It's true that the atomic theory states that every physical substance is made up of atoms. However, it's important to understand that "probably not true" implies there's significant evidence to the contrary.

Here's the reality:

* The atomic theory is one of the most well-established scientific theories. It's been supported by countless experiments and observations over centuries.

* We can directly observe atoms using powerful microscopes. We can even manipulate individual atoms.

* The entire field of chemistry is built upon the atomic theory. Without it, we wouldn't be able to explain chemical reactions, the properties of materials, or the formation of molecules.

While there might be some theoretical refinements or edge cases in the future, the fundamental idea that matter is made up of atoms is incredibly robust and has stood the test of time.

So, it's safe to say that the atomic theory is extremely well-supported and, in fact, is one of the most fundamental and essential concepts in science.