Luckily, we don't have to count them one by one. When you purchase through links on our site, we may earn an affiliate commission. Here’s how it works. All matter in the universe — no matter how big, ...

I love thinking about things I can’t see with just my eyes. Like the atoms that make up everything. I asked my friend Fred Gittes how to figure out the number of atoms in a leaf. He’s a physicist at ...