Even if the inside of the balloon is completely empty (or massless), the surface of the balloon must be made of something, and that something will have mass and inertia, so rotating the balloon will distort.
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One day, lasers may be propelling craft into space.
The momentum of photons is too low to lift a sizeable object against Earth's gravity, but the photon has far more energy than is absorbed by a solar sail. If I understand it correctly, the kinetic energy transferred to the spacecraft is contributed by the slight redshift of photons reflected from the solar sail.
The idea is to build a space elevator, but you don't want the elevator to be carrying its own fuel, so you could use ground-based lasers to power the elevator.
(I would expect that you could also power it by electricity from the ground - only a conductive space elevator is likely to be destroyed by lightning...)