How to levitate objects sans magic

In fiction, magic makes levitation easy. With a simple swish-and-flick of his wand, Ron Weasley yanks a troll’s club high above its head in Harry Potter and the Sorcerer’s Stone. Through graceful martial arts, element benders in TV’s Avatar series launch boulders and waves of water skyward. And a casual gesture is all Marvel hero Scarlet Witch needs to fling away enemies.

In the real world, sound, magnets and electricity can all create upward forces strong enough to cancel out gravity. Just don’t expect these levitation techniques to toss boulders or bad guys. At least, not without some outrageous — and dangerous — upgrades.

Acoustic levitation devices use vibrations to hold objects aloft. These machines typically blast sound waves too high-pitched for humans to hear. The waves create alternating regions of high- and low-intensity “noise” in the air. Noisier areas push objects away, trapping them in pockets of relative quiet — but only if the objects are very small and lightweight. Some of the heaviest stuff to ever surf sound waves are Styrofoam beads.

Bigger objects need longer, lower-frequency sound waves to cradle them, says Luke Cox, a mechanical engineer who heads Impulsonics in Bristol, England. He estimates you would need at least 275-hertz sound waves with 1.25-meter wavelengths to levitate a person. A bass guitar plays notes about that low. But it would have to be devastatingly loud to lift someone off their feet. 

You’d probably need the energy output of a nuclear power plant to run such a device, Cox muses. Plus a shield to protect anyone you levitated from the heat generated by that amount of power. Otherwise, your gnarly, nuclear-powered bass solo might literally melt their face off.

Magnets get objects much bigger than people off the ground without destroying them. For instance, the ones on maglev train cars and rails interact to make the trains hover just centimeters above their tracks.

Using magnetism to levitate something not strapped to a magnet is trickier, but not impossible. Many seemingly nonmagnetic materials, including water and proteins, are diamagnetic: In a strong magnetic field, they become weakly magnetized and start to repel the field.

In 1997, scientists famously used that fact to levitate a frog. They placed the creature inside nested coils of wire that created a magnetic field 16 teslas strong — or about 10 times the strength of magnets used to pick up cars in junkyards. That was just enough to buoy the frog to near the top of the 18-centimeter-tall inner coil of wire.

You could theoretically levitate a person this way. It would take one heck of a magnet, though. One of the frog floaters estimated in 1998 that you’d need a 40-tesla field created by a magnet running on 1 gigawatt of power — roughly half the output of the Hoover Dam.

Ballooning spiders use a different way of levitation. They electrically charge themselves up by spinning out long threads of silk, says Igor Bargatin, a physicist at the University of Pennsylvania. That charge allows the spiders to lift off in Earth’s electric field and then ride the wind up to kilometers high.

The spidey way of levitation won’t work for large objects like people, Bargatin says. You’d have to build up so much charge that you’d end up triggering lightning strikes around you and fry yourself before ever taking off.

Even if real-world levitation never measures up to on-screen superpowers, it can still be useful. Acoustic levitation could provide hands-off handling of lab samples to avoid contamination. Magnetic levitation could make parts of motors float, allowing them to spin faster without wearing down. And scientists continue dreaming up new uses for levitation — ones that don’t cause deadly collateral damage.