Half a croissant, on a plate, with a sign in front of it saying '50c'
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common sanity test

If we're generally so wrong in our world models, how can we trust anything?
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A sanity test is a basic check to quickly decide whether a claim or result can possibly be true. I want a test which evaluates the reliability of the user's world model; a sanity test for their common sense.

I believe that people generally develop their understanding of the world at between about four to eight years old (give or take), and have not since had cause to reconsider their basic understanding of how things work.
I have found several questions which expose fairly significant misunderstandings in most people. These are generally not things which specifically affect them directly, but neither are they esoteric and non-intuitive phenomena like the theory of relativity or quantum effects. They are also not 'trick' questions. I will give one example below.
This is disquieting to me, because it is not clear that I am not the same, just for a different subset of theories.

I'd like a website documenting this - with a suitable test - to exist, and am willing to make one. But I need help. I'm also open to suggestions.

I need suitable questions. But what I don't want is a single page with a list of the correct answers freely searchable on the web.
Please don't post or discuss the answers to any questions posted to the page. I may use the delete button (please note that I'm generally averse to that).

Until I have a better system, I will accept questions and answers to my address at >>lysis games of google mail dot com<< I think most people should be able to interpret that, but most bots will not. Eventually the answers will need to be in multiple choice format, but I expect to have to discuss most of them by email before that point.

Example

Read the question carefully, think and decide for yourself before looking at the answers.

Question : Sometimes, the Moon looks crescent shaped. Why is that?

a) The Moon is shaped like a croissant, which rotates.
b) The Earth's shadow.
c) The direction of the Sun.
d) The Moon and the Sun are different sides of the same thing.
e) The shadow of another planet; Venus or Mars etc.
f) other
(remember - don't discuss or post the answer on this page!)

Now you may scoff at that, because the answer is obvious. Are you sure you're right? Feel free to email me and check. I've been asking that to people for years (just the question, not the answers), and at least 90% of them were wrong. I've had an *Astrophysicist* be wrong. Try asking people yourself and see if they match what you think.
I have one or two more questions like that, but they are a bit more knowledge-based. I'd like many more. Please share any you have discovered.

Loris, Jan 10 2017

Sanity test https://en.wikipedi...g/wiki/Sanity_check
[Loris, Jan 11 2017]

[link]






       Q38. The International Space Station orbits about 400km above the surface of the earth. At this height, the strength of gravity compared to its strength on the ground is:   

       (a) 1/400th
(b) zero
(c) almost the same
  

       Q39. An ordinary coin is flipped 5 times, and each time comes up heads. The odds of its coming up heads next time are:   

       (a) One in 32
(b) One in two
(c) 31 in 32.
  

       Q40. You have 1 litre of pure alcohol. You want to dilute it to a strength of 10%. Do you add:   

       (a) 99 litres of water
(b) 10 litres of water
(c) 9 litres of water
(d) No water, just a little ice and a miniature parasol.
MaxwellBuchanan, Jan 10 2017
  

       Q40 For shame. Adding water to alcohol is bad practice. You should always add alcohol to water.
RayfordSteele, Jan 10 2017
  

       Sorry beany - you were warned.   

       Regarding your questions Max, I'm not sure about Q38. It seems a bit to much like a trick to me.
Q39 is a good idea. It's definitely worth including something similar.
Q40 seems a bit more tricksy because people will worry about percentage by volume, weight or moles (and perhaps proof since it uses alcohol). And I won't discuss the answers but there's more to say about that.
Loris, Jan 10 2017
  

       I think Q38 is fair. The only background information you need is that the earth is a lot more than 400km in diameter.   

       Q40 - fair point.   

         

       Q41. In temperate and polar regions, seasons happen because:   

       (a) The Earth's orbit is not a perfect circle
(b) The Earth's axis is tilted
(c) The sun's brightness changes
  

       Q42. Scribing a shallow line into a sheet of glass allows you to break it along the line by gently bending it because:   

       (a) The glass is slightly thinner, and therefore weaker, at the line
(b) The line concentrates the stress caused by bending
(c) Scribing the line changes the type of molecular bonds in the glass.
  

