# Why do we pretend days, weeks, months exist? **URL:** \ **Category:** In My Humble Opinion\ **Created:** [October 1, 2018, 9:43pm UTC](https://boards.straightdope.com/t/why-do-we-pretend-days-weeks-months-exist/822288 "2018-10-01T21:43:26Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Machinaforce](https://avatars.discourse-cdn.com/v4/letter/m/aeb1de/32.png) [@Machinaforce](https://boards.straightdope.com/u/Machinaforce)\ **Post date:** [October 1, 2018, 9:43pm UTC](https://boards.straightdope.com/t/why-do-we-pretend-days-weeks-months-exist/822288/1 "2018-10-01T21:43:26Z")
Why do we act like these things exist? Isn’t it just changes in light? How do we divide such things in a manner like that? How do we decide how many days in a month? Would it apply if we weren’t on earth? ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [October 1, 2018, 9:51pm UTC](https://boards.straightdope.com/t/why-do-we-pretend-days-weeks-months-exist/822288/2 "2018-10-01T21:51:15Z")
Because they do exist. Next question? ---
**Author:** ![HMS\_Irruncible](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hms_irruncible/32/7394_2.png) [@HMS\_Irruncible](https://boards.straightdope.com/u/HMS_Irruncible)\ **Post date:** [October 1, 2018, 9:51pm UTC](https://boards.straightdope.com/t/why-do-we-pretend-days-weeks-months-exist/822288/3 "2018-10-01T21:51:26Z")
Dude, puff it or pass it. ---
**Author:** ![begbert2](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/begbert2/32/3357_2.png) [@begbert2](https://boards.straightdope.com/u/begbert2)\ **Post date:** [October 1, 2018, 9:51pm UTC](https://boards.straightdope.com/t/why-do-we-pretend-days-weeks-months-exist/822288/4 "2018-10-01T21:51:42Z")
Days obviously exist - the earth actually rotates, and a “day” is merely a way of describing the side effects of that fact. Weeks and months only exist because we say they do\*. We do this because it’s a convenient way of keeping track of things. We like convenient things because they’re convenient. - Months used to be based on the cycles of the moon, which, like the rotation of the earth is a real thing. not so much anymore though. ETA: Were we to leave earth we’d probably still use “days” because they’re convenient - among other things human sleep patterns line up pretty okay with them. Were we to go to a different planet with a different rotation we’d get all confused and society would collapse. ---
**Author:** ![OldGuy](https://avatars.discourse-cdn.com/v4/letter/o/3bc359/32.png) [@OldGuy](https://boards.straightdope.com/u/OldGuy)\ **Post date:** [October 1, 2018, 9:57pm UTC](https://boards.straightdope.com/t/why-do-we-pretend-days-weeks-months-exist/822288/5 "2018-10-01T21:57:04Z")
Well days are probably the most obvious natural time. I expect mankind had a word (or words) for day and night almost as soon as language developed. Whether or not we had a word for one day & night together is not so clear. Months, almost certainly were developed from one cycle in the phases of the moon. I expect such a word was also quite early. Year is a hard concept, particularly because a year’s not an even number of months. ---
**Author:** ![Ethilrist](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ethilrist/32/4604_2.png) [@Ethilrist](https://boards.straightdope.com/u/Ethilrist)\ **Post date:** [October 1, 2018, 9:57pm UTC](https://boards.straightdope.com/t/why-do-we-pretend-days-weeks-months-exist/822288/6 "2018-10-01T21:57:05Z")
To keep everything from happening all at once. ---
**Author:** ![JB99](https://avatars.discourse-cdn.com/v4/letter/j/439d5e/32.png) [@JB99](https://boards.straightdope.com/u/JB99)\ **Post date:** [October 1, 2018, 10:13pm UTC](https://boards.straightdope.com/t/why-do-we-pretend-days-weeks-months-exist/822288/7 "2018-10-01T22:13:50Z")
Okay, I’m gonna give OP the benefit of the doubt here… Days and years are very definitely real and objectively measurable. The Earth rotates on its axes, and it also circumnavigates the Sun. So no matter where you are on Earth or in outer space, an Earth-Day and and Earth-Year and the equinoxes are all objectively observable phenomenon. Weeks and months are a human invention, because we find it convenient to divide the year into segments. It helps maintain our rhythm and pattern of life. More specifically, we are using a calendar introduced by a Pope in 1582. There are many other perfectly good calendars that do not include