My daughter asked me when we could expect hoverboards. OK.
In the old film Back to the Future, the hero rides a hoverboard instead of a skateboard. We don’t see many of them around yet, but there are a few ways you could do it. One is clumsy and involves using a compressor and air jets to make a small hovercraft that you can ride on.
Another has no moving parts, so would be much more in keeping with the one Michael J Fox modelled.
I wrote a while ago about the future of bicycles:
The basic idea was to add a plate to the front forks of the bike that would be pulled along a linear induction mat.
A highly skilled skateboard user with an excellent sense of balance might be able to dispense with the bike bit. Instead, repulsion between the magnetic forces created by the mat and circuits in the board would keep it afloat. Pulling the board along would be no problem of course, as the filed can propagate down the mat just as for the bikes.
The big question is whether sufficient force could be generated with everyday simple circuits, or even with permanent neodymium magnets. And how easy it would be to balance the board. I suspect it ought to be doable but my EM theory is rather rusty and although I have designed magnetic clutches before, and the principle should be similar, I am no longer up to the job.
It isn’t essential to have a linear induction mat cannibalised from bicycle lane use. If there is sufficient demand for hover-skate-board parks, special surfaces with loads of coils could be switched on and off to coordinate with the board circuits to make it far easier. Rather like a Segway manages to stay upright by rapidly adjusting torques, a hoverboard could easily house enough electronics to do the job. It would cost more than an ordinary skateboard of course, but with no wheels, maybe a wider range of tricks might be feasible too. With no wheels, they could slide sideways and spin around easily. That would make them harder in some ways, but also more versatile, so sports could evolve that are even more fun that regular skateboards. As someone who has never managed to stay on a real skateboard more than 25m yet, I feel inadequate to advise on techniques, but the engineering should be feasible.
In terms of timescale, there is nothing here that is beyond current technology. Nobody has bothered yet, as far as I know. But if there was a demand, someone could make hoverboards soon, and they could fly, and you could probably make some pretty fun sports with them too.