There appears to be a design limitation for long running loops. If you have any designs that require continuous operation for, say, 50 billion years you are going to need to optimize and cut the time down. To be on the safe side your program is going to need to complete in less than 10 billion years:

But two new studies by Stanford University cosmologists suggest that it may be time to rethink this popular view of a "runaway universe." Instead of expanding exponentially, our cosmos may be in danger of collapsing in a "mere" 10 to 20 billion years, according to the Stanford team.

"The standard vision at the moment is that the universe is speeding up," said physics Professor Andrei Linde, "so we were surprised to find that a collapse could happen within such a short amount of time."

Linde and his wife, Renata Kallosh – also a professor of physics at Stanford – have authored two companion studies that raise the possibility of a cosmic "big crunch." Both papers are available on the physics research website, www.arXiv.org. "We tried our best to come up with a good theory that explains the acceleration of the universe, but ours is just a model," Linde noted. "It's just part of the answer."

If the Linde-Kallosh model is correct, then the universe, which appears to accelerating now, will begin to slow down and contract. "The universe may be doomed to collapse and disappear," Linde said. "Everything we see now, and at a much larger distance that we cannot see, will collapse into a point smaller than a proton. Locally, it will be the same as if you were inside a black hole. You will just discontinue your existence."

I hope this obvious design bug in the universe doesn't break too much existing software.