But Why?

When you hold your smartphone in your hand, the incredible wonders of physics are on display for you, right there in front of you. It’s almost like an impromptu lesson in the way the universe works.

Your screen shows off the photoelectric effect, employing tiny organic compounds that emit light when electricity passes through them. When you run your finger over your screen, there’s a tiny grid of wires under the glass with a constant current, creating an electric field. You create a new circuit with your finger, and specialized circuits can detect even the subtlest disturbance.

Polarized light passes through liquid crystals which can be manipulated by tiny electric currents to rotate. This rotation, combined with additional polarizing filters, controls the amount of light allowed through each pixel, creating the colors you see.

Even the way your phone sends messages is a little science experiment: wireless communication means sending and receiving radio waves, leveraging a deep understanding of the way light travels as a wave.

All of this wondrous physics on display is fantastic, but I want to circle back to you holding that smartphone in your hand. Why doesn’t the smartphone just fall to the ground when you hold it?

“Because your hand is there” doesn’t really do the trick.

It might seem like your hand is rock solid, completely full of closely connected atoms, like a ball pit. It’s not quite like this, though: instead of touching, it’s almost as thought he atoms are in a complex financial relationship with one another. Instead of money or contracts, they trade electrons.

Okay, so this little swarm of ultra-tiny electrons keeps the atoms bonded, but aren’t atoms themselves mostly empty space?

Atoms are so very empty. If an atom was a football stadium, the nucleus would be around the size of a mosquito. Why don’t atoms just fly right past one another? Why can’t another mosquito fly into the stadium?

It turns out that empty space isn’t really all that empty. Remember the financial transactions I mentioned earlier? The atoms are like companies. When the atoms bump up against one another, it’s sort of akin to companies doing business with one another. There are limited (but important) exchanges from time to time.

Mainly, though, those investment firms have a moat around them, protecting individuals from other companies from entering their building (maybe to spy on their proprietary information). This is a lot like the repellant forces electrons give off to one another, making it dicey for two atoms to get too close together under most circumstances.

Inside of the atom, the “space” in between the nucleus and the electrons is more like the inside of a very, very busy firm. These “employees” interact with one another all day every day, constantly going back and forth in a “cloud” of activity.

There’s an awful lot more to say about electrons, nuclei, and quantum mechanics in general, but I’m going to lay down my keyboard on the subject for now, because this is plenty.

Grab your phone right now. Hold its weight in your hand. Think about why it doesn’t just fall to the ground. It turns out that the very same force that lets you drag your finger in order to control what happens on your phone’s screen, is doing this.

It’s the same exact phenomenon that lets us send and receive those radio waves.

Does this give you a “whoa” moment?