clock monotonic time

get_monotonic_time.php

<?php # idea from https://www.netmeister.org/blog/epoch.html

// so Mac apparently set their origin of time using to 2001-01-01 00:00:00 (clock monotonic) which is unix epoch (1971-01-01) aka -30 years ago.
# ((31556926) * 30) = (number of seconds per year according to epochconverter) * 30 years = 946707780 
# per article, it is -978307200 (2001-01-01 00:00:00) so I wonder what explains the diff??
functions get_monotonic($timestamp) {
  return time() - strtotime('2001-01-01 00:00:00'));
}
return get_monotonic();

edit: unix itme is apparently 1970 not 1971! I always thought it was 1971 for some reason