In the physical world, time is relative. In the digital world, time must be absolute. Enter the Unix Epoch.
Why January 1st, 1970?
When the Unix operating system was being developed at Bell Labs, engineers needed a uniform way to track file modifications. They chose 00:00:00 UTC on January 1, 1970, as the arbitrary starting line. Why? Because it was a convenient round number close to the date they were actually writing the code.
The Year 2038 Problem
Just like the Y2K bug, Unix time has an expiration date. Older systems store time as a signed 32-bit integer. The maximum value this integer can hold corresponds to January 19, 2038.
On that date, at 03:14:07 UTC, 32-bit clocks will overflow and wrap around to the year 1901. Modern 64-bit systems have already solved this (pushing the end date billions of years into the future), but legacy embedded systems are still at risk.
Universal Synchronization
Despite these quirks, Unix time remains the gold standard because it is timezone-agnostic. 1732560000 happens at the exact same moment in Tokyo as it does in New York.
Calculate the Epoch
See exactly how many seconds have passed since 1970.
Conclusion
Understanding the Epoch gives you insight into how computers "think" about time. It simplifies complex date math into basic subtraction, making global coordination possible.