So what is UNIX time? UNIX time is a system that describes points in time, without using leap seconds, by measuring the time elapsed since midnight January 1, 1970 Coordinated Universal Time (UTC). You can gain some interesting insight on Wikipedia if you want to learn more about the topic. For example, while UNIX time starts from January 1, 1970, the present form of UTC, which includes leap seconds, did not exist until 1972. The days that passed from 1970 to 1972 make no difference in the current system.
If you remember Y2K, then you might know some of the issues UNIX time has faced. The Y2K issue, mirroring the paranoia caused by the LHC experiments, led some people to predict the end of the world. This issue was caused in part by the use of UNIX time stamping. The short story is that UNIX time stamping (time_t) stored dates and times in 32-bit formatting. Thus, the fear in that respect was that since most applications and systems used a two digit format for the year, 2000 would end up as 1900. This led to another issue, Y2K38, ( 2038 ) where some software is predicted to fail because of the 32-bit time_t that is used in UNIX.
Allegedly, on January 19, 2038 clocks will go negative, and report a negative UNIX timestamp. This will revert the date to 1970 instead of 2038. To address this problem, several development languages and systems moved to a 64-bit way of keeping time. Even 64-bit usage comes with problems, but those issues won’t happen until about the same time the sun burns out. In the next 20 years, computers around the world will need to be updated to 64-bit which should give them enough time before the next upgrade is due, 293 billion years down the road.
Another aspect of the 1234567890 event comes from the security sector. There are rumors and conspiracy theories that there are some Malware authors who have allowed rogue software to lay dormant until this date, thus once the time arrives, a massive attack on end users will kick off.
So if you subscribe to the conspiracy, then get those tin foil hats on. If you are a geek, then take a second to cackle like mad, its only once in a lifetime that the time is 1234567890. For the history buffs, the last time something major happened with UNIX time was in 2001-09-09T01:46:40 GMT. On this date, Unix time passed 1,000,000,000 seconds.