[SUBMAN1]

The real holodeck is coming. It just needs a little something called utility fog. Only problem is, if you could design one, you would also have the capability to build the morphing terminator from terminator 2 - complete with its intelligent killing ability.

http://www.nanotech-now.com/utility-fog.htm

-S

Question 5: Tell us about Utility Fog. How did you come across the concept, and how extensively could such a technology be used?
I invented Utility Fog in a typically serendipitous way. Virtually everyone working with nanotechnology has had ideas for a polymorphic material to make objects out of. But I was driving in to work one day and became conscious of my seat belt. I began wondering how good a seat belt you could make with nanotechnology. One of my pet peeves about safe cars is the they're built to collapse in an accident; the crumpling of the structure gives you a longer deceleration path, which is what makes it safe.

Suppose your vehicle looked more like a living room inside, with lots of space around you. It would be a lot more comfortable than a conventional car, and there would be room to decelerate without trashing the vehicle. Next thought: the cases they ship delicate equipment in, with form-fitting foam interiors. Suppose you could do a similar thing as a seat belt, in such a way that it didn't appear to be there when it wasn't needed. Once the basic notion was there, it remained only to figure out how to implement it.

Utility Fog consists of a mass of tiny robots. Unlike water fog, they do not float in the air but form a lattice by holding hands in 12 directions (corresponding to the struts in an octet truss). Each robot has a body that is fairly small compared to its armspread, and the arms are relatively thin. Each arm is telescoping, an action driven by a relatively powerful motor, and can be waved back and forth (2 more degrees of freedom) by relatively weak motors.

The material properties of this mass depend on the programming of the robots. The geometry is such that stresses in the material all appear as longitudinal forces along the arms. Each Foglet can sense the force along each arm, and do something depending on the magnitude and relation of those forces. If the program says, extend when the force is trying to stretch, retract when it is trying to compress, you have a soft material. If it says, resist any change up to a certain force, then let go, you have a hard but brittle material.

If the programming says, maintain a constant total among the extension of all arms, but otherwise do whatever the forces would indicate; and when a particular arm gets to the end of its envelope, let go, and look for another arm coming into reach to grab; you have a liquid. If you allow the sum of the arm extensions to vary with the sum of the forces on the arms, you have something that approximates a gas within a certain pressure range. Note that because the Foglets can use their own power to move or resist moving, the apparent density and viscosity of the fluid can anything from molasses to near vacuum.

Now you can begin to get cute. Run a distributed program that at a specified time, changes a certain volume from running water to running wood. A solid object would seem to appear in the midst of fluid. It can just as easily disappear. Now fill your entire house with the stuff, running air in background mode. Have an operating system that has a library of programs for simulating any object you may care to; by giving the proper command you can cause any object to appear anywhere at any time. You could carry a remote control, which might happen to be shaped like a wand with a star on the end...