One of my favorite things about the BBC series Red Dwarf is its devotion to conspicuously ignoring scientific validity. The writers of Red Dwarf know their science and technology well enough that the series has a good sense of verisimilitude, and when they massively break the rules of science, they do it flagrantly and with full knowledge. Their attention to technical detail can best be seen in the novels they’ve published. The novels take the better episodes of the series, tie them together and flesh out some of the stories. When you consider some of the things they think of when writing their material, it shows Rob Grant and Doug Naylor read a lot of good SF growing up.
The best example of this is holograms. Rob Grant and Doug Naylor (Grant Naylor as they like to call themselves) originally said in the first season that holograms were restricted to the inside of the ship, and when they went planetside, they needed a special projection cage. Then they realized there was an even better way so they introduced the concept of a light bee: a small floating device that powers and displays hologram people. This freed them up to do more episodes with Rimmer (the crew hologram).
Alas, most SFTV don’t try that hard. If all you ever learned about science came from SFTV, you’d think holograms can be projected from afar without support equipment at the point of reception. You’d be wrong. Currently, holograms are limited to the wave front reconstruction technique. This is where a special 2-D surface (like a photographic glass plate) reconstructs the light wave front of a scene. The complete explanation can take a while and there are websites that do the job better than I do, but suffice it to say, we haven’t entered the realm of real-time holograms yet.
There have been a couple developments that may point the way. One technique uses a pair of spinning plastic disks and a laser to draw in 3-D space. There has also been progress on 3-D printers (systems that can create 3-dimensional solids from a computer), but these technically speaking aren’t holograms.