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One Punch Man: Unnecessary Science

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Let’s start this one off by saying that One Punch Man is one of my favorite anime of this year, if not all time. I saw the manga when I went to japan the year before last but I had almost forgotten about it… when suddenly a wild anime appeared!

Quick note, there are some SPOILERS in here, so if you haven’t seen the anime yet… go do that, then come back.

As a general summary for those of you who for some reason haven’t heard of it until now, the story follows the hero Saitama. The self-proclaimed ‘hero for fun’ has become so strong that he defeats all opponents with just one punch (hence the catchy title) and he has become bored with his life. It’s a great idea and it’s been executed amazingly well, but if you want more on that there are more articles on the site about it here, and there. This is unnecessary science though, and as a science nut I can’t help but wonder about the numbers involved…


Studio - Madhouse
Studio – Madhouse

To start, we’ll look at one of the ‘’villains’’, the self proclaimed rival of One Punch Man. Speed o’ sound Sonic, a physically redundant name as anything which is travelling at the speed of sound in air is ‘’sonic’’ (they even point it out in the anime <3 ). This ninja’s main claim to fame is the incredible speed he is named for but as with all things of this nature they have a big flaw. Newton’s third law (just so useful!) says that any action has an equal and opposite reaction, so every time someone jumps super-fast (say at the speed of sound) there should be an equivalent force the other way, probably obliterating whatever they launched from. ‘Probably’ isn’t quite enough for me though. So I did some basic calculations:

Assuming he has a weight of about 60 kg, being a skinny guy, and is actually travelling at the speed of sound, 330 m/s, accelerating to this speed in (for the sake of argument) 0.1 seconds would be a force of 198000 N (From the formula Force = Mass x Acceleration). For a rough comparison that’s about the same as a T-Rex bite… or lifting a semi-trailer with one leg. Ouch! And not only that! If you are already in motion, to redirect yourself back the way you came at the same speed you would need TWICE the force. So two semi-trailers… or one regular trailer? In any event the ground should shatter every time he jumps.

Though in fairness to this show he does have incredible strength to go with his speed which he would actually need! So good job there!! I guess we’ll just have to attribute the lack of impact to his super ninja powers.


Next to come under the scrutiny of science is the big gormless guy himself! Saitama-Sensei, the One Punch Man.

Studio - Madhouse
Studio – Madhouse

There is so much here… So much to pick from. But watching this anime comes with a large suspense of my disbelief. The whole point of a lot of it is the comedy of him obtaining all of this power with basic strength training and how ridiculous it is! So instead of tearing the logic apart, I’ll just try and take one of the biggest achievements to date in the anime and quantify it a bit.

The obvious choice here would be the destruction of the meteor, but that’s been done. I’m sure you could google it quickly and find some forum threads or someone who has worked it out already for superman or another hero. So I decided to go with what I thought was potentially more impressive feat, the sparring match with Genos. Not the match itself, though the animation was AMAZING! I am more interested in the concussion blast Saitama ends it with, cleaving a gaping hole in the side of the cliff.

It’s not a spectacularly brilliant bit of damage in comparison to some of the other mayhem he has wrought but it is special in that he doesn’t actually touch it at all. It’s a pure air palm, which barely ruffles Genos’ hair. Physically this has two explanations:

  1. Genos is incredibly tough and just took it like a champ.
  2. There is no option 2.

I can think of literally no other explanation as to how this happened. There was no way of applying additional force after it passed Genos and if anything it would have been more powerful when it hit Genos as it would be more ‘concentrated’. And the hole was fully taken out so it wasn’t just a punch around him. Seriously, if anyone has any explanations that hold water please leave them in the comments, I’m drawing a blank here.

In terms of the force though clearing a hole like that would require some high powered explosives in the real world. So just making a rough guess at the mountain/plateau thing being about 1 km deep and 100 m high. Given it is rock, this might equate to needing 1 stick of TNT per 20 m cubed. A quick volume calculation shows the hole is 100050503.12 (from a cylinder volume) leaving us with 7800000 m^3 of rock. That is a whole lot of rock! And would need roughly 390000 sticks of dynamite. Google then tells me that TNT has an energy output of 5 MJ. So for the whole explosion there would be 1950000 MJ (or 1.9510^12 MJ), which is a LOT of energy. For a rough comparison, that’s about a tenth as much energy of the Little Boy atomic bomb dropped on Hiroshima in WWII. AND HE DIDN’T EVEN TOUCH THE THING!

Studio - Madhouse
Studio – Madhouse

This insane level of power was him playing around too… He’s more than a little broken. Though to give Genos his due credit he took that to the face and only ended up with a bad hair day. This is a very rough calculation though and doesn’t take very much into account but even being off by a factor of 100 or more gives an incredible amount of power.

To summarize, Saitama is broken, Sonic is magic, and the whole show is INCREDIBLE! Seriously, if you haven’t seen One Punch Man yet I highly recommend you do ASAP.




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  1. In Martial Arts novels there are technique to transfer force beyond the target while leaving it unscath. One of best demonstration of this is in the first story arc of Jojo’s Bizarre Adventures where Baron Zeppeli was teaching our hero Jonathan Joestar the art of Ripple. He place turtle atop a boulder and proceed on executing a tremendous punch. The boulder is split in half, but the turtle is utterly unharmed.

    This is probably a parody of that, as Saitama need to have absolute control over his power or he wouldn’t have any place to live as every single action he takes can literally destroy everything around without even trying.

    1. Yeah I think I’m going to have to consign this one to ”anime sense”. Science can only get you so far and it has been shown that Anime>Science.

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