While checking to see where my visitors come from, I discovered that some arrived here 18,207 days ago, almost fifty years in the past. This is curious, since I have been online for maybe twenty-five years and launched my first website a bit more than twenty years ago. I’m too lazy to do the arithmetic, but I have a hunch these early visits occurred on January 1, 1970.
“I’m too lazy to do the arithmetic”
Just asking google “what day was it 18211 days ago?” (adjusting for the 4 day difference from your post to my comment) worked. It was Thursday , Jan 1 1970.
So your hunch appears to be exactly correct.
And I just learned that UNIX time started on a Thursday.