This probably belongs in one of the physics or engineering forums, but I don't know which one... so I post here with a request that it be moved if appropriate. Back in the early 70's, I desired to build a diorama of the Enterprise and a D7 Klingon cruiser. It would, of course, have to be fully lighted, but I wanted more. My idea for a photon torpedo strike, at that time, was to drop a blob of mercury (about half of what you find in a tilt switch) down a glass tube, with spotlights on it. I didn't like it, but it was the best that I could come up with at the time. Given my current state of unemployment and borderline boredom, I might actually be able to build the thing. Now, of course, I have to choose between a couple of dozen versions of Enterprise, but that's beside the point. My current thought is to drop a bead of mercury down a strand of 'invisible thread', which illusionists use for close-up magic tricks. You can't see the stuff from more than a few inches away. There will be a red laser aimed down along the thread from the firing ship, and another aimed upward from the target. That should result in a nice shimmering red object traveling from one ship to the other, and then splattering when it hits. A recycling system will then collect the mercury and return it to the torpedo reservoirs. What I need to know from any physicists, chemists, or engineers is whether or not mercury will actually follow a thread. My personal suspicion is that it will simply fall straight downward due to its weight, rather than follow the thread. Due to the toxic nature of the substance, I prefer to not experiment with it to find the answer on my own. Any help?