Lightsabers: Science fiction, or scientific possibility?

“Any sufficiently advanced technology is indistinguishable from magic”

Arthur C. Clarke

SciFi is one of the most popular genres of storytelling out there. Greats like Lucas, Asimov, and Shelley have inspired generations to think weirder and imagine bigger. In the last 15 years alone, we have developed prototypes for jetpacks, driverless cars and organ printing – ideas that were completely conceived in the realm of science fiction. Over the next couple of my blog entries, I’ll take iconic scientific fiction technologies and assess where current technology stacks up. Up first, the construction of a lightsaber, an elegant weapon for a more civilized time.

 

First shown in the 1977 movie Star Wars, in 2008 the lightsaber was named the most popular weapon in film history, beating out Dirty Harry’s .44 magnum and Indiana Jones’ bullwhip. As we all know, a lightsaber is essentially a combat energy sword with many distinctive characteristics, and the successful construction of this weapon should recreate these characteristics. For the sake of brevity, I’ve narrowed the list to three essential criteria.

  1. It has to have the look and feel of sword:
  • The energy blade must be visible – Invisible swords are dangerous, to everyone.
  • The weapon should sound like a lightsaber – Though deadly, a lightsaber without that distinctive ‘vrummmp’ sound isn’t worth it.
  • The energy blade must have a set length – Blade lengths vary by make, but the katana, the sword a lightsaber was based upon, ranges from 70-73 cm.
  1. It has to cut through any material (save another lightsaber) – As an offensive weapon, lightsabers are shown cutting through metal, tree trunks, and even the limb of a Wampa, but never another lightsaber.
  1. The weapon is self contained – This is in direct regards to a battery source. Doesn’t matter if it’s a Kyber Crystal or a Duracell, a lightsaber needs an internal power supply to produce the energy blade.

Since its iconic inception many engineers and physicists have taken these characteristics and contemplated if creating such a weapon is possible with current technology. Scouring the web and blogospheres has revealed two technological front runners for lightsaber construction, LASERs and plasma manipulation.

LASERs or light amplification by stimulated emission of radiation differ from other sources of light in that the light waves are spatially coherent, or grouped, allowing the them to become focused into a tight directional beam (Figure 2; Left). So, could LASERs be used to construct the lightsabers we know and love? Criteria 1: can LASERs convey the look and feel of a lightsaber? Though focused, LASERs are still beams of light, and just like any beam of light, a LASER based lightsaber would go on indefinitely until all of the energy output is either absorbed or reflected [1]. So set blade length is out. Additionally, similar to having multiple lights in a room, LASER beams can pass through each other and are invisible in brightly lit environments. Moreover, light waves are not sound waves; so like my desire for Jar Jar Binks, your LASER lightsaber would be invisible and silent. Criteria 2: could a LASER cut through anything? Varying in power, LASERs are used in a myriad of ways, from entertaining cats with presentation pointers to shooting down military drones with powerful US Naval weapons. Though they can easily pierce metal, high powered LASERs require constant contact with a target and only bore holes the diameter of the beam. So, we’ll put that as a yes/maybe. Criteria 3: could this be self contained? As demonstrated in the naval video, high powered LASERs require vast amounts of power, and could not be contained to the small hilt of a lightsaber. So, LASERs may be great for entertaining a Wookiee, but in terms of constructing a working lightsaber – LASERs aren’t the tech we’re looking for.

What about plasma? Plasma is the fourth fundamental state of matter (the more familiar states are solid, liquid, and gas), and is created by subjecting gas to a strong electromagnetic field, resulting in the formation of charged particles called “ions”. When these ions go through a nonconductive media such as air, an electrical arc is produced from the origin of the ions to their oppositely charged source [2]. Lightning strikes (Force induced or otherwise) are a clear example of this phenomenon. So how does plasma stack up to our criteria? 1: Can plasma create the look and feel of a lightsaber? Artificially, we can recreate strong electrical arcs in common metal working tools known as plasma torches (Figure 2; Right). Miller Spectrum plasma cutters typically have plasma streams reaching 3-4 cm, though this can fluctuate slightly depending on the amount of current sent to the machine. Further, plasma streams are loud and brightly colored, enough that anyone within range would notice. Criteria 2: Can plasma cutters cut through anything? According to the Miller Spectrum cutter specifications, plasma streams can reach upwards of 30,000˚F [3], hot enough to cut through anything. Unfortunately, much like LASERs, plasma cutters require immense amounts of energy, roughly 15 kW for 3-4 cm streams [3], which if scaled up could meet the 70-73 cm lightsaber blade length requirement.

Results:

                                                          LASER                               Plasma

Visible Blade:                                   Nope                                        Yes

Sound:                                               Nope                                        Yes

Set Blade Length:                            Nope                                        Yes

Cutting Power:                                 Yes/Maybe                             Yes

Self-Contained Machine:              Nope                                         Nope

Clearly plasma is the better choice, at least over LASERs – but it’s still NOT a lightsaber – so how do we fix this, at least theoretically? Thankfully, physicist Michio Kaku has some suggestions. First, power! Kaku believes carbon nanotubes are the key to maximizing electrical power, while minimizing space. Expected to be in wide use by 2020, these graphene tubes can hold an electric charge, and due to their small size (nanometers in diameter), you can layer billions and billions of them (say in a sword hilt) for increased electrical output [4]. Another hurdle is heat. Since plasma can reach extremely high temperatures, safety is an obvious concern. Mechanists who operate plasma cutters regularly wear industrial gloves, but this will limit combat flexibility in a fight. Kaku again offers a solution, this time ceramics. Ceramic tiles dispel heat quickly, and are used by NASA to shield space shuttles upon reentry into the atmosphere. Though not capable of withstanding 30,000˚F (yet), NASA’s LI-900 tile is completely safe to touch seconds after being in an oven at 2,200˚F. Though not perfect, already existing technology could be used to cobble together the semblance of a lightsaber.

Recently a friend asked me, ‘why would someone want to make a lightsaber?’ Unfortunately, the only answer I can think of is, ‘why not?’ But is that a bad answer? I understand that lightsabers don’t serve a great practical application and, without the Force, are fairly useless in a combat scenario against scum and villainy. However, constructing an object purely rooted in science fiction embraces this broader notion of human ingenuity and push for scientific discovery. To paraphrase Clarke, science fiction is just science we have yet to figure out, and until such time, I will keep hoping scientists stay on target and create cinema’s favorite weapon.

I’ll be back over the summer with more blogs. Until then, happy Star Wars day everyone, and May the 4th be with you!

References:

[1] Weschler, M. (2000) “How Lasers Work” HowStuffWorks.com. link

[2] Electrical Arc (Wikipedia article) http://en.wikipedia.org/wiki/Electric_arc

[3] Venketramani, N. (2002) “Industrial plasma torches and applications.” Current Science 83(3).

[4] Zhu et al. (2011) “Carbon-Based Supercapacitors Produced by Activation of Graphene.” Science 332.

Me CropRishi R. Masalia is a PhD candidate in the Department of Plant Biology at the University of Georgia studying the genetics of drought resistance in sunflower. He is a biologist,  bioinformatician, artist, comedy gold mine, smooth dance machine and all around nerd. Rishi is a founding member of the Athens Science Cafe, and the current President of the student organization: Science Café, UGA Chapter. He can be reached at masalia@uga.edu, or followed on Twitter @RishiMasalia.