Why do objects fall?

“Gravity!”, you exclaim.

And then we both nod our heads an go our separate ways, confident that you know the answer to the question.

Or do you?

All you’ve shown is that you know the accepted answer to the question. You know the word that gets me to stop checking whether you actually know why things fall. You know an agreed-upon label for a powerful concept – but do you actually know the concept?

If you ask why objects fall, and I say “gravity”, do you know any more than you did before? Or do you just have a new name for your confusion?

Schools are very good at teaching you to recite the teacher’s password. Do not mistake knowledge of the password with actual understanding.

A good rule of thumb for whether you actually understand a concept is whether you can re-create the answer yourself. If I were to eliminate the world gravity from your mind, and eliminate all of the equations you memorized which say $F = G\frac{m_1 m_2}{r^2}$, then would you be able to re-invent gravity?

If you went back in time to before Newton, would you be able to astound the world with your knowledge of why things fall?

If I took away your knowledge of the experimental predictions that Einstein made, and I took away any of the relativistic equations that you learned, could you go back to 1900 and teach the world about the principles of general relativity?

If you had the final answers removed, would you be able to derive them on your own?

What I cannot create, I do not understand.

If not, then you might be memorizing passwords. Learning things shouldn’t feel like memorizing answers. Learning things should feel like those things becoming obvious. Learning about the nature of reality should shift your worldview until it seems like reality couldn’t be any other way. Learning about the world should unify concepts irrevocably until alternatives seem ridiculous.

Once you attain understanding, the little words like “gravity” don’t matter. They’re disposable.

Up until you get to that point, watch your tongue. Avoid claiming possession of knowledge that you do not have. Stop trying to guess the teacher’s password.

Don’t pretend you know things that you do not know: if something is mysterious, admit it. Then tackle it, pull it out of the darkness, and stare it straight in the eyes: mysteries are personal roads to wonder.