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Myth: The astronauts didn’t float away because they had heavy boots

169 points by andrelaszlo 13y ago

andyjohnson0 13y ago
Site seems to be down. Cached version is here: http://webcache.googleusercontent.com/search?q=cache:uWHPLrGJYW4J:blog.sciencegeekgirl.com/2009/11/09/myth-because-the-astronauts-had-heavy-boots/ http://webcache.googleusercontent.com/search?q=cache:uWHPLrG... A significant part of the article is a reposting of http://www.phys.ufl.edu/~det/phy2060/heavyboots.html http://www.phys.ufl.edu/~det/phy2060/heavyboots.html Edit: Changed wording re how much of article is repost
- gametheoretic 13y ago
  Thanks for posting that. Not one to complain about blogspam, but that's one of the all-time great "internet motherfucker" posts. Neither Sciencegeekgirl.com (lol, brand yourself harder) nor anyone else can do much to add to it.
  - brazzy 13y ago
    Actually, Sciencegeekgirl.com adds VERY MUCH to the article, namely a highly interesting discussion of WHY students give these wrong answers. No, it's not because they're stupid or ignorant.
    - enko 13y ago
      > it's not because they're stupid or ignorant They may not be stupid, but that's pretty much the definition of ignorance.
      - brazzy 13y ago
        Obviously, anyone who answers a question incorrectly is ignorant of the correct answer, but the point is that in many cases the wrong answer seems to be logically based on a wrong mental model of how gravity works. Just like Aristotelian physics. And Newtonian physics as well. Would you call Aristotle and Newton ignorant? The interesting part is the discussion of what these wrong mental models look like and how you can teach a correct one.
        plorkyeran 13y ago
        > Would you call Aristotle and Newton ignorant? By modern standards, absolutely.
        DanBC 13y ago
        > Would you call Aristotle and Newton ignorant? By your definition they're ignorant, but not stupid?
        mbrutsch 13y ago
        > Would you call Aristotle and Newton ignorant? Absolutely. There was much they did not know, as is true of anyone. "Ignorant" is not an insult, it simply means you do not know something. Would you say Aristotle and Newton knew everything about everything? If not, then they would be, by definition, ignorant of the things they did not know.
        almosnow 13y ago
        There's absolutely no way to justify a student attending a physics class and not knowing that the Moon does have gravity as well.
        brazzy 13y ago
        The problem is that they may know that the Moon has gravity, but they don't understand what that concretely means when it comes to questions like this.
        tene 13y ago
        I would dispute the validity of calling that state of mind "knowing that the moon has gravity". I would instead call it "memorized a couple of correlated keywords".
    - gametheoretic 13y ago
      No. Where writing is concerned, 2+2 is greater than 4.
- nailer 13y ago
  'Heavy boots' is actually a reasonable answer in that it doesn't preclude the moon having gravity.
  - brazzy 13y ago
    On its own yes, but if combined with the previous statement that a pen would float away, it just exhibits a piecemeal and inconsistent understanding of physics.
    - judk 13y ago
      Why? On earth, heavy boots hold you down, but dust and feathers float away. The moon has less gravity than the Earth, so a pen is like a feather. Blah blah atmosphere electro-magnetism blah, the universe is big ad complicated.
      - na85 13y ago
        Oh god. Feathers and dust don't float away because they're weightless. They float away because air currents exert forces on them that are greater than their weight. Eventually, in a still-air environment, the feather and the dust will settle to the ground. You can verify this by going to your nearest attic.
        cousin_it 13y ago
        To be fair, your nearest attic might have dust on the walls and ceiling as well, though maybe not as much...
      - deleted 13y ago
        [deleted]
      - pjc50 13y ago
        See the famous video of one of the lunar astronauts dropping a hammer and a feather at the same time. Both of them drop fairly rapidly to the surface.
- MrBuddyCasino 13y ago
  This was a pretty entertaining read. First I thought I would sense a smug sense of superiority of natural science over the humanities, but then I realized he performed the same test on his physics students.
  - pothibo 13y ago
    I always sucked in tests. In the first question, I would have hesitated between b) and d). The reason for choosing b) would have been that the moon's gravity being weak, the earth's gravity nullified the moon's thus having a floating pen. The reason for choosing d) would be because Moon's gravity is stronger than Earth's. This is why I think tests are stupids. If I had chosen b) instead of d) I would have gotten a wrong answer. Even though my thought process would be correct. Just missing the right information (which could have been easily found outside a test environment).
    - mikeash 13y ago
      The relative strength of gravity mostly does not matter. If the Earth pulled on you harder than the moon, you'd still fall towards the moon, because the moon is just as strongly affected by that gravity as you are (momentarily ignoring tides). So no, I'm pretty sure your thought process wasn't remotely correct.
      - dennisgorelik 13y ago
        His thought process is correct, but his "pen on the Moon" model is missing vital element (that Moon is in free fall/orbiting Earth). If Moon was hanging on a stick connected to Earth (instead of orbiting Earth) and Earth gravity forces on a pen were stronger than Moon's gravity forces, then pen would fall in Earth. Of course you and I know that there are no such strong materials for that Earth-Moon stick, but that's yet another level of complexity that most people don't have to know about.
        Dylan16807 13y ago
        >If Moon was hanging on a stick connected to Earth (instead of orbiting Earth) and Earth gravity forces on a pen were stronger than Moon's gravity forces, then pen would fall in Earth. Technically that's true, but it would require a completely different scenario. Earth's gravity is miniscule at that altitude. For the moon to have a weaker force it would have to be so small that it would likely not even qualify as a moon any more.
- masklinn 13y ago
  >Article is mainly just a reposting of http://www.phys.ufl.edu/~det/phy2060/heavyboots.html http://www.phys.ufl.edu/~det/phy2060/heavyboots.html though... That is an unfair characterisation, I think. The article does indeed reproduce heavyboots in its 725 words entirety (according to pages's word count for what that one's worth), but tacks a further 930 words afterwards. And these 930 are interesting indeed as they're further explorations of the phenomenon and discussion on its underlying reasons.
  - andyjohnson0 13y ago
    Fair enough - I've changed the wording a bit. Personally, though, I thought that the follow-on discussion didn't add much beyond what was mentioned in the original heavyboots article.
