"How long would Bruce Wayne have to train to become Batman?
In some of the timelines you see in the comics, the backstory is he goes away for five years—some it's three to five years, or eight years, or 12 years. In terms of the physical changes (strength and conditioning), that's happening fairly quickly. We're talking three to five years. In terms of the physical skills to be able to defend himself against all these opponents all the time, I would benchmark that at 10 to 12 years. Probably the most reality-based representation of Batman and his training was in Batman Begins.
Why such a long training time?
Batman can't really afford to lose. Losing means death—or at least not being able to be Batman anymore. But another benchmark is having enough skill and experience to defend himself without killing anyone. Because that's part of his credo. It would be much easier to fight somebody if you could incapacitate them with extreme force. Punching somebody in the throat could be a lethal blow. That's pretty easy to do.
But if you're thinking about something that doesn't result in lethal force, that's more tricky. It's really hard for people to get their heads around, I think. To be that good, to not actually lethally injure anyone, requires an extremely high level of skill that would take maybe 15 to 18 years to accumulate."
Read the rest of the article at Scientific American.
Thanks Defense Tech for the link.