It's not hard to work out, since stellar distances are measured in light years (the distance light will travel in a year) and a LASER beam is just coherent light. (Iain is of course referring to the nearest stars outside our own Solar system, being the Alpha Centauri stellar cluster.)

It's also doubtful whether a LASER from a DVD player would be coherent enough to span an interstellar distance and still be visible, not to mention it would most likely be drowned out by the light from the local star and in any case would probably be distorted by time, space and gravity.

All of which makes LASER communications unsuitable for interstellar distances, unless you have very good aim and masses of patience.

Oh, incidentally: The first bubble in the third panel is coming from Manny. I may need to re-engineer that so it's clearer.