       Q43. Which of these is the biggest:   

       (a) solar system
(b) galaxy
(c) universe
  

       Q44. All molecules are made of:   

       (a) atoms
(b) ions
(c) electrons
MaxwellBuchanan, Jan 10 2017
  

       I think the questions will generally need at least 5 answers dilute out the guessers, but that shouldn't be a problem.   

       Q41 is great.   

       Q43 is good, but I'm concerned that we're starting to have a lot of space-based questions.   

       I'm not sure about Q42 and 44. Q44 is perhaps too knowledge-based. I mean, adults ought to know the answer, but if they didn't they wouldn't be able to work it out without looking up what the words meant.   

       Q42 I think would need discussion by email.
(I'm happy to do the same for Q38. It's not that it's not a good question, and it could probably be reworded to mitigate my concerns.)
Loris, Jan 10 2017
  

       I think the questions proposed so far are testing for science knowledge rather than a sanity. Most of us here see the world through the eyes of a scientist (so we will all easily pass the test), but not everyone does and that's OK.   

       I find it amazing that some people don't have the inquisitiveness or interest in things like the cause of a waxing/waning moon and the seasons. However, those people probably find it amazing that I have no interest in hair care, horoscopes, acupuncture, homeopathy, or tax minimisation strategies. And I would completely bomb on a test of any of these subjects.   

       I think that an interest in science is not necessary or even desirable for all people. Perhaps the "division of interests" (to borrow from the economist's concept of the "division of labour") keeps people happier than they would otherwise be.
xaviergisz, Jan 10 2017
  

       //I think the questions proposed so far are testing for science knowledge rather than a sanity.//   

       I think you're right. But the question about seasons is more or less similar to the question about the crescent moon - and the wrong answers can be eliminated by common sense in both cases.
MaxwellBuchanan, Jan 10 2017
  

       I also don't think the word sanity applies. This is a spatial relation/mechanical reasoning test.
That said;
  

       (45) If a bird flying by poops while directly over your head, does it hit you?
(y)
(n)
  

       (46)If the first gear in series is turning clockwise, which direction is the seventh meshed gear turning?   

       (48) An airplane drops a bomb, does it;
(a) drop straight down?
(b) drop on an angle?
(c) curve in an arc?
(d) none of the above.
  

       (49) Which falls faster, a pebble or a boulder?   

       (50) Without gravity what shape would fire take?   

       (51) Did you notice that there was no (47)?
Be honest.
  

       Q52 If your car can stop in exactly 20m when driving at 50km/hr, how much room do you need to stop when driving at 100 km/hr?   

       a) 20m
b) 40m
c) 80m
d) 150m
  

       Q53 If you have a measuring cup full of ice and water and the water level is exactly at the 1 cup mark (some ice is floating above this line) - and you let the ice melt - what level do you think the water will be immediately after the ice is melted? Please ignore evaporation.   

       a) below the 1-cup mark
b) exactly at the 1-cup mark
c) above the 1-cup mark.
  

       [edit - this line spacing is killing me. Try this. Second edit - fixing numbers in Q52 to be more realistic]
Custardguts, Jan 10 2017
  

       //I also don't think the word sanity applies.//   

       The word is used in the sense of "sanity test". This is explained in the first line of the body text. I have added link.
That said, I'm open to suggestions for a better name.
  

       // This is a spatial relation/mechanical reasoning test.//   

       It isn't intended to be restricted to that; I would love to have as diverse a set of questions as possible. Except that I'm inclined to rule out law questions out of hand because they're arbitrary and not universal.   

       One definite issue with this is that if something doesn't fit the test curator's erroneous world model (i.e. mine) then it would get excluded. Thus in that event I urge you to argue your case (by email, please)   

       Q48 and Q53 I think would work with some minor modifications.
Something along the lines of Q52 would work if it wasn't specifically about cars - my concerns here are that my memory suggests that the highway code was quite equivocal on the subject, and there's thinking time as a distractor.
Loris, Jan 11 2017
  

       In the interest of prompting some less physicsy questions, here's one:   

       Q2. A tree is cut down and the wood allowed to dry over several years. Where did the material which makes the dry wood predominantly come from?   

       a) Water from the ground.
b) Sunlight converted into matter.
c) Soil.
d) Water from the ground and gas from the air.
e) soil and sunlight converted into matter.
  

