# Tell us an interesting random fact you stumbled across (Part 1) **URL:** \ **Category:** Miscellaneous and Personal Stuff I Must Share\ **Created:** [April 13, 2020, 3:19am UTC](https://boards.straightdope.com/t/tell-us-an-interesting-random-fact-you-stumbled-across-part-1/851674 "2020-04-13T03:19:22Z")\ **Posts on this page:** 20\ **Page:** 216
**Author:** ![EastUmpqua](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eastumpqua/32/6025_2.png) [@EastUmpqua](https://boards.straightdope.com/u/EastUmpqua)\ **Post date:** [April 30, 2022, 9:28pm UTC](https://boards.straightdope.com/t/tell-us-an-interesting-random-fact-you-stumbled-across-part-1/851674/4309 "2022-04-30T21:28:37Z")
I stumbled across the reason why there are two high tides per day. I always understood why there’s one high tide (the moon’s gravity pulling the water towards it). The reason there are two high tides doesn’t actually have much to do with the Sun’s gravity. ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [April 30, 2022, 9:56pm UTC](https://boards.straightdope.com/t/tell-us-an-interesting-random-fact-you-stumbled-across-part-1/851674/4310 "2022-04-30T21:56:04Z")
Not sure what reason you stumbled across, but one reason _isn’t_ that the moon is pulling the water towards it – Tides are the result of a gravitational gradient – the pull of the moon’s gravity varies across the diameter of the earth becauswe gravity varies as the inverse square of the distance. There’s an “average” pull at the earth’s center that’s different from the pull at the side closest to the moon and also different from the pull at the point opposite the moon. You can find this in lots of places on the internet. Here’s one of the first that popped u – [Lunar Tides](http://www.pas.rochester.edu/~blackman/ast104/tides.html) There are tides due to the sun, as well. They’re not as large, because the sun id so far away that the gradient (change across the diameter of the earth) is much smaller, not because the pull of the sun’s gravity is weaker than that of the moon (it isn’t). ---
**Author:** ![Jim\_B](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jim_b/32/4338_2.png) [@Jim\_B](https://boards.straightdope.com/u/Jim_B)\ **Post date:** [May 1, 2022, 2:38pm UTC](https://boards.straightdope.com/t/tell-us-an-interesting-random-fact-you-stumbled-across-part-1/851674/4311 "2022-05-01T14:38:41Z")
I actually discovered this fact rather by accident (believe it or not, most of what I know about computers, laptops and smartphones comes from trial-and-error). But believe it or not, you really don’t need a mouse to control your computer. Oh, I wouldn’t be without one for sure. But everything it does, could in theory be handled by your keyboard. I’m serious. I think the TAB button will allow you to jump from item to item. And then if you want to highlight an item it takes you to, just hit the SPACE bar. I’m serious. And of course to choose a highlighted item, hit ENTER. But you probably knew that 😉 🙂 EDIT: Here, and this list is invaluable, I have found: Ctrl + A to select all items Ctrl + C to copy selected text or items Ctrl + V to paste the contents of the clipboard Ctrl + P to print Ctrl + Z to undo Ctrl + X to cut selected text Ctrl + B to add/remove Bold formatting Ctrl + I to add/remove Italic formatting Ctrl + W to close the active window Ctrl while dragging a file to copy the file Ctrl + Shift while dragging a file to create a shortcut Ctrl + holding this down, highlights multiple files, you choose. Ctrl-O Open; Ctrl-F Find; Ctrl-S Save; Ctrl-H Replace; Ctrl-N New; Etc. [There of course is an Alt list too, But we’ll save that for next time 😉 🙂 .] EDIT QUESTION: Just thought of something. Highlighting the text you want. How could you do that [without a mouse]? Hmmm… ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [May 1, 2022, 2:48pm UTC](https://boards.straightdope.com/t/tell-us-an-interesting-random-fact-you-stumbled-across-part-1/851674/4312 "2022-05-01T14:48:07Z")
> [@Jim\_B](#): > > (believe it or not, most of what I know about computers, laptops and smartphones comes from trial-and-error). I’m not having a hard time believing it. ---
