Nanotechnology and Society? 134
VoiceOfZule writes "Bringing advanced sci-tech and humanities grad students to teach undergrads about nanotech and its implications is a great idea. I was in this class on Nanotechnology and Society at the University of Wisconsin-Madison this spring, and a lot of the course materials were just put online along with a preprint paper about the new course, and some of the student research projects. The class was a lot of fun (some nano, some scitech studies, some scifi/future stuff), I learned a lot (about the reality of nanotech and its societal implications beyond the B.S. hype out there), and the world of nano now seems like a good career path to me. Are similar experiences going on across the country? In light of recent worries concerning science and engineering in the US, I hope so."
I'm taking one of these too.... (Score:2, Informative)
Heh (Score:2, Informative)
During my comprehensive exams, one of my committee members cynically advised me to rephrase my answer using the prefix "nano", since that's what funding agencies like to see on grant proposals.
CBEN at Rice (Score:4, Informative)
The course also explored the possible environmental effects of nanotechnology, and the possible regulation that might help manage those effects. When dealing with one class of nanotech, like fullerenes, this is quite a broad and complex topic. When on introduces the everything that might be nanotech, it becomes nearly unmanageable.
Another project that has some popularity is the nanokids [rice.edu].
There is actually quite a bit from the course that can be used in any number of high school courses. And, since Nanotech is likely to tbe defining technology of the next generation, kids who are familiar with the concepts are going to be better prepared than those who are not.
Why nano weapons won't happen (Score:3, Informative)
For reasons which will become apparent as you read this I doubt that true nano scale weapons will ever exist. What could possibly be built are micro
scale robotic devices of a non self replicating type which could possibly be used as weapons. Let us find out how practical they might be.
Let us start by examining the effects of scaling on things. We'll start with my Nissan Maxima and reduce it in size by a factor of ten. Instead of being about 17 feet long the scaled car will be about 1.7 feet long. Instead of weighing about 3000 lbs it will weigh about 3 lbs. Why is that? The answer is that the mass of a scaled object is proportional to its volume - which goes as the cube of the dimensional ratio. Ten times as long, ten times as wide, ten times as high has 1000 times the volume.
The scaled engine would be 3 cc in displacement instead of 3000 cc. Instead of 222 Hp it would produce
However, the fuel consumption of the smaller vehicle is proportionally greater. Why? The smaller vehicle is one thousandth the weight but the frontal area of the vehicle - the size of which determines the drag - is one hundredth of that of the larger vehicle. Thus at the same speed the drag of the smaller vehicle is proportionally ten times as great as the larger vehicle.
The optimal speed of the smaller vehicle is lower than that of the larger vehicle. Because drag goes as the square of the velocity, one thousandth of
the fuel consumption will drive the smaller vehicle at a speed which is about 32% of the speed of the larger car and its range will also be about
32% of the full sized car's range.
If we tried to make a car scaled down by a factor of 100 its speed and range would both be only one tenth (square root of a scale factor of 100) that of a full size car. We are forced to conclude that the product of speed and range of any vehicle with an internal fuel supply will scale directly with
the scale factor.
For example reducing the size of a jet plane by a factor of 100 makes it fly at one tenth the speed and one tenth as far. By the time we scale to nano
sizes we have objects which won't go very far or very fast. A nano device is an exceptionally crappy weapon delivery system compared to a full sized device; it can only move slowly, and it can't go very far.
However there are other things which occur which would effect our attempt to simply scale an engine down in size. The first of these is the change in
heat loss. In simplest terms the rate of heat production is proportional to the volume of a heat source, which means that heat production scales with the cube of the scale factor, but heat loss is proportional to the surface area of the object which scales as the square of the scaling factor.
A smaller engine requires much less of a cooling system than a large engine does, if the engine is small enough it doesn't require a cooling system at all - it will lose heat naturally fast enough without one.
Because of the square - cube relationship for heat loss there is a minimum size flame which is possible. A small ball of flame loses heat faster than a large one. If a ball of flame is too small it can't produce enough heat from internal combustion to maintain its temperature above the ignition point, and the flame can't exist.
This means that if we try to scale our engine far enough it will refuse to run, it will lose heat too fast for the fuel to burn. Even making the engine out of heat resistive materials like ceramics only works to a certain size;
eventually the heat loss will keep things from burning.
This is part of the reason that biological cells use c