41

In Star Wars movies we often see poi-style lightsaber movements:

an example of a typical internet fight

Poi performers (e.g. fire performers) use the weight of a prop to make it go round. To my understanding, to do this with a physical sword you need the center of mass (a.k.a. point of balance) to be out of the handle, which is typical for swords:

photo of a sword

However, since lightsaber blade has near-zero mass, its POB must be inside of the handle. Moreover, the Wookipedia article claims that the blade actually has a gyroscopic effect (which makes swinging almost impossible):

Due to the weightlessness of plasma and the strong gyroscopic effect generated by it, lightsabers required a great deal of strength and dexterity to wield, and it was extremely difficult—and dangerous—for the untrained to attempt using.

How the possibility of round movements with a lightsaber can be explained?

Update
I've checked several questions about lightsabers and the Force:

There were no answers, claiming that the Force changes lightsaber's physical properties somehow (i.e. adds weight to the blade). They say Force affects practitioner's body, mind (perception), all the surroundings, but the lightsaber remains the same.

The only exception could be channeling a lighting through the lightsaber blade, but I doubt that adds its weight somehow.

Update 2
In this video Lucas says that fight choreographic was inspired by kendo in the first three movies. Which is perfectly fine, since you actually can strike a weightless blade in kendo style. So the question is primarily about the later films (e.g. Count Dooku style).

  • 29
    The Force did it. – Adamant Jun 13 '16 at 12:38
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    The Rule of Cool? (Warning: TV Tropes link.) – Rand al'Thor Jun 13 '16 at 12:46
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    Lightsaber blades are massless, but the conceit is that they still act as if they have pseudo-weight due to gyroscopic action. They're hard to move and once they start moving, they're hard to stop, hence why only trained force-users tend to use them. – Valorum Jun 13 '16 at 13:13
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    @enkryptor - I wouldn't think too hard about it. Just watch the acrobats having a laser-sword fight. – Valorum Jun 13 '16 at 13:34
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    I can do this with my car keys. I don't see the problem. – Lightness Races in Orbit Jun 13 '16 at 23:04
55

There's nothing impossible in those movements, the actors are performing them just fine.

You can replicate the effect by taking a long stick and doing the same movements until you get used to them, then chop the stick up so you've only got a piece the same length as a lightsaber handle. You'll find you can still twist it through the same permutations easily.

  • Hmmm, sounds interesting. – Adamant Jun 13 '16 at 15:41
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    Note that the actors were using non-weightless blades when filming those scenes--your second paragraph is better evidence. – Milo P Jun 13 '16 at 16:25
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    I used a bottle of Coffee Mate. :) – Hack-R Jun 13 '16 at 22:43
  • Do it with your car keys. Easy peasy. – Lightness Races in Orbit Jun 13 '16 at 23:05
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    A better example of prop would be a metallic/wooden handle and a polystyrene blade. – beppe9000 Jun 14 '16 at 0:15
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As almost anything that has no explanation in SW universe... through the use of the Force.

Force users make incredible acrobatic feats, totally unable to achieve for a standard humanoid, they achieve this through Force use, manipulating the Force and improving their vaulting abilities with it.

The same can be applicable to blade-wielding. Maybe the physics of the blade makes it almost impossible to make certain movements without external help. When this happen, Force users can apply their abilities in the Force to alter the movement of the blade, exactly in the same way they do it when they make an acrobatic feat or when they throw the blade.

  • Updated the question. – enkryptor Jun 13 '16 at 12:54
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    It's not just Force users who make incredible acrobatic feats, don't discount (obviously a Sith lord) Jar Jar doing a triple somersault 30 feet into the air from standing. God forbid he gets his hand on a more elegant weapon than his accent. – Chris Morris Jun 14 '16 at 14:22
  • That's not true. Far more in the SW universe can be explained by Hypermatter than the Force :D @ChrisMorris That's because Jar Jar was originally supposed to be a dark lord of the sith. – Shane Jun 14 '16 at 14:58
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To add a small amount more scientific explanation to the answers stating that this can be done easily (with a bottle of coffee mate no less!):

When poi performers use the weight of the sword to swing it they need to do this because the sword is heavy and therefore requires a large rotational moment to move it round, but once it's going it has a large mass moment of inertia, so it's own mass will keep it swinging.

A lightsaber handle (or a bottle of coffee mate!) is light, so the moment required to spin it in this manner can be easily provided with just a twist of the fingers. The lack of a weighted blade reduces the moment provided, but because the total mass is so much less there is a much smaller moment required - the two changes cancel out.

So in fact the very issue that inspired your question, the weightless blade, solves it!

8

To your point, the blade presumably weighs basically nothing. So it's just the handle which, given how it's so easily handled by even children and Yoda, probably doesn't weigh much either.

As an experiment I just simulated a lightsaber handle with bottle of Coffee Mate. I had no problem swinging it around like "The Star Wars Kid" or the Jedi in your animated gif.

So, I think at least part of the answer is that it's simply easy to handle.

Also, they could've used the force (that's how it works right? OK perhaps not. Idk).

3

while the lightsaber blade itself is weightless the hilt still holds weight to it which allows for a sense of weight and then if you factor in both the gyroscopic factor you could assume that by using that effect in tandem with the weight of the hilt that should be close enough to the over all weight to allow for a user to put the blade into that motion. another to consider is that once its moving all you need to do is keep the blade moving at all times to get to an eventual point where you have the equivalent velocity to use the technique similarly

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