In the 1st and 2nd episodes of the currently running season 4 of Star Wars: The Clone Wars, there were many underwater scenes ınvolvıng lightsabers. If you've watched those episodes, you'd have noticed that there wasn't any effect on water around the lightsabers.

From my point of understanding, lightsaber blades are thousands of degrees Celsius. That's why they could cut metal sheets.
And, with such high temperature, lightsabers could break down water molecules as well as vaporize them (distant molecules), which could create a whirlpool of powerful water currents around it. But nothing happened. Why?

Am I mistaken about temperature? Can the temperature of a lightsaber be controlled using the Force? What's your canonical explanation of this?

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    Are the Clone Wars cartoons considered canon? Commented Feb 6, 2012 at 23:59
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    @JackBNimble - Unfortunately, yes. Extremely unfortunately so, they are T-canon - meaning, only 1 step below movies and HIGHER canon than EU books. The only thing more depressing is Midichlorians Commented Feb 7, 2012 at 0:24
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    This question reminded me of a moment in Ryan vs Dorkman 2 where Ryan is dragging his lightsaber through a puddle, and you can clearly see the steam coming off as the water is vaporizing. So at least their version of lightsabers do affect water.
    – hammar
    Commented Feb 7, 2012 at 0:41
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    @DVK: You mean Jar-Jar depresses you less than T-Level canon and midichlorians? That's scary!
    – Tango
    Commented Mar 15, 2012 at 23:19
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    @TangoOversway - meesa really don't see why people hate Jar Jar so much. Bink wasn't the highlight of the movies, but I don't have any significant objections to him as a character and appreciate him as CGI. Just think of him as a product of cross-breeding of C3PO and Ewok. Commented Mar 15, 2012 at 23:27

3 Answers 3



The Wookieepedia Lightsaber article states:

Water: All lightsabers, unless specially made, would short out when they were submerged in water, due to rapid chain reactions and the instant overpowering of water on the blade. In rain, a lightsaber would steam up, but not short out.

The sources for that statement are:

  • Clone Wars chapter 5 (makes sense - the episode takes place on Mon Calamari)
  • Clone Wars chapter 19

Also, from Wikia for Kit Fisto (the Jedi on Mon Calamari in Chapter 5)

Fisto's lightsaber contained two crystals employing a bifurcating cyclical-ignition pulse that allowed the blade to operate underwater. This proved helpful on Mon Calamari during the Clone Wars (unsourced)

The above piece is unsourced and to be honest sounds like a typical WikiaLucasy technomumbojumbo, but hey....

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    Of course, they did prepare for underwater battle, so they'd have made their lightsaber water-proof. But, I am asking different thing: why didn't it affect water?
    – user931
    Commented Feb 7, 2012 at 8:50
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    @SachinShekhar - No canon info I could find. I'm left with the unsatisfactory "LucasPhysicis". Commented Feb 7, 2012 at 10:52
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    Water is dipolar so should be repelled by the magnetic field....
    – AncientSwordRage
    Commented Mar 15, 2012 at 15:26
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    @Pureferret - Umm.. Shouldn't that just be that it's aligned by the mag field? One side pulled.. one side pushed.. that being why water doesn't normally respond to magnets.. (but the alignment being why it expands when frozen.)
    – K-H-W
    Commented Mar 15, 2012 at 19:45
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    @KeithHWeston If you have a strong enough magnetic field water is repelled by it. Considering these things contain plasma, I'd say the fields are strong enough.
    – AncientSwordRage
    Commented Mar 15, 2012 at 23:12

Water exhibits very weak diamagnetism, and thus under extreme fields, such as those confining a lightsaber blade, the water should be repelled. The repelling effect keeps the hot blade from the water. The same cannot be said about the handle and the electronics within, unfortunately.

As the water is repelled, the heat of the blade should have no effect on the water as the blade never touches the water.

  • How is it answer?
    – user931
    Commented Mar 16, 2012 at 11:24
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    humans are 90% water... lightsabers should not be able to harm humans. Commented Mar 16, 2012 at 12:06
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    If you have two sacs of water bound together and you try to insert a hot magnetic field in between them would rip them apart from the field, and burn the sac. That's what's happening to the cells in the human body when a lightsabre slices through it like a hot knife through butter.
    – AncientSwordRage
    Commented Mar 16, 2012 at 12:13
  • Heat transfer isn't limited to touch.
    – user931
    Commented Mar 27, 2012 at 10:55
  • No it's not, but the convection and radiation I am assuming to minimal.
    – AncientSwordRage
    Commented Mar 27, 2012 at 11:01

Compared to the huge, cool water mass, one lightsaber is not a big source of heat. The water touching the blade would certainly vaporise but the surrounding water would in turn cool the steam almost instantly. In effect, you might get a shell of water steam around your blade, and the surrounding water might warm gradually. Warmer water goes up, but that would be almost invisible even in reality, so not showing it in an animated series is fair.

We should get a physicist to calculate the numbers.

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    Even below boiling temperature, you can find bubbles in water. Lightsabers are big things to deal if water wants to ignore heat fully..
    – user931
    Commented Mar 15, 2012 at 20:16
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    @Raphael If you're interested with real physics, this should be happened: Extreme heat will break near-by water molecules & this hot air will pass heat to distant molecules to vaporize them. This will create a huge pressure difference to trap cool water molecules. Water from top try to come below with equal speed, but air from middle will push them up to equalize pressure. It creates vertex to create whirlpool. Due to this whirlpool, same level water will join its flow to make whirlpool bigger and powerful.
    – user931
    Commented Mar 15, 2012 at 21:10
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    @Raphael The effect I mentioned in question is called Thermolysis: en.wikipedia.org/wiki/Thermolysis . And, Mike is wrong with 500 degree Celsius. Its 2000 degree Celsius for pure water. I didn't mention temperature because it varies based on impurities.
    – user931
    Commented Mar 15, 2012 at 21:27
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    @Raphael More diet to your curious mind: Oxy-Acetylene cutter torch operates between 3200 to 3500 degrees C. As lightsabers cut faster, its safe to assume its temperature higher than 3500 which is greater than 2000 (to do Thermolysis).
    – user931
    Commented Mar 15, 2012 at 21:36
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    having seen much cooler underwater welding, the bubbles of steam rise faster than they can cool.
    – aramis
    Commented Sep 25, 2012 at 0:45

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