       So it's still 'kind of' science, but on some level that's because science is about what is true, so it's always going to be a complaint. You can argue that some answers can't be excluded without some knowlege - but it's pretty basic knowledge which is taught in primary school.
More importantly, it's something people are familar with, and doesn't use any difficult words.
Finding suitable forms for the answers seems pretty significant. We're not aiming to mislead, but neither are we trying to give a keyword to highlight the correct answer.
Loris, Jan 11 2017
  

       Q47 You work for the UN in the former Yugoslavia. While checking one site, you find -   

       A) A mass grave of snowmen.   

       B) A field of carrots.   

       Which one do you report it as?   

       NB lifted from old Milton Jones joke
not_morrison_rm, Jan 11 2017
  

       There are some tests such that their results will always be disbelieved, no matter what answers are chosen. For example:
Q60: If you oppose abortion, you are
(a) indoctrinated by evil preachers who greedily want ever-more people to control, and from to collect tithes
(b) ignorant of humanity's puniness relative to the Universe
(c) deluded
(d) prejudiced
(e) hypocritical
(f) all of the above
  

       The preceding follows from the simple provable fact that there is no valid reason for anyone to generically oppose abortion in this day-and-age, and therefore all existing reasons, since they are invalid, must be each symptomatic of some form of un-sane-ness.
Vernon, Jan 11 2017
  

       'Doing the same thing, over and over, expecting different results' is the official unofficial definition of insanity.   

       Testing anything other than previous axiom qualifies as a form of insanity.   

       This test qualifies as 'doing the same thing (testing), over and over (since tests were invented), expecting different results (that the test will actually determine insanity, rather than simply be a measure of the testing methods).   

       Therefore, this test is insane, and has proven its point. [+]
Sgt Teacup, Jan 11 2017
  

       I thought that was the definition of a scientist?
Ian Tindale, Jan 11 2017
  

       I think this test would measure a person's ability to answer these questions and nothing else. There are lots of things like this; In the same way, a Mensa test doesn't measure IQ, but measures ability to answer the particular culturally-specific set of questions that Mensa have come up with, and a Myers-Briggs questionnaire doesn't measure anything about personality but is designed to convey the impression that the questionnaire has some scientific basis and (often) to justify a consultant's expensive fees.
hippo, Jan 11 2017
  

       If people keep going on about insanity, I'm going to have to change the title.
Would "worldview validity check" be better?
  

       //I think this test would measure a person's ability to answer these questions and nothing else.//   

       I don't think that's fair.
You could say the same about a maths test. The ability to answer certain classes of question appropriately has utility.
In this case, the aim is to detect naive ideas about how things are, which may prove enlightening.
  

         

       //In the same way, a Mensa test doesn't measure IQ//
I may be mistaken, but doesn't the idea of an IQ test (which Mensa use) predate Mensa?
And the thing an IQ test is measuring is _defined_ as the ability to answer the sort of question it asks.
Perhaps you meant that it doesn't measure intelligence, which IQ was intended as a proxy for. Complaints about bias and accuracy against it certainly have a place, but I think it's clear that it is measuring something.
Loris, Jan 11 2017
  

       I think the concept of "worldview" should exclude aspects of the world which are /not things which specifically affect them directly/. Common sense I think means a working model of the world, or world view, upon which one can predicate decisions.   

       It is not very interesting that uneducated people have incorrect ideas about astronomical phenomena. I admit, pretty funny when they are stupendously wrong on camera. But not PhD dissertation material.   

       What is very interesting is how uneducated or differently educated people make decisions that have great impact on their democracies as a whole. It will require delicate sociology to tease out the provenance of the world view which leads to these decisions.
bungston, Jan 11 2017
  

       //Except that I'm inclined to rule out law questions out of hand because they're arbitrary and not universal.//
This is true but a focus on the absolute rules of science is useful for managing expectations, a focus on manmade rules is good for allowing people to manage their behaviours. I have had many infuriating conversations with ostensibly well-educated people who don't understand how rules work (let alone laws). This makes their lives more difficult than is necessary. I will try to think of an example that might work in the striving-for-universality context.
calum, Jan 11 2017
  

       Some responses to questions. I have tried to suggest ways they need improvement without giving any clues to the actual answers.   

