# Well-known obvious facts that a lot of people are ignorant of **URL:** \ **Category:** Miscellaneous and Personal Stuff I Must Share\ **Created:** [April 28, 2016, 12:06am UTC](https://boards.straightdope.com/t/well-known-obvious-facts-that-a-lot-of-people-are-ignorant-of/753294 "2016-04-28T00:06:05Z")\ **Posts on this page:** 20\ **Page:** 4
**Author:** ![Jennshark](https://avatars.discourse-cdn.com/v4/letter/j/8e8cbc/32.png) [@Jennshark](https://boards.straightdope.com/u/Jennshark)\ **Post date:** [April 28, 2016, 5:28pm UTC](https://boards.straightdope.com/t/well-known-obvious-facts-that-a-lot-of-people-are-ignorant-of/753294/61 "2016-04-28T17:28:29Z")
> [@Gatopescado](#): > > šŸ˜• > > Iā€™ve got _a lot_ of cars, and am pretty sure none of them have this ā€œfeatureā€. My BMWs ā€œgas-sideā€ is indicated by which side the hose is on the little gas icon. The Jeep has the arrow; could be a foreign/domestic difference? ---
**Author:** ![bibliophage](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bibliophage/32/7615_2.png) [@bibliophage](https://boards.straightdope.com/u/bibliophage)\ **Post date:** [April 28, 2016, 5:43pm UTC](https://boards.straightdope.com/t/well-known-obvious-facts-that-a-lot-of-people-are-ignorant-of/753294/62 "2016-04-28T17:43:53Z")
I know otherwise intelligent people who had to be told that Daylight Saving Time does not actually add an extra hour of sunlight each day for half the year. > [@chappachula](#): > > Pressing the arrow button on the elevator multiple times will _not_ make it arrive at your floor any faster. And turning the thermostat to 20 degrees hotter than you really want it will not make the room warm up any faster. > [@Common Tater](#): > > The same side of the moon (pretty much) faces the earth all the time. Until satellites and manned spacecraft orbited the moon, no human had ever seen the ā€œDark Sideā€ of the moon. I once pointed this out to an otherwise very intelligent person and he just laughed and didnā€™t believe it. WTF? Iā€™m glad you put ā€œDark Sideā€ in quotes. A lot of people seem to think the so-called dark side of the moon is in constant darkness. Itā€™s better called the far side of the moon. Itā€™s illuminated by the sun just about half the time, the same as the near side. It is a little darker because it gets no reflected light from the earth. > [@Grrr!](#): > > Cold weather itself does not cause one to catch a cold. And antibiotics do not cure the common cold. ---
**Author:** ![Greg\_Charles](https://avatars.discourse-cdn.com/v4/letter/g/839c29/32.png) [@Greg\_Charles](https://boards.straightdope.com/u/Greg_Charles)\ **Post date:** [April 28, 2016, 6:29pm UTC](https://boards.straightdope.com/t/well-known-obvious-facts-that-a-lot-of-people-are-ignorant-of/753294/63 "2016-04-28T18:29:50Z")
> [@Grrr](#): > > Cold weather itself does not cause one to catch a cold. True, but a [Yale study](http://news.yale.edu/2015/01/05/cold-virus-replicates-better-cooler-temperatures) last year showed that the cold virus spreads more effectively when itā€™s cold. Itā€™s not a refutation of medical science, but still a big victory for empiricists. That is, when my mom told me to wear a jacket or Iā€™d catch a cold, she was actually right. On the other hand, Iā€™m not blind, so she wasnā€™t right about _everything_! ---
**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:** [April 28, 2016, 6:42pm UTC](https://boards.straightdope.com/t/well-known-obvious-facts-that-a-lot-of-people-are-ignorant-of/753294/64 "2016-04-28T18:42:00Z")
> [@jtur88](#): > > Air brakes on a truck do not use air pressure to set the brake, but to release it. The default position is for the spring-loaded brakes to be applied, and the air pressure from the running truck holds the brakes in the release position and allows it to rollā€¦ This is a lot safer than having a big rig, semi tractor trailer using the traditional hydraulic brake system used in cars. The fluid is used to press the pads against the drum or disc when the brakes are applied in a hydraulic system. If you have a brake line failure in a car and lose fluid you can probably slow down and stop with a combination of gearing down and using the hand/emergency brake. That is not going to work in a 80,000 lb truck rolling down the freeway. So when a air line goes out and the truck loses air pressure all the brakes engage. There is no air pressure to keep the pads away from the drums and everything comes to a screeching stop. You have probably seen long skid marks on the highway from trucks. Not all, but some of those are from an air brake line failure. When you first start up a truck with air brakes you cannot even move it until the air pressure builds up enough to force the brake pads off the drums. It wonā€™t move at all. This is another of those faulty movie tropes, a guy hops in and starts a truck and he drives off, nope, nope, not until the air pressure releases the brakes. ---
