King of the Seven Seas, Arthur Curry, the Aquaman, has many amazing superpowers. He can breathe underwater, he is strong enough to withstand pressures at the bottom of the ocean that would crush steel, and no man-made vessel can ply the waters as fast as he can swim. But it is his “fish telepathy” for which he is best known. As Bruce Wayne says to Arthur Curry in the Warner Bros. film Justice League, “I hear you can talk to fish.”
I talk to fish too. Only they don’t listen to me. But Aquaman is able to initiate meaningful two-way communication with our finny friends. It turns out that there is a physically valid way for him to do this, provided we grant him a one-time miracle exemption from the laws of nature!
To understand how he does this, it helps to go back to how we, simple land-based mortals, talk to each other. Flexing our diaphragm forces air past our vocal cords, horizontal membranes in our larynx, causing them to vibrate and creating pressure waves in the air leaving our mouth. These sound waves propagate radially away from us until, in the best-case scenario they are detected by the thin flexible membrane in another person’s eardrum or a microphone. But all of these steps first require an instructional voltage to be sent to the diaphragm, that originate is the brain. It is the brain’s electrical signals, coupled with Faraday’s Law of Magnetic Induction, that enable Aquaman to ‘talk’ to fishes.
There are roughly one hundred billion neurons in your brain (more cells than there are stars in the Milky Way galaxy), with each neuron making, on average, one thousand electro-chemical connections (called ‘synapses’) with other cells. Through mechanisms that are not fully understood, the flow of electrical currents in the form of ions (atoms with missing or additional electrons) from one neuron to another convey information, representing a memory, a creative idea, or a signal for the muscles in your diaphragm to flex in a particular manner. Back in the middle of the 19th century, Michael Faraday and other scientists discovered that electrical currents such as those in your brain will generate magnetic fields. Moreover, changing magnetic fields can induce the creation of electrical currents. This beautiful symmetry between electrical currents and magnetic fields is the basis of our wireless communication, from radios to our smart phones.
And it is one way that Aquaman is able to send his thoughts to aquatic creatures. The electromagnetic waves we generate when we think are one billion times weaker than the radio waves that permeate the room you are reading this. Nevertheless these signals can be detected with sensors placed directly on a person’s head. For Aquaman, his super-power presumably entails a special cerebral feature that enables him to amplify these electromagnetic waves. Ocean seawater is a hundred trillion times more electrically conductive than pure deionized water, further increasing his range.
Such an adaptation is not so far fetched, as fish have two unique organs, one that generates small electric fields and another that detects these fields, combining them into a form of radar that allows them to navigate in the murky ocean depths where light does not reach. Sharks have electroreceptors that are so sensitive that, as characterized by Sönke Johnsen and Kenneth J. Lohmann in a 2008 Physics Today article, they can detect the voltage generated by an AA battery over 450 miles away! Given this, it’s not a wonder that Aquaman can mentally communicate with fish, but rather how he could ever keep his thoughts private!
Here in Minnesota, home of 10,000 lakes, this ability of Aquaman’s would be a very useful power to have. Though it would take the sport out of fishing.