Exabit to Petabit

One exabit = 10¹⁸ bits = 125,000 terabytes = 125 petabytes. If every person on Earth (8 billion people) each stored 15 GB of data — roughly a modern smartphone's photos and messages — the total would be about 120 exabytes, or about 960 exabits. The entire human genome is about 1.5 GB; sequencing every person on Earth would produce about 12 exabytes of data.

Cisco's annual internet traffic reports estimated global IP traffic at roughly 4.8 exabytes per day in 2022, rising about 20% per year. Expressed in bits, that's about 38 exabits per day or roughly 440 petabits per second continuously. Video streaming accounts for over 60% of total internet traffic volume.

Data gravity is the principle that massive datasets attract applications, services, and additional data toward them — rather than being moved to where processing occurs. At exabit scale, physically transferring data becomes impractical: moving 1 exabit over a 100 Gbps link takes 116 days. Instead, companies deploy compute resources alongside the data. This effect drives cloud concentration — once an organisation stores exabits in AWS or Azure, the cost and latency of moving that data elsewhere creates powerful vendor lock-in, shaping the economics of the entire cloud industry.

The Square Kilometer Array (SKA), under construction in Australia and South Africa, will be the world's largest radio telescope. Its thousands of antennas will collectively produce roughly 1 exabit of raw sensor data per day — more than the entire global internet traffic of the early 2000s. This data cannot be stored in full; instead, on-site supercomputers reduce it by a factor of ~10,000 in real time, keeping only scientifically relevant signals. The SKA illustrates how radio astronomy pushes data processing to extreme scales that rival commercial internet infrastructure.

At 1 Gbps (a fast home connection), downloading 1 exabit would take 1 billion seconds — about 31.7 years. At 1 Tbps (a high-end data center link), it would take 1 million seconds, or about 11.6 days. This illustrates why exabit-scale data movements require massively parallel infrastructure — no single link or device handles exabit transfers directly.

One petabit = 10¹⁵ bits = 125 terabytes. To put it in perspective: the entire text content of all English Wikipedia articles is roughly 4 GB — so a petabit could hold about 31,000 copies of it. A petabit per second link could transfer all of Wikipedia's text content in about 32 microseconds.

As of 2024, no single commercial link carries 1 Pbps, but laboratory experiments have demonstrated fiber optic transmission exceeding 1 Pbps using dense wavelength-division multiplexing on a single fiber strand. Commercial submarine cables aggregate hundreds of terabits per second across many fibers and wavelengths, collectively reaching petabit-scale capacity per cable system.

A petabit (Pb) = 10¹⁵ bits. A petabyte (PB) = 10¹⁵ bytes = 8 petabits. Storage systems (data centers, archival systems) use petabytes for capacity; aggregate network throughput uses petabits per second. An exabyte-scale data center stores 1,000 petabytes; its internal network may carry multiple petabits per second of traffic.

Qubits and classical bits solve fundamentally different problems — qubits will not simply replace petabit-scale classical storage or networking. A quantum computer with 1,000 logical qubits can explore 2¹⁰⁰⁰ states simultaneously, but measuring those qubits collapses them to classical bits. Quantum networks will likely handle key distribution and entanglement sharing at kilobit-to-megabit rates, while classical infrastructure continues to move petabits of bulk data. The two technologies are complementary, not substitutional.

Submarine fiber optic cables are built by a handful of companies (SubCom, NEC, Alcatel Submarine Networks) and typically cost $200–500 million per system. A modern cable contains 12–24 fiber pairs, each carrying hundreds of wavelengths via dense wavelength-division multiplexing, reaching 400+ Tbps aggregate capacity per cable. Cables are designed to last 25 years on the ocean floor. When faults occur, specialised cable repair ships (fewer than 60 exist worldwide) locate breaks using optical time-domain reflectometry and splice repairs at sea — a process that can take days to weeks depending on depth and weather.