       Re Q38: I think more than one answer could be argued to be correct based on the testee's interpretation of the question, so I think the wording needs to clarify exactly what's being asked about.   

       Re Q45: I think this question needs to specify at fewest three dimensioned quantities. Qualitative specifications should be sufficient to get the idea across.   

       Re Q46: I think it needs a diagram to unambiguously communicate what's being asked about. I assume that was the intention, just that diagrams are more difficult to provide here than text.   

       Re Q48: Multiple answers are arguably correct. To avoid giving too much of a clue, I will say that the flaw is to do with something that is a fundamental part of post- Newtonian physics (not to say that the question isn't correctly solvable using only Newtonian physics).   

       Re Q49: Multiple answers are (more difficultly) arguably correct. The flaw in this question should be obvious and easily corrected. I think saying more might give too much of a clue.
notexactly, Jan 11 2017
  

       Q54: You are driving on the highway to another city. The distance along the highway (from on-ramp to off-ramp) is exactly 100 kilometers. Your speedometer reads exactly 100 kilometers per hour the whole time you are on the highway. How long do you spend on the highway?   

       Q55: (practical) Given a battery, a single piece of wire (which you may not cut), and a lightbulb, please either a) if you think it is possible, successfully light the lightbulb, or b) if you think it is impossible, explain why it is impossible. (You may assume that all parts are fully functional and correctly specified. Specifically for the wire, its ends are uninsulated and it is sufficiently long.)   

       (These are adapted from well-known questions used to demonstrate that friends or college grads aren't as smart as they think they are. I've tried to make them less ambiguous than their previous forms. However, their answers are already searchable, so they should probably be used as inspiration for new questions for this test rather than being used themselves.)
notexactly, Jan 11 2017
  

       //The distance along the highway (from on-ramp to off-ramp) is exactly 100 kilometers.   

       Shades of Waterhouse taking the US navy maths test "the ship moves at x mph and the river current is y mph, how long does it take to get to z?"   

       To him, it was obviously a trick question as the current flow rate depends on how far from the bank you are/the depth of the river etc So he spends the whole time of the exam to modelling the flow current...and so fails the test overall..
not_morrison_rm, Jan 11 2017
  

       I don't think sanity is an option. Sure this is medical science but there is no easy way for me to view it since I'm not educated enough to filter all the 'surveys suggests' or big Pharma bullshit I get from a local doctor.   

       Besides retaking O levels to ensure a brain is still intact, I'm sure this idea addresses Trump and BrExit, and given that most people who voted couldn't retake an O level or even care about formal education then that puts you in a minority.   

       So giving up on any kind of consensus of 'common sense' I think this idea asks for the kind of people or sources one can interact with for credible information.   

       I'd try RT, but if you want a bit more rant or comedy, try TYT or John Oliver.   

       TBH I think your sanity is suffering from the last vestige of Imperialism and all the machinery you got caught up / mangled in. Knowing stuff is all well and good until corrupt people crap on every principle you had, and then there goes your sanity.   

       Q.56. Which is worse ?   

       1) The US intelligence agencies declared with high confidence that Iraq had weapons of mass destruction and invaded the country and killed millions under what was later found to be false pretexts.   

       2) The US intelligence agencies declared with high confidence that Russia hacked America to influence the elections without providing any evidence. Trump calls this fake news.   

       Q.57. Who does the global economy benefit ?   

       a) People who struggle to get jobs
b) Corporates who don't care about health, safety and welfare in other countries
c) Everyone
d) Financial companies gaming stock prices based on instutionalised rules.
bigsleep, Jan 11 2017
  

       c. ( common)
popbottle, Jan 11 2017
  

       Everybody has a different memory capacity. How can you compute a common sanity if 'facts' are remembered differently from person to person?
wjt, Jan 12 2017
  

       Jesus bigs, just write your fucking manifesto, disappear to Montana, and get it over with already.
RayfordSteele, Jan 12 2017
  

       [RS] Hehe. It was illustrative of sanity being a relative thing depending on information sources you've been exposed to and accuracy thereof.   

