We Have No Idea: A Guide to the Unknown Universe

by Jorge Cham

What’s crazy is that most of your body is made out of these bags of beans (protons and neutrons), which means most of your mass doesn’t come from the “stuff” you’re made of (quarks, electrons) but from the energy needed to hold your “stuff” together. In our universe, the mass of something includes the energy needed to keep that stuff together. And the mind-blowing part is that we don’t really know why. What we mean is that we don’t really know why the energy that holds the beans together affects how fast or slow something accelerates in response to a force. If you were to push on your little bag of beans, there’s no real reason why you should be able to feel that energy inside. It shouldn’t matter to you whether the beans are held together with spit or Super Glue. And yet it does. That’s one of the great mysteries of mass. Even though we can measure it, we don’t really know what inertia is or why it’s tied to both the mass of the particles and the energy that binds the particles together.