How does a holodeck work?

Answer 1

We don't really have the technology to build a holodeck. At least not one that "really works" like the ones on Star Trek. The holodeck on Star Trek constructs objects from programmed instructions, or "to order" from the directions of the person(s) using it. And it also makes these objects solid. That is a step far outside holography, which is the 3-D visual or optical representation of a solid object, but it is not itself a solid object. It only appears to be solid. To create a 3-D object and then give it the properties of a "real" solid object requires actually building the object out of matter (which is not "holo" technology), or using the most complex arrangement of discrete force fields to create a "solid feel" to something like, say, another person (a holodeck character) who walks up to you and slaps you on the back. This sets aside the idea of tapping into someone's thoughts and making them "see" and "feel" and "experience" things as if they are real when they are not. (That's a separate technology, and we've seen that on Star Trek, too.) The functions of a holodeck apply technology that is far, far beyond what we currently have. But if we're going there, we're on the right path. It takes big advances in computer power and massive increases in creativity in science (particularly physics) to get to where we can build a holodeck. We're rolling along in that direction, and about all that we can complain about is the speed at which we're moving.

Answer 2

In addition to 3-dimentional holographic imagery, the holodeck also uses force fields to make the images feel solid.