onion2k 13y ago
This must be nonsense. Or an April Fools joke. Or something. I don't want it to be true. It can't be. sobs quietly
- JonnieCache 13y ago
  Read to the end and the bit about buoyancy, you'll be less angry.
  - astrodust 13y ago
    That merely demonstrates people aren't thinking, they're just applying patterns.
    - JonnieCache 13y ago
      You say tomato, I say tomato, let's call the whole thing off.
- Strilanc 13y ago
  Veritasium [1] often interviews people as part of his videos, and the results are consistent with what's being described in the post: somewhat distressing [2]. To the point where you might think he was purposefully making fun of them [3]. 1: http://www.youtube.com/user/1veritasium/videos http://www.youtube.com/user/1veritasium/videos 2: http://www.youtube.com/watch?v=TQxeutcYP6I http://www.youtube.com/watch?v=TQxeutcYP6I 3: http://www.youtube.com/watch?v=cY_o4A1wzsg http://www.youtube.com/watch?v=cY_o4A1wzsg
- deleted 13y ago
  [deleted]
- cstross 13y ago
  Go forth and ask random people whether (a) the earth revolves around the sun, or (b) the sun revolves around the earth. The proportion giving answer (b) will cause you to sob even more. (Yes, I have done this. Afterwards, I hid under my bed bewailing the ignorance of my fellow hominids.)
gadders 13y ago
At my daughter's school, they had an assembly for parents to attend that celebrated, amongst other things, the first landing on the moon. The children boldy proclaimed that the reason the hammer and the feather hit the ground at the same time in the famous experiment was because there was less gravity on the moon. It still rankles with me a year later.
- DanBC 13y ago
  That's a shame. Was there any opportunity to assess the material before it was presented? Was there any method to correct mistakes after? Your daughter presumably understands that it's not about gravity but air resistance. Has she told all her pals? Because that kind of subversive teaching could be really powerful. TEACHERS HATE HER; THE GRAVITY SECRET THEY DON'T WANT YOU TO KNOW!!! etc. May I ask, hold old was your daughter? What kind of science teaching should she be getting? (Obviously, not anything that wrong).
  - gadders 13y ago
    She was 6 at the time. I told her afterwards it was wrong but I regret not telling the teachers.
- mikeash 13y ago
  It's amusing that that kind of is the reason, indirectly. Less gravity means it couldn't retain an atmosphere, and the lack of an atmosphere is why they fall together.
cynichacker 13y ago
I would add another answer choice to the question 25: 25. When the Apollo astronauts were on the Moon, they did not fall off because: (f) They were on Earth
hrvbr 13y ago
There's a similarity between teachers and journalists in that they're supposed to double-check their informations before transmitting them. Not doing it plagues society.
ghshephard 13y ago
When I took physics in high school, Gravity was introduced to me with an equation. After 5 minutes discussion, everyone in the room would have known how to answer the question about "Dropping a rock on the moon." I find it hard to believe that a high school physics student, just fresh from studying gravity module, wouldn't realize that a rock dropped on the moon would fall down. Doesn't pass the smell test.
- sp332 13y ago
  Being introduced to gravity with an equation is not nearly enough to figure out how things will behave. It takes calculus to describe the motion of falling things even without air resistance. Even if someone straight-up tells the students that gravity accelerates things at the same rate regardless of mass, they're probably not going to believe it without some experiments. Edit: a quiz to maybe prove my point :) On the moon, if you throw a rock, what shape would its arc describe? Edit2: not a straight line when you drop it, silly!
  - mnw21cam 13y ago
    Depends how hard you throw it. ;)
    - informatimago 13y ago
      Just like on Earth. That's the point.
      - sp332 13y ago
        That wasn't my point really. Oh well! I though most people would pick a parabola, which is a decent approximation for short throws but not the real shape.
        simias 13y ago
        You got me, what's the real shape? I thought it was a parabola if there was no air friction. Or are you taking the curvature of the moon into account?
buyx 13y ago
Does a lack of knowledge of physics really matter in the real world for most people? I was recently wondering if our terrible road safety problem in South Africa can partly be explained due to a lack of understanding of physics. After all, intuitively Newton's First Law explains why seatbelts are necessary. Concepts like momentum and kinetic energy explain why heavy trucks, speeding down steep inclines are dangerous - authorities don't seem to grasp that very often, and tragedies involving runaway trucks on poorly engineered roads are not infrequent. But I then realised that two of the most reckless drivers I know are my uncle, an Engineering dropout, and my friend who is a practicing engineer. Being good at physics hasn't saved them from being in multiple car crashes. Are there any cases where an understanding of physics helps the average person in everyday life?
- lmm 13y ago
  This isn't a lack of physics knowledge, it's a lack of basic reasoning. If they'd said "the astronauts had magnetic boots", for example, that would be wrong, very wrong, but it would have made sense - at least, it's not outright contradicted by their previous answer.
  - mokus 13y ago
    That was my first reaction too. After thinking and discussing it with some non-technical people, though, I realize it's not a contradiction unless you also assume some physics knowledge. I (and probably you) have so deeply digested the fact that a pen and a heavy boot fall at the same rate that it seems like a logical failure to not incorporate it into a conclusion. It's quite possible that a person's understanding is simply inconsistent (at the frontiers of anyone's knowledge i think inconsistency is quite common; "learning" is largely a process of finding more data and working through implications to resolve them), but it not a foregone conclusion based on these answers. This is the main challenge in teaching people any technical subject - discovering the basic knowledge you have assimilated so deeply that you can't even imagine that others don't share it.
- ckarmann 13y ago
  The thing is, you can go on in life without understanding barely anything. That's one of the wonder of the modern life. You just need to be able to do enough arithmetics to buy stuff at the grocery and pays your bills and taxes. For your uncle and friend, understanding something doesn't mean you feel it's going to apply to you. Road accident are not only a matter of physics but also a matter of statistics and risk calculation. Some people are reckless because they can't compute the probability of accident and often underestimate it, feeling that since they think they are good drivers it won't happen to them. Humans in general are bad at assessing risk, it's a very difficult matter.
