Why quantum mechanics is so hard to understand

In order to demystify quantum mechanics, you have to build a lot of technical machinery from scratch. Box by box, you have to develop control systems for the quantum world. Without that, entanglement and other forms of “quantum weirdness” don’t readily present themselves.

I’m an atomic physicist, which means I spend most of my time building an absurdly complex, room-sized machine for quantum mechanical science experiments. With all its tangled wires and aluminum-foil-wrapped vacuum components, my lab looks like a space station in disrepair. In spite of the mess, similar machines to the one I’m building have been in use for decades — I know they can operate effectively to help us peek into the elusive world of quantum mechanics.

I can’t fully explain quantum mechanics here (that’s a problem for another day, or for several textbooks and a ton of math), but briefly, it’s a way of describing the physical laws of the universe. In one limit, the theory simplifies to Newton’s Laws and describes our everyday observations. In another limit, more unintuitive and interesting laws arise. The latter limit describes systems at extremely tiny energies. For example, the energy of one electron in a hydrogen atom is at this limit.

To really conceptualize how tiny “tiny” is, think about energies ~10⁴³ times smaller than the average calories burned per day by an average American woman. That is, you’ll be at the quantum mechanical limit if you divide your body’s average caloric output by a one followed by forty-three zeros:


Way too small to conceptualize. So why would we expect physical laws at that level to be any easier to understand?

The chasm between the scales of quantum mechanics and human life explains why quantum mechanics seems so confusing. Unless we really go out of our way, we have no experiences relevant to the world of quantum mechanics. It’s not immediately clear how we could ever make sense of systems with these tiny energies, like those of electrons orbiting atoms.

This is where my complicated, messy machine comes into play. Using finely controlled lasers, electric fields, and magnetic fields, atomic physicists like myself can change and measure the energies of individual atoms. All these technical components work together as a system to let us access small scales and laws we wouldn’t see otherwise. We can use clever strategies with these systems to answer interesting scientific questions.

What types of matter exist?

Do the laws of physics change over time?

Can we compute the answers to difficult math problems using quantum systems?

How well can we know where a particle is or where it came from?

Building the complex systems that help us answer these questions, however, requires a lot of from-scratch box-making, especially as a graduate student. From electronics to enclosures, we have to build it all.

I build boxes out of black acrylic to protect lasers from air currents and temperature fluctuations in the lab. (Luckily, this box also helps shield my eyes from the laser light.)

I build aluminum boxes full of electronics (soldered by yours truly) to stabilize the frequencies of lasers to a known, unchanging frequency reference.

I build aluminum and clear acrylic boxes stuffed with foam to stabilize the temperature and optical characteristics of special electro-optical crystals. These crystals help us modulate the phase and frequencies of optical signals.

Along with my lab mates, I keep building, keep iterating, and keep improving all these boxes to make the system more and more robust. One day in the (hopefully) not-too-distant future, the energies of our lasers will be controlled finely enough and the mirrors and lenses will be aligned precisely enough to raise the veil on how quantum mechanics does what it does. Only after years of technical development in labs like mine and confusion over experimental results have scientists guessed at the rules of quantum mechanics. Nothing about how we experience the world relates to the scale of quantum mechanics, so don’t worry if quantum mechanics makes no sense.

It shouldn’t.

Atypical Physicist.

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