       //I believe that people generally develop their understanding of the world at between about four to eight years old//   

       I'd go along with those kind of ages giving a perspective on the world mostly from parental attitude (beatings, alcoholism, neglect etc etc), but I'm not sure sanity is related to early youth.   

       I'd agree that sanity is related to having a functional world view i.e. a hypothetical understanding of how things function (at all levels), but that can be gained at any age. Personally, I'm still back-filling sparsely built areas of my knowledge tree, but the further out you go, the information sources become sketchier.   

       //I mean, adults ought to know the answer//   

       Does this mean this test is for 4-8 year olds ? If so, you should probably highlight that in the idea. That might have saved the whole Trump/sanity bit.
bigsleep, Jan 13 2017
  

       Q.4731: How would you account for the greater incidence of nosological drift in psychiatry, as compared with other fields of medicine?   

       Q.4732: Haven't you anything better to do?
pertinax, Jan 13 2017
  

       Q.4733 If a person wears a hat, and smokes a pipe, then should they use matches or a lighter?
a) matches
b) a lighter
c) both alternately
d) both simultaneously
e) a propane blowtorch
f) “they” is not the neuter singular
pocmloc, Jan 13 2017
  

       //It is not very interesting that uneducated people have incorrect ideas about astronomical phenomena.//   

       But isn't it interesting that a highly educated astrophysicist can have incorrect ideas about astronomical phenomena?   

       //I mean, adults ought to know the answer//
//Does this mean this test is for 4-8 year olds ?//
  

       No, it's for adults. I expect naivity in juveniles.
Looking back to where my initial comment came from, I was effectively saying that the concept isn't to test whether the subject knows the right jargon, but whether the ideas that they do have about how things work are correct.
  

       With that in mind, I am starting to think that there should always be a 'don't know' option, which wouldn't gain or cost you points.
Loris, Jan 13 2017
  

       // 'don't know' option//   

       Or a series of questions that validates a particular world view.   

       The most common fork I can think of is the series of reinforcements that leads to a world view that contains allegiance to a deity written up by Romans of the Council of Nicaea variety.   

       I guess sanity is hard to define with the weird ways people build up their knowledge trees. A 'workable' world view may include all sorts of strange stuff.   

       Personally, I'm not ruling out Lloyd Pye's explanation of the Pantheon of gods. A lot of stuff ties in. Makes more sense than religion.
bigsleep, Jan 13 2017
  

       How many eyes do you need for 3D vision?
a) 1
b) 2
c) 3
d) The number is irrelevant
pocmloc, Jan 14 2017
  

       Which are better, cats or dogs?
a) cats
b) kittens
c) felines
d) all of the above
e) cats
pocmloc, Jan 14 2017
  

       A 10m high wall only just holds back the water in a a small reservoir. The same wall is then built to hold back the same length and level of water on the side of a large ocean.   

       Will the wall: 1. Fall down due to the extra amount of water. 2. Not fall down because the water pressure is the same. 3. I'm an engineer that wants to know about densities, heights of waves, local geography and tidal effects before answering.
Ling, Jan 14 2017
  

       The reason that high mountains have snow on them all year round is because
a) High mountain tops are further from the sun
b) the air pressure is less, so the wind has less force and can't blow the snow off
c) It's an optical illusion like mirages in the desert
d) It is colder the higher you go
e) The molecular structure of water changes as the air pressure reduces, making it freeze more easily
pocmloc, Jan 14 2017
  

       The "how many eyes" question is tricky. Monocular people still perceive depth, based on things such as focal distance and parallax effects.   

       The "reservoir/ocean" question is also tricky. Does the wall "only just" hold back the reservoir because it's "only just" tall enough, or because it's "only just" strong enough?   

       How about:   

       Q666   

       When you hold a book up to face a mirror in front of you, the text appears flipped left to right, not top to bottom. This is because:   

       (a) Mirrors only reverse left/right, not top/bottom
(b) You have left and right eyes, not top and bottom eyes
(c) You flipped the book left/right to make it face the mirror.
MaxwellBuchanan, Jan 14 2017
  

       An object appears to be green because:   

       (a) It absorbs the green wavelength of light.
(b) It envies the other colours.
(c) It reflects the green wavelength of light.
(d) It isn't easy to be that way.
  

