I want to create a sword that can pass through an opponent's weapon/armor (mostly made of metal like steel/iron, bronze, copper, lead, silver, gold, etc) like it was ethereal or hologram thing upon contact with opponent weapons (not breaking the opponent weapon/armor even when passing through though, so it not separate/shredding the material molecule so super nanomolecular sharp is out even if the molecules rebond or attach back after that, and superheating the sword to melt the opponent's weapon/armor like a lightsaber is also out), and turn back in solid shape to the part that doesn't contact with metal material (preferably the weapon still intact after pass through or even some part of it stuck in that state), it may or may not pass through other material like wood, preferably not pass through flesh (it will maintain solid form to cut flesh) but I am curious if it also passes through flesh (or is that the only option the science answer can achieve).

It still maintains the shape even when it passes through so it doesn't turn liquid, melt, or spread out mist/gas (kinda...., at least in my mind it look like a mist but not spread out or still in sword form like it was a hologram) upon contact with higher temperature than this material, like gallium, and I already have this type of weapon, so gallium or similar property is out of the question.

Nanomachine/sand-like is out of the question too because I also already have that.

I want to know if there is another scientific phenomenon that can achieve this and what kinds of other effects/side effects or properties it would have, and if possible also include a way to create or shape it if it requires an unorthodox way to make this weapon.

I am not asking how to use this weapon or the martial arts, so don't bring that up including your opinion about why this sword is bad or good in a fight, after all, if your opponent knows your way of fighting, of course they can counter it and vice versa, and this is not restricted to swords, it can be made into other types of weapon including blunt weapons, I just want to make a sword for simplicity's sake.

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    $\begingroup$ Evgeny Voiskunsky and Isai Lukodyanov, The Crew of the Mekong, English translation by Leonard Stoklinsky, Mir Publishers;, Moscow, 1974. (There is an on-line copy at lib.ru, if you know what lib.ru is; opening in a private window is recommended.) $\endgroup$
    – AlexP
    Nov 6, 2019 at 14:18
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    $\begingroup$ Consider if regelation might work for you $\endgroup$
    – nzaman
    Nov 6, 2019 at 16:38
  • $\begingroup$ @nzaman thats basically what i mean with the gallium or similar propreties $\endgroup$
    – Li Jun
    Nov 6, 2019 at 21:57

2 Answers 2


Quite surprisingly for some, matter is made mostly by empty space: if I am not mistaken in my memories, if an atom was the size of a football field, its nucleus would be a ping pong ball at its center, the rest being vacuum.

The reason why solids to not easily penetrate each other is that the electron clouds strongly interact with each other with a repulsive force due to Coulomb interaction between similar charges.

As such, there is no way for a solid to pass through another solid without damaging it. One of the two sides has to yield and get a deformation in the form of a fracture.

You can only penetrate a solid with another substance if you strip out the electrons. This is what Geiger-Marsden did in their famous experiment, where they fired alpha particles against a thin sheet of gold. Most of the particles crossed the gold on a straight line, but some of them bounced back on the gold nuclei.

However, a bunch of electronless atoms doesn't qualify as a solid, being an ionic beam.


No material or physical process known to current science is able to achieve the kind of 'phasing' you describe.

In principle subatomic particles are able to undergo quantum-tunneling, which is sort of like teleporting through other things (energy barriers specifically, but sub-atomically matter & energy is kinda the same anyway).
However claiming you have a material that can do controlled macro-scale quantum-tunneling is very firmly in the 'technology indistinguishable from magic' block of technobabble. (Somewhat relevant xkcd)


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