quantum mechanics - Is it theoretically possible for a person to pass through a solid wall/object?

I understand that matter cannot pass through other solid matter because of the electrons that orbit an atom prevents this but I was curious to know if it is theoretically possible to somehow get passed this problem caused by the electron shell and by doing so would this allow th effective passage of matter through matter.

My thinking was that on the scale of the atom the amount of space taken up by actual particle mass is small compared to the space between the nucleus and the electron cloud so if the electron problem can be circumvented then all that space could possibly be used to pass through.

It would probably take some fanciful piece of tech based on unknown physics but i though i would ask!! Thanks.

Answer

Macroscopic objects, as a human being, are expressed on an underlying quantum mechanical framework. All matter is composed of atoms and molecules , which are quantum mechanical entities.

The Bohr model of the atom does not really hold. It is a model that has similarities with the quantum mechanical one, but has been superseded by it. Quantum mechanics is all about probabilities, everything can be described by a mathematical wave function whose complex conjugate squared gives the probability for the interaction , in this case passing through a wall, to occur.

For simple quantum mechanical entities, like an electron or an alpha particle, there exists a measurable probability to pass a barrier because the probability is non zero. It is called the tunneling effect.

It is worth reading the link to get a feeling of the complexity of the set up, even for one quantum mechanically described particle. Note that the energy level is the same, inside and outside the barrier.

The human body is composed out of ~10^23 particles (Avogadro's number). The wall will have orders of magnitude more in the proposed path through the wall. It is not possible to represent in a simple manner as in the image above the wave function of the system "human+wall" but a formalism exists, the density matrix, which allows for a many body representation. The density matrix formalism, gives that the probability of a complex object to tunnel through the wall barrier is effectively zero.

One can have an intuitive grasp on this as even for simple states as in the above example, the phases have to be kept in the wavefunction formalism. When one is dealing with orders of 10^23 the probability of all the phases to be just right for penetration is effectively zero.