why do you keep thinking in a rational way that is known to us :p you can't make light end after one meter either, so what?
This solution is fairly simple, and draws on the plastic lightsaber toys I’m sure you’ve all seen. These toys have a set of ever decreasing conical tubes which can “collapse” into themselves, or extend. The decreasing shape of each tube keeps them from simply sliding off each other when extending, and compression “locks” the extended plastic “lightsaber” in the open position.
What I’m proposing is to have a relatively slim metal version of this design extend from the center of our lightsaber. This technology already is decades old, and you’ve all seen it. Where? A retracting, segmented auto antenna. There are several ways this device could expand and retract. You could simply yank the unit out of an old Cadillac, or create your own design, possibly using electromagnets Here’s why we need this metal tube:
1) At the end of it we’ll place a cap of some sort to stop our “blade” from extending on to infinity.
2) This gives our “light” saber a solid core. Why is this important? Remember in our duel with the Sith lord how our blade failed to block his? Now our blades can’t pass through each other.