"A plasma field contained in a magnetic field could be constructed to create a lightsabre. The plasma could be contained in the handle, when the switch is flipped the electromagnetic field is energized and the plasma is ejected within it. Although creating the high temperature of the plasma would require a large energy supply, the lightsabre would perform just as in the movies and is not a technical impossibility," wrote Michael Ernst, a physics graduate student at the University of Miami.

While a working lightsabre isn't likely to hit the shelves in the near future, Star Wars enthusiasts are starting to think about practical ways of making them; the most promising underlying technology found so far has its roots in plasma. Unlike lasers, plasma could stop itself, allowing for the blocking and parrying seen in the Star Wars movies. Plasma also has a limited range. Lasers which extend only a metre would be difficult to develop.

Plasma is considered the fourth state of matter; solid, liquid, and gas are the other three. They change depending on heat (or energy). Heat up a solid and it becomes liquid, heat up a liquid and it becomes gas, heat up a gas and it becomes plasma.

The energy required to turn gas to plasma divides the gas into positively charged ions and loose electrons (an ion is an electrically charged particle). This radiates both visible light and heat.

Examples of plasma surround us everyday. The sun is a sphere of plasma - superheated, glowing hydrogen. Neon and fluorescent tubes use electric charge to ignite gas, though at much lower temperatures. It is the interaction of plasma from the sun and the earth's magnetosphere that causes the Aurora Borealis (Northern Lights). These interactions pose a great challenge to engineering, as they disrupt satellite, telephone, radio, and power systems.

Nuclear fusion technology seeks to fuse atoms in plasma, a reaction which would result in a tremendous release of energy. The development of this technology would result in cheaper and more efficient means of energy production. Nuclear fusion is referred to as the "big brother" of nuclear fission (the power behind the atom bomb and nuclear electrical generating stations). But rather than fission's process of smashing atoms apart, nuclear fusion smashes atoms together.

Development in advance techniques of space travel centre around harnessing the power of plasma. At the NASA Marshall Space Flight Centre in Huntsville, Alabama, development of a Variable Specific Impulse Magnetosphere Rocket (VASMR) is underway. The technology is aimed at future manned missions to Mars. The VASMR is made of a long chain of donut-shaped electromagnets that trap a narrow cylinder of plasma inside a tight tube of electromagnetic forces. Hydrogen bounces back and fourth in this magnetic bottle where it becomes plasma. The plasma is then heated with radio waves. When it becomes hot enough, fusion begins, producing a burst of energy that drives the spacecraft. With today's chemical rockets, a trip to Mars would take 8-10 months. With the VASMR, a trip to Mars would take just 90 days.

Because of plasma's electromagnetic characteristics, it is very sensitive to magnetic interference. A plasma weapon like the lightsabre could cause chaotic destruction if its magnetic field were to be distorted. So, if you're ever confronted by a Jedi with a lightsabre, you're best defence might be an ordinary kitchen magnet.