https://xkcd.com/2897

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When Pope Gregory XIII briefly shortened the light-year in 1582, it led to navigational chaos and the loss of several Papal starships.

  • Sibbo
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    704 months ago

    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!

    • @Kecessa@sh.itjust.works
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      4 months ago

      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.

      • Sibbo
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        24 months ago

        Okay, but now whenever you state one light year, it’s just a normal year. When you state four, it is three normal ones and one leap year. So four times one light year would not equal four light years.

        • @Kecessa@sh.itjust.works
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          4 months ago

          You asked for a lightyear adjusted based on leap years, I provided the number. It’s a bit more than 365 light days and a bit less than 366 light days, it’s closer to the real distance covered by light during the time the earth goes around the sun.

          Edit: Don’t know why anyone would downvote me for providing what OP asked for in the first place, especially when their reply didn’t really make sense in the context…

  • BarqsHasBite
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    4 months ago

    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.

    • callyral [he/they]
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      4 months ago

      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).

      • @MBM@lemmings.world
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        274 months ago

        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

      • @KISSmyOS@feddit.de
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        104 months ago

        No, years divisible by 100 aren’t leap years, except if they’re also divisible by 400.

        • @schnurrito@discuss.tchncs.de
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          24 months ago

          I don’t think that is what Wikipedia says. Whatever one’s thoughts on Wikipedia, I’m pretty sure it is getting this right.

          365.25 is what you get if you have leap years every four years with no exceptions. This is what was done in the Julian calendar which was used in the Christian world some centuries ago (how long exactly depends on what part of the Christian world).

          365.2425 is the average year length in the Gregorian calendar which we use (where leap years are 1592, 1596, 1600, 1604, 1608, … 1692, 1696, 1704, 1708, …, 1792, 1796, 1704, 1708, …, 1892, 1896, 1904, 1908, … 1992, 1996, 2000, 2004, 2008, …, 2092, 2096, 2104, 2108, …).

          The actual average solar year is better approximated by the latter than the former, but it is still slightly off.

          • @fahfahfahfah@lemmy.billiam.net
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            14 months ago

            This seems pretty definitive to me:

            As defined by the International Astronomical Union (IAU), the light-year is the product of the Julian year (365.25 days, as opposed to the 365.2425-day Gregorian year or the 365.24219-day Tropical year that both approximate) and the speed of light (299792458 m/s).

      • BarqsHasBite
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        4 months ago

        They skip leap years every now and then. And then skip the skip. Etc. The rotation of the earth around the sun and the spin of the earth on its axis simply don’t line up into a nice number.

        • EtzBetz
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          14 months ago

          Oh okay. Yeah I only have that rule of “every 4 years” in my head. I did some other programming exercise way back where we had some other rule, but I was thinking that it would end up being the same.

      • @psud@lemmy.world
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        4 months ago

        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

        • @IHawkMike@lemmy.world
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          14 months ago

          I almost certainly won’t be alive for it, but it’s funny to think about how confused people are going to be when 2100 isn’t a leap year.

    • @psud@lemmy.world
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      34 months ago

      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

    • @Opafi@feddit.de
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      1024 months ago

      do people actually find xkcd funny?

      Yes. And I should know, I’m a people.

    • wrath_of_grunge
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      824 months ago

      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.

    • @NeatNit@discuss.tchncs.de
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      234 months ago

      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.

    • umbraroze
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      144 months ago

      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.

    • @psud@lemmy.world
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      24 months ago

      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

          • @psud@lemmy.world
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            34 months ago

            I see people like you, and I am reminded that Lemmy has nothing to dissuade those who chase the largest negative score.

            Not saying that’s what you’re doing, just that if you aren’t, you should consider it since you seem good at it

            • @suction@lemmy.world
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              4 months ago

              The day I start caring for internet points I want to be shot on the spot, please. I know, hard concept to grasp for low-to-middle educated Japanese culture aficionados.

      • @BeigeAgenda@lemmy.ca
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        174 months ago

        I think it’s hilarious that you promote nerd bashing on a platform where the majority is working with IT, just look how often posts from Programmer Humor trend.

        • @suction@lemmy.world
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          -244 months ago

          Is it „bashing“ though to point out the well researched fact that the new right wing demagogues and fascists are finding a lot of sympathy from nerd circles ? The „manosphere“, gamers, Japanese culture afficionados (because alleged racial purity), 4chan trolls, etc.

          Just saying „that’s not all nerds“ isn’t doing a good job of convincing anyone that they’re a problem and they didn’t use to be one. Something has changed.

          • @BeigeAgenda@lemmy.ca
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            194 months ago

            What a depressing load of conspiracy nonsense you got hold of there. 🙄

            I really don’t want to get any links to pages that “prove” your point.

          • @Miaou@jlai.lu
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            114 months ago

            I think your average afd voter is more likely to bully nerds than befriend them.

            Academia, the place where the woke idealogy is propped up by… Querdenker nerds? Lol give me a break

          • Sage the Lawyer
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            64 months ago

            Fucking what?

            It is well documented that the more educated someone is, the more likely they are to vote for left-wing politics. https://www.pewresearch.org/politics/2016/04/26/a-wider-ideological-gap-between-more-and-less-educated-adults/

            Thus the right’s war on education. They want uneducated masses to inundate with propaganda, not critical thinkers.

            Also I think your definition of “nerd” is absurdly narrow. Dictionary says it’s someone who is either highly enthusiastic about a particular topic or someone who is boringly studious. That’s like, virtually everyone with a college degree. People tend to major in things they’re enthusiastic about. Or, if they’re just after the “best” diploma, they’re probably in the “boringly studious” category.

            You can be a nerd about anything, and I’d actually wager most people are a nerd about at least one thing. It’s not limited to the categories you arbitrarily selected to make your point (without any actual evidence presented, I might add).

      • @sleen@lemmy.zip
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        144 months ago

        If not for nerds you wouldn’t be typing this paragraph due to the internet being non existent.

          • @moriquende@lemmy.world
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            154 months ago

            Citation needed for your entire previous comment lmao. Most nerds are actually really nice people and lean left politically.

          • @psud@lemmy.world
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            4 months ago

            It really does feel mainstream to come up with tech specs for a new comms technology, not the sort of thing that nerds* might do /s

            Tim Burners-Lee** worked in particle accelerators. Total jock****.

            * People excessively interested in tech

            ** Inventor of HTML - the web

            **** I’m old. The world is divided into nerds and jocks per Revenge of the Nerds (1984)