You are seeing two effects here. The first one is that you use a way of writing for a date that can be written in multiple forms:
0000-01-01 same as 0000-01-01
0000-01-00 same as -0001-12-31
0000-00-01 same as -0001-12-01
0000-00-00 same as -0001-11-30
So by the date itself, you already specify the 30th November -1.
Now there's the time offset left that differs about the 9 minutes and 21 seconds. That is because of a change in the clock compared to UTC in Paris/France that happened 10 Mar 1911 23:51:38/39 local time.
I modified your code example a bit and introduced the Europe/Paris setting as you have it, which is playing a role. This code is telling as well the offset in seconds from UTC (Z
) which is what you're looking for:
$dt = new DateTime('0000-00-00 00:00:00', new DateTimeZone('Europe/Paris'));
printf("%s secs offset from UTC\n", $dt->format('r T (e) Z'));
I changed the dates a bit
Fri, 10 Mar 1911 23:51:38 +0009 PMT (Europe/Paris) 561 secs offset from UTC
^^^
One second later:
Fri, 10 Mar 1911 23:51:39 +0000 WET (Europe/Paris) 0 secs offset from UTC
When local standard time was about to reach
Saturday, 11 March 1911, 00:01:00 clocks were turned backward 0:09:21 hours to
Friday, 10 March 1911, 23:51:39 local standard time instead.
That are 561 Secs. Reference: Clock changes in Paris - Time change dates in 1911 and Time zone changes and daylight saving time start/end dates between year 1900 and 1924.
new \DateTime
? – Barium