To anyone reading this now and thinking, “299,792,458 m/s is the speed of light!”: stairlane’s comment originally gave 299,456,352 m/s as the speed of light. Unfortunately they’ve since edited it to the correct value, thus ruining a very good exchange

This is the most terrifying exchange I've read on HN in a while

The smack to the head sent him into a parallel dimension with a different speed of light and he's just now finding out.

Harsh. Considering that most of us remember it as 3x10^8 m/s I was willing to roll with it.

Apparently he is a little off. 299,792,458 m/s according to Wikipedia

https://en.wikipedia.org/wiki/Speed_of_light

Right, and that's a definition. Modern SI works by defining constants, so then when scientists figure out a way to measure more exactly they're actually refining our understanding of the SI units, the numbers (such as the speed of light in metres per second) never change any more, so that's convenient.

It is in a material with a refractive index of 1.001122387 ¯\_(ツ)_/¯

Probably meant to type km/s

Just the wrong number, at least for light in a vacuum. 299,792,458 m/s is the correct value.