TL;DR: A coin is the middle point in size between an atom and the USA.
Every time you scroll down on your phone, you are pushing against a net made of thousands of trillions of atoms.
Atoms create everything that we see around us, and they are really, really small. They have a diameter of 0.1 nanometers, but that gives no real context of how small they really are.
Two quick stories will help us visualise the minuscule world of the atoms.
They start with the world’s most classic road trip, the coast to coast drive across the USA.
It’s the trip made famous by the novelist Jack Kerouac and his Beat Generation of artists in the late 1940’s. Countless travellers have followed in his footsteps since by hitchhiking or renting an old car and driving the four to five-day journey across the great American continent.
All experiences are different, but something that everyone who completes this journey comes away with is a perspective of the prodigious size of the USA.
Jack Kerouac writes in his novel about the experience:
All that raw land that rolls in one unbelievable huge bulge over to the West Coast, and all that road going, all the people dreaming in the immensity of it.
Jack Kerouac, On The Road
Imagine that somewhere at the end of this journey, perhaps when driving across San Francisco’s Golden Gate Bridge, a loose quarter fell from the car and clattered onto the road, unnoticed.
Try to imagine the size of the quarter on the ground, compared to the vast country Kerouac just traveled across.
It seems incomparably small, so microscopic – that it almost doesn’t exist.
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Now let’s jump perspectives.
Twenty years later, another great journey is taking place.
This time it’s Buzz Aldrin, and he’s on his way to the moon. He looks out the window of Apollo 11 and down at the blue Earth below.
He can see the whole United States at once, the entire continent that took Kerouac five days to drive across.
Let’s imagine he knows the quarter story, and wants to visualise it for himself.
Kerouac’s tiny quarter on the road would be far, far too small to see. At this distance, he could make out large structures like lakes and mountain ranges, and the lights of cities, but not much more.
When the clouds parted, he could just make out the San Francisco Bay Area, the darkness of its bay distinguished from the lights of its shore and its distinctive Peninsula and Marin County forming a recognisable shape.
He couldn’t actually see it at this distance, but he imagined the thin line of the Golden Gate Bridge connecting the peninsulas.
Let’s imagine him thinking of Kerouac’s quarter lying on the bridge all the way down below. He certainly couldn’t see it but in his minds eye, it was there.
Buzz took out a quarter of his own and held it up against the United States, with the Bay Area and the Golden Gate Bridge just jutting out on the underside edge.
In his minds eye the quarter was certainly tiny. But it wasn’t non-existent.
He imagined the atoms on the edge of his quarter jittering and dancing right next to where he imagined Kerouac’s quarter to be.
This is where the penny drops.
Because from Buzz’s perspective, the atoms in his quarter and the tiny coin all the way down on the ground would appear to be the same exact size.
Said another way, a quarter lies exactly in the middle in size between an atom and the USA.
That is how big an atom is.
These minuscule particles are small, but are not smaller than we can imagine.
Every surface is coated with billions upon billions of these tiny things. Their properties, like their attraction to each other, determine very real and tangible effects in our world, such as if a material is as brittle as charcoal or as hard as a diamond.
The light waves that they reflect determine what colour something is, and their sharing of electrons creates the electricity and magnetism that powers our civilisation.
Almost every phenomena in our world is an ’emergent property’, an illusion, created by the interactions of billions of trillions of these tiny atoms.