weeks or months. They are just less convenient and less widespread than the Gregorian Calendar. We have other ways of validating our measurements. For instance, a light-second is a unit of length equal to the distance light in empty space travels in one second, and is exactly 299,792,458 meters. This means that even if someone destroyed every clock on the planet Earth, we would still be able to calculate the length of one second, so long as we can calculate the speed of light. Would it still apply if we weren’t on Earth? Good question. Does the Earth continue to move in this scenario? Since it is really, really,\*\* really \*\*hard to stop 5.9 sextillion tonnes of rock and molten metal, I’m going to assume that, yes, the Earth continues to move much as it has in the past. Therefore, the value of an Earth-day and an Earth-year still has meaning. If you were to land on Mars, it might not mean much to you because a Mars-day and a Mars-year are not the same length as their Terran counterparts, but if you intend to send a communication back to Earth it might be helpful to know what day of the Earth-week it is. ---
**Author:** ![Kimstu](https://avatars.discourse-cdn.com/v4/letter/k/ecd19e/32.png) [@Kimstu](https://boards.straightdope.com/u/Kimstu)\ **Post date:** [October 1, 2018, 10:38pm UTC](https://boards.straightdope.com/t/why-do-we-pretend-days-weeks-months-exist/822288/8 "2018-10-01T22:38:23Z")
> [@JB99](#): > > Days and years are very definitely real and objectively measurable. […] > > Weeks and months are a human invention, because we find it convenient to divide the year into segments. Nitpick: As other posters have noted, the unit of the month was originally (and in some calendars still is) based on the cycle of the moon’s phases, which is also very definitely real and objectively measurable. Weeks are more arbitrary and more variable, although the 7-day week is probably at least partly inspired by the real and measurable lunar phases of new moon, full moon and half moons. ---
**Author:** ![DrFidelius](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/drfidelius/32/3447_2.png) [@DrFidelius](https://boards.straightdope.com/u/DrFidelius)\ **Post date:** [October 1, 2018, 10:41pm UTC](https://boards.straightdope.com/t/why-do-we-pretend-days-weeks-months-exist/822288/9 "2018-10-01T22:41:04Z")
People live in societies and It is much easier to coordinate things like plantings or harvests if we all agree to meet the second Grunesday after the Flying Fox moon. ---
**Author:** ![elfkin477](https://avatars.discourse-cdn.com/v4/letter/e/a9a28c/32.png) [@elfkin477](https://boards.straightdope.com/u/elfkin477)\ **Post date:** [October 1, 2018, 10:56pm UTC](https://boards.straightdope.com/t/why-do-we-pretend-days-weeks-months-exist/822288/10 "2018-10-01T22:56:35Z")
Humans find it easier if we can agree on a name for an otherwise arbitrary block of time. Can you see what difficulty there would be in trying to coordinate to get things accomplished _with other people_ if we either had independent terms for a segment of time **or** no concept of time at all? ---
**Author:** ![burpo\_the\_wonder\_mutt](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/burpo_the_wonder_mutt/32/365_2.png) [@burpo\_the\_wonder\_mutt](https://boards.straightdope.com/u/burpo_the_wonder_mutt)\ **Post date:** [October 1, 2018, 10:59pm UTC](https://boards.straightdope.com/t/why-do-we-pretend-days-weeks-months-exist/822288/11 "2018-10-01T22:59:53Z")
> [@DrFidelius](#): > > People live in societies and It is much easier to coordinate things like plantings or harvests if we all agree to meet the second Grunesday after the Flying Fox moon. They’re closed on Grunesday. ---
**Author:** ![BobBitchin](https://avatars.discourse-cdn.com/v4/letter/b/7ea924/32.png) [@BobBitchin](https://boards.straightdope.com/u/BobBitchin)\ **Post date:** [October 1, 2018, 11:21pm UTC](https://boards.straightdope.com/t/why-do-we-pretend-days-weeks-months-exist/822288/12 "2018-10-01T23:21:20Z")
> [@HMS\_Irruncible](#): > > Dude, puff it or pass it. :D:cool: I’m there, man:p I support both, recreational activities:D, and engaging in sessions of questioning everything as a practice of sorts for critical thinking. Challenging ones own assumptions/beliefs has to be a good thing right? You weed out the bad reasoning:cool: (or he’s baked:p) ---
