2020 is a significant year for Unix. At the very start of the year, Unix turns 50.
While some of the early development of Unix predates the official start of its "epoch," Jan 1, 1970 remains the zero-point in POSIX time and the recognized beginning of all things Unix. Jan 1, 2020 will mark 50 years since that moment.
Unix time vs human time
In terms of human time, 50 years is a big deal. In terms of Unix time, there's nothing particularly special about 50 years. 48.7 years would be no less significant.
Unix (including Linux) systems store date/time values as the number of seconds that have elapsed since 1970-01-01 00:00:00 UTC in 32 bits. To determine how many seconds have passed since that time and, thus, what right now looks like as a Unix time value, you can issue a command like this:
Thanks to Sandra Henry-Stocker (see source)