Most people understand that computers have technically been around for about a half century or so. But there have been multiple reports of computer-like items before that time, depending on your definition of a computer.
Then there's the Ancient Moon computer, which is about 2,000 years old. According to a recent article published in the journal Nature, this device may have been used to predict eclipses of the solar and lunar variety.
While the "computer" was discovered more than 100 years ago, it has taken researchers time to interpret what exactly it does. They also learned it potentially told of the planetary movements in precise fashion.
So why is this technology so much more advanced than anything during the next 1,000 years? Unless you vote for the alien visit, it's tough to come up with a reasonable answer.