[stairlane]

I had a severe concussion 18 weeks before finals my 3rd year of college. Crashed hard mountain biking, broke my arm, and smashed my face. For 8 hours I was a broken record so the first hospital I visited sent me off to a trauma center in the next city over. I came out of that concussed state after they were asking me questions I should know the answer to, but couldn’t remember them for the life of me. I remember it feeling like my neurons couldn’t grab ahold of any connection. Funny enough, the two things I could remember was the speed of light and the Bohr’s magneton. After I said those two constants out loud, everything came back. To this day it was the most surreal feeling I’ve experienced.

That accident happened on a Saturday, and I didn’t sleep at all the next day for fear of going into a coma. I went to school and work on Monday, and managed to finish the semester without any issues.

I know I’m extremely lucky, but I think the fact that I went back to life as if nothing happened was what helped me recover so quickly. I still can recite 299,792,458 m/s as the speed of light and 5.788e-5 eV/T as if it’s the most hard wired connection in my brain.

[squabbles]

That isn't the speed of light.

[Handprint4469]

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

[Boogie_Man]

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

[rimunroe]

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

[MobileVet]

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

[tialaramex]

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.

[bhaney]

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

[posix_compliant]

Probably meant to type km/s

[SAI_Peregrinus]

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

[Marsymars]

I have a surprisingly similar anecdote! Face-planted skating during finals week in my first year at university. My first memories are some hours later in the waiting room at a hospital that my friends had brought me to, holding a notepad with some hand-written responses to "What happened?" and "Where am I?" because my friends had gotten tired of repeating answers to the questions I'd forget having asked every few minutes.

I only had a couple finals remaining, and my profs gave me deferrals as soon as they saw the state of my face when I showed up at their offices. Wrote them a week or two later without issue.

Didn't notice any lingering mental issues, though it's now been nearly two decades and a nerve in my face still feels a bit funny, and my current dentist pointed out that it seems like I've done some damage to some of my jaw tendons at some point. (But as it doesn't cause me problems, didn't recommend treatment.)

[IncreasePosts]

I don't have any concussions as far as I know, but my brain feels like this sometimes. I wake up and it just feels empty, there's very minimal internal monologue and it feels hard to recall anything of note. I've taken to loading up a bunch of Jeopardy questions into Anki and then doing 50 or 100 random questions over a period of a few minutes, and that seems to get my brain turned on and the inner monologue comes back, and I can recall things. I'd love to know why this happens.