Shields up! How to build a Star Wars-style laser-deflector shield

In honor of Star Wars Day (May 4) -- "May the fourth be with you"
May 4, 2014

A space laser (adapted from a photograph of the Laser Guide Star adaptive optics system used on a telescope in Chile; credit: European Southern Observatory)

Laser shields, such as those protecting spaceships in the Star Wars film series, are scientifically feasible, three University of Leicester physics students have shown.

Here’s how: a plasma can refract (bend) a beam of radiation. In fact, that’s already done in principle; by refracting radio signals, the ionosphere around our planet enables shortwave radio programs from Europe, for example, to be heard in the U.S.

A strong magnetic field would be needed to contain the plasma (the Earth’s magnetosphere provides that in the case of the ionosphere), but the students calculated that a magnetic field of less than 5 Tesla* would suffice to shield the visible-light lasers shown in Star Wars movies and TV shows. The catch: the plasma shield would also refract incoming light, making the ship pilots blind, except for objects in the blue, violet, and (with special sensors) ultraviolet range (and above).

Magnetic field required to deflect incident radiation as a function of frequency (credit: J. McGuire et al./Journal of Physics Special Topics)

Of course, Klingons and others could counter the 5 T field by switching to ultraviolet light. Defending against that would require an even stronger field, as shown in the chart above (the strongest magnetic field produced on Earth is 91.4 T, so that technology would protect the crew into most of the UV range**).

The students presented their findings in a paper in the open-access Journal of Physics Special Topics, a peer-reviewed student journal run by the University’s Department of Physics and Astronomy and designed to give students practical experience of writing, editing, publishing and reviewing scientific papers.

* About the magnetic field strength of an MRI machines, but itsf field extends within a smaller space.

** But only for a few milliseconds, which the students’ paper did not mention.

As part of their Physics Special Projects module, 3 fourth-year students at the University of Leicester asked the question “Could deflector shields seen in Star Wars really defend a space ship against laser attack?” They found that it is not only within the realm of reality but they could also be built with today’s technology. However there is a big ‘but’….. the students explain all in this video clip.