Why are dates calculated from January 1st, 1970?

Question

Is there any reason behind using date(January 1st, 1970) as default standard for time manipulation? I have seen this standard in Java as well as in Python. These two languag

Answer 1

It is the standard of Unix time.

Unix time, or POSIX time, is a system for describing points in time, defined as the number of seconds elapsed since midnight proleptic Coordinated Universal Time (UTC) of January 1, 1970, not counting leap seconds.