiv:gr-qc/9702049 ✓