jeena 13y ago
Fascinating, I was so confused at first because I first misunderstood the fact who was right and who was wrong in this philosophy class. I will ask this question on parties, this will be funny :D
mnw21cam 13y ago
A long while back, I read a scifi book (really a kids scifi book) about a kid that finds a red pebble which cancels gravity for anything it's in contact with (except kids, obviously), causing those objects to be pulled strongly up into the sky. Why? Because they were attracted by the moon's gravity. They even got it to spin round and suggested using that for free energy. Can't for the life of me remember the title or author, but I remember it really grated against my sensibilities, and I never read anything by the same author again.
- cynicalkane 13y ago
  If you had a way to cancel gravity, you could use that to get free energy because the no-curl condition for energy conserving fields would no longer hold. You could create a closed path in space where gravity is always pulling you along the path.
- dTal 13y ago
  I couldn't resist crunching the numbers: the acceleration due to the moon's gravity as felt from the Earth is roughly 3.319×10^-5 m/s². By contrast, the centripetal acceleration due to Earth's rotation is 0.0337 m/s², several orders of magnitude larger (and just about perceptible as a gentle tendency to float up). (A similar example to your red pebble would be "Cavorite" from the H. G. Wells story "The first men in the moon", which also negated gravity causing objects to shoot violently upwards. The explanation given however was buoyancy, which makes more sense I suppose.)
- teahat 13y ago
  Pretty sure it was Antigrav by Nicholas Fisk. It was a cool story - if you were a kid. I never did find any red pebbles though.
  - mnw21cam 13y ago
    That sounds about right.
rz2k 13y ago
I think a lot of people who are skeptical of this story just don't realize that they appended to be surrounded by people who have developed unusually accurate physical models. I recommend browsing Amazon reviews of (non heat pump) electric heaters for statements about which ones are more efficient. (The less efficient one produce more waste heat?) Because there are few consumer products that exercise people's understanding of gravity, basic thermodynamics might be a good proxy. However the real point of the article isn't all the misconceptions that must be "plucked out" one by one, but the struggle of trying to figure out how to encourage students to form more comprehensive models. I'd also add that an important goal in teaching is students' facility in applying principles, and confidence to question intuition and consensus.
- jhonkola 13y ago
  Well, in case of electric heaters used to heat a home the efficiency should really be measured in terms of "how much electricity is consumed if the heated room is kept at constant 20C measured at e.g. center of room". This is somewhat dependent on the quality of the thermostat controlling the heater. Then, I think that there are some real differences found in the efficiency of the heaters.
  - alanctgardner2 13y ago
    I don't think energy efficiency is really so critical as the control system: how much steady-state error is there, and how quickly can it initially heat the room? Overheating the room is obviously a bit of a waste of power, but it's also uncomfortable.
  - quasse 13y ago
    If you're still talking about electrical heaters here, there's literally no where for the energy used to go other than into heat for the room. If you have two 1000w heaters, one made from a potato and ten clothes hangers and the other made from the highest quality materials known to man, they will still both heat a room the same amount. Granted, one might have a better fan or more airflow and might therefore provide a more even heat distribution in the room, but they will both be providing the same amount of heat to the interior of the room. That's just how energy balances work. If 1000w is flowing from the plug into the heater and it's not being stored anywhere in the heater itself there's nowhere for it to go but into heat for the room.
steveridout 13y ago
I think the people who answered wrongly aren't thinking in a first principles, physics-based mindset, but just instead just recalling previous memories and reasoning in an intuitive, fuzzy kind of pattern-matching. We've all seen images of pens floating weightless in space on films and TV, and we probably haven't ever seen pens falling on the moon. But the moon is in space right? so... yeah, why not, it floats. And for the guys on the moon, well I haven't got any memories of astronauts without boots on, and those boots sure look big and heavy, they're special gravity boots, I'm sure I heard that on TV once, yeah, that's probably it. The first principles approach of applying the concept of universal gravitational attraction probably isn't even entering their heads, even if they've been taught it. This used to get on my nerves, how can people be so stupid? Why won't they just think for a moment!? But recently I've been focussing some effort on learning a language (Spanish) and realise that in that this case the first-principles style of learning that works so well for physics and maths is largely useless, and it's better to turn off the analytical side of your brain and not think too much, just keep exposing yourself, trying to communicate, and let your subconscious do it's stupid fuzzy pattern-matching, and it does a remarkably good job!
- judk 13y ago
  Check put the PhD thesis and TED talk of the guy running veritasium. It is all about sciencrofic misconceptions and education. Veritasium is an extension of that work.
  - jlees 13y ago
    TED talk link: https://www.youtube.com/watch?v=RQaW2bFieo8 https://www.youtube.com/watch?v=RQaW2bFieo8
- ghayes 13y ago
  It would have been really interesting to ask people to draw a free-body diagram listing out each of force acting on the rock, prior to asking the question of what would happen when dropped. It would be hard to make up a force besides lunar gravity and any Physics 101 student should now answer correctly by analytic reasoning.
b3tta 13y ago
And that's my basic problem with talking with other people: It's hard for me to understand how one can not know or comprehend what I know and classify as "basic knowledge"... Of course I understand that and can for instance explain it to them, but it often still remains surprising for me.
deleted 13y ago
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DateK 13y ago
