Curious kids: can our brain perceive electromagnetic waves?

Can our brain perceive electromagnetic waves? Taye, age 10, London

Electromagnetic waves are packets of energy that travel around us. Some of these waves have a lot of energy and some have less.

We call the lowest energy electromagnetic waves radio waves. There’s a good chance that radio waves are moving around you right now, beaming from Wi-Fi routers, laptops, and cell phones.

The most powerful electromagnetic waves are gamma rays, although you’ll never have had them anywhere near you unless you’ve spent time hanging out among exploding stars or inside a nuclear reactor.

And there are some electromagnetic waves that we can actually see. This is visible light, the light that we can see around us.

Most of the electromagnetic waves around you simply pass by without you noticing, but some of them are perceived by your brain and form a very important part of your daily experience of the world.

Brain and body

But your brain can’t detect them on its own. Instead, it has to make sense of information about electromagnetic waves that have been picked up from other parts of your body.

Much of the human brain is devoted to making sense of a type of electromagnetic wave we call visible light. This type of electromagnetic wave bounces off objects and into our eyes.

At the back of the human eye are millions of tiny cells that produce electrical signals when struck by an electromagnetic wave with a particular amount of energy. Some of these cells are designed to detect an amount of energy that we call the color red. Others specialize in another amount of energy which we call the color green, or another which we call blue.

The eye then sends electrical signals to your brain to describe the type of electromagnetic wave that detected what color the light was and where it was coming from. Finally, through a tremendously complicated sequence of electrical signals, a sighted person has the experience of seeing.

The fact that human eyes can detect visible light but not other types of electromagnetic waves is just how human eyes evolved. The eyes of other animals evolved differently. For example, butterflies can see an electromagnetic wave of slightly higher energy that our eyes can’t detect, but which we call ultraviolet. Some flowers reflect a lot of ultraviolet waves, which makes it easier for butterflies to find them for food.

Invisible waves

Another type of electromagnetic wave that our brain perceives indirectly is called infrared. We can perceive it as heat.

When you are near a campfire, your skin detects the infrared electromagnetic waves of the fire. It then sends electrical signals to the brain to tell it that there’s something hot nearby. The brain was unable to detect this wave on its own.

But the human body has no way of detecting radio waves, so our brains are completely unaware of them as they pass around us. But we can use technology like a radio or wifi to convert the electrical energy in radio waves into something we can detect, like music playing on a radio station.

We also use technology to detect X-rays, another type of electromagnetic wave. X-rays are used in hospitals to look inside bodies, for example, to see if a bone is broken. If you have an X-ray, hospital specialists send the X-rays through your body, and a machine can detect how easily the X-rays have traveled through different parts of your body. Areas that are harder for X-rays to pass through, such as bone, appear white.

Curious Kids is a series from The Conversation that offers children the chance to get expert answers to their questions about the world. If you have a question you’d like an expert answered, please send it to curiouskids@theconversation.com and be sure to include the asker’s name, age and city. We won’t be able to answer all questions, but we will do our best.

Even if your brain is ridiculously intelligent, it wouldn’t know anything without the information it gets from the rest of your body. You and all your experiences come from your body, your organs and your senses which detect the world around you and send that information to your brain.

A hugely complicated set of tiny electrical signals after and you have a conscious experience of being yourself, inside your body, and in a world literally filled with electromagnetic waves.