Free Will and Schrödinger’s Cat – A Guide to Fundamental Principles of Quantum Mechanics

Here’s a little something about conventional physics: Everything is predictable.

This is called determinism.

If you knew the exact particles and their position in the Big Bang, you could theoretically use physics to predict everything up to the creation of you, and of course, you reading this post.

This is a problem because it shatters our idea of free will. And that’s not very good, considering most of us don’t like the idea of being little puppets being driven by Newton.

So here’s the part where I go into confusing quantum physics stuff. I can almost hear the views dropping.

Intro to Quantum Mechanics

Quick Explanation of Quantum Mechanics: The study of atoms and particles smaller than atoms. The way they act is really weird and is completely different from conventional physics.

Before we conquer the idea of “free will,” I’ll explain the basics of quantum mechanics by oversimplifying a ton of information, but you’ll get the main idea.

How Did Quantum Physics Start?
The driving forces behind quantum physics are black body radiation, the Ultraviolet Catastrophe, and light quanta.

Light Quanta: Small packets of energy carried by light. (AKA: Photons.)

A black body is a thing that absorbs everything in the electromagnetic spectrum. And it also can emit everything on the electromagnetic spectrum. Giving it stuff results in it giving stuff back. The “giving stuff back” part is called black body radiation.

What really propelled people into quantum physics in the Ultraviolet Catastrophe. Since a black body is at an equal temperature with its surroundings, when we shoot stuff from really high up in the electromagnetic spectrum at it, the black-body responds with more energy than we sent into it (because the temperature cannot change, only what it sends and receives are the things that can be affected.)

If you really pay attention, you can see that line on the graph that extends outwards into infinity. Yeah, that’s the catastrophe.

And since our universe hasn’t been completely obliterated yet, we know that the UV catastrophe can’t be true.

A German physicist named Max Planck came up with a solution. He proposed that bodies didn’t absorb energy in ginormous bulk and that waves don’t carry energy the way people thought. Rather, waves carry energy in tiny packets of energy (called quanta) that ride along in the waves.

You’ve probably heard of Planck’s Equation. It figures out the size and power of the quanta using Planck’s constant.


Note: ‘h’ is planck’s constant, which is another confusing thing Max Planck made. It is used in lots of equations in quantum physics, which sucks, because memorizing it looks really hard.



e=energy in the quanta

This means higher-frequency waves have less powerful quanta, which means that when we shoot high-frequency wavelengths at black bodies we aren’t actually sending enough energy to make a black body start ripping apart space and time.

Waves and Stuff

Light is both a wave and a particle. You’ve probably already heard this a gazillion times in your old science classes, but here’s a quick explanation just as a refresher.

The Double-Slit Experiment

The experiment shows light’s wave-like properties.

It makes use of two properties of waves and demonstrates that they work on light.

1 If a wave reaches a small opening, it diffracts.

See the source image

2When waves collide, they don’t just “cancel-out.” The interaction of these waves is called interference. If they both have an equal displacement (fancy way to say “height”), they combine in constructive interference. If their displacements are opposite they will cancel each other out in deconstructive interference.

See the source image

The Experiment: Two slits were set up and the light was sent through them. (Yeah, that’s all they actually did.)


The first panel shows the slits. The screen with two strips of light is what would happen if the light behaved like a particle. The final screen shows how the light actually behaved, like a wave.

However, light isn’t just a wave. It’s also a particle, and that’s because of the photoelectric effect.


An atom has protons, neutrons, and electrons. You should know that. If you don’t, then I recommend you navigate away from this page and go read a 1st-grade science textbook before coming back.


An interesting thing happens when an electron absorbs lots of high-frequency waves, it escapes the shell of the atom. This is called the photoelectric effect, and the runaway electrons are called photoelectrons.

Why Stuff Gets Weird

Since light behaves like a wave, the more intense the light on an atom, the more powerful a photoelectron will be, right?

However, this hasn’t been observed. Which means that the only way to explain the photoelectric effect is for light to behave like a particle.

If light was like a particle, the photoelectric effect makes sense because while we are sending more photons/quanta, the photons can still have equal amounts of energy, not like waves.

(If light behaved like a wave it’d absorb some of the energy we were inputting and the photoelectrons would’ve increased, which didn’t happen..)

This means if we send higher-frequency waves to try to buff-up the power of these photoelectrons, Planck’s Equation tells us the quanta won’t carry enough energy to actually do this.

Thus, the double-slit experiment and the photoelectric effect means that light behaves like a particle and a wave.