       When a bullet hits a target, the amount of force it imparts is:   

       (a) Greater than the force of the recoil.
(b) Less than the force of the recoil.
(c) Equal to the force of the recoil.
(d) Dependant on the caliber of the bullet.
  

       If our Sun instantly ceased to exist the Earth would feel the effect of its loss:   

       (a) Instantly.
(b) At the speed of light, (roughly 8 minutes)
(c) The only effect would be darkness.
(d) Nobody knows.
  

       Rain falls from the sky because:   

       (a) The air has reached saturation.
(b) Gravity.
(c) Dust particles cause water vapor to condense around them.
(d) All of the above.
(e) None of the above.
  

       Given the current sociological, economic, political, and religious tension of the world in 2017, we all appear to be headed to Hell in a:   

       (a) Hand-cart.
(b) Hand-basket.
(c) Hand-maiden.
(d) Hand-shake.
  

       //An object appears to be green because:   

       (a) It absorbs the green wavelength of light. (b) It envies the other colours. (c) It reflects the green wavelength of light. (d) It isn't easy to be that way.   

       If it's transparent (like green glass), it's because it transmits mainly green light. Or because it transmits mainly blue and yellow light. Equally, if it's opaque, it may be green because it reflects blue and yellow. Or because of iridescence.   

       When a bullet hits a target, the amount of force it imparts is:   

       (a) Greater than the force of the recoil. (b) Less than the force of the recoil. (c) Equal to the force of the recoil. (d) Dependant on the caliber of the bullet.   

       Both (b) and (d) are true (assuming that different caliber bullets have different masses and/or velocities).   

         

       Rain falls from the sky because:   

       (a) The air has reached saturation. (b) Gravity. (c) Dust particles cause water vapor to condense around them. (d) All of the above. (e) None of the above.   

       To be picky, you don't need dust to make rain. Bacteria, for example, are major rain-nucleators. Given high enough saturation, even ionizing radiation can nucleate rain. And if there were none of that, you'd eventually reach a saturation where nucleation happened spontaneously, I think.   

       Given the current sociological, economic, political, and religious tension of the world in 2017, we all appear to be headed to Hell in a:   

       (a) Hand-cart. (b) Hand-basket. (c) Hand-maiden. (d) Hand-shake.   

       (e) Trice.
MaxwellBuchanan, Jan 14 2017
  

       Fuck, this post is boring, and I just realised why. All these staggered spiky stuttering questions don't constitute any form of actual communication, just noise, or if they do, it is a highly rude and ill mannered communication.   

       I wonder if I sat through all my tests at school without realising this?
Ian Tindale, Jan 14 2017
  

       Well, thanks so much for clarifying, [Ian].
MaxwellBuchanan, Jan 14 2017
  

       If you want a biblical one...   

       Q[] "All the rivers run into the sea, but the sea is never full, so the water returns to whence the river came". Howcome?   

       Written presumably by an ur-halfbaker in the early Pondering Epoch..
not_morrison_rm, Jan 14 2017
  

       It's hard to think of questions that are possible to reason out without prior knowledge while also wording them in a way that doesn't allow for exceptions.   

       p.s. I was kinda hoping for feedback on my 'Sun disappearing' question, because I have no clue.
Now I've got to go look up the speed of gravity... if that's even a thing.
  

       I didn't feed back because I assumed you knew. The answer is (b).   

       8 minutes after the sun disappeared, (1) it would get dark and (2) there would be tidal surges, because the tidal contributions of the sun's gravity would be abruptly removed.   

       Of course, the Earth would also go flying off into space at a tangent, but we wouldn't notice that immediately.   

       As for the moon, that would depend on where it was in its orbit when the sun vanished. If the Earth, moon and sun formed a right-angle at the time the sun vanished, then nothing much would happen - the moon would continue orbiting the Earth smoothly. If the moon were between the Earth and the sun, then the moon would end up a teeny tiny bit closer to Earth, since it would be released from solar gravity a second or so before the Earth. And if it were on the far side of the Earth, it would also end up a teensy but closer to Earth, since the Earth would be released from solar gravity a second or so before the moon. And in any case, the shape of the moon's orbit around the Earth would change very slightly, since the moon's orbit would not be traversing a solar gravitational field gradient as it circled the Earth.   

