The main idea here is that us, humans we experience the world through our senses; and if we can trick our senses through the use of some technology then we can change our experience and create new, imagined, virtual experiences.
The five senses are commonly believed to be vision, hearing, smell, taste and touch... we shall see that there is more to it. Have you ever ridden a roller coaster? Have you felt anything? What was it?
Tricking the ears is quite easy. Think about how you can listen to music even though there are no real musicians nearby. It just comes from the speakers. How many people listen to virtual sounds on the public transit through their airpods and headphones - instead of listening to the real world?
girl listening to virtual sounds
In the real world we assign spatial information to sounds. If you're on my left hand side then I hear your voice more from my left ear. If I turn my head and face towards you the left and right ears equal out. VR headsets and some headphones such as the Apple AirPods Max have sensors for this reason that detect the change in the orientation of the device.
See High Fidelity a company offering develpment kit to build spatial audio experiences. They had an interesting pivot, narrowing their focus on on spatial audio after being too early to the VR market. They had cool, record breaking shared social VR experiences.
Real-time Spatial Audio Solutions for Group Voice Chat | High Fidelity
Tricking our eyes we can do with placing a screen in fron of your eyes. Of course it's not that easy to do it right: we need to get a nice view with good resolution, high refresh rate, broad field of view and so light that you don't even notice it.
The resolution of the human eye is 576 megapixels. If we put a 4K screen in fron of an eye that's about 8 megapixels. Do we really need 576 before it get really really good?
Touch can be tricked we so called haptics.
What About Smell and Taste?
Actually, when we taste food much of the tasting we attribute to our tongue actually happens in the nose.
Is it possible to recreate any smell the way we build up any color from Red, Green and Blue (RGB)?
Some research indicates it is.
Digitizing Odors: Israelis Whiff the Future With ‘Smellophone’ Tech Breakthrough
American Committee for the Weizmann Institute of Science