Smart people call this property of light, “wave-particle duality.” Which rolls off the tongue easier than “thing that is like a wave, but also like a particle.”

Welcome to the Macroworld

Some guy named Louis de Broglie decided to make a hypothesis that all matter followed wave-particle duality. His theory was that all objects are surrounded by some sort of wave comparable to quanta. His groundbreaking theory was scoffed at. (Technically, the actual theory is that matter can behave like a wave, but we observe the waves, not the actual matter, so we just call it a matter wave.)

But now we’ve accepted Broglie’s idea, and the actual term for these waves around all matter is a matter wave.

A New Sign Joins the Battle!

A new symbol was introduced to suit this new burst of stuff in quantum physics. It’s the wave function, which can be written as Ψ or ψ. You are probably familiar with it if you’ve ever had a really ranty science teacher that goes far too off-topic.

(The sign wasn’t created. It was just some Greek sign that was repurposed.)

The wave function is used a lot, and it’s what makes those quantum equations look even more confusing.

Quantum Superposition

You know how things are only supposed to have one position and velocity?

While that certainly applies to everything we’ve observed in the big normal world, quantum physics lives the thug life and this rule doesn’t apply to it.

This rebellious act against Newton called superposition.

Thug Life

If you throw two identical balls in the exact identical way they’ll end up with the exact same paths and movement. They’ll have the same trajectory, arch, and ending point.

Unfortunately for us, quantum superposition says a big no-no to that, because now that object is capable of existing in multiple places at the same time.

From what you’ve observed, you are probably used to things having one velocity and point in space instead of multiple, which makes sense because observing an object in superposition “breaks” its superposition.

Wave Function Collapse

Here’s what those three simple words mean: If you observe a quantum object, superposition no longer works because you have determined that objects properties. Which means you’ve determined its exact state and narrowed it’s multiple velocities and points in space down to one velocity and point (you turn off its superpowers.)

Oversimplification of Wave Function Collapse: If you observe a particle, it’ll no longer have superposition and revert to the properties of a “normal” thing.

Wave Function Collapse completely breaks the deterministic properties of the world.

Therefore, the only way to figure out where a quantum particle is to assign probabilities of its position in a wave (remember that wacky Greek symbol?) This is where the wave function (you know, the one with the goofy symbol) comes in handy.

See the source image

However, if you observed the particle, wave function collapse would occur, which temporarily determines the position of the particle and removes the effect of superposition.

See the source image

Why Aren’t We Affected by Superposition?

Since bigger objects interact with these super-duper-uber small particles, that counts as “observing” because we are indirectly determining the positions of the particles.

This means we aren’t affected by all of these cool phenomena because the bigger and normal things are already determined to have only one position and velocity.

And to be honest, I’m fine with that. I don’t like the idea of my kidneys teleporting out of my body.

Another reason to why we don’t behave like quantum particles is because the more mass an object has, the smaller the wavelength of its matter wave will be, but the super-small stuff has huge matter waves, which is also a problem because we can’t observe quantum particles.

Why We Can’t Observe/Interact With Quantum Particles

If a quantum particle gets hit by light, it’ll get messed up because particles in the light are much larger than the quantum particle.

The same thing happens for everything else we try to do with it. So not only is there a “no lookie” rule, but there is also a “no touching” rule. Sucks, I know. No teleporting kidneys for now.

Luckily, people have been finding ways to use quantum particles, like in quantum computing. (I’ll link that post here when it comes out.)

Schrödinger’s Cat

Schrödinger’s Cat is a thought experiment created by Austrian physicist Erwin Schrödinger in 1935 in order to demonstrate the weirdness of quantum physics interacting with bigger objects. It was mostly created to help show the wave function collapse, and how vague the term “observe” actually was. Needless to say, the thought experiment sparked a lot of debate and divided people up as they took different interpretations of the experiment. Much like the comment sections on news articles.

This is the exact way it was written in the EPR article by Erwin Schrödinger:
A cat is penned up in a steel chamber, along with the following device (which must be secured against direct interference by the cat): in a Geiger counter, there is a tiny bit of radioactive substance, so small, that perhaps in the course of the hour one of the atoms decays, but also, with equal probability, perhaps none; if it happens, the counter tube discharges and through a relay releases a hammer that shatters a small flask of hydrocyanic acid. If one has left this entire system to itself for an hour, one would say that the cat still lives if meanwhile no atom has decayed. The first atomic decay would have poisoned it. The psi-function of the entire system would express this by having in it the living and dead cat (pardon the expression) mixed or smeared out in equal parts.

What Does it Mean?

All of the complex-ishy-advanced-wordiness basically means the cat has a 50/50 chance of being alive or dead.

