UNIX time is the number of seconds elapsed from 1 January 1970 to the present time. The Unix timestamp at the time of writing this is '1533004322'. This is a signed 32-bit integer, which has a maximum storage capacity of 2^31-1 = 2,147,483,647. That is 2,147,483,647 seconds after 1 January 1970. Due to the insufficient capacity of the chosen storage unit, this is highly likely to go crazy on 03:14:08 UTC on Tuesday, 19 January 2038. After that, the counter runs out of usable digit bits, flips the sign bit instead, and reports a maximally negative number (continuing to count up, toward zero). Resulting erroneous calculations on such systems are likely to cause problems for users and other relying parties. There is no universal solution to this problem. Even if we change the datatype to an unsigned integer, all the dates before 1 January 1970 will be represented in negative numbers.
