Currently I am working on how to explain a character that can "phase" through objects in a similar manner to Martian ManHunter. His abilities are negated by certain (rare) metals. His ability could be meta-human (like The Flash etc.), biological (ManHunter), or technology based.

What scientifically-plausible ability (not principle, though if you can show a principle and a way to manipulate it that's fine) would make the most sense for him to be able to doing this?


  1. Must be able to pass through most materials at will.
  2. Must have at least one material that cannot be phased through.
  3. Must be able to phase himself and any object within two feet that has less mass than his body mass.


  1. Must become weightless or have a way to maintain current elevation so he doesn't go falling through the floor.
  • $\begingroup$ If your superhero can control electrons at will... $\endgroup$
    – user6760
    Commented Apr 27, 2015 at 1:23
  • $\begingroup$ How would this help? $\endgroup$ Commented Apr 27, 2015 at 4:04
  • $\begingroup$ If an atom is more than 99% empty space why don't we fall from a chair straight away? Answer is electrostatic repulsion as your electrons and the chair electrons repel each other. The rest of the story I shall leave it to your imagination... $\endgroup$
    – user6760
    Commented Apr 27, 2015 at 4:15
  • $\begingroup$ Not electromagnetic repulsion or the normal repelling of electrons. It's pauli repulsion based on the same mechanismm as the Pauli Exclusion Principle. $\endgroup$
    – JDługosz
    Commented Apr 27, 2015 at 4:26
  • $\begingroup$ @JDlugosz I totally agree with you it is Pauli Exclusion Principle anyway see (fromquarkstoquasars.com/…) $\endgroup$
    – user6760
    Commented Apr 27, 2015 at 4:42

7 Answers 7



I think it would be difficult for someone to alter themselves to pass through ordinary matter without altering themselves into something for which the chemistry life depends on wouldn't work. But it might be possible to achieve a similar results.

He doesn't go through the matter physically. He jumps at the wall he wants through and, just before impact, shifts himself into a pocket universe for a second. When he comes out, it's as if he's kept moving that same direction in normal space-time for the time he was gone. He doesn't go FTL -- if he's moving one foot per second when he goes into his pocket universe and emerges one second later, then he's one foot from where he started.

It's a "pocket universe" that is precisely the same volume as he is, so he doesn't have to worry about being in a hard vacuum while there. There isn't any vacuum outside him in the pocket universe, because the pocket universe ends at the outside of his skin. He can't breathe in there, though.

Objects he pulls along come with him, in their own universe, but they emerge into normal space-time when he does.

When he emerges from the pocket universe either whatever would be in his way is sent into its own pocket universe forever, or he emerges from it like going through a door. Either way, any air where he is going to emerge is taken care of, but this does make a difference if there was something solid where he emerges. Either he ends up in a him-shaped hole in the wall (which could be the end of our hero -- since he's at a standstill in the wall, even if he hyperspaces he'll end up back in the same place when he emerges), or he can't come out there.

There could be logical limitations like not being able to do this upwards -- if he coasts upward for a few seconds in his pocket universe, when he emerges, gravitational potential energy has appeared from nowhere. Going downward would be OK if the gravitational potential energy that was lost appeared as heat (as long as there isn't too much of it!), but the reverse (heat disappearing if he goes upward) might violate the Second Law of Thermodynamics. But this part is a minor nit, and you might be safe ignoring it.

As far as a substance he cannot get through, maybe something significantly dense casts a "shadow" outside normal space-time, one his pocket universe cannot get around. Or maybe electric current -- someone turns on a light switch at the wrong time and he cannot get past that.

  • $\begingroup$ So... Instead of traditional "hyperspace" more like a personal spatial collapse? So how could one stop a moving spatial collapse? $\endgroup$ Commented Apr 28, 2015 at 15:16
  • $\begingroup$ You could just have him unable to re-emerge in normal space-time if the villain has set up, say, an electromagnetic field of sufficient strength and frequency. So he could try to "phase" into a room but be unable to emerge into it if the villain (or anyone by accident) had set up such a field. He'd have to coast past and hope there was a spot to emerge into further on... $\endgroup$ Commented Apr 28, 2015 at 16:17
  • $\begingroup$ Alternatively, if you really want substances he can't get through, I think you'd need the following space-time continua: (1) Normal space-time. Where you keep all your stuff. (2) Your hero's pocket universe. And another for any other items he brings with him. (3) A space-time continuum that the pocket universe travels through. Mass (or whatever) in normal space-time could cast a "shadow" into this space-time, and some of the shadows might be strong enough that the hero's pocket universe would bounce off them. Maybe very dense substances, like gold, lead, or osmium. $\endgroup$ Commented Apr 28, 2015 at 16:19

First, I will mention a particle that can do this extremely well: the neutrino. Why can it do this? It can because it has little mass and no charge (I could explain why these properties allow this, if you want me too, but it would take 1-2 good paragraphs). Therefore, as we approach these conditions, we phase through matter more easily. We can satisfy your conditions be given your superhero the power to reduce mass (both his and that of objects). This immediately satisfies 1 and 3 but not 2. 2 is satisfied, if we limit his power. He can only lower mass to a certain extent. Since he cannot lower it indefinitely, very dense objects would stop him.

