I would imagine that whatever material used for a vacuum cell would have to be extremely light, extremely strong, and extremely gas impermeable. Has anyone invented such a material yet? Or, better yet, has anyone created a functional vacuum cell yet?

Lighter-than-air (aerostatic) lift may be explained by the principal of buoyancy, also known as the "Archimedes Principal" which states: "an object immersed in a fluid experiences a buoyant force that is equal in magnitude to the force of gravity on the displaced fluid." Stated differently, the lifting capability is equal to the weight of the surrounding fluid mass that it displaces. Displacing a cubic foot of air creates a lifting capacity equal to the weight of a cubic foot of air, which is .0755 pounds per cubic foot. The lifting capability of helium in air is .062828 pounds per cubic foot at sea level. Hydrogen has a greater lifting capability in air than helium and can lift .0724 pounds per cubic foot at sea level. However, the lifting capability of a vacuum (the absence of any gas molecules at all) beats them both at .0755 pounds per cubic foot at sea level, which is equal to the weight of a cubic foot of air. The reason the lifting capacity of hydrogen or helium is less than the lifting capacity of a vacuum is that the weight of the helium or hydrogen must be subtracted from the lifting capacity in order to obtain a net lifting capacity. Helium is heavier than hydrogen and the lighter hydrogen, therefore, has a greater lifting capacity than does helium.

University of Texas at Dallas nanotechnologists have made alcohol- and hydrogen-powered artificial muscles that are 100 times stronger than natural muscles, able to do 100 times greater work per cycle and produce, at reduced strengths, larger contractions than natural muscles. Among other possibilities, these muscles could enable fuel-powered artificial limbs, "smart skins" and morphing structures for air and marine vehicles, autonomous robots having very long mission capabilities and smart sensors that detect and self-actuate to change the environment.


While humans on long, strenuous missions are able to carry the food that powers their bodies, today's most athletically capable robots cannot freely move about, since they are wired to stationary electrical power sources. Though batteries can be used for autonomous robots, they store too little energy and deliver it at too low a rate for prolonged or intense activity. To solve these problems, the team from UTD's NanoTech Institute developed two different types of artificial muscles that, like natural muscles, convert the chemical energy of an energetic fuel to mechanical energy.

The breakthroughs are described in the March 17 issue of the prestigious journal Science.

The development of these revolutionary muscles was motivated by a visit of Dr. John Main from the Defense Advanced Projects Agency (DARPA) to Dr. Ray H. Baughman, Robert A. Welch Professor of Chemistry and director of the UTD NanoTech Institute. During the visit, Main described his visions of a future that could include such advancements as artificial muscles for autonomous humanoid robots that protect people from danger, artificial limbs that act like natural limbs and exoskeletons that provide super-human strength to firefighters, astronauts and soldiers -- all of which are able to perform lengthy missions by using shots of alcohol as a highly energetic fuel.