By Bradley Stockwell
I once had a friend after a long night of drinking consult me on his living room couch, “What does quantum mechanics really mean?” I was taken aback for this particular friend and I had never discussed physics—let alone quantum mechanics—in our entire five year relationship. He was a former UCSB frat boy and he was the friend I turned to when I needed a break from my intellectual studies to indulge in the simpler pleasures of life such as women and beer. He was also so heavily inebriated that I was pretty sure he wasn’t even going to remember asking the question in the morning (which I was indeed later proven right).
I answered casually, “Well, it’s the physics of atoms and atoms make up everything, so I guess it means everything.” Not satisfied with my answer he replied slurredly, “No really, what does it mean? We can’t really see what goes on in an atom so how do we really know? What if it’s just some guys too smart for their own good making it all up? Can we really trust it? From what I know we still don’t completely understand it so how do we know if it’s really real? Maybe there’s just some things as humans were not supposed to understand.”
I’ll be honest I was in shock for I had never heard my friend express this type of existential thinking before. Not to paint him one-sidedly, we had had many intelligent discussions on finances, the economy, politics, but never physics and philosophy. Maybe it had something to do with the marijuana joint I just passed to him. Anyways, after a few moments of contemplation I answered, “Everything from your smartphone to the latest advances in medicine, computer and materials technology, to the fact you’re changing channels on the TV with that remote in your hand is a result of understanding quantum mechanics. But you’re right; we still don’t fully understand it and it’s continually showing us that the universe is probably a place we’ll never fully grasp, but that doesn’t mean we should give up…” I then continued with what might’ve been too highbrow of an explanation of quantum mechanics for an extremely drunk person at 3 a.m. because halfway through he fell asleep.
As my friend snored beside me, I couldn’t help but be bothered that he and so many others still considered quantum mechanics such an abstract thing more than a hundred years after its discovery. I thought if only I could ground it in some way to make people realize that they interact with quantum mechanics every day; that it really was rooted in reality and not a part of some abstract world only understood by physicists. I myself being a layperson with no university-level education in science learned to understand it with nothing more than some old physics books and free online classes. Granted it wasn’t easy and took a lot of work—work I’m still continuing, but it’s an extremely rewarding work because the more I understand, the more exciting and wonderful the world around me becomes.
This was my inspiration behind The Party Trick Physicist blog; to teach others about the extraordinary world of science and physics in a format that drunk people at 3 a.m. might understand. I make no promises and do at times offer more in-depth posts, but I do my best. With this said, as unimaginative as a post about at-home physics experiments felt to me initially, there’s probably no better way to ground quantum mechanics—to even a drunk person at 3 a.m.—than some hands on experience. Below are four simple quantum mechanical experiments that anyone can do at home, or even at a party.
1. See Electron Footprints
For this experiment you’ll be building an easy to make spectroscope/ spectrograph to capture or photograph light spectra. For the step-by-step tutorial on how to build one click here. After following the instructions you should end up with, or see a partial emission spectrum like this one below.
Now what exactly do these colored lines have to do with electrons? Detailed in a previous post, The Layman’s Guide to Quantum Mechanics- Part 2: Let’s Get Weird, they are electron footprints! You see, electrons can only occupy certain orbital paths within an atom and in order to move up to a higher orbital path, they need energy and they get it by absorbing light—but only the right portions of light. They need specific ranges of energy, or colors, to make these jumps. Then when they jump back down, they emit the light they absorbed and that’s what you’re seeing above; an emission spectrum. An emission spectrum is the specific energies, or colors an electron needs—in this case mercury electrons within the florescent light bulb—to make these orbital, or ‘quantum’ leaps. Every element has a unique emission spectrum and that’s how we identify the chemical composition of something, or know what faraway planets and stars are made of; just by looking at the light they emit.
2. Measure The Speed of Light With a Chocolate Bar
This is probably the easiest experiment as it only requires a chocolate bar, a microwave oven, a ruler and calculator. I’ve actually done this one myself at a party and while you’ll come off as a nerd, you’ll be the coolest one there. Click here for a great step-by-step tutorial and explanation from planet-science.com
3. Prove Light Acts as a Wave
This is how you can replicate Thomas Young’s famous double slit experiment that definitively proved (for about 100 years) that light acts as a wave. All you need is a laser pointer, electrical tape, wire and scissors. Click here for a step-by-step video tutorial.
4. Prove Light Also Acts as a Particle
This experiment is probably only for the most ambitious at-home physicists because it is the most labor and materials extensive. However this was the experiment that started it all; the one that gave birth to quantum mechanics and eventually led to our modern view of the subatomic world; that particles, whether they be of light or matter, act as both a wave and a particle. Explained in detail in my previous post The Layman’s Guide to Quantum Mechanics- Part I: The Beginning, this was the experiment that proved Einstein’s photoelectric effect theory, for which he won his only Nobel Prize. Click here to learn how to make your own photoelectric effect experiment.
Good luck my fellow party trick physicists and until next time, stay curious.