**Author:** ![Doctor\_Jackson](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/doctor_jackson/32/32_2.png) [@Doctor\_Jackson](https://boards.straightdope.com/u/Doctor_Jackson)\ **Post date:** [April 28, 2016, 7:26pm UTC](https://boards.straightdope.com/t/well-known-obvious-facts-that-a-lot-of-people-are-ignorant-of/753294/65 "2016-04-28T19:26:47Z")
> [@Jennshark](#): > > My BMWs ā€œgas-sideā€ is indicated by which side the hose is on the little gas icon. The Jeep has the arrow; could be a foreign/domestic difference? Not that, either! My daughterā€™s 2003 Honda CRV has the pump icon with the hose on the right, no arrow. The filler cap is on the left. My 1985 Mazda has the icon with the hose on the left, no arrow, filler cap on the left. My 2005 & 2006 Hyundai SUVā€™s have the arrow pointing to the correct side. I think itā€™s just model specific. ---
**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:** [April 28, 2016, 7:27pm UTC](https://boards.straightdope.com/t/well-known-obvious-facts-that-a-lot-of-people-are-ignorant-of/753294/66 "2016-04-28T19:27:05Z")
> [@Dallas\_Jones](#): > > When you first start up a truck with air brakes you cannot even move it until the air pressure builds up enough to force the brake pads off the drums. It wonā€™t move at all. This is another of those faulty movie tropes, a guy hops in and starts a truck and he drives off, nope, nope, not until the air pressure releases the brakes. I was under the impression that there is a compressed-air storage tank somewhere on the tractor, so that the compressor doesnā€™t have to run full-time. Wouldnā€™t such a tank have an ample supply of compressed air stored up at the time the engine is shut off, and therefore available at the next restart? and if there isnā€™t a storage tank, wouldnā€™t the compressor fill up the tiny volume of the air lines pretty quickly once it starts pumping? ---
**Author:** ![bump](https://avatars.discourse-cdn.com/v4/letter/b/7c8e57/32.png) [@bump](https://boards.straightdope.com/u/bump)\ **Post date:** [April 28, 2016, 7:35pm UTC](https://boards.straightdope.com/t/well-known-obvious-facts-that-a-lot-of-people-are-ignorant-of/753294/67 "2016-04-28T19:35:28Z")
> [@Shagnasty](#): > > Stable orbits are just about falling so quickly that you always miss the surface. To go along with this one, most people seem to think that the trick for the Space Shuttle or any astronauts/satellites, etcā€¦ to get into orbit is merely getting high enough, and that the rockets take off upward and head more or less straight up. In reality, the trick is to get going fast enough to where you literally fall \*around \*the Earth, rather than down onto it. Which means you have to get going _ **FAST** _, rather than strictly high up. ---
**Author:** ![RickJay](https://avatars.discourse-cdn.com/v4/letter/r/bb73d2/32.png) [@RickJay](https://boards.straightdope.com/u/RickJay)\ **Post date:** [April 28, 2016, 7:49pm UTC](https://boards.straightdope.com/t/well-known-obvious-facts-that-a-lot-of-people-are-ignorant-of/753294/68 "2016-04-28T19:49:19Z")
We had a thread awhile back from a Doper - I do not remember who, but he or she was a prolific poster and did not otherwise seem like a drooling idiot - who did not know why the moon changes phase. You know, why sometimes itā€™s a full moon, quarter moon, etc. I made a point of trying to see if other people were similarly ignorant, and was amazed to find many are. ---
**Author:** ![dasmoocher](https://avatars.discourse-cdn.com/v4/letter/d/dbc845/32.png) [@dasmoocher](https://boards.straightdope.com/u/dasmoocher)\ **Post date:** [April 28, 2016, 8:02pm UTC](https://boards.straightdope.com/t/well-known-obvious-facts-that-a-lot-of-people-are-ignorant-of/753294/69 "2016-04-28T20:02:27Z")
> [@Razrak](#): > > This may not be what you had in mind but, correlation does not imply causation. > [@kayaker](#): > > And people who do not get this will argue their point until, somehow, a light clicks on. [xkcd](https://m.xkcd.com/552/): Guy: I used to think correlation implied causation. Then I took a statistics course. Now I donā€™t. Gal: Sounds like the class helped. Guy: Well, maybe. ---
