In Revenge of the Sith, Anakin, Obi-Wan, and Palpatine are trapped by a ray shield on the Separatist ship the Invisible Hand:

enter image description here

It is specifically called it a "ray shield" by multiple characters:


BODYGUARD: General, we found the Jedi. They're in hallway 328.

GENERAL GRIEVOUS: Activate ray shields.


They run down the hallway. Suddenly, ray shields drop around them, putting them in an electronic box in the middle of the hallway.

ANAKIN: Ray shields!

However, ray shields are (usually) only capable of stopping energy like blaster bolts. To physically block an object you need a particle shield.

The fact that ray shields do not block physical objects is supported by the (fully canon) Star Wars: The Clone Wars episode "Landing at Point Rain", in which Anakin was seeing running through a ray shield along with clone troopers1:

enter image description here

This shield is described as a ray shield in the episode description:

...On Geonosis, Separatist leader Poggle the Lesser, safe in his newly ray-shielded factories, creates thousands of terrible new weapons which march off the assembly line against the outnumbered clone army...

Ray shields' inability to block physical objects is also supported as a major plot point in A New Hope during the Battle of Yavin briefing:

DODONNA: The target area is only two meters wide. It's a small thermal exhaust port, right below the main port. The shaft leads directly to the reactor system. A precise hit will start a chain reaction which should destroy the station. Only a precise hit will set up a chain reaction. The shaft is ray-shielded, so you'll have to use proton torpedoes.

The Rebels needed to use proton torpedoes (as opposed to, say, the X-Wing's four blaster cannons) because proton torpedoes are physical objects:

enter image description here

MG7-A proton torpedo

Hence, the Death Star was only destroyed because its ray shielded thermal exhaust port was vulnerable to physical proton torpedoes.

How were Anakin, Obi-Wan, and Palpatine physically impeded by the Separatist ray shield when the plot in two other canon sources depended on ray shields' inability to block physical objects (including humans)?

Note that this question is not tagged with -- I have provisionally accepted the Legends answer, but I am still looking for a canon answer.

1 GIF taken from 15:44 of this Youtube video.

  • 4
    Hand wavium forgetism... Basically it had been such a long time between the 2 movies that they forgot they had used the term "ray shield" and given it X definition. Alternatively, attention spans had shrunk drastically between the 2 movies so they decided "ray shield" worked better then "particle shield" because who doesn't like rays? and it takes less time to say.
    – Ryan
    Aug 12, 2015 at 17:16
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    Maybe ray shielding works better on human flesh than on torpedoes?
    – Max
    Aug 12, 2015 at 17:41
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    Actually reading the quote directly and the page on wookipedia it looks like they are never explicitly defined as only blocking physical objects. Seems the actual functionality wasn't ever defined more explicitly then "they can be broken by proton torpedoes".
    – Ryan
    Aug 12, 2015 at 18:07
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    @ryan, this exact lack of specific information on the technology is why it's often easy for me to classify Star Wars as science fantasy instead of science fiction in many (but certainly not all) instances. Aug 12, 2015 at 20:32
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    Part B - If they are magnetic shields, not plasma windows, then that could explain why they can stop blaster bolts but not proton torpedos whose exteriors are presumably electrically neutral. If the proton ordinance was shielded then the magnetic fields wouldn't be able to interact with it and thus it could pass through/around them. But I don't know exactly how proton torpedos work, and this is all very handwavey.
    – Phyneas
    Aug 12, 2015 at 21:29

4 Answers 4


Okay so I did some googling and this is what I came up with from the starwars.wikia.com on deflector shields themselves not either of the 'sub-shields'.

Ray shields were also used as capture devices onboard capital ships; Obi-Wan Kenobi, Anakin Skywalker and Supreme Chancellor Palpatine were caught in a ray shield trap onboard Invisible Hand. Although designed to counter energy attacks, the energy given off by the ray shield would likely have disintegrated the Jedi duo had they attempted to pass through it.

Which fits in the behavior we have observed in the movies (obviously). Like I stated in my comment, in the original 3 movies the only definition given to a ray shields functionality is that it can be broken by proton torpedoes. That's it. So any behavior we see applied to them in later movies that doesn't directly contradict the "can be broken with proton torpedoes" rule we have to accept as acceptable behavior. Because that's what cannon is saying it can do.

To go along with this (this was the best clip I could find)

we can clearly see that they don't try to touch it and tend to not move much at all. Which seems to support the line "would likely have disintegrated them."

After reading here, here and following and reading a bunch of links from this page, and links on this page I've come up with this LEGENDS answer.

Ray/Energy shields are meant to deflect energy from blaster bolts. They are different from Particle shields in that they always allow physical objects to pass through them. However the radiation/electrostatic energy coming off a ray shield can be anywhere from annoying to deadly for organic matter.

Also the strength of a ray shield seems to be in "how much energy can I absorb before my circuits overload" not "how strong is the field I project". This is what made ray-shields useful as capture devices. They can be used anywhere without worry of suffocating your captured victim (which a particle shield would do as it inhibits all particles from crossing it's barrier), and still act as effective movement inhibitors because a strongly projected ray shield would be deadly to organic captives.

This leads to the following 2 scenarios pictured in the question. A weakly projected large shield on Geonosis capable of absorbing lots of energy but also capable of allowing clones/Geonosians to pass through it. And a much smaller but much more strongly projected capture field on the capital ship which would have allowed the Jedi/chancellor to pass but would have killed them in the process.

