NASA’s Voyager 1 space probe reached beyond our solar system’s boundary last year, and it’s set to rendezvous with a star named AC+79 3888—in about 40,000 years. It may seem like a long time, but imagine an alien race that’s 40,000 years ahead of us in technological development.

What if that race sent out a probe 40,000 years ago? Could we be at the receiving end of similar attempts at space exploration? What if that race had a million-year head start on humanity?

University of Edinburgh professors Arwen Nicholson and Duncan Forgana have pondered such questions and formulated some related theories.

They published an article in the International Journal of Astrobiology last year explaining techniques that could dramatically cut down the time needed to send probes far and wide. They also said it is not only possible that aliens could reach our solar system with such probes, but they may have even done so a very long time ago. And this may be ongoing, with several different alien cultures sending probes at the same time.

To read more, click here.