He does something weird with computers, electricity and maybe death rays.
He didn't have computers or even a calculator.
Rows of computers and monitors lined the room.
The Babylonian computers were not only aware that Venus returns in almost exactly eight years to a given starting-point in the sky, but they had established similar periodic relations in 4 6, 59, 79 and 83 years severally for Mercury, Saturn, Mars and Jupiter.
We don't need our computers to be infinitely fast, just a whole lot faster than they are today.