To start considering the nature of existence, I pose the question: "Are particles infinitely divisible?"

Let's start with matter: We can cut an apple, and cut it again, and again, and again... Eventually, we will have cut it down to its molecules. Even those we can cut down further, down to their atoms. Consider the simplest one: hydrogen, which consists of just one proton and one electron. The electron we can't cut down any further, but the proton we can divide into quarks. But at that point, is it even matter anymore? No. It stops having the properties of matter and starts having the properties of energy.

We already know that matter and energy are essentially the same thing (E=mc²). So, if we cut down matter as far as we can, we end up with energy.

Energy, we can't cut further down. Not only that, but our best current theories of physics predict that there is something at the end that isn't made out of something else—a sort of base building block, if you will.

It is important to note that these are unproven theories. However, they have the best explanatory power, considering both logic and the information we gain through testing.