About 200 years after Newton, Albert Einstein produced his famous equation E = mc2, demonstrating that energy and matter are so fundamentally related that they are one and the same. Essentially, his work showed that matter and energy are completely interchangeable.

This directly contradicted Newton and Descartes, and ushered in a new understanding of how the universe functions.

Einstein didn’t single-handedly crumble our previous view of the nature of reality. But he did undermine its foundation, and that eventually led to the collapse of some of our narrow, rigid ways of thinking. His theories set off an exploration of the puzzling behavior of light. Scientists then observed that light sometimes behaves like a wave (when it bends around a corner, for example), and at other times, it behaves like a particle. How could light be both a wave and a particle? According to the outlook of Descartes and Newton, it couldn’t—a phenomenon had to be either one or the other.

Quickly, it became clear that the dualistic Cartesian/Newtonian model was flawed at the most basic level of all: the subatomic. (Subatomic refers to the parts—electrons, protons, neutrons, and so on—that make up atoms, which are the building blocks of all things physical.) The most fundamental components of our so called physical world are both waves (energy) and particles (physical matter), depending on the mind of the observer (we’ll come back to that). To understand how the world works, we had to look to its tiniest components.

Thus, out of these particular experiments, a new field of science was born, called quantum physics.

This change was a complete reimagining of the world we’d thought we lived in, and it led to the proverbial rug being pulled out from under our feet—feet we used to think were planted on solid ground. How so? Think back to those old toothpick-and-Styrofoam- ball models of the atom. Before quantum physics came along, people believed that an atom was made of a relatively solid nucleus with smaller, less substantial objects either located in or around it. The very idea that with a powerful enough instrument we could measure (calculate the mass of) and count (number) the subatomic particles that made up an atom made them seem as inert as cows grazing in a pasture. Atoms seemed to be made of solid stuff, right?

Nothing could be further from the truth as revealed by the quantum model. Atoms are mostly empty space; atoms are energy.

Think about this: everything physical in your life is not solid matter—rather, it’s all fields of energy or frequency patterns of information. All matter is more “no thing” (energy) than “some thing” (particles).

But this alone wasn’t enough to explain the nature of reality.

Einstein and others had another puzzle to solve—matter didn’t always seem to behave in the same ways. When physicists began observing and measuring the tiny world of the atom, they noticed that at the subatomic level the fundamental elements of the atom didn’t obey the laws of classical physics the way that larger objects did.

Events involving objects in the “large” world were predictable, reproducible, and consistent. When that legendary apple fell from a tree and moved toward the center of the earth until it collided with Newton’s head, its mass accelerated with a consistent force.

But electrons, as particles, behaved in unpredictable, unusual ways. When they interacted with the nucleus of the atom and moved toward its center, they gained and lost energy, appeared and disappeared, and seemed to show up all over the place without regard to the boundaries of time and space.

Did the world of the small and the world of the large operate under very different sets of rules? Since subatomic particles like electrons were the building blocks of everything in nature, how could they be subject to one set of rules, and the things they made up behave according to another set of rules?