User blog comment:Wythagoras/My Turing machines/@comment-6768393-20131012123348/@comment-1605058-20131013110723

What if BB(7) is at level of 10^10^10? And BB(8) is already about 10^^100? Quantum computation will certainly help finding bounds, but not values. If such simple machine halts after such long time, it must exhibit some non-trivial regularity which eventually leads to halting, and such behaviour is hard to analyse by any computational device.