One explanation for the wrong answers is how people use the phrase 'pen floats', and how people are imprecise about using words. The gravitational constant is 1/6 of the Earth's. This means that I can jump on the Moon 6 times higher than here and the pen will tale 6 times longer to fall down. It will take 6 times longer for gravity to 'kick-in' and cause the perceivable movement, as we got used to here on Earth - where on Earth the pen moved already 6 cm on the Moon the movement is still 1 cm. It looks as if the things are moving slower. I can catch a falling egg before it reaches the ground, my reactions are like of a fly on Earth. So I can say that the things are floating on Moon, because they are not accelerating and falling fast enough, in common terms. In interstellar space the pen will fall onto the neighbor galaxy, but will do this so slow, that I will perceive as if it is floating. If the pen will move alongside with an object much smaller than the Moon (a rock), the pen will fall onto the rock with much slower acceleration. For time perception of humans it will float in space. Another explanation for wrong answers is that if you feed people with stupid questions, you will get stupid answers. Have you asked me to answer these questions I will surely answer wrongly 'pen floats' and 'heavy boots' on purpose only to prove the point. These answers seem to be serious enough to mislead you.
- informatimago 13y ago
  The gravitational constant is constant DUH! It's worth the same 6.67384 × 10-11 m3 kg-1 s-2 on the Moon than on Earth than in the other corner of the Universe! (AFAWCK for the other corner of the Universe, from the kind of stellar light we get from there).
  - DateK 13y ago
    Thanks, you caught me in my incompetency. The standard gravity on Moon it supposed to be.
- kens 13y ago
  No, it does not take the pen 6 times longer to fall down on the Moon compared to Earth. Not even close. That's not how acceleration works. [I can give the equation, but I think it's more instructive if people think about it themselves :-) ] Also, actually try dropping a pen, like right now. Gravity "kicks in" immediately - there's no perceptible delay. (Unless your perception is way different from mine.)
informatimago 13y ago
I think the key is this sentence: "Many students thought the pen would float away. One year, she asked them instead about a crescent wrench instead of the “apocryphal pen.” They all answered that question correctly!" People just DO NOT think. Everybody has SEEN (on TV, where they spend more time in front of, than in school or reading books) astronauts in orbit demonstrate they're weighless, by showing a pen float in front of them. So space = floating pens, in their visual memory. Moon is in space, therefore pens float. What about a wrench? Oops, no visual memory to answer, bummer, they'll have to think! And of course, some of the little teaching they had pegged, and they can answer correctly. That's all. People DO NO think. Why do you think, IBM had to put up "THINK!" panels in its offices?
- DanBC 13y ago
  That's one possible reason. The other might be "pen == light, wrench == heavy".
- dennisgorelik 13y ago
  > People just DO NOT think. People think. They just generally do not think about Physics.
  - Double_Cast 13y ago
    I think he's referring to cached thoughts. Thinking critically takes more effort than retrieving cached thoughts. So why think critically in lieu of a ready made meme?
- mml 13y ago
  I've found that the main problem is that people do think. About things that they've seen on tv, or read, that are just plain fictional. Humans have a huge advantage in being able to communicate knowledge across generations, and a huge disadvantage in being able to communicate bullshit across generations.
DanBC 13y ago
See also this website. They ask the question to students, and we know the courses the students are taking. http://www.falstad.com/gravity.html http://www.falstad.com/gravity.html > Physics 324 - Modern Physics for Engineers > "A body is at rest tends to stay at rest, plus there's no gravity" > "The gravity of the moon can be said to be negligible, and also the moon's a vacuum, there is no external force on the pen. Therefore it will float where it is." > "The pen will float away because the gravitational pull of the moon, being approximately 1/6 that of the earth, will not be enough to cause the pen to fall nor remain stationary where it is. The gravatational pull of other objects would influence the pen" It's a bit scary seeing what the answers are. I guess we need to remember just how long ago it was that anyone was on the moon, or any distance into space. An ASCII diagram. e g m earth geosynchronous moon Since 1980 we've sent people maybe a pixel from e.
- christianmann 13y ago
  >> "The gravity of the moon can be said to be negligible, and also the moon's a vacuum, there is no external force on the pen. Therefore it will float where it is." That one's almost correct; it's just an issue of scale; they don't realize how big/heavy the moon actually is.
  - Crito 13y ago
    The issue is that they presumably understand that the moons gravity isn't negligible, since damn near everybody on earth has seen the Apollo 11 moon landing videos. They are not merely missing information needed to answer the question and making the wrong assumption. They have all of the necessary information, but get it wrong anyway because for whatever reason, they aren't using all of the information they have.
    - DanBC 13y ago
      > since damn near everybody on earth has seen the Apollo 11 moon landing videos. Is that true? I suspect it's true for people over 30 or who have special interest in STEM, but not so true for anyone else.
josephlord 13y ago
From the comments: > I answered gravity on a physics test in high school for the question “What force works at a distance” and got it wrong because the professor wanted electromagnetism. When I took the paper up to him to contest it, he told me that gravity doesn’t count because it only exists between planets. I got the physics book and ..." I was sure at that point he was going to say "dropped it on the floor" but no such luck. > "...read to him out of it but he cut me off and claimed that what I had read proved his point."
leoc 13y ago
The heavy-boots answer seems pretty justifiable in the case where you have a correct intuition about how gravity itself works but simply underestimate how strong the Moon's gravity happens to be. Set the parameters just-so and there would be a threshold effect, as on an asteroid massive enough to walk on but not-massive enough to jump off.
- jere 13y ago
  Exactly! This reminded me of the Little Planet what if http://what-if.xkcd.com/68/ http://what-if.xkcd.com/68/ Munroe claims on a small, super massive planet, you could overcome escape velocity with a sprint. It doesn't work the same on the moon obviously, but only because the moon has significant gravity. >Which, pointed out a discussant, suggests that students are using buoyancy as an analogy — if you’re heavy enough you sink, if you’re light enough you float. Why is this such a stupid assumption? That's how it works on Earth. I don't believe that these kids are failing to think; they're using reasonable analogies, but lacking specific knowledge about the environment on the moon. >"All science is either physics or stamp collecting." - Ernest Rutherford Basically the authors are complaining that the students haven't collected a specific stamp.
