How does Laputa stay in the air and do you think that such an island really could exist by using modern technology?

Gulliver finds that the way the island floats is by a magnet. By changing the degree at which the magnet is placed, it makes the island rise and fall. The island cannot go beyond the domains of the country and it cannot go over four miles high. In modern times, the closest equivalent to such a floating island of people is probably an airplane, but the magnetic principle is so believable that, some day soon, modern scientists might find similar methods to actually make a floating island.