And since the status of the radioactive decay of the substance is not known, the cat is under superposition until you actually open the box to observe what has happened.

So is the cat in a state of being both alive and dead?

But even then, some people state that the air particles around the substance and moving cat, and the fact that the cat can “observe” whether the prussic acid was released, superposition is prevented.

Some people even came up with a “many-worlds” interpretation of Schrödinger’s cat. The idea is that when at least two quantum systems interact, reality is spliced into multiple worlds, each holding an instance of a possibility.

See the source image

This means at least two universes are created, one having a dead cat, another having a living one. Which is pretty cool but it sucks for the universe with the dead cat.

But for the most part, Erwin’s theoretical cat achieved its goal, which is to make your physics classes needlessly confusing.

Uncertainty Principle

If we shoot a photoelectron into a wall, the effect of superposition means that we can only make guesses at the probability of where it’s gonna go.

See the source image

Something to note is that this has no relation to the observer effect, the uncertainty principle means that we are never certain of where the photoelectron is gonna go.

Reiterating this Idea: I gotta get this into your skull. The uncertainty principle and observer effect are completely different things!

Since there always is a tiny bit of uncertainty of the energy levels anywhere, some crazy stuff happens in vacuums, space, and time. Which is why Hawking Radiation and a bunch of other stuff exist. And that’s not very intro-to stuff, so fuck it.

Update: Shit, Hawking fucking died that’s sad.

A Quick Overview of A Few Other Cool Phenomena

These aren’t going to be as thoroughly explained in this post because I only intend to explain the bare minimum of stuff so I could talk about quantum mechanic’s role in messing up determinism. If you’re still interested, just plug everything in bold text into a search engine.

For example, if I typed Sonic Porn in bold, that’d mean I’m telling you to search for porn.

Quantum Tunneling – Particles or whole atoms always have a probability of going through a barrier, even if they don’t have enough energy to do so. This happens regularly inside of the Sun when it fuses atoms together to give us energy.

Spin – Quantum objects have a rotation that is purely intrinsic. This spin makes very weak magnetic fields. Some materials have lots of electrons in the atoms, overpowering the magnetic effect. (That’s why wood doesn’t behave like a magnet.) But the configuration of the shape of atoms also affects the magnetic properties. Also, the measure of an atoms spin is based off Planck’s Constant. Things with half-integer spins are called fermions. Things with integer spins are bosons. I’m too lazy to elaborate on this. Google it yourself.

Wave Function Symmetry – No two objects are actually identical. However, we can still have things that are indistinguishable, which works out well for all of the mathematics running the show. (Or else we’d have to invent math for even more stuff, which sucks.)

Antimatter – Antimatter particles have an equal mass to “normal” matter, except everything about them is oppositely charged. When they come into contact with matter, they cause “annihilation.” Their energy levels (which are opposites and determined by their spin) will combine to form zero. And a bunch of gamma ray photons is released, too. Cool beans.

Quantum Entanglement – Quantum entanglement is a phenomenon that occurs due to superposition and annihilation energy. Let’s take two photons from annihilation. We know that these two particles’ energy levels combined equal zero, so their spins must be opposites, too. As soon as one of the particles is measured, their wave function collapses. And by doing this, you are indirectly observing the other photon’s energy level, too. (Because the opposite of the directly observed photon’s spin will tell you the other photon’s spin.) Therefore, the other photon, no matter how far away it is, has its wave function collapse, too. This means can instantly determine another photon’s properties at infinite distances.

Virtual Particles – Some crazy stuff for another post.

Sonic Porn – Do not.


Quantum mechanics can still influence our bigger world. (Schrödinger’s cat is a good example.)

And so, the law of uncertainty might be our best explanation of whether or not we have free will.

There was once a chilling belief that we lived in a world that moved like clockwork. Whatever happened was, “destined,” to happen. And that free will did not exist.

Compatibilists believed that determinism and free will could exist together without conflict. (But all they did was change the definition of free will so that they could mash the two ideas together. They didn’t do anything else.)

Although quantum mechanics has been more open to the idea of free will (sorry, Newton), we aren’t absolutely sure of its existence. However, this might be our escape from universal fates and destinies.

Now let’s say that your brain is not deterministic, and now you’ve gone down a whole other rabbit hole. At this point, you can give your future actions percentages. There’d be a large group of similar actions at one point, and sometimes a vast plethora of very different chances of things happening.

But is randomness truly freedom?

Well, I’m not a philosophical preachy kind-of person so you’ll just have to do your own thinking on that one.

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