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Comment by achow | Hacker News Reader

Now it makes sense..

Human bone is five times stiffer than concrete and fifty times harder to break

Stuff like that is why I laugh a little at cyberpunk "cyborg metal arms" stuff.

Sure, it opens new possibilities for when you really need to be able to crush rocks with your hands, but often people don't realize how much our default equipment--literally nanotechnology beyond human understanding--manages to accomplish when it comes to the total package of features and design-constraints.

Including but not limited to:

1. Supports a very large number of individual movements and articulations

2. Meets certain weight-restrictions (overall system must be near-buoyant in water)

3. Supports a wide variety of automatic self-repair techniques, many of which can occur without ceasing operation

4. Is entirely produced and usually maintained by unskilled (unconscious?) labor from common raw materials

5. Contains a comprehensive suite of sensors

6. Not too brittle, flexes to store and release mechanical energy from certain impacts

7. Selectively reinforces itself when strain is detected

8. Has areas for the storage of long-term energy reserves, which double as an impact cushion

9. Houses small fabricators to replenish some of its own operating fluids

10. Subsystems for thermal management (evaporative cooling, automatic micro-activation)

P.S.: Mark my words, nobody is gonna be replace their limbs and torsos in order to shape molten metal or punch asteroids or whatever while paying off the ruinous loan underwritten by by their employer MegaCorp.

Instead you're gonna clock-in to the work office and and plug your mostly-meat-body in to a nice comfy chair, and from there you will control one of the MegaCorp's array of metal-twisting asteroid-punching robots out in the field. MegaCorp knows they are much cheaper to manufacture and insure, easier to repair, and they can be seamlessly tasked to some other worker without messy surgery.

At the end if the day you will log out and hand things off to the next shift, and you can you go home and hug your family without accidentally maiming them.

Peripherals

Caveat: the bones in the hand are really thin.

My old kenpo sensei used to say punching someone in the face is the last thing you want to do in a fight, since you're likely to do more damage to your hand than to your opponent. And most people don't know how to make a fist properly anyway.

On the subject of "what to strike with", I'm reminded of a Terry Pratchett book-quote:

> [The werewolf] gave him a ringing slap and that would have ended it, except that it also pulled itself a little further up the tree and brought itself within the range of the Vimes Elbow.

> It justified the capital letter. It had triumphed in a number of street fights. Vimes had learned early on in his career that the graveyards were full of people who'd read the Marquis of Fantailler. The whole idea of fighting was to stop the other bloke hitting you as soon as possible. It wasn't to earn marks. Vimes had often fought in circumstances where being able to use the hands freely was a luxury, but it was amazing how a well-placed elbow could make a point, possibly assisted by a knee.

-- The Fifth Elephant by Terry Pratchett

A footnote from an earlier reference explains that:

> * The Marquis of Fantailler got into many fights in his youth, most of them as a result of being known as the Marquis of Fantailler, and wrote a set of rules for what he termed ‘the noble art of fisticuffs’, which mostly consisted of a list of places where people weren’t allowed to hit him. Many people were impressed with his work and later stood with noble chest out-thrust and fists balled in a spirit of manly aggression against people who hadn’t read the Marquis’s book but did know how to knock people senseless with a chair.

The classic martial arts trivia (or possibly a teaching) is that serious brain injuries became more common in boxing after padded gloves started being used. Bare knuckle boxing seems more brutal but it's said to have been safer in that regard.

Using padded gloves allows for hitting the opponent much harder without injury to the hand, so they make it possible to hit with a lot more force. Serious brain injury is caused by accelerational forces, and those are only slightly reduced by the padding, but the padding gives significant protection to the thin bones of the hand. Without the protection the bones in the hand could break when struck against the relatively hardy bones of the skull.

Of course if you did happen to nicely hit the jaw, that's one of the common target spots for a knockout. A hit on the jaw causes a rotational force on the head which can more easily lead to a knockout (as well as injury to the brain).

This fact was already discussed during the antiquity.

In the Ancient Greece and then in the Roman Republic and Empire, there were 3 combat sports: wrestling, pugilism (i.e. boxing) and pancratium (i.e. MMA).

Punching was allowed in both pugilism and pancratium, but only the pugilists bandaged their hands with leather straps, to protect them from injuries (analogous to the big boxing gloves and the small MMA gloves of today).

Because of their bandaged hands, the pugilists were using hard strikes to the head much more frequently than the pancratium fighters, so finishing a fight with severe injuries was much more common for pugilists.

Some ancient writers have commented about this and they have mentioned that at big competitions like the Olympic Games it has been decided to schedule the pancratium matches before the pugilism matches, because there were some people who desired to compete in both tournaments. Had pugilism been scheduled the first, there would have been a high risk for them to be injured, preventing them to also compete in pancratium, while with pancratium before, they had good chances to be able to compete in both.

Towards the end of the 19th century, immediately after the opening of Japan, the Westerners learned for the first time about the Japanese martial arts and one of the things that were the most surprising for them was that instead of fighting with fists, like it was preferred especially in USA and UK, the Japanese preferred to use the open hand, preferably the edge or the base, as being much safer and more effective.

At the same time in Okinawa they preferred to use the fists, but that was right for them only because those using fists practiced daily conditionining of the fists by hitting a maki-wara.

Also today, for anyone who does not punch regularly some training device, hitting either with the open hand (edge or base) or only with the external side of the fist (hammer fist) is the right choice for any purpose.

In training a couple of weeks ago, my son accidently delivered a straight right to my forehead, with significant power.

It took me a few seconds to recover, but when I did it was to check his hand was okay, as we weren't wearing gloves.

He was fine. I had a headache for two days.

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