Light Sabers 
Light sabers are one such technology. These are unique to the Star Wars trilogy and, in essence, are blades of pure energy capable of cutting through virtually anything. Curiously, the Star Wars homepage has provided a detailed explanation of how these devices work, however, it is entirely fictitious. In an attempt to rectify this situation, scientists have arduously speculated over how such a weapon could be constructed.  However, it appears that the force is not with the laser physicists of our galaxy, and they have been unsuccessful in their searches. 

The main problem is that a light saber cannot simply exist as a focused laser beam, interference pattern or evanescent wave; because these beams would pass straight through each other in a duel (light beams don’t repel each other). The alternative is to construct an intense electromagnetic field with one of these devices, and fire high-energy photons into its interior. The photons would be reflected off the sides of the field and hence be contained within it, therefore creating the glowing and humming effects of a light saber. But the problems arise when we consider the stability, versatility and power requirements of such a model. The energy dissipated in the electromagnetic field when the saber is disabled would be sufficient to annihilate its user, its low stability making it more of a self-destructive weapon than an offensive one. 

So until someone discovers a new law of physics, it looks like we will have to settle for those retina burning laser pointers and plastic imitation light sabers, which will no doubt be in abundance over the next few months. 

Ray Guns
Today we can construct laser beams that are powerful enough to blast through steel. The only restriction on the power that we can pack into a laser beam is the stability of the lasing material and the energy source that we use to drive the laser. The main problem with creating the ray guns depicted in Star Wars, is that in order to blast the amount of power of a nuclear power plant out of one of these ray guns, the gun must first be connected to a nuclear power plant (and I didn’t see too many nuclear power plants attached to ray guns in the Star Wars trilogy). A portable power pack for a ray gun does not currently exist, and scientists don’t even know where to start looking. 

It appears that George Lucas didn’t know either, when he made Star Wars. If you look closely at a ray gun or blaster whenever it is fired, you can actually see it ejecting spent shells. In the scene where Luke and Leia make their tarzan-like swing on the Death Star, you can actually see these shells hit the floor and roll around. This is because Lucasfilms actually modified ordinary guns to make their blasters, and loaded them with blanks so that they would recoil. 

The American Star Wars Program 
The problem of portable nuclear power plants was also faced by actor and US President, Ronald Reagan, when he proposed the American Star Wars program in 1983. The original scheme was to place thousands of hydrogen bombs in a number of X-ray lasers orbiting Earth in small satellites. When a bomb was detonated, its burst of X-rays would be diverted along copper rods to generate intense X-ray laser beams capable of shooting down thousands of Russian warheads in a very short period of time. However, calculations after the proposal revealed that even these bomb-driven X-ray lasers would not have the energy required to execute these attacks. 

But despite the dismissal of the Star Wars program by many American scientists, Gorbachev took the threat seriously, and the program has actually been credited as one of the contributing factors involved in the eventual breakup of the Soviet Union (or the “evil empire” as Reagan called it). 

Research into the Star Wars program is still going ahead, however it has adopted the less assuming role of defense for the time being. In 1990, Boeing was awarded a contract with the US Government to design and develop ETVs (or Exoatmospheric kinetic Kill Vehicles). But don’t be fooled by the name (which is probably intentional) - these vehicles are actually part of the National Missile Defense system. When a foreign missile is detected, they are launched, attached to Ground-Based Interceptors. Then, in space, they separate from their Ground-Based Interceptors, detect target missiles and destroy them by interception. 

Force Fields
These transparent, impenetrable walls of pure energy portrayed in the Star Wars trilogy would surely be a desirable addition to America’s National Missile Defense system. But before we consider how we might construct such a field, we find that our current knowledge of physics doesn’t even allow us to construct one. 
 
We can’t use electromagnetic fields as force fields, because electromagnetically neutral objects (such as plastics) would travel straight through them without being deflected. We can’t use gravitational fields because they are attractive rather than repulsive, and they are extremely weak. And we can’t use the weak and strong nuclear forces either, because they act over atomic and subatomic distances (in contrast to the force fields in Star Wars which act over kilometers). 

With no other forces to choose from, there is nothing we know of that could give rise to these force fields. So if we really want to protect ourselves against potentially irritating surprise plastic raids from space in the near future, then our only hope lies in the opinions of nuclear physicists, who generally agree that our current quantum theory is incomplete. And so there is a small possibility that future developments in this branch of physics might one day make these elusive structures possible. 

The Unified Theory of Star Wars 
But maybe we are looking for answers in all the wrong places (or the wrong Universes). There is a group of Internet Star Wars fans who believe that this is the case, and that they have found the answer to all of the apparent inconsistencies that I have mentioned. Unsatisfied with the restrictive and constraining physical laws that our Universe seems to have imposed upon us, they have invested their spare time laboriously reinventing the laws of physics so that these laws may be consistent with Star Wars phenomena and technology in another Universe. In order to formulate their equations, they have utilized any information they have been able to extract or deduce from the movie series, including: 
 

1. Physical and orbital characteristics of the filmed celestial bodies
2. The dimensions, structure and capabilities of the Death Star
3. Physical speculations into superluminal travel as depicted in the movie series
4. The speed of rays emitted from ray blasters (which is surprisingly lower the speed of light)