Due to comments, I will explain why low mass matters. It is mostly due to momentum, and a low mass means a low momentum. The lower a particles momentum, the more prominent is its wave nature. Therefore, this superhero's power is the ability to have a prominent wave nature. Having a neutral charge is important as well.

  • $\begingroup$ So, how would he be able to reduce his mass/other objects mass? Maybe inducing a neutrinic (I know that's not a real word) like state in the area around him or (for the sake of writing) leave it at "his abilities allowed him to reduce the density of objects around him"? $\endgroup$ Commented Apr 26, 2015 at 20:29
  • $\begingroup$ @HadesHerald I would go with "his abilities allowed him to reduce the density of objects around him" but change density to mass. $\endgroup$
    – Jimmy360
    Commented Apr 26, 2015 at 20:30
  • 1
    $\begingroup$ The fact that neutrinos have very little mass isn't why they don't interact with any other sub atomic particles (though a low mass helps, regular sub atomic particles have such little mass that gravitational effects can basically be ignored on the kind of scales we're talking about). Neutrinos don't interact because they have no charge, and thus don't feel EM fields generated by electrons and protons. The hero would need to turn all the particles in his body neutral (which would turn him into a pile of dust presumably killing him) in order to have neutrino like properties. $\endgroup$
    – alessandro
    Commented Apr 26, 2015 at 23:57
  • $\begingroup$ I don't think the low mass has anything to do with it. Something that is not electricly charged (and not an electron) will simply not interact and can pass through matter like a ghost. For example, Cold Dark Matter or WIMPs would do that, even orbiting inside a star. $\endgroup$
    – JDługosz
    Commented Apr 27, 2015 at 4:29
  • $\begingroup$ But the OP requested that there be a "weakness" to specific atomic MATERIALS, something that wouldn't apply to coherent neutrino masses. $\endgroup$ Commented Apr 27, 2015 at 11:58

I understand that you want to pass through walls and such, but have no idea why you refer to it as a phase. You mean like different phases of matter like he turns into a gas?

In the hard sf novel Pushing Ice a character from the near future is transported via a "travel cowl" from the far future, where nanotechnology is perfected. Shenis astonished how she got sevel levels and past several security doors, instantly. "In small pieces" was the reply.

More along the lines you're thinking of, The particles in his body could be changed into something else, which have analogous properties relative to themselves. That is, atoms and molecules exist unchanged because the use of electric charge is changed to X charge in a uniform manner. But it won't interact with normal matter at all, so, he can pass through walls and would fall through the floor.

How about an envelope that changes the nature of space by fiddling with some parameters, and whats inside seems normal within but acts as explained above. Now how to selectively interact so can see, push against the floor, etc? It provides an interface layer that can be tuned to touch normal matter when needed. Recall that charge is not enough to be solid, but that has to do with being (exactly) electrons, so the envelope would need ro prodice an exposed layer of matter and somehow react with that in some other way.

E.g. the bottom of the shoe and anywhere touchnis desired is coated with a thin layer of room temperature superconductor. The envelope contracts to expose the conductor and manages to still stay connected rigidly woth it by using flux pinning and thus a pure electromagnetic effect that applies to anything with charge. The interface (on the inside of the envelope) produces a transition material that interacts (at half strength) with both the X force and the electric force. Superconductive currents of these intermediate particles (since only pure X-regime electrons touch in the normal manner) can be controlled with X-regime electrons and induce a charge in the normal superconductor, so flux pinning can keepmthe sandwich together.

The exposed material then interacts with matter in the normal way.

To get your shoe through the wall too, the envelope is extended to cover everything. This has to be orchestrated carefully to change the properties and the tuning of the mechanisms that hold it together. And that provides our Hero with (quite literally) his Achilles Heel. I think it would only be vulnerable when shifting, but if he's walking through a wall that needs more than one step to pass through, the shoe needs to turn On interaction whike still embedded inside matter, and thus not take up any room. Without going into how that might be done, note that the whole interface business uses superconductors and strong localized electromagnetic fields. What if the surrounding material interfered with that?

If the mechanism were compromised he would not only be unable to take a step but would not be supported by the floor and would fall into the earth never to return until he ran out of air or power.

If he passes through something that damages the interface but succeeds; e.g. jump through a thin wall and then turn it completely off before hitting the ground; it would render him crippled, only able to safely use the power by jumping while running at the wall and then turning it on.