  - leoc 13y ago
    Well, the lack of an atmosphere on the Moon should rule out buoyancy. Myself I don't doubt that many of the wrong answers really were the result of faulty intuitions or dodgy reasoning.
    - jere 13y ago
      Of course, but that's another environmental variable.
  - informatimago 13y ago
    No, on the contrary! It's a packers vs. mappers question. The packers collect stamps, and when asked whether the pen falls on the Moon, get out the stamp that says that pens don't fall in space. The mappers will apply the physics model, the formula, and come out with the right answer (or approximation) corresponding to the right situation. That's a big problem with packers: you teach them stuff, but they retain only half of it, forgetting the applicability conditions. "Nothing can go faster than light!" Only material stuff, and only in the vacuum. But there are mediums where light will go slower than a walking human. "There's no perpetual motion machine!" Right, only when you consider a CLOSED system. There's no physical entity smaller than the Universe that's a closed system. Even black holes have inputs AND outputs! And so on.
fosap 13y ago
I call it bullshit. I just asked that question to a seminar of paedagogic students, without a single person with physics background. 2 Choose answer the first answer, 3 the sencond one, the other 20 choose the correct answer. I expect much better results for students with physics background. /edit, well bullshit is a bit strong, but replication failed
- mml 13y ago
  Only counts if you forbade them to communicate with each-other.
dennisgorelik 13y ago
If 47% of students fail that "pen on the Moon" question -- that means that about half of professionals are clueless about physics. On the other hand, most professionals are quite functional in their role (if it wasn't the case, why would employers pay them?). These two observations mean that understanding of physics is not mandatory for being functional professional.
- informatimago 13y ago
  No, it means they're not functional, and that employers pay them to heat their chairs. Why else would employers insist on having people come to the office, instead of working at home, as we almost all could, in this day and age? Further: http://www.technologyreview.com/view/519241/report-suggests-nearly-half-of-us-jobs-are-vulnerable-to-computerization/ http://www.technologyreview.com/view/519241/report-suggests-...
robmcm 13y ago
This is why Super Mario Galaxy is a great educational tool!
downer95 13y ago
That entire article made me angry like when I hear about creationism and evolution being taught as equal theoretical concepts.
mml 13y ago
My wife posited that perhaps their gravity suits kept them on the ground (which i found charming, at least she was thinking of gravity, and/or science fiction). My 8 year old daughter thought for a second and said the rock would fall, then on her way out of the room said it would float (no doubt taking some time to catalogue everything she's ever seen or read about space). I'm fairly sure if the question were posed as multiple choice, they both would have answered correctly. No indictment of either (or anyone else who would answer incorrectly). After all, not many people think of physics very often on a day to day basis, particularly physics of extraterrestrial bodies.
njharman 13y ago
I'm more stunned by this than when people go around and ask college students who the VP is or where is France. Those are facts and you either studied and memorized them or not. That many people suck at "reasoning" about problems boggles my mind. Most these students knew the facts of Newtonian mechanics but could not apply them (in my opinion) to a very simple problem. Not bragging. I must be good enough at reasoning that I am cognitively unable to comprehend that other people have trouble with it. Everyone knows how to breath or think about future. I assumed everyone can take things they know, combine/apply them to new situations. What I would call reason about things. Maybe they can. And the results are an artifact of college environment (study/memorize/pass test vs actually learn/challenge/grow). See, I so can't comprehend it that I'm trying to come up with rationalizations.
ivan_ah 13y ago
I think the false association in this context is the following: space --> weightlessness Thinking this makes people look for "alternate" explanations, like the weight of the boots, etc. People who have not been trained in physics often have a different "intuition" about the laws of physics. An interesting effort to qualify these "physics misconceptions" is the Force Concept Inventory (FCI) questionnaire[1], which which asks students to answer some basic qualitative problems from Newtonian mechanics. You should try it and see how you fare... Interestingly, researchers have found that even after taking a Newtonian mechanics class, many students still hold on to their misconceptions---their score on the FCI is only slightly improved... [1] http://prst-per.aps.org/multimedia/PRSTPER/v3/i1/e010102/e010102_app.pdf http://prst-per.aps.org/multimedia/PRSTPER/v3/i1/e010102/e01...
essayist 13y ago
I can't find the reference now, but in the 1980's, there was a study done on honors physics students -- undergraduates IIRC -- at Johns Hopkins. They were asked questions that they had the physics training to answer, but that were not problem set or exam questions. For instance: Coil a garden hose in a spiral, then force a ping pong ball out through the hose from the center to the periphery with a blast of air; how does it move once it leaves the hose: (a) continues in spiral (b) straight out - the tangent of the spiral where the hose ends (c) bending outward, away from the spiral. Some large percentage of the students got it wrong. Explanations: (i) students limited their "physics know-how" to the textbook context, and this was something different; (ii) textbook problem sets are, over time, edited to weed out confusing problems, even if they're valid. I've encountered something similar in teaching basic financial present value analysis to engineers - even the students who do well in the class go back to "folk" thinking when we discuss their mortgages and credit cards. To me, it says that the cue of the classroom, or the awareness that "this is part of Physics 101" is critical to getting some people to apply a particular frame, and without that cue, they go back to "common sense". That does explain what happened (in the blog post) in the Philosophy class, and in the phone poll, but not as well what happened when the blog author tested her physics students.
- sb23 13y ago
  Well shit, now I want to know the answer. It's "straight out" right?
  - quasse 13y ago
