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Quantum mechanics is the most intimidating concept 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 breaks down and is replaced with a world where logic gave up and intuition goes to die.
The first thing to know is that there is a framework to know, like a new periodic table, of all the quantum mechanical particles. It’s called The Standard Model. It explains what the particles are, but in this email I want to talk about how they behave.
The objects that we are used to range in size from around a grain of sand, to around a skyscraper. The position and movement (which particle physicists call the ‘state’) of objects of these sizes is always clear and predictable to us. We’ve evolved to understand them.
From a quantum mechanics perspective, millions of times smaller than a grain of sand, and thousands of times smaller than an atom, these objects are absolutely huge. Even a grain of sand is a mountain, and it is covered by billions of atoms in the surrounding air and water.
These ‘huge’ objects that we’re used to interact with other things all the time. Like, every nanosecond of every day. They are jostling with their own internal particles through friction, light bounces off them, air atoms bounce off them, and if we touch them the electromagnetic force repels our atoms from their atoms. Lots of interactions, all the time.
But as we’ve looked deeper into the tiny depths of the universe, you get less and less interaction. The tiny internal particles of all atoms, take for instance a boson, will often interact with other particles like other bosons, and when it does we can track its position and movement just like we can with sand and skyscrapers.
But, because it is so tiny, it regularly goes for stretches of time without interacting with any other particle at all.
That is where things get trippy.
We don’t know what happens to our boson when it’s this phase. It’s gone off the reservation. Disappeared into the jungle. But from clever experiments like the double slit experiment, we know that while they’re MIA, they do not act like normal particles.
They move similar to what we see in waves like water or sound.
The particle no longer has a clear, easily defined position and movement. Instead, it has a range of possible places in which it can reappear, and the probability of these places follows the same ripple-like pattern as a wave. This wave-like set of a particle’s possible locations is called 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.
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 ideas have been suggested about how quantum sized particles do this:
- Maybe waves are the true nature of things, and the point particles that we’re used to are an illusion caused by interaction.
- They temporarily disappear into another universe
- They cause other universes to be created
- Seriously we have no idea
Eventually, boson 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 is like if you lookat 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, it’s our world that’s the strange one.