# Why can't we use magnets to levitate small objects like in Harry Potter or Star Wars? [closed]

In Harry Potter there is a spell which allows a person to levitate an object at will around a room. In Star Wars, Jedi mind control allows you to do the same thing. I'm surprised that no one has tried to replicate this sort of levitation using magnets: the levitating of a small object at eye level with the ability to control where the object moves. Of course we use magnets to levitate things like Maglev trains, and many children's toys use magnets to make objects float. But levitating an object in a controlled manner several feet above the ground is quite different.

I don't see why this is so hard to accomplish? Suppose we constructed a room with powerful electromagnetics embedded in the walls, floor, and ceiling. We have some metal object which is placed in the room. When the electromagnets are turned on, the object floats several feet above the ground. By manipulating the magnetic field (using a computer), a technician outside the room can control the movement of the object at will. Now, it's easy to see why this particular setup is extremely costly, but I imagine something similar could work?

Ideally, we want a person in the room to control the object himself (not using a computer). Perhaps we can make a glove with powerful magnets embedded in it. The strength of the magnets can be manipulated by closing or opening your hand.

I'm sure this sounds very childish and naive. I haven't considered the relevant physics yet, but I don't see why this would impossible in principle. Whether we can do this cheaply is another story.

• Not impossible in principle, but it may be infeasible depending on the size of the room. The main reason this hasn't been done is because there is no practical purpose. It would be absurdly costly. Apr 17, 2015 at 23:57
• Well actually I am not suprised it hasn't been done because yes its very very costly and completley useless. Well how much would it cost roughly? Also I Imagine there might be some possible application. Apr 18, 2015 at 0:00
• In Star Wars and Harry Potter this levitation is done in a normal environment. What you propose is a specialized room with many electromagnets, who do Bad Things to everyday objects, devices and perhaps even your person. Plus, the continuous use of such magnets would require extreme amounts of energy. Apr 18, 2015 at 0:02
• @JoshuaBenabou Hundreds of millions of dollars for something smaller than a broom closet. Operating costs would also be very high. There isn't an application that can't be better achieved another way. Apr 18, 2015 at 0:06
• Hi Joshua. While this is a by interesting question, I'm not sure it belongs on this site as it's more physics based, I've voted to close it as such. If you want it migrated to the Physics SE site, you can flag it using the 'other' reason and explain that you want it migrated. Apr 18, 2015 at 7:17

## We can, actually

I recall this little frog being levitated using a (somewhere between 1-100 Tesla) magnetic coil using diamagnetism about a decade or more ago. There he is:

Water is diamagnetic, as are many good conductors. So frogs and more recently, small mammals, have been levitated.

Material           χv (× 10−5)
Superconductor      −105
Pyrolytic carbon    −40.9
Bismuth             −16.6
Mercury             −2.9
Silver              −2.6
Carbon (diamond)    −2.1
Carbon (graphite)   −1.6
Copper              −1.0
Water               −0.91


More relevant to your question, there was a spinning-stabilized toy patented in the 70s and more recently, there are commercially available solutions such as the Levitron for low weight objects in a limited range.

Heck, you can build one yourself with a few magnets.

• The spinning magnetic levitation was actually one of those situations where someone just tried to float a magnet above another without knowing that the calculations show it can't be done for stationary magnets. Both of these solutions are missing "the ability to control where the object moves" requirement though. Apr 18, 2015 at 2:08
• @Samuel Just put the base under the floor and make it mobile. Not that big a deal. Apr 18, 2015 at 12:03

There is a significantly better way to do it than magnets, a way that's already being done.

Acoustic Levitation

As you can see in this video, small objects can be made to levitate and move around by controlling the amplitude and frequency of the ultrasonic waves.

Acoustic waves are just pressure waves, by bouncing the waves between two plates objects can be suspended in the low pressure nodes.

You can build simple ones at home with an ultrasonic transducer from ebay. This is a significantly cheaper way to get the same effect as magnetic levitation.

• I've seen this before, but the objects have to be really light for this to work, no? Apr 18, 2015 at 3:45
• Yeah, fairly light and small objects. They need to be supported by air pressure and also fit inside the waveform. Apr 18, 2015 at 3:55