[Simon Green]

Once it got to where it was going, how did it 'slow down'?

The same lasers can be used to decelerate the spacesship as well.

Forward’s separable sail concept used for deceleration, from his paper “Roundtrip Interstellar Travel Using Laser-Pushed Lightsails,” Journal of Spacecraft and Rockets 21 (1984), pp. 187-195. The ‘paralens’ in the image is a huge Fresnel lens made of concentric rings of lightweight, transparent material, with free space between the rings and spars to hold the vast structure together, all of this located between the orbits of Saturn and Uranus.

So granted, this concept requires that we have the capability of constructing a thousand mile wide structure in deep space.

But that's just a minor engineering issue. The math works, it seems. :-)

[UCANSEE2]

The math works, it seems.

Probably the only part of it that does or ever will work.

[UCANSEE2]

Using the concept you cited, how long would it take the ‘craft’ to slow back down to where it could orbit a planet (assuming that it accelerated to a speed fast enough to get the passengers to Eridani within their lifetime) ?