Supposedly they are made of projected light. This makes no sense. Light needs to reflect of something and into to your eyes before you can see something. I suppose that the light bee (and RD's own projection system) could project light on to the eyeball of the observer, but it sounds unlikely.

My own theory: The light bee (and RD's own projection system)do not project light as such, but a light reflecting forcefield. It must be variable, to reflect different colours.

Yeah, that's what scientists are stumbling on at the moment - either you use a forcefield or you "bend" the light as such as it forms this appearance of a man.

In seasons 1 & 2 Rimmer seems to be able to pass through anything. It's my theory that in season 1 & 2 Rimmer is directly projected from Holly, & cannot go away from Red Dwarf or Blue Midget without the hologram cage, (except in "Kryten", where he could be projected by Nova 5's computer.) During the gap between seasons 2 & 3 the crew must find the light bee, & from this point onwards he can travel unaided.

Perhaps light waves are emited at a frequency and amplitude that causes them to interfere with one another heating a small volume of air until it emits light at preffered frequency.

To answer your question, Richard, your theory about Rimmer's Projection status is largely correct, though Rimmer does'nt get the Hard Light Drive aka the "Light Bee" until the Series VI Episode "Legion", as he is given it by Legion !

Actually he had the light bee but was a soft light hologram for several episodes before legion. I think it was waxworld that first brings it up and from the way Lister and the cat reacted to the way Kryten explained what the light bee is I dont think the dwarfers found it and installed it other than maybe Rimmer and the scutters or Kryten although I wuld think Kryten might have told Lister at some point.

The light bee was introduced in Meltdown.

And I think the reason they introduced the idea of the Hard Light Drive is so that Rimmer can now pick things up.