on May 4th, 2022

On 4 May the world celebrates Star Wars Day, but there is one artifact in the Star Wars universe that perplexes scientists and engineers – the Lightsaber.

The laser-like sword has been deemed impossible to exist, so in celebration of Star Wars Day, we look at why this weapon used by the Jedi and the Sith is so unlikely (for now).

Let your imagination take flight

Imaginative engineering is at the core of what has made Star Wars so successful according to scholars. In the world of Star Wars space ships, cities and weapons go far beyond what can ever be created on earth to create an immersive story for everyone.

Lego Star Wars figurines with lightsabers
Photo by Eric & Niklas on Unsplash

Because the viewer is unable to unpack the science behind these creations, it opens us up to rather look at the narrative storytelling.

But for Canadian academics Francois Fillion-Gourdeau and Jean-Sebastien Gagnon the Lightsaber is of particular interest. The two scientists penned On the physical (im)possibility of lightsabers in 2019 inspired by the Star Wars universe.

They believe that lightsabers are not impossible just because there are limits to the laws of physics, but rather that it is implausible due to the high intensities of energies that would be needed to create these kinds of weapons.

Lightsabers captured the imagination of the audience and engineers alike in 1977 when the weapon was introduced in Star Wars: A New Hope.

The lightsaber is in essence a conventional sword with a blade of light (often in green and blue for Jedi and red for the Sith). The weapon can cut through steel, it can ward off laser blasts and can cut through bone and flesh with a smooth cut.

What also captured the imagination of many was that finite light blades are implausible since light cannot stop after propagating for a certain length in the real world.

On top of that, the cinematic blades seem solid when it encounters another blade, and light does not have that quality.

Fundamental limitations in the laws of physics

A key problem with Lightsabers is that they would require a nonlinear medium for light to propagate.

waves of light
Photo by Channel 82 on Unsplash

The medium would likely have to be a gas of atoms maintained in nano kelvins – which would be difficult to achieve in the case of lightsabers because it would mean the swords need some sort of refrigerated case around the blade to be able to contain it.

Above all, in the paper, the authors establish the effects of light-by-light scattering when two blades cross paths. The force felt on a lightsaber hilt due to the scattered light coming from another lightsaber is of particular intrigue – since it goes against Maxwell’s equations.

The vacuum in classical physics is empty and light-by-light scattering is not possible in a classical vacuum. However, this is different when quantum effects are considered. It is accepted that a quantum vacuum is filled with virtual particles.

But these particles could not be used in a lightsaber. The virtual particles are due to the relation E=mc2 from special relativity and the Heisenberg uncertainty principle.

When charge conservation is not violated, energy would be able to be “borrowed” from the vacuum to create virtual particles (electron-positron pairs) and be returned to the vacuum for a short time to not contradict the Heisenberg uncertainty principle.

The rest of On the physical (im)possibility of lightsabers explores the math and other principles that make lightsabers so improbable with the conclusion that the type of light interaction required by lasers in terms of Lightsabers requires enormous power that is beyond the capabilities of present-day technology.

If you read the above and became discouraged about the fantasy aspect of Star Wars, don’t!

This particular paper by Francois Fillion-Gourdeau and Jean-Sebastien Gagnon had a specific goal to show how examples from science fiction can be used as pedagogical tools to introduce advanced physics to undergraduates in a university setting.

In the case of Lightsabers, it was to show nonlinear effects in electrodynamics due to the quantum vacuums.

Play with ideas

Lightsabers and Star Wars also create STEM-based imaginative play – and on Star Wars Day Lego has released another set of Star Wars toys that are heavily rooted in play that speaks to budding engineers.

Star Wars Lego celebrates 23 Years in 2022 and over the years Star Wars led to the inspiration of new designs and robotics at Lego.

In a press release, Lego Mentioned some things new Star Wars toys inspired (see below).

The play personified in the sets has been valuable for Lego, which has used its brand to reach STEM education targets. In 2015 Lego says children continued to have a high interest in core Lego Themes, including Star Wars.

The creativity and play of the products, coupled with educational programs using Lego have contributed to young minds being more interested in math and science.

So, while we can’t build Lightsabers just yet – we can tip our hats to Star Wars for helping to inspire engineers’ past, present, and future.

Some new Lego Star Wars inspired:

  • 1999: The first male hairpiece in 20 years is designed for Qui-Gon Jinn on a Lego Minifigure.
  • 1999: The first specially designed Minifigure for Jar Jar Binks get the greenlight.
  • 1999: A Mindstorms Droid Developer Kit is launched for fans to create their own droid.
  • 2000: The first Chewbacca Minifigure is launched and the design team needed to solve a way to have a head with fur covering the front and back of the figure’s torso. Since then the same front and back covering has been used in other figures.
  • 2007: Motorized Walking AT-AT sets launch. The model can move its head and walk – forward and backwards thanks to robotics.
  • 2013: The world’s largest Lego model, a 1:1 replica of an X-Wing starfighter is revealed in New York City. It took 5,3 million bricks to complete.
  • 2015: The CCBS platform (Character and Creature Building System) with large-scale buildable figures launches.


Fillion-Gourdeau, F., & Gagnon, J.-S. (2019). On the physical (im)possibility of lightsabers. European Journal of Physics, 40(5), 055201. https://doi.org/10.1088/1361-6404/AB274A

Lego, 2019. The Greatest Build Since 1999 celebrating 20 Years of Lego Star Wars Fandom. [online] Available at: https://www.lego.com/en-us/aboutus/news/2019/april/the-greatest-battles-built-since-1999-celebrating-20-years-of-lego-star-wars-fandom [Accessed 4 May 2022]

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