Out of universe I'll go back to my first comment:

Hand wavium forgetism... Basically it had been such a long time between the 2 movies that they forgot they had used the term "ray shield" and given it X definition. Alternatively, attention spans had shrunk drastically between the 2 movies so they decided "ray shield" worked better then "particle shield" because who doesn't like rays? and it takes less time to say.

  • The "disintegration" argument seems plausible, although it's unfortunately unsourced so it's anyone's guess who originally wrote that. +1 for the find, though. And, yes, your out-of-universe answer is the one I suspect is the real reason.
    – Null
    Aug 12, 2015 at 20:47
  • I found an example from The Clone Wars TV series where Anakin was able to pass through a ray shield wearing much the same clothes, so the "disintegration" argument can only stand by hand-waving that they're different kinds of ray shields or something. (Not your fault -- I think this was a screw-up in the Episode III script.)
    – Null
    Aug 13, 2015 at 17:13
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    I would argue that the strength and/or nature of the ray shield affects its secondary properties. The Second Battle of Geonosis is not the first set of battlefield scale ray shields to be penetrated. The Trade Federation could walk through Gungan ray shields too, although in that case Gungan shields had more elastic resistance than Geonosian ones. Mar 31, 2016 at 16:25
  • I'm inclined to believe, just like blaster bolts of different colours, that shields can be created using different technologies. Ray shields of different natures could be differently resistant to physical objects, and differently lethal too. Perhaps some ray shields double as particle shields, and perhaps some have no physical impedance at all. Let's not forget the shields that divided Obi-Wan, Qui-Gonn and Maul - those are definitely ray and particle shielded. Mar 31, 2016 at 16:31

It doesn't actually say that they can't block physical objects. In fact, there is documented use of ray shields to imprison people; Ahsoka Tano was restrained by Cad Bane with one, and the Republic used them to house prisoners in their base on Coruscant.

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    Well, my question has a documented use of ray shields to imprison people... The question is: how could a "ray shield" imprison a person yet it is specifically unable to block a (physical) proton torpedo? I don't see how this answers that question.
    – Null
    Aug 12, 2015 at 20:05
  • @Null - Because nowhere in the accepted canon does it say that a ray shield blocks physical objects.
    – Valorum
    Aug 12, 2015 at 20:11
  • @Richard Did you mean "nowhere...does it say that a ray shield doesn't block physical objects"? Because my assumption is that it doesn't block physical objects.
    – Null
    Aug 12, 2015 at 20:20
  • @Null - That's what I meant. All we know from the original film is that they block blasters (somehow) and that Photon torpedoes can penetrate them. That's it. Everything else comes from non-canon sources like the various technical books.
    – Valorum
    Aug 12, 2015 at 20:23
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    @Null - Not so much sloppy as simply ill-defined. Like most mature technologies, people in-universe don't feel the need to describe it since they're used to it.
    – Valorum
    Aug 12, 2015 at 20:39

This answer uses information that has been marked as Legends, therefore it is not canon to Star Wars.

(Source: Star Wars Complete Cross Sections: page 11, Technology)

Concussion shields are used to repel space debris, and deflector shields (ray and particle shields) help to protect craft during battle. Ray shields deflect or break up the beams from energy weapons. Particle shields protect against impacts from high velocity projectiles and proton weapons.

Most shields that are shown in Star Wars are "deflector shields", a combination of particle and ray shields. What they are calling "ray shields" in ROTS are actually concussion shields. The Death Star's exhaust port was protected by ray shields, therefore they had to use proton torpedoes to attack it. Only particle shields protect against missiles. Most shields shown in star wars are either deflector shields or concussion shields.

  • Anything that blocks movement, like the shields placed on Obi-Wan and Anakin, is a concussion shield, though they may be a combination of deflector and concussion if they are shown to block blaster fire as well as physical mass.

  • The shields shown in The Clone Wars that protect strategic areas are deflector shields because people can walk through them, but block blaster and cannon fire.

  • Droideka shields and the Death Star exhaust port shields are ray shields that don't block projectiles.

So when people say "ray shielded" in the OT they actually mean ray shields but when people say "ray shields" in the PT they are talking about concussion shields. Hope this answers your question.

  • Hmm, interesting. Can you quote from your source? You can format text as a quote by beginning the line of text with >.
    – Null
    Mar 23, 2021 at 20:10
  • Well, that source may not be canon but I have added a quote @Null ♦ Mar 23, 2021 at 22:24
  • Wookieepedia labels the book as Legends (not canon) but that's okay. I've provisionally accepted a Legends answer until (if) a canon explanation is ever given. This explanation is that Grievous and Anakin misspoke and meant to say "concussion shield" -- still a plot hole but it makes a little more sense. Thanks for the answer, and +1!
    – Null
    Mar 24, 2021 at 0:32
  • The Clone Wars actually shows that Droideka shields block projectiles if they are moving at a high enough speed (so throwing a rock at them will bounce off the shield). The shields seem to be designed to stop anything that moves faster than the droids do while walking.
    – Kadima
    Mar 24, 2021 at 18:26
  • Oh really? I thought rocks went through the shields. Mar 24, 2021 at 18:41

A potential physical explanation could be that ray shields may interact with different types of matter based upon the frequency of their emission. That would explain why they interact with solid matter and plasma differently.

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