A lightspeed wire is a wick which burns nondestructively at the speed of light, such as the portion shown at the right (a c agar crawler). A semi-infinite wire functioning as a fuse would not be as interesting as a finite segment surrounded by structures (ie. fenceposts) capable or emitting and absorbing anomalies which in turn could be interpreted as signals.
Alternatively, the boundary of the channel containing the wire might be modified in some way that could detect and respond to the signal. Some of these ambitions have been realized, such as fenceposts for many wires; others still await implementation.
For example, if the wire could be made to turn corners and allow a loop be formed, oscillators of different periods would follow. This inspired Dean Hickerson to create his drifter searcher. The program has failed to find a valid 2c/3 signal turn, but has found many of the known billiard table oscillators.
In February 2003, Jason Summers completed a lightspeed telegraph that can send information at lightspeed along a chain of beehives at a rate of one bit per 1440 ticks. In 2010, Adam P. Goucher constructed a version of the telegraph using only stable circuitry, such that a single incoming glider produces a lightspeed signal, which is detected at the other end of the telegraph and converted back into a glider -- but at the cost of a much slower transmission speed, one bit per 91080 ticks. In February 2017, Louis-François Handfield completed a high-bandwidth telegraph using periodic components, improving the transmission rate to one bit per 192 ticks.
2c/3 and 5c/9 wires
Diagonal wires have been made that propagate signals at the speeds of 2c/3 or 5c/9 diagonally. The prospect of making a 2c/3 signal turn a corner is a lot closer to reality than turning a lightspeed orthogonal signal, especially because Dave Greene and Noam Elkies have already engineered a stable 2c/3 signal transceiver.
5c/9 signals are easier to produce, but much harder to detect. Only two distinct fizzles have been found for the 5c/9 signal, whereas hundreds exist for the 2c/3 signal.