9 articles
Engineering and Built Systems
Engineering explainers about sorting algorithms, power grids, traffic lights, airports, GPS, water systems, shipping, and built systems.
The emphasis is on how things work: constraints, tradeoffs, failure modes, and why design choices matter.
How GPS Actually Works — And Why It Depends on Einstein
Your phone knows where it is within a few meters using signals from satellites 20,000 km away. The system only works because of corrections predicted by general relativity.
Where Your Tap Water Actually Comes From
The journey from source to tap involves reservoirs, chemical treatment, pressure zones, and a network of pipes that most cities couldn't fully map if they tried.
The Machine That Sorts Your Mail at 35,000 Pieces Per Hour
Inside the mechanical city that processes half the world's mail — optical scanners, barcode tattoos, and a conveyor system the size of three football fields.
How a Box Changed the World: The Invisible Logic of Container Shipping
The shipping container is one of the most consequential inventions of the 20th century. Here's the system that moves 90% of world trade.
The Power Grid Has to Balance Supply and Demand Every Second. Here's How.
Electricity can't be stored at scale. Every joule generated has to be consumed instantly. The system that keeps this in balance is more elegant than most people realize.
What Happens After You Flush
The sewage treatment process is one of the great unsung achievements of public health. Here's exactly what happens to wastewater between the toilet and the river.
What Actually Happens to Your Bag Between Check-In and the Carousel
Airport baggage systems are among the most complex automated logistics networks ever built. Here's what's happening underground while you walk to your gate.
The Internet Runs on 400 Cables at the Bottom of the Ocean
Satellites get the credit. Undersea cables do the work. Here's what the actual physical infrastructure of the global internet looks like.
How a City Actually Decides Where to Put a Traffic Light
It's not random, it's not obvious, and the answer involves a surprisingly specific formula called the Manual on Uniform Traffic Control Devices.