**Author:** ![Knowed\_Out](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/knowed_out/32/7380_2.png) [@Knowed\_Out](https://boards.straightdope.com/u/Knowed_Out)\ **Post date:** [April 28, 2016, 8:21pm UTC](https://boards.straightdope.com/t/well-known-obvious-facts-that-a-lot-of-people-are-ignorant-of/753294/70 "2016-04-28T20:21:12Z")
> [@Chronos](#): > > Dr. Oz is irrelevant. The ingredients lists themselves say that thereā€™s sand in there. Itā€™s usually listed as ā€œsilicon dioxide (to ensure free flowing)ā€. Maybe thatā€™s what HIā€™s cellmate was talking about in _[Raising Arizona](https://www.youtube.com/watch?v=Wgn9fAymS2g)_. ---
**Author:** ![Joey\_P](https://avatars.discourse-cdn.com/v4/letter/j/919ad9/32.png) [@Joey\_P](https://boards.straightdope.com/u/Joey_P)\ **Post date:** [April 28, 2016, 8:34pm UTC](https://boards.straightdope.com/t/well-known-obvious-facts-that-a-lot-of-people-are-ignorant-of/753294/71 "2016-04-28T20:34:12Z")
> [@Machine\_Elf](#): > > I was under the impression that there is a compressed-air storage tank somewhere on the tractor, so that the compressor doesnā€™t have to run full-time. Wouldnā€™t such a tank have an ample supply of compressed air stored up at the time the engine is shut off, and therefore available at the next restart? > > and if there isnā€™t a storage tank, wouldnā€™t the compressor fill up the tiny volume of the air lines pretty quickly once it starts pumping? That PSSHHHHHH you hear when a tractor-trailer parks is the reservoir being emptied so the parking brakes set. ---
**Author:** ![Kimballkid](https://avatars.discourse-cdn.com/v4/letter/k/b5a626/32.png) [@Kimballkid](https://boards.straightdope.com/u/Kimballkid)\ **Post date:** [April 28, 2016, 8:54pm UTC](https://boards.straightdope.com/t/well-known-obvious-facts-that-a-lot-of-people-are-ignorant-of/753294/72 "2016-04-28T20:54:21Z")
I was working in a trailer manufacturing plant doing air line assembly (brakes and bags) when they were just switching from ā€˜need air pressure to keep onā€™-type brakes to the ā€˜need air pressure to keep offā€™-type brakes. ---
**Author:** ![usedtobe](https://avatars.discourse-cdn.com/v4/letter/u/ec9cab/32.png) [@usedtobe](https://boards.straightdope.com/u/usedtobe)\ **Post date:** [April 28, 2016, 9:18pm UTC](https://boards.straightdope.com/t/well-known-obvious-facts-that-a-lot-of-people-are-ignorant-of/753294/73 "2016-04-28T21:18:49Z")
re. Brakes. See: Westinghouse, George Invented the modern air brake - for trains. ---
**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:** [April 28, 2016, 9:20pm UTC](https://boards.straightdope.com/t/well-known-obvious-facts-that-a-lot-of-people-are-ignorant-of/753294/74 "2016-04-28T21:20:10Z")
> [@Jennshark](#): > > My BMWs ā€œgas-sideā€ is indicated by which side the hose is on the little gas icon. The Jeep has the arrow; could be a foreign/domestic difference? I donā€™t think Iā€™ve ever seen a BMW with the filler on the wrong side (left). ---
**Author:** ![usedtobe](https://avatars.discourse-cdn.com/v4/letter/u/ec9cab/32.png) [@usedtobe](https://boards.straightdope.com/u/usedtobe)\ **Post date:** [April 28, 2016, 9:20pm UTC](https://boards.straightdope.com/t/well-known-obvious-facts-that-a-lot-of-people-are-ignorant-of/753294/75 "2016-04-28T21:20:34Z")
And Mr. Otis invented the ā€œSafety Elevatorā€ - the one that doesnā€™t crash if the cable breaks (or even if all 6 or so break). ---
**Author:** ![Balance](https://avatars.discourse-cdn.com/v4/letter/b/ccd318/32.png) [@Balance](https://boards.straightdope.com/u/Balance)\ **Post date:** [April 28, 2016, 9:35pm UTC](https://boards.straightdope.com/t/well-known-obvious-facts-that-a-lot-of-people-are-ignorant-of/753294/76 "2016-04-28T21:35:35Z")
> [@Spice\_Weasel](#): > > This is called synchronous rotation, and when I learned about it in college astronomy class it blew my fucking mind. I donā€™t understand how it works. My poor professor stayed with me after class and used actual physical models and everything and I nodded and pretended to understand but I still for the life of me do not grasp the physics involved. One of my high school science teachers didnā€™t get it, either. He refused to believe it until we actually demonstrated it to him with a student walking in circles around him, rotating for one loop and not rotating for the next. ---