**Author:** ![pjd](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pjd/32/3009_2.png) [@pjd](https://boards.straightdope.com/u/pjd)\ **Post date:** [May 1, 2022, 3:53pm UTC](https://boards.straightdope.com/t/tell-us-an-interesting-random-fact-you-stumbled-across-part-1/851674/4313 "2022-05-01T15:53:42Z")
> [@Jim\_B](#): > > Just thought of something. Highlighting the text you want. How could you do that [without a mouse]? Hmmm… Shift + Arrow keys ---
**Author:** ![alovem](https://avatars.discourse-cdn.com/v4/letter/a/b38774/32.png) [@alovem](https://boards.straightdope.com/u/alovem)\ **Post date:** [May 1, 2022, 5:01pm UTC](https://boards.straightdope.com/t/tell-us-an-interesting-random-fact-you-stumbled-across-part-1/851674/4314 "2022-05-01T17:01:24Z")
And pressing the [Windows](https://en.wikipedia.org/wiki/Windows_key) and “d” keys simultanously will minimize all open windows (“d” for desktop). ---
**Author:** ![EastUmpqua](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eastumpqua/32/6025_2.png) [@EastUmpqua](https://boards.straightdope.com/u/EastUmpqua)\ **Post date:** [May 1, 2022, 10:07pm UTC](https://boards.straightdope.com/t/tell-us-an-interesting-random-fact-you-stumbled-across-part-1/851674/4315 "2022-05-01T22:07:59Z")
> [@CalMeacham](#): > > but one reason _isn’t_ that the moon is pulling the water towards it – Tides are the result of a gravitational gradient I don’t understand this. What I thought I stumbled across is that one high tide is caused by the gravitational gradient caused by the moon’s mass. The second high tide is caused by [centrifugal force](https://en.wikipedia.org/wiki/Centrifugal_force) on the opposite side of the planet. From a wiki article: “This is the case for the [Earth–Moon system](https://en.wikipedia.org/wiki/Lunar_theory), whose barycenter is located on average 4,671 km (2,902 mi) from Earth’s center, which is 75% of Earth’s radius of 6,378 km (3,963 mi)”. ---
**Author:** ![carnut](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnut/32/3531_2.png) [@carnut](https://boards.straightdope.com/u/carnut)\ **Post date:** [May 1, 2022, 10:44pm UTC](https://boards.straightdope.com/t/tell-us-an-interesting-random-fact-you-stumbled-across-part-1/851674/4316 "2022-05-01T22:44:22Z")
If you google “keyboard shortcuts” you’ll be able to find lots of them. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [May 2, 2022, 12:16pm UTC](https://boards.straightdope.com/t/tell-us-an-interesting-random-fact-you-stumbled-across-part-1/851674/4317 "2022-05-02T12:16:43Z")
> [@EastUmpqua](#): > > The second high tide is caused by [centrifugal force](https://en.wikipedia.org/wiki/Centrifugal_force) on the opposite side of the planet. From a wiki article: “This is the case for the [Earth–Moon system](https://en.wikipedia.org/wiki/Lunar_theory), whose barycenter is located on average 4,671 km (2,902 mi) from Earth’s center, which is 75% of Earth’s radius of 6,378 km (3,963 mi)”. You could take centrifugal force out of the picture entirely, and you’d still have two tides. Imagine the earth and moon are not orbiting each other. Instead, they are falling straight toward each other. The earth itself is accelerating toward the moon at a particular rate based on its distance. On the near side, the oceans are experiencing stronger lunar gravity than the earth is, so water piles up there, forming a high tide. On the far side of the earth, the oceans are experiencing weaker lunar gravity than the earth is, so the ocean lags behind and piles up there too, forming another high tide. There is also a component of the lunar gravity gradient directed perpendicular to the earth-moon axis, which also tends to move water toward the near/far points of the earth without discriminating between two. > **[Tidal force](https://en.wikipedia.org/wiki/Tidal_force)** > > The tidal force or tide-generating force is a gravitational effect that stretches a body along the line towards and away from the center of mass of another body due to spatial variations in strength in gravitational field from the other body. It is responsible for the tides and related phenomena, including solid-earth tides, tidal locking, breaking apart of celestial bodies and formation of ring systems within the Roche limit, and in extreme cases, spaghettification of objects. It arises because ... ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [May 2, 2022, 1:13pm UTC](https://boards.straightdope.com/t/tell-us-an-interesting-random-fact-you-stumbled-across-part-1/851674/4318 "2022-05-02T13:13:19Z")
