Certainly possible. Just for fun, let's do some quick math. Imagine that we had 100 billion processes running constantly at 10 GHz since ~1970. This would result in ~10^30 clock ticks (10^9 sec * 10^10 ticks/sec * 10^11 processors).

That number is child's play compared to numbers like Graham's number. The exponent of Graham's number is so large that it can't be written down. 30 is pretty easy to write down. For comparison there are about 10^80 atoms in the universe. That's still a tiny number compared to Graham's number.