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  • Matter is everywhere: we eat it, breathe it, drink it. It is who we are.

  • But what is matter?

  • The most basic particle physics definition of matter comes down to one surprising rule:

  • The Pauli exclusion principle - or, essentially, electrons hate being alike.

  • To understand why, we have to remember the fact that every electron is exactly the same.

  • Not "kind of the same"… They're perfectly identical.

  • Just as you can at anytime, anywhere, spontaneously write down the number three and it will mean exactly, perfectly three.

  • As if there were some everywhere-permeating "three-ness" always available to produce a three at your whim.

  • It's the same case with the electron.

  • There's an everywhere-permeating "electron-ness" called a "quantum field," and from that field every electron in existence has been summoned, and they are all, exactly, "electron".

  • So when someone says "Every time you breathe, you inhale a few of the same electrons that used to be in Jesus or Mozart"

  • That's about as deep as saying that every time you do arithmetic you use the same number three as Archimedes.

  • What's more?

  • Just like you can call on the "three-ness" to summon "negative-three", which has all the exact same properties of three except opposite.

  • And when it meets three they annihilate - you can summon "anti-electron" from the electron field and it will annihilate electron when they meet.

  • So, given that electrons are all exactly alike, it's a little surprising that they actually hate being like each other.

  • In fact, electrons despise alikeness so much that the universe is forbidden from summoning two or more into the same quantum state.

  • This is called "the Pauli Exclusion principle," and what it means in practice is that you can't cram too much matter into the same placelike a city where building higher than one story is prohibited:

  • Instead of skyscrapers, compounds sprawl outwards.

  • So at the most fundamental level, matter is just any field, like "electron", "quark", or "neutrino" from which you can summon particles and anti-particles,

  • but only one at every point, which means that, quite literally, matter is everything that takes up space.

  • Like Walmart.

Matter is everywhere: we eat it, breathe it, drink it. It is who we are.

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