Preface to the Quantum World

Atoms, the cat, wave-particle duality, superposition, and entanglement.

What is matter made of?

The world around you is filled with objects. As homo sapiens, we are the most object-dependent creatures on Earth. As social as we are in the 21st century, we require an endless list of physical items to get us through the day, from toothbrushes to cars to satellites. Our poets thrive in this world; after all, to write poetry is to see deeper truths through the medium of objects and solid surfaces—Tennyson’s subjects of beauty are crowned with moss and lit by silver-backed poplars; Lucille Clifton re-envisions an entire history through vegetables in “cutting greens.” However, the turmoil, frenzy, and restlessness of their words only truly manifests when we zoom into the matter itself (bad pun unintended).

A gentle reminder. The field of quantum physics is one that is both extraordinarily fascinating and difficult to comprehend. The basis of quantum physics, quantum mechanics, is a whole lot of mathematics describing the world in the gorgeous detail that classical mechanics failed to capture in the 20th century. Even Einstein refused to accept much of quantum logic toward the end of his life. As poets, we’ll do our best to approach the subject through concept, perception, and imagination. Remember that much of the why gets lost in translation from the language of numbers and symbols to letters.

The first thing that pops to mind when you think of the word quantum might be science’s most famous cat: Schrödinger’s cat. At its simplest: a cat is placed in a closed box with a radioactive atom, which shatters a vial of poison if the atom decays. As long as the box isn’t opened and the state of the atom (and of the vial of poison) is never observed, the cat can be both dead and alive at the same time.

There is a single principle that allows the cat to be both dead and alive: Heisenberg’s Uncertainty Principle.

At the most rudimentary level, matter is made of atoms. You might remember from high school chemistry Bohr’s or Rutherford’s model of the atom, composed of a proton and neutron core, with electrons orbiting in standardized positions around the nucleus. However, neither Bohr’s nor Rutherford’s model quite passes the requirements of quantum existence.

In Newtonian physics, and even in Einstein’s theory of general relativity (which we explored in “On the Make of Time, Part II”) physical phenomena tend to exist as they are—that is to say, the Sun is a yellow dwarf of hot plasma (at least our Sun is), and a baseball going at 60mph is a leather sphere going at 60mph. It’s very possible to find the momentum (mass times velocity, mv) and position (s) of the Sun or a baseball at a given point in time, because they will always made of atoms, no matter when you measure their momentum or position.

However, in both special relativity (which we explored in “On the Make of Time, Part I”) and quantum physics, this type of certainty becomes fallible. At the atomic level, we can observe the wild disjunction between a classical reality and a quantum one, where the particles forming matter no longer exist in a singular, unchanging state. Quantum systems reject classical logic by existing in a superposition of several states at once. This phenomenon is known as wave-particle duality, where a particle exists both in a particulate state, composed fundamentally of quarks, and in a wave state.

This way of thinking—through probability rather than classical mechanics—revolutionizes the atom, replacing electron orbitals with electron clouds, and replacing position with possible paths. If relativity tells us that every observation is relative to your person, quantum physics tells us that everything is unobservable in its original state.

But how can this be, since particles make up solid matter? If the atoms making up your electronic screen are both particles and waves, how is it possible that you’re able to touch and scroll, when you certainly can’t touch and scroll something like sound, which travels in waves?

When the top of Schrödinger’s cat box is opened, the atom will have either decayed or remained stable by the time a measurement or observation of its state is made. By using a macroscopic instrument on a quantum system, the quantum wave function is forced to yield to the particulate state of the macroscopic instrument. By simply interacting with an object, the quantum system becomes inextricably tied to it through a process called entanglement. In other words, the particles making your phone screen interact with the macroscopic objects around them (like your fingers).

Introduced as a theory in 1935, quantum entanglement stunned the scientific community. Einstein famously said that entanglement was “spooky action at a distance,” and for good reason; it seemed to contradict every breakthrough made up until then. Suddenly, there could be travel that surpassed the speed of light, teleportation seemed possible, and particles that were light years apart could communicate with each other instantly. If all these things were impossible, how was it that entanglement could be possible?

Next time, we’ll learn about the reality of entanglement, the de Broglie wavelength, and Schrödinger’s equation. Then, we’ll make our way to reconciling (or failing to reconcile) “On the Make of Time” and the make of matter.

In the meantime, let me know if you come up with the next theory of everything. See you later.