Every single thing you can see, touch, smell, or stub your toe on is made of the same basic building blocks. Your phone. The air. That overpriced coffee. You. All of it, at the deepest level, is just atoms arranged in different ways. The universe is basically LEGO, except the bricks are incomprehensibly small and there are only about 118 kinds of them.

An atom is almost unimaginably tiny. A single strand of your hair is roughly a million atoms wide. If you scaled an atom up to the size of a football stadium, the nucleus — the dense core at the center — would be a marble sitting on the fifty-yard line. Everything else? Empty space. That's not a metaphor. That's literally the structure. A tiny dense center, a cloud of electrons orbiting way out on the edges, and almost nothing in between.

So what makes one atom different from another? One thing: the number of protons in its nucleus. That's it. An atom with 1 proton is hydrogen — the lightest element, the most abundant thing in the universe. Add a proton and you get helium. Keep adding and you climb the periodic table. 6 protons? Carbon. 8? Oxygen. 79? Gold. The proton count is the atom's identity. Change it and you literally have a different element — a different substance entirely.

Remember the hook — empty space almost everywhere, and yet nothing falls through anything? Here's the answer. The reason solid things feel solid — the reason your hand doesn't pass through a table — has nothing to do with atoms being packed tightly together. It's electromagnetic repulsion. The electrons on the outer edges of your atoms and the electrons on the outer edges of the table's atoms repel each other. You're not touching the table. You're hovering nanometers above it, held up by invisible electric force fields. Every time you've ever 'touched' something, that's what was actually happening.