This episode of SciShow is brought to you by Emerson.

Visit Emerson.com/WeLoveSTEM to learn more. You can experience some pretty amazing things with virtual reality — aka VR.

When you throw on a headset, you can do things that would be impossible, dangerous, or just plain impractical in the real world. And it’s more than a fun way to fight terrifying, life-sized aliens in video games. VR has a ton of potential for scientists and engineers.

Like, imagine you’re designing a sports car. There’s plenty of computer-aided design, or CAD, software you can use to create a 3D model of the car on your computer. But with VR, you can see a life-sized version of that model.

You can walk around it and see exactly what the car would look like from every angle, and play around with different elements of the design. All without having to build a prototype. The ultimate virtual reality system might be something like the holodeck on Star Trek, where you could program a room with any environment or scenario you wanted, then explore it as though it were real.

It would all look real, and even feel real, with people and objects you could actually touch. We’re not quite at holodeck-levels of awesome yet, but we’re getting closer. And the next major step might be a simulation you can reach out and touch.

Right now, some of the best VR systems let you interact with a simulated world around you as you walk around a real life room. Most of the time, you use controllers to do things like punch an enemy or adjust the model of your design. Interacting with a virtual world this way can be pretty intuitive, and the controllers can add a layer of realism by vibrating slightly for example, when you make the car model bigger so you can get a closer look at the way the hood curves.

But it’s not quite as immersive as feeling the smoothness and contours of the car’s metal frame with your fingertips. That kind of tactile feedback, where you’re getting a sensation of force even though there’s nothing really there, is called haptic feedback. The simplest kind of haptic feedback, where something like a controller or special glove vibrates against your hand, isn’t that hard to program.

The technology’s been around for decades. But it’s a lot more difficult to make thin air feel like an enemy’s skin or a car. Because if you’re not holding anything that can vibrate against your hand, how can it feel like you’re touching something?

The answer lies in … sound. Sound waves are really just vibrations. When you talk, you set the air molecules around you moving back and forth, which in turn vibrates your eardrums.

Your brain interprets those vibrations as sound. You can only hear within a certain range of vibration frequencies, though from about 20 Hertz, or oscillations per second, to 20,000 Hertz. Sound waves that vibrate faster than 20,000 times per second, known as ultrasound, are too high-pitched for you to hear, unless you’re secretly Superman.

But even though you can’t hear them, the sound waves are still there. And if they’re strong enough, you can actually feel the vibrating air. With your fingers.

You might be able to guess where I’m going with this: if you can concentrate ultrasound waves in the right way, you can create vibrations that make the air feel like a solid object. Which is exactly what some VR experts have spent the last decade or so trying to do. Researchers from the University of Tokyo first figured out how to make this work in 2008.

They used an array of transducers, which emit sound, to produce ultrasound waves that would interact at specific points in the air. If you touched that part of the air, the pressure from the sound waves would feel like you were touching something solid. Researchers have been building on the idea ever since, and they’ve gotten to the point where they can create all kinds of different shapes and textures.

If you push hard enough, you can break through the area of pressure, so it’s not exactly the same as touching...like, a car, but it’s something. One company has even created a special box lined with transducers and programmed them to generate a kind of 3D touchable hologram, where you can stick your hand in the box and do things like pet a deer or bounce a beach ball. So, we’ve made a lot of progress, but there’s still a long way to go before we can incorporate this kind of haptic feedback into a full VR simulation.

For one thing, you’d need more than just a box you’d need a whole room full of transducers, which would be pretty expensive. Computer scientists also need to figure out how to program the sense of touch into simulations, which is especially tricky because it would take a lot of processing power. So, it’s hard to know how long it’ll be before you’re actually able to feel the Martian soil between your toes, or run your hand along the hood of the car you’re designing.

But the sense of touch will open up a whole new way to experience virtual reality one that will change the face of entertainment, engineering, and all kinds of other fields. And in the process, it’ll get us one giant step closer to a holodeck. If you like this episode of SciShow, thank Emerson for supporting it.

If you want to keep getting smarter with us, you can go to youtube.com/scishow to subscribe. And if you want to support us, check out Emerson.com/WeLoveSTEM to learn a little bit more about what Emerson’s about.