Levitate a Frog

Go to your refrigerator and grab a magnet. Now try to stick it to your body. Of course, the magnet falls to the ground because our bodies are not magnetic.

Right?

Colloquially, yes. Technically, the answer is more complex (though you obviously still won’t find magnetism in your vaccines; I can’t believe I feel the need to add this side-note).

We usually associate magnetism with an attractive quality. This attribute is how the magnets above stick to my refrigerator. If you recall science classes during schooling, you might remember that magnets have poles. When opposite poles near each other, the magnets cling; if one tries to push similar poles together, repulsion occurs. Though we industrially focus on the adherence qualities of magnets, they actually attract and repel.

We differentiate between different types of magnetism. The most famous kinds are ferromagnetic (the Latin prefix for iron is ferro). This special class of magnets refers to the ability of some metals to form permanent magnets. The two main branches of magnets are paramagnetic substances and diamagnetic substances.

Magnetic fields arise because of moving electrical charges. Paramagnetic things are attracted by a magnetic field, while diamagnetic items are repelled. All matter in the universe is diamagnetic. Some things display both properties. If a mass demonstrates paramagnetic properties, this conduct dominates. In other words, a substance must be purely diamagnetic to demonstrate a non-attractive interaction with a magnetic field. Paired with the fact that diamagnetic properties are often small relative to human perception, we developed the idiomatic mindset that magnets attract and objects that repel, however so slightly, are non-magnetic. Technically, this perception is incorrect.

Our bodies are (dia)magnetic!

The repulsive powers of magnetic fields make sense if we step away from the proclivity to think about attraction. It’s how magnetic bullet trains function. It’s how a top can spin midair inside a wine glass, as in the video above. But non-metallic substances might intuitively seem anti-magnetic.

Paper is diamagnetic. Your shoes are diamagnetic. Water is diamagnetic.

Yes, water can levitate. Here’s a simple video of water being repelled by a magnetic field:

What things are primarily composed of water? Living bodies are primarily composed of water!

So, can we levitate?

Oh yeah!

Of course, the power needed to levitate a human body is incredibly high. A levitating substance is working against the immense pull of gravity, so the magnetic field needs to be extraordinarily intense. The power required for such a field is currently impractical.

But some living bodies are much smaller. Frogs are tiny and have a lot of water. Can we levitate a frog?

Of course, we can. And a grasshopper, to boot. And all thanks to diamagnetics!

The magnetic field required to make this frog float was 16 teslas. The power needed to produce a field that strong was 4 megawatts (4 million watts)! That’s about the amount of energy created by 40 automobile engines. A 2 MW turbine can power approximately 400 homes. So, you can see how the power demanded by bigger beings might spiral out of control.

Still, it’s possible! Important to note, no frogs or other living beings were harmed in the levitating of the frogs or other living beings. The scientists involved in the experiments reported the frogs happily hopped back to their fellow amphibians.

Bonus question: if we can levitate a train with magnets, why would the power required to levitate a human be impractical? The answer is somewhat complex, but, for the train, we do not utilize diamagnetism. Instead, we employ superconductors, cool temperatures, and opposing poles of paramagnetic substances. Check out the Further Reading and Exploration section below for an article on how it works.