“I think I can safely say that nobody understands quantum mechanics.”
Finding good quotes on quantum mechanics is easy. Apparently, the astonishing world it describes is an excellent muse. That quote belongs to Richard Feynman, who wrote the text that I (and many, many other science students) used in Quantum Mechanics 101.
His quote resonates with me, all too well. Even with the benefit of Feynman’s excellent text, I received a 20% on the final exam in that course. Lots of red X’s, interrupted by one or two check marks. It was pretty humbling for a physics major—and one of the reasons I dropped the physics major. I was also majoring in English lit, a more useful degree for seminary.
Surprisingly, it was seminary where I began to grasp a bit more of quantum mechanics, as much as anyone can grasp it. I crossed the street from Princeton Seminary to Princeton University, auditing philosophy of physic courses, where I was taught the concepts without the mathematics.
Let’s face it: Physics is hard—both for me the guide and for you the reader. But it’s also fascinating, and this week we will consider some of its wackiest ideas. And remember, the hyperlinks below are our friends, leading to trusted sources who really do know the material. I’m pretty sure they not only understood Feynman, but also scored well north of 20% on their exams.
My Three-Point Quantum Message
Before digging in here, I encourage you to read this First Things article by Catholic physicist Stephen Barr, which I shared last week. Barr explains physics brilliantly and considers its implications for philosophy and faith.
Last week, we considered three aspects of quantum mechanics: the dual nature of particles, the role of the observer (or measurement effect), and the probabilistic nature of quantum mechanics. As if those are not counterintuitive enough, this week will depart even further from our intuitive sense of how the world should work.
This week, three takeaways from the quantum world:
First is Heisenberg’s famous uncertainty principle, which states that the position and the velocity of an object cannot both be measured precisely at the same time. In fact, the more you know of one aspect—be it the location or the velocity—the less you can know about the other. Check the TEDEd video below, and note how the video explains that this uncertainty does not appear to be an epistemic limit in the act of measuring—the idea that the impact of measuring one aspect hinders the ability to measure the other. Rather, it suggests a fundamental uncertainty within nature that is especially evident in the microscopic realm.
Second is quantum entanglement, the idea Einstein famously called “spooky action at a distance.” And he called it that for a reason. When microscopic particles interact, they often become what physicists call “entangled.” That is they are connected in an unusual way that becomes clear when you measure a feature of one particle—particle spin is the common example, but the feature is not what is important. What is important is that once you measure the feature of the first, no matter the distance between the two entangled particles, you know precisely the measurement you will get of the other.
So how can the measurement of one tell you about the other? This is the “action at a distance” part—it happens at distances such that no information can travel between the particles, even at light speed. But how to explain this phenomenon? Is there some coordination, or hidden instructions, that are the result of their entanglement? This is the spooky part: clever experiments have more or less confirmed that there are no hidden “instructions” to help these entangled particles coordinate in any way.
Third, and final for this week, is Schrödinger’s Cat. This thought experiment extrapolates the wackiness of duality in the quantum realm into the world of everyday experience. Here’s the idea: A cat is closed up in a box, and its future is determined by a mechanism that obeys quantum physics—such that there is a 50% chance the cat will be killed and a 50% chance it will not. What can we say about the state of the cat? Before we peer into the box, is it alive or dead? Intuition says it must be one or the other, but quantum mechanics suggests that the cat is in a dual state—what is called a superposition—meaning the cat is both alive and dead. That is, until you open the box and look. Only then—remember the “observer effect” that is part of quantum mechanics—is the state of the cat determined to be either dead or live.
Understand? Do these three ideas make sense? If not, then perhaps you are ready for your final exam.
- Stephen Barr’s fantastic introduction to quantum physics.
- Takeaway 1: TEDEd elucidates the uncertainty principle.
- Takeaway 2: Quantum entanglement and entangled science writers and are explained.
- Takeaway 3: IDTIMWYTIM explains Schrödinger’s cat, although you might prefer Sheldon’s version.
- Stephen Barr considers the implications for belief in God at Big Questions Online.
- Don’t miss the other three parts in our Quantum Series! Part 1, Part 3, and Part 4
At the Bottom, God?
Occasionally, you see catchy phrases like quantum quackery or, my personal favorite, quantum flapdoodle to describe the misuse of quantum mechanics into non-physics topics. For example, some new-age spiritual systems are particularly attracted to the mysterious, fuzzy, and counterintuitive ideas we just covered—uncertain, entangled, living yet also dead cats.
Last week, I warned against making too much of quantum physics—avoiding God of the gaps—because we are one scientific revolution away from needing to reimagine the quantum world. At the same time, I realize that the world described by quantum mechanics can resonates with some of our spiritual ideas.
Try out these two quotes – from two key players mentioned above. Erwin Schrödinger suggested, “Quantum physics reveals a basic oneness of the universe.” Werner Heisenberg said of atoms and particles, “They form a world of potentialities and possibilities rather than one of things or facts.”
Add Schrödinger’s “oneness” and Heisenberg’s “potentiality” to all the other ideas we have covered, and it is easy to think we have left the realm of science and entered the ineffable realm of the divine. I truly hope you grasp this sense from the science—quantum mechanics describes a different nature, underneath the physics of the everyday. It’s a nature that doesn’t abide by the typical hard-and-fast rules that apply to everyday physics—Newton’s apple will always fall, for example— but seems to follow a different set of rules that are sometimes “spooky” and always counterintuitive. Quantum physics suggests more depth.
While it is debated whether he actually said it, let’s give Heisenberg, a Lutheran, the final quote, “The first gulp of the glass of natural sciences will make you an atheist, but at the bottom of the glass, God is waiting.” This is the spiritual sense many have found in the quantum realm: God lurking underneath.