Utility Fog: The Stuff that Dreams are Made
Of
Source: Rutgers
University
Nanotechnology is based on the concept of tiny, self-replicating
robots. The Utility Fog is a very simple extension of the idea: Suppose, instead
of building the object you want atom by atom, the tiny robots linked their arms
together to form a solid mass in the shape of the object you wanted? Then, when
you got tired of that avant-garde coffeetable, the robots could simply shift
around a little and you'd have an elegant Queen Anne piece instead.
The color and reflectivity of an object are results of its
properties as an antenna in the micron wavelength region. Each robot could have
an "antenna arm" that it could manipulate to vary those properties, and thus the
surface of a Utility Fog object could look just about however you wanted it to.
A "thin film" of robots could act as a video screen, varying their optical
properties in real time.
Rather than paint the walls, coat them with Utility Fog and they
can be a different color every day, or act as a floor-to-ceiling TV. Indeed,
make the entire wall of the Fog and you can change the floor plan of your house
to suit the occasion. Make the floor of it and never gets dirty, looks like
hardwood but feels like foam rubber, and extrudes furniture in any form you
desire. Indeed, your whole domestic environment can be constructed from Utility
Fog; it can form any object you want (except food) and whenever you don't want
an object any more, the robots that formed it spread out and form part of the
floor again.
You may as well make your car of Utility Fog, too; then you can
have a "new" one every day. But better than that, the *interior* of the car is
filled with robots as well as its shell. You'll need to wear holographic
"eyephones" to see, but the Fog will hold them up in front of your eyes and
they'll feel and look as if they weren't there. Although heavier than air, the
Fog is programmed to simulate its physical properties, so you can't feel it:
when you move your arm, it flows out of the way. Except when there's a crash!
Then it forms an instant form-fitting "seatbelt" protecting every inch of your
body. You can take a 100-mph impact without messing your hair.
But you'll never have a 100-mph impact, or any other kind.
Remember that each of these robots contains a fair-sized computer. They already
have to be able to talk to each other and coordinate actions in a quite
sophisticated way (even the original nano-assemblers have to, to build any
macroscopic object). You can simply cover the road with a thick layer of robots.
Then your car "calls ahead" and makes a reservation for every position in time
and space it will occupy during the trip.
As long as you're covering the roads with Fog you may as well make
it thick enough to hold the cars up so they can cross intersections at different
levels. But now your car is no longer a specific set of robots, but a *pattern*
in the road robots that moves along like a wave, just as a picture of a car
moves across the pixels of a video screen. The appearance of the car at this
point is completely arbitrary, and could even be dispensed with--all the road
Fog is transparent, and you appear to fly along unsupported.
If you filled your house in with Fog this way, furniture no longer
need be extruded from the floor; it can appear instantly as a pattern formed out
of the "air" robots. Non-Fog objects can float around at will the way you did in
your "car". But what's more, your surroundings can take on the appearance, and
feel, of any other environment they can communicate with. Say you want to visit
a friend; you both set your houses to an identical pattern. Then a Fog replica
of him appears in your house, and one of you appears in his. The "air" fog
around you can measure your actions so your simulacrum copies them exactly.
The pattern you both set your houses to could be anything,
including a computer-generated illusion. In this way, Utility Fog can act as a
transparent interface between "cyberspace" and physical reality.
Tech Specs
Active, polymorphic material ("Utility Fog") can be designed as a
conglomeration of 100-micron robotic cells ("foglets"). Such robots could be
built withthe techniques of molecular nanotechnology (see Drexler,
"Nanosystems", Wiley, 1992). Using designs from that source, controllers with
processing capabilities of 1000 MIPS per cubic micron, and electric motors with
power densities of one milliwatt per cubic micron are assumed.
Each Foglet has twelve arms, arranged as the faces of a
dodecahedron. The central body of the foglet is roughly spherical, 10 microns in
diameter. The arms are 5 microns in diameter and 50 microns long. A convex hull
of the foglet approximates a 100-micron sphere. Each Foglet will weigh about 20
micrograms and contain about 5 quadrillion atoms. Its mechanical motions will
have a precision of about a micron.
The arms telescope rather than having joints. The arms swivel on a
universal joint at the base, and the gripper at the end can rotate about the
arm's axis. The gripper is a hexagonal structure with three fingers, mounted on
alternating faces of the hexagon. Two Foglets "grasp hands" in an interleaved
six-finger grip. Since the fingers are designed to match the end of the other
arm, this provides a relatively rigid connection; forces are only transmitted
axially through the grip. When at rest, foglets form a lattice whose structure
is that of a face-centered cubic crystal (i.e. an octet truss).
For a mass of Utility Fog to flow from one shape to another, or to
exert dynamic forces (as in manipulating objects), a laminar flow field for the
deformation is calculated. The foglets in each lamina remain attached to each
other, but "walk" hand over hand across the adjacent layers. Although each layer
can only move at a speed differential of 5 m/s with its neighbor, the cumulative
shear rate in a reasonable thickness of Fog is considerable, up to 500 m/s per
centimeter of thickness.
The atomically-precise crystals of the foglets' structural members
will have a tensile strength of at least 100,000 psi. As an open lattice, the
foglets occupy only about 3% of the volume they encompass. When locked in place,
the Fog has a more or less anisotropic tensile strength of 1000 psi. In motion,
this is reduced to about 500 if measured perpendicular to the shear plane. As a
bulk material it has a density of 0.2 g/cc.
Without altering the lattice connectivity, Fog can contract by up
to about 40% in any linear dimension, reducing its overall volume by a factor of
five. (This is done by retracting all arms simultaneously.) Selective
application of this technique allows Fog to simulate shapes and flow fields to a
precision considerably greater than 100 microns.
An appropriate mass of Utility Fog can be programmed to simulate
most of the physical properties of any macroscopic object (including air and
water), to roughly the same precision those properties are measured by human
senses. The major exceptions are taste, smell, and transparency. The latter an
be overcome with holographic "eyephones" if a person is to be completely
embedded in Fog.
Consider the application of Utility Fog to a task such as
telepresence. The worksite is enclosed in a cloud of Fog, which simulates the
hands of the operators to assemble the parts and manipulate tools. The operator
is likewise completely embedded in Fog. Here, the Fog simulates the objects that
are at the worksite, and allows the operator to manipulate them.
The Fog can also support the operator in such a way as to simulate
weightlessness, if desired. Alternatively, the Fog at the worksite could
simulate the effect of gravity on the objects there (in any desired direction).
http://nanotech.rutgers.edu/nanotech/Ufog.html