**Author:** ![burpo\_the\_wonder\_mutt](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/burpo_the_wonder_mutt/32/365_2.png) [@burpo\_the\_wonder\_mutt](https://boards.straightdope.com/u/burpo_the_wonder_mutt)\ **Post date:** [October 1, 2018, 11:30pm UTC](https://boards.straightdope.com/t/why-do-we-pretend-days-weeks-months-exist/822288/13 "2018-10-01T23:30:19Z")
> [@bobbitchin'](#): > > \ you weed out the bad reasoning \ iswydt ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [October 1, 2018, 11:38pm UTC](https://boards.straightdope.com/t/why-do-we-pretend-days-weeks-months-exist/822288/14 "2018-10-01T23:38:06Z")
Also, what’s the deal with “hours” and “minutes”? Do we really _need_ those? And don’t get me started on “seconds”… What’s next, _thirds_? ---
**Author:** ![Mr.Bill](https://avatars.discourse-cdn.com/v4/letter/m/5f9b8f/32.png) [@Mr.Bill](https://boards.straightdope.com/u/Mr.Bill)\ **Post date:** [October 1, 2018, 11:49pm UTC](https://boards.straightdope.com/t/why-do-we-pretend-days-weeks-months-exist/822288/15 "2018-10-01T23:49:58Z")
> [@Darren\_Garrison](#): > > Also, what’s the deal with “hours” and “minutes”? Do we really _need_ those? And don’t get me started on “seconds”… What’s next, _thirds_? Well, when you are trying to run a complex society, you need to be able to know WHEN someone is supposed to arrive at a certain place. Do you want to go to your doctor’s office and find 15 other people all waiting in line for the next appointment, because everybody’s appointment was for “Grunesday”? As far as seconds, and even shorter units, when you are trying to navigate at sea, fixing the time to within a second turns out to be pretty important. And a lot of scientific investigation would be impossible without very short units of time. ---
**Author:** ![begbert2](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/begbert2/32/3357_2.png) [@begbert2](https://boards.straightdope.com/u/begbert2)\ **Post date:** [October 1, 2018, 11:50pm UTC](https://boards.straightdope.com/t/why-do-we-pretend-days-weeks-months-exist/822288/16 "2018-10-01T23:50:05Z")
> [@Darren\_Garrison](#): > > Also, what’s the deal with “hours” and “minutes”? Do we really _need_ those? And don’t get me started on “seconds”… What’s next, _thirds_? Based on how ‘seconds’ got named, a third would be 1/60th of a second. Which, obviously, it a measure of time we desperately need. ---
**Author:** ![Gatopescado](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gatopescado/32/5711_2.png) [@Gatopescado](https://boards.straightdope.com/u/Gatopescado)\ **Post date:** [October 1, 2018, 11:53pm UTC](https://boards.straightdope.com/t/why-do-we-pretend-days-weeks-months-exist/822288/17 "2018-10-01T23:53:41Z")
How else would we know when "Garbage Day’ is? 😕 ---
**Author:** ![Dallas\_Jones](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dallas_jones/32/3277_2.png) [@Dallas\_Jones](https://boards.straightdope.com/u/Dallas_Jones)\ **Post date:** [October 2, 2018, 12:26am UTC](https://boards.straightdope.com/t/why-do-we-pretend-days-weeks-months-exist/822288/18 "2018-10-02T00:26:23Z")
It is a convenient way to keep track of when we should bathe next. ---
**Author:** ![Ukulele\_Ike](https://avatars.discourse-cdn.com/v4/letter/u/df788c/32.png) [@Ukulele\_Ike](https://boards.straightdope.com/u/Ukulele_Ike)\ **Post date:** [October 2, 2018, 12:47am UTC](https://boards.straightdope.com/t/why-do-we-pretend-days-weeks-months-exist/822288/19 "2018-10-02T00:47:33Z")
Time was invented by the railroad companies in 1848, so they could tell if they were running on time. ---
**Author:** ![Ukulele\_Ike](https://avatars.discourse-cdn.com/v4/letter/u/df788c/32.png) [@Ukulele\_Ike](https://boards.straightdope.com/u/Ukulele_Ike)\ **Post date:** [October 2, 2018, 12:52am UTC](https://boards.straightdope.com/t/why-do-we-pretend-days-weeks-months-exist/822288/20 "2018-10-02T00:52:57Z")
> [@Machinaforce](#): > > Would it apply if we weren’t on earth? Of course not. Why do you think William Shatner started every episode by saying “Captain’s log! Stardate (number)” ? Since you couldn’t have weeks in space, they invented some other measurement system. Not sure where they got “five-year mission.” Kirk: “Take over, Spock. I’ll be in the men’s room for the next 15 minutes.” Spock: “The MEN’S ROOM? I can’t believe my ears!” Kirk: “I can’t believe your ears either, Mr Spock.” [Next page](https://boards.straightdope.com/t/why-do-we-pretend-days-weeks-months-exist/822288.md?page=2)