Quantum tunneling is a phenomenon where particles like electrons pass through physical barriers they classically shouldn’t be able to cross. According to Live Science, while this allows subatomic particles to “tunnel” through walls, the probability of a human doing so is roughly one in 10 raised to the power of 10 raised to 30, making it effectively impossible in a physical lifetime.
Why “Empty” Atoms Create Solid Walls
It is a common scientific talking point that atoms are 99,99999% empty space. If an atom were scaled to the size of a football stadium, the nucleus would be a single grain of sand in the center, with electrons far in the distance. However, this vacuum doesn’t make walls permeable.
Electrons don’t orbit like planets. Instead, they exist in a “probability cloud.” The YouTube channel Life Noggin compares this to a spinning fan; you don’t see individual blades, but a solid-looking disc. This cloud concentrates negative charge on the atom’s exterior.
When two objects meet, these electron clouds repel each other. This electrostatic repulsion acts as the first line of defense, preventing your hand from sliding through a door. It’s similar to how two identical poles of a magnet push away from each other.
The Pauli Exclusion Principle: The Quantum No-Fly Zone
Even if you could neutralize electrostatic repulsion, a more fundamental law stands in the way. Formulated by Austrian physicist Wolfgang Pauli in 1925, the Pauli Exclusion Principle dictates that two electrons cannot occupy the same quantum state simultaneously.
Essentially, the electrons in your body cannot coexist in the same space as the electrons in a wall. This rule applies to all fermions, the family of particles that make up matter. This principle ensures that matter maintains its structure and doesn’t simply collapse or merge.
A 2003 paper in the American Journal of Physics, cited by Science Alert, notes that calling this a “force” is a simplification. It isn’t a physical wall pushing back, but a complex quantum requirement that prevents overlap.
Quantum Tunneling and the Odds of “Ghosting” Through Walls
Physics does provide a loophole: the tunnel effect. Because particles behave like waves, a particle’s wave function doesn’t stop abruptly at a barrier; it attenuates. A tiny fraction of that wave can extend to the other side, allowing a particle to occasionally appear there.
Raheem Hashmani, a physics PhD student at the University of Wisconsin-Madison, told Live Science that the odds of a person tunneling through a wall are so low that "no calculator on the planet" would provide a result other than zero.
Steven Rolston, a physicist at the University of Maryland, adds that while the probability exists mathematically, it is so small that it wouldn’t happen once during the entire age of the universe.
Frequently Asked Questions
Can we ever use technology to walk through walls?
Based on the Pauli Exclusion Principle and the astronomical odds of quantum tunneling, there is no known scientific mechanism to allow a macroscopic human object to pass through solid matter.
If atoms are empty, why don’t I fall through the floor?
You are held up by electrostatic repulsion and the Pauli Exclusion Principle, which prevent the electrons in your feet from occupying the same space as the electrons in the floor.
What is the "tunnel effect" used for in real life?
What do you think? Does the fact that we are mostly “empty space” change how you perceive the physical world? Share your thoughts in the comments below or subscribe to our newsletter for more deep dives into quantum mechanics.