  • $\begingroup$ I'll just add that the term 'Phasing' being used in this way is possibly the fault of RPG's like D&D. Though its derpy to scientists; phasing in this sense is a status effect that allows you to ignore move restrictions and walk through walls! $\endgroup$
    – eharper256
    Commented Apr 27, 2015 at 8:25
  • 1
    $\begingroup$ I've also seen the phrase in many science-fiction TV shows (Trek and Stargate to name two) where people who are rendered invisible are said to be "out of phase." How they still see normally and don't fall through the floor is invariably never addressed. $\endgroup$ Commented Apr 27, 2015 at 14:44
  • 2
    $\begingroup$ I call it phase because that is the traditional name of the ability to go intangible $\endgroup$ Commented Apr 28, 2015 at 16:25
  • $\begingroup$ Or in the context of a video game: noclip. ;-) $\endgroup$
    – Ajedi32
    Commented Jul 29, 2015 at 13:42

https://www.sciencealert.com/99-9999999-of-your-body-is-empty-space There are two ways to go about this. The first would be to nullify the charge of the electrons. That seems problematic, as molecular connections rely on those charges, meaning your body would probably just fall into a pile of subatomic particles if they had no charge.

The second option would be to stop the motion of the electrons. Because they are moving so fast, they exist throughout the entire space of the atom all at once. But if you could somehow stop their motion, there would be enough empty space for you to slip through the atoms of other materials. Their analogy is that electrons are like the blades of a fan. While spinning, they prevent anything from going through. But stop them, and you could slip between the blades easily.

To prevent yourself from falling through the Earth, you would need to be able to selectively control the movement of those electrons. So they aren't moving in any kind of vertical movement, but they do move horizontally, so that you aren't impeded moving horizontally, but are impeded vertically. Think of it like tipping a fan face down. You can move your hand above and below the blades freely, but try to stick your hand down or up into the blades, and you'll get hurt.


Dark matter seems to fit the bill here. Recent observations suggest minor "dragging" occurs in the dark matter halos, implying some forms of self interaction. But this means your superhero would only be stopped by dense dark matter "walls!"

There's a more fundamental constraint:

Since they can't interact with normal matter, they can only "breathe" what limited air they convert with them into dark matter form. This appends a time limit to their transition that makes it akin to "dark matter diving." Heck, they might even bring along an oxygen tank and/or a CO2 conversion unit to extend their transition period.

Though their "real" vulnerability would be hard to construct (except by a parallel baddie with similar powers), they wouldn't be able to phase back into normal matter in the middle of a solid object (without dying, anyhow), so solid ground too thick to pass through without transitioning back would still stop them.


Another angle that could be considered, rather than changing physical composition or density, or jumping into alternate spaces, would be changing "reality" itself.

What if the person is able to walk through a wall because he caused the reality of the wall (completely altering all physics in a localized area) to be that he can simply just walk through it. It just ceases to be an obstacle as if it wasn't there... a "ghost" image.

Some objects, or areas, may be impassible due to their age (their reality has been set for millennia and as such cannot be altered easily), or magic (which also bends reality), or mental blocking (the reality is altered because he wills it so, thus if he doesn't think he can... he can't), etc.

Just a thought.


4D movement. The analogy of this would be, that, say there were humans who existed in two dimensional spaces. If I were to build a 3D 1 foot tall around these individuals, than that barrier would be impossible for them to escape from because they cannot traverse height, only width and depth. They would find themselves in a room with no way out. Now, if by some mutant ability, one of the 2D people could become 3D or some how shift himself into 3D space, he would be able to walk over the fence... but to his 2D buddies, he would appear to go through a solid wall, because they only see him in 2D space.

Essentially, your character could have the ability to shift into an X-dimensional, which would ad a movement that cannot happen in 3D space. Human construction is not built in this dimension cause we cannot percieve it. In essence, you can move through this space, which lack barriers, and to your non x-dimensional buddies, they don't see the trick and think you just phased through the wall. You won't fall down, because you will still have your original 3Dimensions, so the floor is not being phased through... but you could leap from that floor by to go through it through the dimension gaps. Similarly, can easily extend the field to most other objects.

I would say that a governing componant is that while you are moving through the dimension gaps, you are not aware of the new dimension, which allows you to see it as a phase through solid stuff... This means there is an subconcious correction method which automatically finds a gap you can move through and moves you in your intended direction. This can also allow bullets to pass through you as it is not accounting for your XD measurements which can be some distance off.

While the single impassable container would not work here, you could say that the thickness of the object will affect your travel time through the gap, so if it's a few hundred feet thick, you have to pass through a very long doorway... as the thickness increases, the door becomes less of a door and more of a tunnel. So very thick walls could block you because they take longer for you to travel through and you lose energy to maintain a dimensional shift and cannot get through without a rest, essentially pushing you back into a 3D space. This means that the bad guy doesn't have to build with exotic materials, but rather build the prison extra super thick to keep you inside.


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