Do Lightsaber Blades Have Mass?
Lightsabers are iconic weapons in the Star Wars universe, often depicted as glowing blades that can clash like swords. Despite being called 'laser swords' by some characters, they cannot be made of laser light because lasers would be invisible and pass through each other. By analyzing their motion, physics suggests that lightsaber blades likely have mass, indicating they are not pure light but some form of contained energy or plasma.
- ▪Lightsabers cannot be lasers because laser beams are invisible from the side and would not stop at a fixed length.
- ▪Laser beams would pass through each other rather than clashing, which contradicts how lightsabers behave in duels.
- ▪The motion and resistance of lightsabers when swung suggest they have a moment of inertia, implying the presence of mass.
- ▪Anakin Skywalker, Din Djarin, and Luke Skywalker all refer to lightsabers as 'laser swords,' though this is scientifically inaccurate.
- ▪The moment of inertia in rotational motion depends on both mass and how it is distributed, which helps determine if a lightsaber blade resists movement like a physical object.
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Rhett AllainScienceMay 4, 2026 7:00 AMDo Lightsaber Blades Have Mass?On Star Wars Day, we put to rest a question that has bedeviled sci-fi nerds for years.Still from Star Wars: Episode V - The Empire Strikes Back.Photograph: 20th Century Fox/Everett CollectionCommentLoaderSave StorySave this storyCommentLoaderSave StorySave this storyWhen you think of Star Wars, you think of lightsabers. Right? What could be better, from a movie-making standpoint, than a futuristic sword that lets you create awesome fencing duels like in old-time Errol Flynn swashbucklers.
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