 As much as I wish I could say that I'm enjoying a nice vacation at the beach, I'm not. I'm here in Boston at MIT. So how did this little cardboard box make me feel like I'm miles away from where I actually am? How did it create virtual reality? Now if you open this little box up, it's pretty simple. There's a place to put your phone in and the rest of it looks like glasses with these two plastic lenses. Now it's this piece over here that's crucial to making me feel like I'm inside the video on my phone. It's what creates 3D vision. 3D vision is actually pretty simple. We have two eyes that's about three inches apart. And because of this separation, each of our eyes sees the world from a slightly different perspective. Our brain fuses those two views and creates a sense of depth. Hold out your thumb in front of you and close your left eye. Now try closing your right eye. Do you notice how your thumb jumps a little bit to the left or right when you switch between your eyes? Now bring your thumb a little bit closer to you and do the same thing. It seems to jump even more, right? Depending on how close or far you hold out your thumb, it'll jump more or less. Our brain gets a sense of how far an object is depending on how different it appears from the left versus the right eye. And that's 3D vision. Instead of one picture covering the whole screen, this video has two different images made for each eye that are ever so slightly offset. The cardboard box holds the image in the perfect distance to my eyes and divides the image into two so that each eye focuses on the image. This type of video, the stereoscopic display, simulates what our eyes do naturally and folds our brains into thinking that it's looking at a 3D image by creating a sense of depth. But the cardboard and the video do more than create 3D vision. When you move your head around, it actually reveals new areas of the video. The phone has a couple of sensors that measures position and angle, sort of like a GPS, so it can track how your head is moving. And as you move your head around, the image is on the screen adjusts so that you feel like you're not only looking at a video, but actually walking through it. Now, if virtual reality is as easy as sliding a phone into a cardboard box, why are we not all living in a virtual world today? There's a couple of reasons. First, reality is more than just what we see. If I really wanted to feel like I'm at a beach, what are some other elements that I would add in? The feeling of sand between your toes, the smell of salt water, the sound of wind, exactly. But these are things that are harder to make virtual than vision. Things like haptics, the science of touch, will help us to better understand our real senses in order to simulate them in virtual reality. By the way, simulating these other senses, like taste, smell or touch, will eventually help us to improve motion sickness, which a lot of people feel in virtual reality today. Also, to create a fully immersive environment, even if it's just visual, is a lot of work. It's way more than just filming a scene from two different perspectives to create redivision. You need to create or capture an entire three-dimensional world where you can walk around and move your head to see all the possible views. Several companies are developing special software and cameras, but it's still very expensive and time-consuming to do this at high quality. Virtual reality is really cool, but even if we can create a perfect virtual reality, we wouldn't want it to replace actual reality. We still like to experience some things in real life, like snow. And as a society, we're just beginning to think about the ethical and moral aspects of creating simulated realities. So virtual reality may look simple, but it's very complicated. The cool thing is that the better understanding we have of real reality, like how our senses work, the better virtual reality we'll get.