In honor of the SigFig’s birthday, today’s post is about the moment I knew we really had something special.
It is, unsurprisingly, science-related.
Several years ago, we were walking along the waterfront and paused to rest on a high-backed plastic bench. I kissed him and felt a mild shock.
“You’re crackly. Discharge.”
Without missing a beat, he got up and touched his fingertip to a metal railing. He knew exactly what I meant and exactly what he had to do to rectify the situation.
And, just like that, I was hooked.
So what was going on here? It’s all about the electrons.
Everything is made up of atoms, which contain particles called protons and electrons. Protons and electrons have a characteristic called charge; protons have a positive charge and electrons have a negative charge. Reinforcing the notion that many common sayings have their roots in science, opposite (charges) really do attract each other, while similar charges repel each other. Most atoms have the same number of protons as electrons, resulting in an overall charge of zero.
While protons are in a fixed location in the middle of an atom, electrons travel in “clouds” around the outside of an atom. When two surfaces rub against each other- like when the SigFig rubbed against the plastic bench- electrons can transfer from one surface to another. The direction of electron transfer depends on the combination of materials; some materials are more likely to lose electrons, while others are more likely to gain electrons. (The information I’m using is from here.) Electrons transferred from the SigFig onto the bench, leaving him with an overall positive charge and the bench with an overall negative charge.
When I kissed him, the negatively charged electrons in me were attracted to the positively charged SigFig (and really, who can blame them?). The “shock” that I felt was the sensation caused by electrons leaving my body and transferring onto his.
My “discharge” instruction- which he understood perfectly- meant that he needed to gain electrons to make up for the ones he lost, which would restore him to an overall charge of zero. The best source of electrons we have is Earth, since it’s large enough to gain or lose a few electrons without seriously affecting its overall charge, and the most efficient way for electrons to get from the Earth to you is through a conductive object. Conductors are materials that allow electrons to move relatively freely. Metal happens to be an excellent conductor; when the SigFig touched the railing, electrons in the Earth were attracted to his overall positive charge. These electrons flowed from the Earth, through the railing, and into him.
If nothing else, this story shows us that, while they often have different goals, engineers and scientists can always find some common ground.
I’ll explain the terrible pun another day and leave you with this instead.
The movement of electrons also explains why you sometimes feel a shock when you touch a metal doorknob after walking across carpet. Left as an exercise for the reader: based on our description of electron transfer, why would shuffling your feet across the carpet result in a stronger shock than tiptoeing across the carpet?