xkcd #2897: Light Leap Years
xkcd #2897: Light Leap Years
Alt text:
When Pope Gregory XIII briefly shortened the light-year in 1582, it led to navigational chaos and the loss of several Papal starships.
Why not redefine lightyears to include a leap year every four years. Except when the number ends on 00, but only if it is not divisible by 400. Physics would be so much easier!
Well it's in fact easy to calculate...
To make it easier to visualize we'll start with year 400. From year 400 to year 799 you've got a leap year every 4 years except for years 500, 600, 700 and including year 400, so that's 25 leap years for the first century and 24 for the others.
So you've got 25 + (3x24) = 97 leap years
And 75 + (3 x 76) = 303 non leap years
(97 x 366) + (303 x 365) = 146097 days every 400 years which means a year is 365.2425 days long on average.
365.2425 x 24 = 8765.82 hours on average
8765.82 x 60 x 60 = 31 556 952 seconds per year on average
31 556 952 x 299 792 458 (speed of light per second) = a light year is 9460536207068016 meters long or 9460536207068.016 km long when adjusted to take leap years into consideration.
Alt text lol
there's never been a "Papal starship"^[citation ^needed]
There hasn't been a Papal starship yet. I'm pretty sure he could Christen one, or delegate that authority to the bishop of the moon, an actual thing that technically exists.
Hmmm now that I think about this a light year would be (should be) based on an average year, not what we observe in any given year.
365.2425 days. Different searches give different results but that's what I'm going with.
idk, it feels more intuitive for it to be based on the mode (most common) year length (365) instead of the average year length (365.2425).
The boring answer is that in physics a year is just defined as the time it takes for the Earth to orbit the sun, they don't care about calendars and leap years
I would've said 365.25 days?
You'd be imprecise for civil timekeeping, but spot on for astronomy
The civil rule is it's a leap year if the year is divisible by 4, unless it is also divisible by 100 unless it is also divisible by 400
We saw the rules play out in 2000 (at least those of us over 23 saw it) which is a year divisible by 100 and by 400 so it was a leap year
Yours (and astronomy's) is Julian style "if it's divisible by 4"
I prefer the newer calendars, where there is no good mental calculation for leap years - it's a leap year when the computer says it's a leap year
I would think that the best time period to use for a light year is whatever year definition has been used to date
Now let's work on the best second to use for the light second
Just wondering, but do people actually find xkcd funny? Are these comics supposed to be funny?
absolutely.
not every joke is going to land with everyone. sometimes they're not even jokes, just pointing out absurdities.
if they don't land with you, i wouldn't stress it. sometimes the humor is extremely nerdy. it's like the Far Side or Monty Python. it's not everyone's cup of tea, and that's OK.
Wholesome reply 🥰
They're hit or miss. This one is mildly amusing to me. It's been going strong 3 comics a week for how many years now? Not all of them are good of course, some I consider just bad but I think most weeks have at least one good one.
This one made me laugh. Most I just find to be novel, silly, or interesting, but a fair few are pretty funny to me.
It's a comic published multiple times a week. Common social etiquette is that if you find it funny (which is known to happen), you give it a grin or a mild chuckle or whatever, and then move on with your morning and, by extension, the rest of your life.
I would argue that nearly no one finds this one funny but many found this one funny
The OP comic is less accessible than the empiricism one, so the target audience is smaller, some of the smaller audience comics required one knew Firefly, open source memes, and Corey Doctorow. When you're in the target group the comics are especially hilarious
Some have fallen flat for me until I looked up XKCD explained, since I have very low knowledge of pop culture. I wouldn't say those aren't funny, I say I don't get them
I think 5% of them are somewhat funny but 100% of them are pretentious as fuck, so I avoid. Nerds aren’t cool, nerds are the problem. They gave us Trump, 4chan, gamergate, etc.
When we bullied nerds the world was a better place.
You seem nice.