    From a simple F=m*a standpoint maybe, but I'm thinking that the hose would probably put a spin on the ball so it would likely curve outwards? A ball with no spin on it would travel straight outwards because there would be no force acting on it to make it curve in any other direction. I think a ball with spin on it would curve outwards because the ball would rotate the air around itself, which would provide the force needed to accelerate it outwards.
gmoot 13y ago
Here is a related question that has bothered me for some time: in Jules Verne's "From the Earth to the Moon" (1865), he writes the travelers as only achieving weightlessness for a small moment, at just the point where the moon's gravity exactly cancels out the earths gravity. This makes an intuitive kind of sense: you would gradually lose weight as you get farther from earth, then after a moment of weightlessness gradually 'gain' weight as you approach the moon. Obviously this is wrong, but why?
- matthewmacleod 13y ago
  (I'm not a physicist, so take the following with a grain of salt!) It's not wrong, but it would never happen. Let's say we've built a moon elevator. Like a space elevator, but tethered to the moon. You travel from the earth; there is a brief period of acceleration, then you settle down to a steady speed for your journey. After you reach the steady state, you are going to experience normal Earth gravity. As you move further from the earth, however, you will experience less of it. As you approach the moon, its gravity will eventually be stronger - with this transition occurring at the Lagrange point L1 between the earth and the moon, where the gravitational pull from each is equal. In practice, until we build a moon elevator, this isn't going to happen. Instead, we have to throw you at the moon using a rocket. Most of the energy we use for this is actually spent making you go sideways, instead of directly up. It's kind of cool actually - if you are orbiting the earth in, say, the ISS, you are actually experiencing nearly the same gravitational pull as if you were on the surface. You are just moving so ridiculously quickly in a circle around the earth that the centripetal force cancels out gravity - like someone is swinging you around on an invisible rope. Since this is happening to both you and the spaceship you are in, there is no relative acceleration - so you appear to be weightless. If we fire some more rockets to accelerate you towards a lunar orbit, nothing else changes - you are still not accelerating relative to your spacecraft (assuming you are strapped in!) and so you continue to appear weightless. You transfer into orbit around the moon - and you are in the same situation you were in when orbiting earth. But if you drop a lunar lander, which slows itself down - it'll fall! Orbital mechanics and gravity can certainly be counterintuitive, but it's thoroughly fascinating.
aaron695 13y ago
Myth: This story Truth: There are dumbasses in this world... those who believe this story, because it gives them a superiority over (mythical) others. Lol, those stupid uni students who don't even know there's gravity on the moon. Lucky I didn't get a degree and become dumber/Lucky my Uni was better. It's even a friend of a friend of a friend. Seriously, why is this on the front page?
moo 13y ago
I could have benefited from an unhurried, contemplative learning about science in elementary school. The primary concern approach with example and counter example even seems fun. The "heavy boots" problem of focusing on what is not the primary concern is a problem in understanding other issues like in politics. In politics though people have a self interested agenda and will warp reality to make it fit like having the earth the center of the galaxy. People should strive in political learning to use the first principle approach of the article, like eliminate oppression, and unbiasedly apply it universally.
novaleaf 13y ago
it blows my mind that half got the first question wrong... :(
stcredzero 13y ago
I wonder what the poll percentages would be like in other countries? I suspect that fewer people would be this ignorant in industrialized countries other than the US.
brownbat 13y ago
Towards the end, there are some guesses as to what theory of gravity the students hold, if it's a buoyancy analogy, or a threshold theory... A lot of people don't really subscribe to any coherent system of the world at all. When you press someone, it's not uncommon for them to just pile on another fact about the subject matter and reassert the claim. It's like brute force puzzle solving, kind of like I used to do in adventure games - you know the result you want, juggle all the stuff in your inventory or mind until it works. And for a lot of subjects, for a lot of education, that approach works really well. You're told three facts about some historical event. You're asked a question on a test about the event. List one of those facts to win. I'm guessing they jump to "boots" because the bootprint on the moon is a pretty widely seen and memorable image, and boots in our normal life are sometimes heavy. Heavy things make it harder to float, that's what heaviness sort of means. Having arrived at "floating's hard," they then call it a day without really understanding anything about how they got there. There's no underlying theory, they kick away the scaffolding as soon as they get to any answer. People don't have a list of facts in their heads that are constantly checked for mutual consistency, and people can stubbornly hang on to any premise they want. In other words, the students (+ phil TA) aren't just stupid on this point, they are so stupid, the physics teachers don't even understand how stupid they are.
foobarian 13y ago
When I read the title I thought this would be about space walks. Having heavy boots would help create a greater gravitational attraction to the space station, making it harder to float away. It's interesting to consider the forces involved. At 10m, with a 100kg astronaut and a 15 ton space station the gravitational force is about 1e-7 Newtons. At that acceleration, if the astronaut kicked off at the speed of 1cm/s--or 36 meters per hour--and assuming the force doesn't change, it would take about 24 days to get back.
7402 13y ago
Great video of Apollo 15 astronaut dropping feather and hammer on the moon: http://youtu.be/03SPBXALJZI http://youtu.be/03SPBXALJZI Too bad this isn't part of current events any more.
brownbat 13y ago
On a few sites, a commenter known as "Russ Brown" claims he posted the original on usenet, referring to a class he took in 1981. He claims that the quiz results were added to his version of events. http://www.openeducation.net/2009/05/07/how-were-apollo-astronauts-able-to-walk-on-the-moon-why-heavy-boots-of-course/ http://www.openeducation.net/2009/05/07/how-were-apollo-astr... http://worldofweirdthings.com/2009/04/27/a-gravity-fail-goes-viral-but-is-it-real/ http://worldofweirdthings.com/2009/04/27/a-gravity-fail-goes... I believe this is the original: https://groups.google.com/forum/#!search/"heavy$20boots"$20after$3A1988$2F01$2F01$20before$3A1990$2F12$2F31/sci.astro/nooS8qezfRE/80FcCjnIvDwJ https://groups.google.com/forum/#!search/"heavy$20boots"$20a...

