You’ll probably never go to Mars, swim with dolphins, run an Olympic 100 meters, or sing onstage with the Rolling Stones. But if virtual reality ever lives up to its promise, you might be able to do all these things—and many more—without even leaving your home. Unlike real reality (the actual world in which we live), virtual reality means simulating bits of our world (or completely imaginary worlds) using high-performance computers and sensory equipment, like headsets and gloves. Apart from games and entertainment, it’s long been used for training airline pilots and surgeons and for helping scientists to figure out complex problems such as the structure of protein molecules. How does it work? Let’s take a closer look!
What is virtual reality?
Virtual reality (VR) means experiencing things through our computers that don’t really exist. From that simple definition, the idea doesn’t sound especially new. When you look at an amazing Canaletto painting, for example, you’re experiencing the sites and sounds of Italy as it was about 250 years ago—so that’s a kind of virtual reality. In the same way, if you listen to ambient instrumental or classical music with your eyes closed, and start dreaming about things, isn’t that an example of virtual reality—an experience of a world that doesn’t really exist? What about losing yourself in a book or a movie? Surely that’s a kind of virtual reality?
If we’re going to understand why books, movies, paintings, and pieces of music aren’t the same thing as virtual reality, we need to define VR fairly clearly. For the purposes of this simple, introductory article, I’m going to define it as:
A believable, interactive 3D computer-created world that you can explore so you feel you really are there, both mentally and physically.
Putting it another way, virtual reality is essentially:
Believable: You really need to feel like you’re in your virtual world (on Mars, or wherever) and to keep believing that, or the illusion of virtual reality will disappear.
Interactive: As you move around, the VR world needs to move with you. You can watch a 3D movie and be transported up to the Moon or down to the seabed—but it’s not interactive in any sense.
Computer-generated: Why is that important? Because only powerful machines, with realistic 3D computer graphics, are fast enough to make believable, interactive, alternative worlds that change in real-time as we move around them.
Explorable: A VR world needs to be big and detailed enough for you to explore. However realistic a painting is, it shows only one scene, from one perspective. A book can describe a vast and complex “virtual world,” but you can only really explore it in a linear way, exactly as the author describes it.
Immersive: To be both believable and interactive, VR needs to engage both your body and your mind. Paintings by war artists can give us glimpses of conflict, but they can never fully convey the sight, sound, smell, taste, and feel of battle. You can play a flight simulator game on your home PC and be lost in a very realistic, interactive experience for hours (the landscape will constantly change as your plane flies through it), but it’s not like using a real flight simulator (where you sit in a hydraulically operated mockup of a real cockpit and feel actual forces as it tips and tilts), and even less like flying a plane.
We can see from this why reading a book, looking at a painting, listening to a classical symphony, or watching a movie don’t qualify as virtual reality. All of them offer partial glimpses of another reality, but none are interactive, explorable, or fully believable. If you’re sitting in a movie theater looking at a giant picture of Mars on the screen, and you suddenly turn your head too far, you’ll see and remember that you’re actually on Earth and the illusion will disappear. If you see something interesting on the screen, you can’t reach out and touch it or walk towards it; again, the illusion will simply disappear. So these forms of entertainment are essentially passive: however plausible they might be, they don’t actively engage you in any way.
VR is quite different. It makes you think you are actually living inside a completely believable virtual world (one in which, to use the technical jargon, you are partly or fully immersed). It is two-way interactive: as you respond to what you see, what you see responds to you: if you turn your head around, what you see or hear in VR changes to match your new perspective.
Types of virtual reality
“Virtual reality” has often been used as a marketing buzzword for compelling, interactive video games or even 3D movies and television programs, none of which really count as VR because they don’t immerse you either fully or partially in a virtual world. Search for “virtual reality” in your cellphone app store and you’ll find hundreds of hits, even though a tiny cellphone screen could never get anywhere near producing the convincing experience of VR. Nevertheless, things like interactive games and computer simulations would certainly meet parts of our definition up above, so there’s clearly more than one approach to building virtual worlds—and more than one flavor of virtual reality. Here are a few of the bigger variations:
For the complete VR experience, we need three things. First, a plausible, and richly detailed virtual world to explore; a computer model or simulation, in other words. Second, a powerful computer that can detect what we’re going and adjust our experience accordingly, in real time (so what we see or hear changes as fast as we move—just like in real reality). Third, hardware linked to the computer that fully immerses us in the virtual world as we roam around. Usually, we’d need to put on what’s called a head-mounted display (HMD) with two screens and stereo sound, and wear one or more sensory gloves. Alternatively, we could move around inside a room, fitted out with surround-sound loudspeakers, onto which changing images are projected from outside. We’ll explore VR equipment in more detail in a moment.
A highly realistic flight simulator on a home PC might qualify as nonimmersive virtual reality, especially if it uses a very wide screen, with headphones or surround sound, and a realistic joystick and other controls. Not everyone wants or needs to be fully immersed in an alternative reality. An architect might build a detailed 3D model of a new building to show to clients that can be explored on a desktop computer by moving a mouse. Most people would classify that as a kind of virtual reality, even if it doesn’t fully immerse you. In the same way, computer archaeologists often create engaging 3D reconstructions of long-lost settlements that you can move around and explore. They don’t take you back hundreds or thousands of years or create the sounds, smells, and tastes of prehistory, but they give a much richer experience than a few pastel drawings or even an animated movie.
What about “virtual world” games like Second Life and Minecraft? Do they count as virtual reality? Although they meet the first four of our criteria (believable, interactive, computer-created and explorable), they don’t really meet the fifth: they don’t fully immerse you. But one thing they do offer that cutting-edge VR typically doesn’t is collaboration: the idea of sharing an experience in a virtual world with other people, often in real time or something very close to it. Collaboration and sharing are likely to become increasingly important features of VR in future.
Virtual reality was one of the hottest, fastest-growing technologies in the late 1980s and early 1990s, but the rapid rise of the World Wide Web largely killed off interest after that. Even though computer scientists developed a way of building virtual worlds on the Web (using a technology analogous to HTML called Virtual Reality Markup Language, VRML), ordinary people were much more interested in the way the Web gave them new ways to access real reality—new ways to find and publish information, shop, and share thoughts, ideas, and experiences with friends through social media. With Facebook’s growing interest in the technology, the future of VR seems likely to be both Web-based and collaborative.