Comment by btilly

It slows down by releasing a large light sail in front of it, designed to reflect light back to a much smaller light sail behind it. The laser then pushes the large sail away, and as the sail goes it pushes the smaller sail (and ship) back. This leaves the ship at moderate speed relative to the new star, and a large sail traveling very, very quickly beyond it.

We do not yet have this technology. But we can show that it is plausible.