169 points by andrelaszlo 13y ago

Site seems to be down. Cached version is here: http://webcache.googleusercontent.com/search?q=cache:uWHPLrGJYW4J:blog.sciencegeekgirl.com/2009/11/09/myth-because-the-astronauts-had-heavy-boots/ http://webcache.googleusercontent.com/search?q=cache:uWHPLrG... A significant part of the article is a reposting of http://www.phys.ufl.edu/~det/phy2060/heavyboots.html http://www.phys.ufl.edu/~det/phy2060/heavyboots.html Edit: Changed wording re how much of article is repost

gametheoretic 13y ago
Thanks for posting that. Not one to complain about blogspam, but that's one of the all-time great "internet motherfucker" posts. Neither Sciencegeekgirl.com (lol, brand yourself harder) nor anyone else can do much to add to it.
- brazzy 13y ago
  Actually, Sciencegeekgirl.com adds VERY MUCH to the article, namely a highly interesting discussion of WHY students give these wrong answers. No, it's not because they're stupid or ignorant.
  - enko 13y ago
    > it's not because they're stupid or ignorant They may not be stupid, but that's pretty much the definition of ignorance.
    - brazzy 13y ago
      Obviously, anyone who answers a question incorrectly is ignorant of the correct answer, but the point is that in many cases the wrong answer seems to be logically based on a wrong mental model of how gravity works. Just like Aristotelian physics. And Newtonian physics as well. Would you call Aristotle and Newton ignorant? The interesting part is the discussion of what these wrong mental models look like and how you can teach a correct one.
      - plorkyeran 13y ago
        > Would you call Aristotle and Newton ignorant? By modern standards, absolutely.
      - DanBC 13y ago
        > Would you call Aristotle and Newton ignorant? By your definition they're ignorant, but not stupid?
      - mbrutsch 13y ago
        > Would you call Aristotle and Newton ignorant? Absolutely. There was much they did not know, as is true of anyone. "Ignorant" is not an insult, it simply means you do not know something. Would you say Aristotle and Newton knew everything about everything? If not, then they would be, by definition, ignorant of the things they did not know.
      - almosnow 13y ago
        There's absolutely no way to justify a student attending a physics class and not knowing that the Moon does have gravity as well.
        brazzy 13y ago
        The problem is that they may know that the Moon has gravity, but they don't understand what that concretely means when it comes to questions like this.
        tene 13y ago
        I would dispute the validity of calling that state of mind "knowing that the moon has gravity". I would instead call it "memorized a couple of correlated keywords".
  - gametheoretic 13y ago
    No. Where writing is concerned, 2+2 is greater than 4.
nailer 13y ago
'Heavy boots' is actually a reasonable answer in that it doesn't preclude the moon having gravity.
- brazzy 13y ago
  On its own yes, but if combined with the previous statement that a pen would float away, it just exhibits a piecemeal and inconsistent understanding of physics.
  - judk 13y ago
    Why? On earth, heavy boots hold you down, but dust and feathers float away. The moon has less gravity than the Earth, so a pen is like a feather. Blah blah atmosphere electro-magnetism blah, the universe is big ad complicated.
    - na85 13y ago
      Oh god. Feathers and dust don't float away because they're weightless. They float away because air currents exert forces on them that are greater than their weight. Eventually, in a still-air environment, the feather and the dust will settle to the ground. You can verify this by going to your nearest attic.
      - cousin_it 13y ago
        To be fair, your nearest attic might have dust on the walls and ceiling as well, though maybe not as much...
    - deleted 13y ago
      [deleted]
    - pjc50 13y ago
      See the famous video of one of the lunar astronauts dropping a hammer and a feather at the same time. Both of them drop fairly rapidly to the surface.
MrBuddyCasino 13y ago
This was a pretty entertaining read. First I thought I would sense a smug sense of superiority of natural science over the humanities, but then I realized he performed the same test on his physics students.
- pothibo 13y ago
  I always sucked in tests. In the first question, I would have hesitated between b) and d). The reason for choosing b) would have been that the moon's gravity being weak, the earth's gravity nullified the moon's thus having a floating pen. The reason for choosing d) would be because Moon's gravity is stronger than Earth's. This is why I think tests are stupids. If I had chosen b) instead of d) I would have gotten a wrong answer. Even though my thought process would be correct. Just missing the right information (which could have been easily found outside a test environment).
  - mikeash 13y ago
    The relative strength of gravity mostly does not matter. If the Earth pulled on you harder than the moon, you'd still fall towards the moon, because the moon is just as strongly affected by that gravity as you are (momentarily ignoring tides). So no, I'm pretty sure your thought process wasn't remotely correct.
    - dennisgorelik 13y ago
      His thought process is correct, but his "pen on the Moon" model is missing vital element (that Moon is in free fall/orbiting Earth). If Moon was hanging on a stick connected to Earth (instead of orbiting Earth) and Earth gravity forces on a pen were stronger than Moon's gravity forces, then pen would fall in Earth. Of course you and I know that there are no such strong materials for that Earth-Moon stick, but that's yet another level of complexity that most people don't have to know about.
      - Dylan16807 13y ago
        >If Moon was hanging on a stick connected to Earth (instead of orbiting Earth) and Earth gravity forces on a pen were stronger than Moon's gravity forces, then pen would fall in Earth. Technically that's true, but it would require a completely different scenario. Earth's gravity is miniscule at that altitude. For the moon to have a weaker force it would have to be so small that it would likely not even qualify as a moon any more.
masklinn 13y ago
>Article is mainly just a reposting of http://www.phys.ufl.edu/~det/phy2060/heavyboots.html http://www.phys.ufl.edu/~det/phy2060/heavyboots.html though... That is an unfair characterisation, I think. The article does indeed reproduce heavyboots in its 725 words entirety (according to pages's word count for what that one's worth), but tacks a further 930 words afterwards. And these 930 are interesting indeed as they're further explorations of the phenomenon and discussion on its underlying reasons.
- andyjohnson0 13y ago
  Fair enough - I've changed the wording a bit. Personally, though, I thought that the follow-on discussion didn't add much beyond what was mentioned in the original heavyboots article.

