Meet Hamilton, Schrodinger's Cat

Aaron Grisez
March 19, 2018

Hi there! If you’ve wandered on to this page, you’re probably one of these things:

And even if you aren’t, that’s okay too! The whole point of Qhord is that you (whoever that may be) can do it too.

What are we doing? Well, Quantum Music of course!

I promise it isn’t going to be scary. Let me introduce myself. My name is Hamilton, and I am the physicist Irwin Schrodinger’s pet cat. I’m going to be walking through this little adventure with you every step of the way.

So why are we going to make Quantum Music? Well, typically when someone hears the words “Quantum Mechanics”, they want to go run and hide. And I don’t blame them--most people talk about this quantum experiment where I’m in a box with some poison and I’m either dead or alive. Or both. Geez! That doesn’t sound very good.

Needless to say, I am alive and well. And I’m going to show you why Quantum Mechanics isn’t that scary. It will take some time (the loony scientist/musicians who roped me into this are still figuring out what they’re doing!), but I promise: together, you and I can find that physics is not all that scary.

Let’s Start with a Tiny Bit of Physics

In this video, you can listen to some examples of Quantum Music. What makes the music quantum is the instrument it’s played on. In theory, you can take well-known tunes in their original form (played on normal, “classical” instruments), and then you can listen to their quantum (or as we like to say, “qhordified”) version. This second version is the same exact music (believe it or not!). It’s just played on an instrument that obeys the laws of quantum mechanics.

There are three key ingredients to understanding the most common approach to quantum mechanics: probabilities, waves, and measurements.

Probabilities

Probably the first thing you will hear is that different notes make up the melodies in the qhordified version. This is because on a quantum instrument, if you play a note, you might not hear that note every single time. For example, if you press middle C on a regular (“classical”) piano, you will always hear the same pitch: what we call a C.

Now, if you press the same key on a “quantum” piano, you won’t always hear middle C. In fact, you might hear any note! Weird, right?! This is because quantum mechanics is inherently “probabilistic”. You may have heard that quantum mechanics is “random” but technically that is incorrect--there is randomness involved, but it isn’t just a roll of the dice--there’s a lot of complex physics going on behind the scenes.

Quantum physicists have actually developed a whole theory that can tell you exactly what your odds are of hearing a middle C or any other note. So, while you might not be able to predict the precise future, you sure can bet on what’s going to happen with a lot of certainty. This is the art of quantum mechanics: determining just how likely you are to hear a certain pitch under particular conditions.

Waves

Ever heard of a particle acting like both a wave and a particle but not always a particle and sometimes a wave? Let’s think about waves for a second: consider the ocean.

Water waves have a high point and a low point, right? Well, quantum waves do too. But instead of more water and less water, these quantum waves are talking about probability. High points on the waves represent high probability and low points represent low probability. If we had a quantum wave passing by us, the high points are where we’d be likely to see the thing we’re looking for (an electron, a photon, a cat, etc.)

Now, these quantum waves of probability act kind of like the waves you would see in the ocean. They ebb and flow, all according to a single equation. That’s Schrodinger’s equation! So, if you know what your quantum wave looks like at one time, you can use this equation to see where the wave is going to be at any other point in time. Neat, right? This is what physicists do all the time with quantum mechanics.

Measurements

When we talk about probabilities (like with dice), there are two parts: before we roll the dice, we can say things about our chances of rolling a 3, 4, 5, snake eyes, etc. But then when we actually roll them, that’s the end of the story. What we rolled is what we get. Full stop.

Something similar happens with these quantum waves. See, while they’re ebbing and flowing all around according to Schrodinger’s equation, they’re all quantum-y. But as soon as someone looks at the wave, it’s like rolling the dice. We get one answer. That’s why we never see a chair in two places. That’s why we never see quantum effects in our daily lives. The quantum wave is so fragile that just looking at it breaks it and makes the system choose to be in one state.

Congrats! You made it. You now know some of the basics of quantum mechanics. This definitely isn’t the whole picture. There’s plenty more we could (and will) talk about: superpositions, coherence/decoherence, entanglement, weak measurement, contextuality... We’ll talk about all that next week and beyond right here for you to check out. Hope we have a high probability of seeing you then! 😉

Let’s Play Physics.