# Gas Giants Have Been Ghostwriting Letters Of Support From Elected Officials That’s the headline in the Huffington Post. I was stunned. Who knew that Jupiter, Saturn, Uranus, and Neptune were even sentient, let alone that they had a connection with the US Mail or possibly even an e-mail link? But i was quickly disabused of this notion: > [@](#): > > Internal emails show pipeline firms provided North Carolina and Virginia leaders with draft letters and talking points praising their own projects. > > For the past several months, local officials in Virginia and North Carolina, primarily elected [Republicans](https://www.huffpost.com/news/topic/republican-party), have been peppering federal regulators with glowing letters in support of gas projects in their states. Internal emails reviewed by HuffPost show that these letters all had something in common: They were ghostwritten by lobbyists and consultants of the two major pipeline firms behind those projects. Of _course!_ The letters were written by lobbyists! Not by large planets or minor Republican officials! Why would I ever think they were capable of writing such letters? > **[Gas Giants Have Been Ghostwriting Letters Of Support From Elected Officials](https://www.huffpost.com/entry/williams-tc-energy-pipeline-projects-influence-virginia-north-carolina_n_6261e382e4b0dc52f494659e)** > > Internal emails show pipeline firms provided North Carolina and Virginia leaders with draft letters and talking points praising their own projects. ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [May 2, 2022, 5:35pm UTC](https://boards.straightdope.com/t/tell-us-an-interesting-random-fact-you-stumbled-across-part-1/851674/4319 "2022-05-02T17:35:07Z")
There is a glass bridge between two peaks (actually, more “across a valley” in Vietnam as a tourist attraction: > [@](#): > > The Bach Long bridge is open for thrill-seeking visitors, offering a glass-bottomed walkway suspended nearly 500 feet above the ground [https://www.cnn.com/videos/travel/2022/04/30/bach-long-glass-bridge-vietnam-travel-lon-orig-na-kj.cnn](https://www.cnn.com/videos/travel/2022/04/30/bach-long-glass-bridge-vietnam-travel-lon-orig-na-kj.cnn) I’m irresistably reminded of this Monty Python routine, especially at 1:30 in [![]( " - YouTube") ](https://www.youtube.com/watch?v=IdTy1j7z-K4) ---
**Author:** ![EastUmpqua](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eastumpqua/32/6025_2.png) [@EastUmpqua](https://boards.straightdope.com/u/EastUmpqua)\ **Post date:** [May 2, 2022, 8:59pm UTC](https://boards.straightdope.com/t/tell-us-an-interesting-random-fact-you-stumbled-across-part-1/851674/4320 "2022-05-02T20:59:26Z")
> [@Machine\_Elf](#): > > You could take centrifugal force out of the picture entirely, and you’d still have two tides. According to this [NOAA article on tides](https://tidesandcurrents.noaa.gov/restles3.html), centrifugal force is one of the basic forces that cause Earth’s tides. Quote from article: “The tide-raising forces at the earth’s surface thus result from a combination of basic forces: (1) the force of gravitation exerted by the moon (and sun) upon the earth; and (2) centrifugal forces produced by the revolutions of the earth and moon (and earth and sun) around their common center-of-gravity (mass) or barycenter.” ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [May 2, 2022, 10:43pm UTC](https://boards.straightdope.com/t/tell-us-an-interesting-random-fact-you-stumbled-across-part-1/851674/4321 "2022-05-02T22:43:44Z")
