{"id":145339,"date":"2025-09-10T00:35:13","date_gmt":"2025-09-10T00:35:13","guid":{"rendered":"https:\/\/www.newsbeep.com\/us\/145339\/"},"modified":"2025-09-10T00:35:13","modified_gmt":"2025-09-10T00:35:13","slug":"why-we-cant-walk-through-walls-even-though-atoms-are-mostly-empty","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/us\/145339\/","title":{"rendered":"Why We Can\u2019t Walk Through Walls Even Though Atoms Are Mostly Empty"},"content":{"rendered":"

It\u2019s a fair question: atoms are made mostly of empty space, so why does solid matter feel, well\u2026 solid? As strange as it seems, two laws of physics stop us from walking through walls\u2014and the reasons have nothing to do with magic.<\/p>\n

Think of Vision in Avengers, or Harry Potter vanishing into Platform 9\u00be. Easy enough in fiction. But try it in the real world, and you\u2019ll be greeted by a sore nose and a very stubborn wall.<\/p>\n

What atoms are made of\u2014and why it matters<\/p>\n

Atoms are the building blocks of matter, and they\u2019re surprisingly hollow. A tiny nucleus sits in the center\u2014about 100,000 times smaller than the atom itself\u2014while electrons orbit far away. So again, why do solid things feel so\u2026 solid?<\/p>\n

Experts point to two fundamental principles: electrostatic repulsion and the Pauli exclusion principle.<\/p>\n

In a classical view, electrons orbit the nucleus like planets around the sun. But in quantum physics, they don\u2019t follow tidy paths. Instead, they form a \u201cprobability cloud\u201d\u2014a fuzzy region where they\u2019re likely to be found. \u201cIt just sits there,\u201d said Raheem Hashmani, a physics PhD student at the University of Wisconsin\u2013Madison. \u201cIt shows where the electron is most likely to be.\u201d<\/p>\n

This electron cloud gives the atom a negative electric charge<\/a> around its outer edges. So if you try to walk into a wall, your atoms and the wall\u2019s atoms repel each other\u2014just like trying to push two like poles of magnets together, explained physicist Steven Rolston of the University of Maryland.<\/p>\n

\"\"<\/p>\n

Atoms have a central nucleus surrounded by a \u201cprobability cloud\u201d of electrons. (Image credit: KTSDesign\/SCIENCEPHOTOLIBRARY via Getty Images)<\/p>\n

Forces that keep solid matter solid<\/p>\n

This electromagnetic repulsion keeps atoms from overlapping. Electrons don\u2019t just bounce\u2014they interact through electromagnetic waves. These invisible forces are why solid objects don\u2019t pass through each other.<\/p>\n

But what if you did manage to get atoms closer together?<\/p>\n

Enter the Pauli exclusion principle. It says fermions\u2014particles like electrons\u2014can\u2019t occupy the same space at the same time. \u201cWhen the electron clouds overlap, it means two electrons might share the same space,\u201d Hashmani said. \u201cThe Pauli principle doesn\u2019t allow that.\u201d<\/p>\n

These two forces\u2014Pauli exclusion and electromagnetic repulsion\u2014prevent atoms from cramming into one another. Without them, solids would collapse. Even in liquids and gases, where atoms can move more freely, the same principles apply: atoms can move, but they can\u2019t overlap.<\/p>\n

A quantum exception: tunneling through barriers<\/p>\n

And yet\u2026 quantum mechanics always has a twist.<\/p>\n

Particles like electrons act like waves<\/a>, not little balls. And sometimes, those waves tunnel through barriers.<\/p>\n

Picture a wave hitting a wall. In classical physics, it\u2019d just bounce off. But quantum waves decay slowly when they hit a barrier. If the wall is thin enough, a bit of the wave might still sneak through to the other side. That means there\u2019s a slim\u2014but real\u2014chance the particle could appear beyond the wall. This is quantum tunneling.<\/p>\n

But don\u2019t get any ideas.<\/p>\n

The odds of an entire person quantum tunneling through a wall? \u201cRoughly one in 10 to the 10 to the 30,\u201d said Hashmani. \u201cPunch that into a calculator and you\u2019ll just get zero. That\u2019s how tiny the probability is.\u201d<\/p>\n

Rolston put it another way: \u201cIt\u2019s about as close to zero as you can get\u2014but it\u2019s still not zero. I\u2019m confident it wouldn\u2019t happen in the lifetime of the universe.\u201d<\/p>\n

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