Board Thread:Questions and Answers/@comment-25908228-20141222101442/@comment-1173941-20180118100926

Putting aside that SAO isn't a "throw physics out the window" sort of anime where humans can smash cars barehanded and leap across buildings without effort, Kirito going at "light speed" is absolutely absurd. You don't need to be going at "light speed" for the human eye to not see you; bullets don't even approach a speed where relativistic effects would even matter, and they're absolutely invisible to the human eye.

Fan blades, which are also significantly slower than a bullet, and actually within speeds a human can momentarily produce, can also appear to be at least partially none-"visible to the human eye". The idea that the human eye can register movement at any significant fraction of the speed of light is so blatantly silly, I had to come into this thread just to tell you how wrong you are, even though I just want to go to sleep.