> [@EastUmpqua](#): > > According to this [NOAA article on tides](https://tidesandcurrents.noaa.gov/restles3.html), centrifugal force is one of the basic forces that cause Earth’s tides. Quote from article: “The tide-raising forces at the earth’s surface thus result from a combination of basic forces: (1) the force of gravitation exerted by the moon (and sun) upon the earth; and (2) centrifugal forces produced by the revolutions of the earth and moon (and earth and sun) around their common center-of-gravity (mass) or barycenter.” From your link: > _The Effect of Centrifugal Force._ It is this little known aspect of the moon’s orbital motion which is responsible for one of the two force components creating the tides. Centrifugal force is one component of it, but I stand by my earlier statement: if you removed centrifugal force from the situation and replaced it with linear acceleration of the earth toward the moon (under the influence of mutual gravitational attraction), you’d still have two high tides per day to the gradient of lunar gravitational force. ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [May 3, 2022, 12:08pm UTC](https://boards.straightdope.com/t/tell-us-an-interesting-random-fact-you-stumbled-across-part-1/851674/4322 "2022-05-03T12:08:39Z")
More than you ever wanted to know about gravitational gradient and centrifugal force affecting tides below. Lotsa math. Unfortunately, they don’t calculate or estimate the size of the relative contributions. But the centrifugal part is much smaller than the gravitational gradient. If you had a non-rotating earth, both the moon and sun would still give you tides. The centrifugal force, like the fluid flow around the features of continents, is a contributing factor to the tides that can drive anyone trying to calculate the tides insane. > **[1506.04085.pdf](https://arxiv.org/ftp/arxiv/papers/1506/1506.04085.pdf)** > > 995.85 KB Here’s an explanation without all the math: [https://www.lockhaven.edu/~dsimanek/scenario/tides.htm](https://www.lockhaven.edu/~dsimanek/scenario/tides.htm) ---
**Author:** ![commasense](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/commasense/32/3017_2.png) [@commasense](https://boards.straightdope.com/u/commasense)\ **Post date:** [May 3, 2022, 2:21pm UTC](https://boards.straightdope.com/t/tell-us-an-interesting-random-fact-you-stumbled-across-part-1/851674/4323 "2022-05-03T14:21:24Z")
> [@Jim\_B](#): > > But believe it or not, you really don’t need a mouse to control your computer. > > Oh, I wouldn’t be without one for sure. But everything it does, could in theory be handled by your keyboard. I’m serious. Gather around, children, and let ol’ Grampa Comma tell you all about computers in the good old days. Believe it or not, back in the early days of home computers, you couldn’t talk to your computer. Most computers didn’t even have a mouse. Hell, some computers didn’t even have [keyboards](https://en.m.wikipedia.org/wiki/Altair_8800#/media/File%3AAltair_8800_Computer.jpg)! The screens were tiny, they only displayed green characters on a black background, no pictures or graphics. And we liked it that way! Then some busybodies thought it would be better to have colors and pictures and something called a gooey, and instead of typing your commands using the keyboard, like God intended, you would point at things with this mouse thingamajig. We warned them that this would mean the end of civilization as we knew it, because then even stupid people would be able to use computers, but would they listen? No! So a couple of hippies named Steve made this new computer (using ideas they had stolen, by the way) that had a color screen and a mouse, and everyone just went crazy. Bill, who had personally created DOS (at least, that’s what he told IBM), the perfect operating system, succumbed to the pressure and personally wrote every line of something called Windows, which was also in color and used a mouse. But since he had been one of us before he sold out, he made sure that those of us who refused on principle to buy a mouse would be able to do everything those newby slackers could do with their friggin’ mice. And thanks to certain pictures some of us have of certain people, we have had the power to make sure that almost all those keyboard commands have been carried down in every generation of operating system ever since. And so it will be forever and ever. Amen. Now, you young whippersnappers get back to your FaceGram, InstaTok, and SnapBook. Old Grampa Comma wants to get back to his exciting game of [Microsoft Adventure](https://en.m.wikipedia.org/wiki/Microsoft_Adventure) before I take my nap. I’ve only got a few more treasures to find! ---
