The idea of virtual reality has been around for decades. You put on a pair of goggles, and suddenly you find yourself immersed in a computer-generated 3D world. Technology has been slow at bringing this idea to fruition, but this is an area where we can be very confident that spectacular progress will be made. There are absolutely no theoretical roadblocks to creating an extremely vivid 3D landscape that you can view with virtual reality goggles. Making virtual reality a household reality is just a matter of making more progress in visualization technology that has been progressing at a high rate of progress for decades. No doubt within twenty years, you will be able to have spectacular virtual reality experiences at a reasonable cost.
But what about interacting with the 3D world you see while wearing the virtual reality goggles? It will be hard for an interface to allow seamless interactions. Someone wearing virtual reality goggles may be able to manipulate a controller with his hands, maybe something like a video controller. But this creates a kind of imperfect blend. You are using your hands (which you cannot see with the goggles on) to interact with the world you view while wearing the goggles. And what if you want to interact with the virtual world or its inhabitants in a way that the simple controller doesn't allow? For example, in the virtual world you might want to kiss a character on the cheek, but your simple controller may offer no way to do that.
Another idea for interacting with a computer-generated reality is an idea advanced on the TV show Star Trek: The Next Generation: the idea of a holodeck. The idea is that you go into some special room where there are very sophisticated holographic projectors. All of the walls, the ceiling, and the floor of the holodeck are involved in the holographic projection. So after entering such a room, you might suddenly find yourself seeing just what someone would see at the Grand Canyon. You look all around, and everything looks just as it would if you were in the Grand Canyon, even at your feet. You may also interact with what looks like other people, but these too are just holographic projections. There is no need to wear any special goggles.
The basic idea of a holodeck seems technically feasible, although in both Star Trek: The Next Generation and Star Trek: Voyager, the idea was stretched to what seemed like unrealistic extremes, as we would see people using the holodeck sitting on holographic chairs and lying on holographic beds. It would seem that a holographic projection would offer no such solidity.
The main drawback of a holograph is that it isn't a “use around the house” kind of thing, requiring a large expensive room capable of sophisticated holographic projection. Another drawback is that a holodeck seems unsuitable for a simulation in which you are walking around for long distances, such as a simulation in which you are walking around on the streets of a city.
But there's another idea for how future humans could experience something like virtual reality, an idea rarely considered. The idea is to somehow upgrade human imagination. If human imagination were somehow to be expanded far beyond its current limits, then people might have within their own minds something that would be better than virtual reality or a holodeck.
Consider the human imagination. Any one of us can conjure up a “movie in our minds,” in which we can imagine anything we can please. But what we see in our mind's eye when we daydream is kind of pale, dim, and shadowy, without many details. But imagine if that “movie in our minds” could somehow become as detailed and vivid and life-like as a widescreen IMAX movie. And imagine if we could fill in endless imaginative details effortlessly.
Such a thing might be possible in the future, given some imagination upgrade in the human mind that might be achieved through technology, neural implants, drugs, or genetic enhancements. After such an upgrade, you might have no need for VR goggles or a holodeck. You could simply close your eyes and see in your mind's eye something that might be as vivid as virtual reality or a modern video game on a wide-screen TV. And you could shape that very-vivid reality effortlessly, just by imagining something different. In your mind's eye you could move from one city to another effortlessly, or from one planet to another planet, seeing each one as vividly as if you were watching a wide-screen movie. A hundred vivid details might flow into such scenes, flowing effortlessly from the wellsprings of your enhanced imagination.
It might be dangerous to make such an imagination upgrade a permanent part of the human mind. For with such an imagination, prisons would not be such a deterrent. Every prisoner would know that from his jail cell he could have something as enjoyable as trips to a thousand Disney Worlds, just by closing his eyes and letting his imagination gush forth.