[Leszek]

> All finite initial configurations tested eventually converge to the same repetitive pattern, suggesting that the "highway" is an attractor of Langton's ant, but no one has been able to prove that this is true for all such initial configurations

If Langton's ant is capable of universal computation, wouldn't non-halting programs be a counterexample to this convergence?

[Igglyboo]

I'd have to agree. From my understanding of that sentence, all programs would "halt" eventually because they all end up doing the highway. So unless your computation somehow ended with the highway then you couldn't run infinitely long computations.

[sp332]

Langton's ant has no halting state. It can't halt. But you're right, that description doesn't leave any room for programs that run in a specific loop forever instead of making a highway. So that doesn't seem to be Turing-complete.