**Author:** ![Lumpy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lumpy/32/446_2.png) [@Lumpy](https://boards.straightdope.com/u/Lumpy)\ **Post date:** [May 3, 2022, 2:40pm UTC](https://boards.straightdope.com/t/tell-us-an-interesting-random-fact-you-stumbled-across-part-1/851674/4324 "2022-05-03T14:40:28Z")
Here’s an interesting video about how the first 19th century mechanical computers tackled the surprisingly complex factors in predicting tides. Apparently no fewer than ten frequencies have to be accounted for: [![](https://img.youtube.com/vi/IgF3OX8nT0w/maxresdefault.jpg "The Most Powerful Computers You've Never Heard Of") ](https://www.youtube.com/watch?v=IgF3OX8nT0w) ---
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [May 3, 2022, 5:01pm UTC](https://boards.straightdope.com/t/tell-us-an-interesting-random-fact-you-stumbled-across-part-1/851674/4325 "2022-05-03T17:01:28Z")
Keyboard shortcuts as we know them today were pioneered by Larry Tesler of the Xerox Palo Alto Research Centre (PARC) in 1974. Some functions, like Undo, had preceded those, but his Gypsy word processor software included cut, copy, and paste. So they’ll soon be celebrating their golden anniversary. ---
**Author:** ![Limmin](https://avatars.discourse-cdn.com/v4/letter/l/f04885/32.png) [@Limmin](https://boards.straightdope.com/u/Limmin)\ **Post date:** [May 3, 2022, 5:09pm UTC](https://boards.straightdope.com/t/tell-us-an-interesting-random-fact-you-stumbled-across-part-1/851674/4326 "2022-05-03T17:09:41Z")
> [@Crafter\_Man](#): > > …Atlas ICBM. For some reason, the skin of the ICBM will crinkle and slightly buckle just sitting there. To keep this from happening, they keep the inside of the ICBM pressurized with 4 psig of air. To continue the Atlas booster balloon analogy, I had read a while back, probably in Wolff’s _The Right Stuff_, which was based partly on actual Mercury astronaut accounts, that John Glenn, during his _Friendship 7_ ascent, when the Atlas booster was nearing its cutoff, felt a motion like a pressurized balloon let go in a room with the inlet left open. The booster wobbled back and forth as it exhausted its contents. Would be nice if anyone can confirm this for me. ---
**Author:** ![EastUmpqua](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eastumpqua/32/6025_2.png) [@EastUmpqua](https://boards.straightdope.com/u/EastUmpqua)\ **Post date:** [May 3, 2022, 7:35pm UTC](https://boards.straightdope.com/t/tell-us-an-interesting-random-fact-you-stumbled-across-part-1/851674/4327 "2022-05-03T19:35:27Z")
> [@CalMeacham](#): > > But the centrifugal part is much smaller than the gravitational gradient. Looking at the diagrams from your link (fig.3 and fig.4), it looks like the black arrow (centrifugal force) at point F is larger than the red arrow (tidal force). So for tides on that side of Earth (away from the moon), the centrifugal force is larger than the tidal force. > [@CalMeacham](#): > > If you had a non-rotating earth, both the moon and sun would still give you tides. If you had a non-rotating Earth, there would be no ocean tides, but there would still be a tidal force. ---
**Author:** ![JohnT](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnt/32/15048_2.png) [@JohnT](https://boards.straightdope.com/u/JohnT)\ **Post date:** [May 3, 2022, 7:42pm UTC](https://boards.straightdope.com/t/tell-us-an-interesting-random-fact-you-stumbled-across-part-1/851674/4328 "2022-05-03T19:42:12Z")
All this back and forth is giving me whiplash. _… i’m sorry, I’ll leave now. This is the door…?_ [Previous page](https://boards.straightdope.com/t/tell-us-an-interesting-random-fact-you-stumbled-across-part-1/851674.md?page=215) [Next page](https://boards.straightdope.com/t/tell-us-an-interesting-random-fact-you-stumbled-across-part-1/851674.md?page=217)