Quantum Mechanics

Quantum Mechanics

Quantum mechanics is one of the most intimidating concepts that I’ve come across, so hold on to your hats for this one.

It’s our description of what’s inside the proton and neutron. The problem is that inside there, our perception of reality is irrelevant because it’s a world where logic gave up and intuition goes to die.

The first thing to know is that there is a framework, like a new periodic table, of all the quantum mechanical particles. It’s called The Standard Model. Check out that article for an explanation of what the particles are, because in this one I’m going to focus on how they behave.

The objects that a human being is used to range in size from around a grain of sand to a skyscraper. The position and movement of objects between these sizes is always clear and predictable to us.

From a quantum mechanical perspective, which looks at worlds millions of times smaller than a grain of sand, these objects are absolutely enormous.

Even when they are sitting still, their atoms are constantly interacting with other atoms.

This is because a grain of sand is surrounded by billions of atoms in the air around it, which are bouncing off it all the time. It’s also jostling with it’s own internal particles through friction at every moment of the day.

But as we look at smaller and smaller objects, you get less and less interaction. Quantum mechanical sized particles, like bosons, are so tiny that they regularly go for stretches of time without interacting with any other particle at all.

That is where things get trippy.

We cannot keep track of the position and momentum (which quantum physicists call the ‘state’) of our boson when it’s this phase of not interacting with anything, because checking in on it in any way creates an interaction.

But from clever experiments like the double slit experiment, we know that while it’s MIA, it does not act like a normal particle.

When the particle finally does interact with something, we’re able to see where it is again. But physicists noticed that there is a broad range of places in which the boson can reappear.

When they repeated their experiments enough times, they noticed that the probability of these places follows the same ripple-like pattern as a wave.

They called this range of a particle’s possible locations it’s ‘wave function’.

Once a particle stops interacting with others, we only know the possible places it can reappear. Those possible places resemble the ripples of a wave moving outwards from the point of disappearance.
Once a particle stops interacting with others, we only know the possible places it can reappear. Those possible places resemble the ripples of a wave moving outwards from the point of disappearance.

You can’t ‘cheat’ and try to see what happens when the particle disappears and starts to moves in this wave pattern. As soon as you set up something to see what’s happening, like a particle detector, the atoms of the detector bump into the particle and you’ve ruined the experiment. Physicists have determined that there’s nothing to help with this, and named it the ‘uncertainty principle’.


A few theories have been suggested as to why quantum mechanical-sized particles behave like this:

  1. Maybe waves are the true nature of things, and the point particles that we’re used to are an illusion caused by interaction.
  2. They temporarily disappear into another universe.
  3. They cause other universes to be created.
  4. We have no idea.

Eventually, an article is bound to bump into something. When it does, we can see it again and its state is now clear and fixed. It’s wave function now becomes irrelevant (particle physicists say that the wave function ‘collapses’).

So as you zoom out of the quantum world and approach the world of reguar sized things like grains of sand and skyscrapers, they are so large, and interact with so many other particles all the time that their wave function is always collapsed, and so everything in our ‘world’ has a state that is fixed. This is called the ‘Correspondence Principle’.

It’s similar to how if you look at a computer screen up close, you see pixels made of multiple colours. But but as you zoom out you get the illusion of a picture.

But from the perspective of quantum mechanics, our world is the illusion.


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