The Physical Internet

The cables, buildings, and ocean floors that connect the world

Illustration companion to Issue 5: The Connected World

The Internet Is Physical
Follow a data packet from your device to a data center across the ocean
Your Device Your Router ISP Internet Service Provider IXP Exchange Point Where networks meet Undersea Fiber Optic Cable As thin as a garden hose 1.3 million km on the ocean floor Cable Landing Station ☁ CLOUD Data Center Where websites live 1 2 3 4 5 6 7
Every time you load a webpage, your request races through this physical gauntlet — from your pocket, through copper and fiber, past exchange points, down through the ocean floor, and into a warehouse full of humming servers. The whole trip takes about 60 milliseconds. You never notice because it happens faster than you can blink.
By the Numbers
The physical scale of the internet, quantified
1.3 Million km
of undersea cables on the ocean floor
~5,000
data centers worldwide
~60 ms
for data to cross the Atlantic Ocean
100+ Tbps
carried by a single optical fiber
99%
of international data travels by undersea cable, not satellite
The Protocol Stack — Envelope Analogy
How your data gets wrapped for its journey across the internet

When you type a URL and hit Enter, your message doesn't just fly across the wire naked. It gets wrapped in layers — like putting a letter into an envelope, then putting that envelope into a bigger envelope, then putting that into a package. Each layer adds routing information so the data can find its way.

SENDING Wrapping your data, layer by layer Application Layer (HTTP) Your message — the actual content GET /hello HTTP/1.1 :443 Transport Layer (TCP) Envelope with port number + sequence Port: 443 · Seq: 1 · ACK: 1 Makes sure all pieces arrive, in order 192.168... Network Layer (IP) Bigger envelope with source + destination From: 192.168.1.5 To: 93.184.216.34 Knows HOW to route across networks MAC Link Layer (Ethernet) Final frame for the physical wire MAC: AA:BB:CC:DD:EE:FF Handles physical transmission (bits on the wire) The Wire RECEIVING Unwrapping your data, layer by layer Unwrap Link Layer Read MAC address, remove frame header Unwrap Network Layer Verify IP address, remove IP header Unwrap Transport Layer Check sequence, reassemble, remove TCP header Your Message Arrives! GET /hello HTTP/1.1 Server reads the request, sends a response Each layer trusts the one below it. No layer needs to know how the others work.
This layered design is the internet's secret superpower. The web browser doesn't need to know about electrical signals. The fiber optic cable doesn't need to understand HTTP. Each layer does one job and passes the result along. That's why the internet can run on copper, fiber, radio waves, or even lasers — only the bottom layer needs to change.
Undersea Cable Cross-Section
What actually lies on the ocean floor, carrying 99% of the world's international data
1. Optical Fibers Hair-thin glass strands (8 shown) Each carries light pulses = your data 2. Gel Filling Jelly protects the delicate fibers 3. Steel Tube Structural support 4. Copper Conductor Powers underwater repeaters every ~80 km to boost the signal 5. Polyethylene Insulation Electrical insulation 6. Steel Wire Armor Shark protection! (yes, really) 7. Outer Polyethylene Jacket Final waterproof layer 25mm Coin for scale ~17mm total diameter Yes, sharks really do bite internet cables. That's why there's armor.

These cables are manufactured in specialized factories and loaded onto ships that can carry thousands of kilometers of cable at once. Cable-laying ships carefully lower the cable to the ocean floor, sometimes to depths of over 8,000 meters. Near coastlines, the cables are buried in the seabed for protection. In the open ocean, they simply rest on the bottom.

Every cable has repeaters — small amplifier pods spaced about 80 km apart — that boost the light signal as it dims during the journey. These repeaters are powered by the copper conductor layer, carrying electricity from shore-based power stations at each end of the cable.

The entire global internet rests on infrastructure that would fit inside a garden hose. About 550 cable systems connect every continent except Antarctica. When you stream a video, send a message, or load a webpage from another country, your data is almost certainly traveling through one of these slender cables on the ocean floor, pulsing as light through hair-thin glass fibers at nearly the speed of light.

From Turing to LLMs and Beyond

This illustration is a companion to Issue 5: The Connected World

← Back to Issue 5