       Also, the moon would go dark either at the same time, or shortly after the Earth got dark - depending on its position relative to Earth.   

       The other planets, as seen from Earth, would go dark at various times after Earth went dark. If you were watching Pluto through a telescope, you'd be able to see it for about a day after the Earth went dark, since it's about half a light-day from the Sun.   

       Also, and perhaps interestingly, even if the sun completely vanished in an instant, sunlight on Earth would fade over the course of about 2 seconds. That's because the sun's radius is about 2 light-seconds; we'd continue to receive light from the edges of the sun for two seconds more than light from the centre (as seen from Earth).   

       Equally interestingly, the sun's gravitational pull would fade out in the same sort of way (over a period of 4 seconds) - we'd still feel the (small) gravitational pull from the very far side of the sun, 4 seconds after we'd lost the pull from the rest of the sun. If we could measure the gravitational pull from the sun, here on Earth, it would disappear in some sort of steep sigmoid manner.   

       Even more interestingly (and alarmingly), the Earth is about 0.04 light-seconds across. Therefore, the disappearance of the sun might cause massive earthquakes, as the drop in solar gravitation would take 40 milliseconds to traverse the Earth. In other words, there would be some huge tidal forces during those 40ms. Or, to look at it another way, there would be a shock wave equal in magnitude to the force of the sun on the Earth, travelling through the Earth at the speed of light.
MaxwellBuchanan, Jan 15 2017
  

       Sweet. Thank you sir, that was far more informative than the wiki page on the subject.   

       It would make for a decent sci-fi premise. An advanced alien species worm-holes our Sun away for its own purposes leaving the Earth space-trucking through the Milky Way while we try to stay alive long enough underground using geothermal energy until we chance to be captured by another star or launch a self sustaining fusion satellite to save us from an eternal ice age.
Working title; Eppur Si Mouve.
  

       I aim to please.
MaxwellBuchanan, Jan 15 2017
  

       Guys, I asked you not to discuss the questions here, because that means I have to either not use the question or delete the comment (which I hate doing, the more so the more it contains).   

       Fortunately in this case I wouldn't use the question (because it involves 'magic'), but next time it might be something useful I wanted to keep.
Loris, Jan 16 2017
  

       Ah - so this is a sanity test you propose to apply to halfbakers? If so, the answer is already known, shirley?
MaxwellBuchanan, Jan 16 2017
  

       You visit a public internet terminal and notice that the previous session is still open, showing a website called halfbakery.com. Do you:
a) cover the terminal with a cloth or cardboard box, and call the police
b) Quickly terminate the old session and start a new one
c) idly flick through a few pages of the site before closing it and loading Facebook
d) Read the posted ideas one after another with mounting fascination until you realise the place is closing and you're being kicked out by security
e) Check for new annotations on your recent ideas
pocmloc, Jan 16 2017
  

       f) all of the above, obviously...
RayfordSteele, Jan 16 2017
  

       //Ah - so this is a sanity test you propose to apply to halfbakers?//   

       Sure, although not primarily. But the main issue is that if answers are easily findable in one place then there will be temptation to read that rather than think, thus negating the purpose of the test.
For what it's worth, the plan is that answers will be available, with discussion as necessary - but hidden from casual searching using robots.txt. Possibly also shrouded with javascript, if I use that in the test.
Loris, Jan 16 2017
  

       Ah. Well, in that case, feel free to delete any anno's of mine that will cause problems.   

       Q185. Assuming a lobster is three times as long as a shrimp but has a similar shape, does it weigh:   

       a. About three times as much as the shrimp
b. About nine times as much as the shrimp
c. About 27 times as much as the shrimp.
  

       Q186. You put a feather and pea on a balance, and find that they weigh the same. But the pea falls faster than the feather if you drop them. This is because:   

       a. The feather has more air resistance than the pea
b. The feather has less mass than the pea
c. The force of gravity is stronger for the pea than for the feather.
MaxwellBuchanan, Jan 16 2017
  

       d) the Force is strong with the feather. This is why it was attracted to Forrest Gump.
RayfordSteele, Jan 16 2017
  
      
[annotate]
  


 

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