**Author:** ![thelurkinghorror](https://avatars.discourse-cdn.com/v4/letter/t/7c8e57/32.png) [@thelurkinghorror](https://boards.straightdope.com/u/thelurkinghorror)\ **Post date:** [April 28, 2016, 10:22pm UTC](https://boards.straightdope.com/t/well-known-obvious-facts-that-a-lot-of-people-are-ignorant-of/753294/77 "2016-04-28T22:22:40Z")
> [@Razrak](#): > > This may not be what you had in mind but, correlation does not imply causation. And even so, lots of people have heard of the concept, but when it comes to applying it they really suck at recognizing that they are making this error. > [@bibliophage](#): > > A lot of people seem to be ignorant of the difference between sleet and freezing rain. Sleet is frozen raindrops that bounce when they land on a hard surface. Freezing rain falls as liquid raindrops that spread out and freeze into a solid coating of ice when they hit a surface that is below the freezing point. Sleet has at least two definitions and it is regional. It can mean either frozen rain or [Dippinā€™ Dots](https://en.wikipedia.org/wiki/Dippin'_Dots). [Wikipedia](https://en.wikipedia.org/wiki/Sleet) says that one definition is US and one isnā€™t but that isnā€™t strictly true. Iā€™ve encountered both terms in the US. > [@silenus](#): > > Dr. Oz is an idiot. Youā€™re probably responding to the above post, but it could just as easily be a response to the OP: itā€™s an obvious fact but millions of people think that the MD makes him credible. On the other hand, maybe heā€™s a genius. Iā€™m sure his wallet isnā€™t suffering. ---
**Author:** ![spamforbrains](https://avatars.discourse-cdn.com/v4/letter/s/e274bd/32.png) [@spamforbrains](https://boards.straightdope.com/u/spamforbrains)\ **Post date:** [April 28, 2016, 10:30pm UTC](https://boards.straightdope.com/t/well-known-obvious-facts-that-a-lot-of-people-are-ignorant-of/753294/78 "2016-04-28T22:30:00Z")
> [@](#): > > traffic light sensors. Just noticed on my evening drive a lady waiting for a left turn arrow, but she had pulled past the thick white line and thus her carā€™s magnetic field no longer would trigger the light to change. Most of the traffic lights around here use cameras to detect cars, not magnetic fields. Are you sure yours use magnetic fields? ---
**Author:** ![Flyer](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/flyer/32/7298_2.png) [@Flyer](https://boards.straightdope.com/u/Flyer)\ **Post date:** [April 28, 2016, 10:38pm UTC](https://boards.straightdope.com/t/well-known-obvious-facts-that-a-lot-of-people-are-ignorant-of/753294/79 "2016-04-28T22:38:34Z")
> [@WildBlueYonder](#): > > If you put a un-nutered female cat outside for any length of time, she will return pregnant, no doubt about this. EVERY female is un-neutered. šŸ˜‰ ---
**Author:** ![fstbk1968](https://avatars.discourse-cdn.com/v4/letter/f/3bc359/32.png) [@fstbk1968](https://boards.straightdope.com/u/fstbk1968)\ **Post date:** [April 28, 2016, 10:46pm UTC](https://boards.straightdope.com/t/well-known-obvious-facts-that-a-lot-of-people-are-ignorant-of/753294/80 "2016-04-28T22:46:51Z")
> [@spamforbrains](#): > > Most of the traffic lights around here use cameras to detect cars, not magnetic fields. Are you sure yours use magnetic fields? By me both are used. Wires embedded in the pavement are used to create the magnetic fields, they are called detector loops. Typically we put several of them at different positions to detect vehicles. One directly behind the 12" wide white line (called the stop bar) and unfortunately we often have to put one past the stop bar because folks arenā€™t very good at stopping where they are supposed to. There is often one or more at a set distance back; this is to detect if a long line of cars are queuing and it can initiatie a different signal timing. Since wires in the pavement break and cars use less ferrous metals, among other reasons, cameras are being used more frequently for detection. [Previous page](https://boards.straightdope.com/t/well-known-obvious-facts-that-a-lot-of-people-are-ignorant-of/753294.md?page=3) [Next page](https://boards.straightdope.com/t/well-known-obvious-facts-that-a-lot-of-people-are-ignorant-of/753294.md?page=5)