onion2k 13y ago

This must be nonsense. Or an April Fools joke. Or something. I don't want it to be true. It can't be. sobs quietly

JonnieCache 13y ago
Read to the end and the bit about buoyancy, you'll be less angry.
- astrodust 13y ago
  That merely demonstrates people aren't thinking, they're just applying patterns.
  - JonnieCache 13y ago
    You say tomato, I say tomato, let's call the whole thing off.
Strilanc 13y ago
Veritasium [1] often interviews people as part of his videos, and the results are consistent with what's being described in the post: somewhat distressing [2]. To the point where you might think he was purposefully making fun of them [3]. 1: http://www.youtube.com/user/1veritasium/videos http://www.youtube.com/user/1veritasium/videos 2: http://www.youtube.com/watch?v=TQxeutcYP6I http://www.youtube.com/watch?v=TQxeutcYP6I 3: http://www.youtube.com/watch?v=cY_o4A1wzsg http://www.youtube.com/watch?v=cY_o4A1wzsg
deleted 13y ago
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cstross 13y ago
Go forth and ask random people whether (a) the earth revolves around the sun, or (b) the sun revolves around the earth. The proportion giving answer (b) will cause you to sob even more. (Yes, I have done this. Afterwards, I hid under my bed bewailing the ignorance of my fellow hominids.)

gadders 13y ago

At my daughter's school, they had an assembly for parents to attend that celebrated, amongst other things, the first landing on the moon. The children boldy proclaimed that the reason the hammer and the feather hit the ground at the same time in the famous experiment was because there was less gravity on the moon. It still rankles with me a year later.

DanBC 13y ago
That's a shame. Was there any opportunity to assess the material before it was presented? Was there any method to correct mistakes after? Your daughter presumably understands that it's not about gravity but air resistance. Has she told all her pals? Because that kind of subversive teaching could be really powerful. TEACHERS HATE HER; THE GRAVITY SECRET THEY DON'T WANT YOU TO KNOW!!! etc. May I ask, hold old was your daughter? What kind of science teaching should she be getting? (Obviously, not anything that wrong).
- gadders 13y ago
  She was 6 at the time. I told her afterwards it was wrong but I regret not telling the teachers.
mikeash 13y ago
It's amusing that that kind of is the reason, indirectly. Less gravity means it couldn't retain an atmosphere, and the lack of an atmosphere is why they fall together.

cynichacker 13y ago

I would add another answer choice to the question 25: 25. When the Apollo astronauts were on the Moon, they did not fall off because: (f) They were on Earth

hrvbr 13y ago

There's a similarity between teachers and journalists in that they're supposed to double-check their informations before transmitting them. Not doing it plagues society.

ghshephard 13y ago

When I took physics in high school, Gravity was introduced to me with an equation. After 5 minutes discussion, everyone in the room would have known how to answer the question about "Dropping a rock on the moon." I find it hard to believe that a high school physics student, just fresh from studying gravity module, wouldn't realize that a rock dropped on the moon would fall down. Doesn't pass the smell test.

sp332 13y ago
Being introduced to gravity with an equation is not nearly enough to figure out how things will behave. It takes calculus to describe the motion of falling things even without air resistance. Even if someone straight-up tells the students that gravity accelerates things at the same rate regardless of mass, they're probably not going to believe it without some experiments. Edit: a quiz to maybe prove my point :) On the moon, if you throw a rock, what shape would its arc describe? Edit2: not a straight line when you drop it, silly!
- mnw21cam 13y ago
  Depends how hard you throw it. ;)
  - informatimago 13y ago
    Just like on Earth. That's the point.
    - sp332 13y ago
      That wasn't my point really. Oh well! I though most people would pick a parabola, which is a decent approximation for short throws but not the real shape.
      - simias 13y ago
        You got me, what's the real shape? I thought it was a parabola if there was no air friction. Or are you taking the curvature of the moon into account?

buyx 13y ago

Does a lack of knowledge of physics really matter in the real world for most people? I was recently wondering if our terrible road safety problem in South Africa can partly be explained due to a lack of understanding of physics. After all, intuitively Newton's First Law explains why seatbelts are necessary. Concepts like momentum and kinetic energy explain why heavy trucks, speeding down steep inclines are dangerous - authorities don't seem to grasp that very often, and tragedies involving runaway trucks on poorly engineered roads are not infrequent. But I then realised that two of the most reckless drivers I know are my uncle, an Engineering dropout, and my friend who is a practicing engineer. Being good at physics hasn't saved them from being in multiple car crashes. Are there any cases where an understanding of physics helps the average person in everyday life?

lmm 13y ago
This isn't a lack of physics knowledge, it's a lack of basic reasoning. If they'd said "the astronauts had magnetic boots", for example, that would be wrong, very wrong, but it would have made sense - at least, it's not outright contradicted by their previous answer.
- mokus 13y ago
  That was my first reaction too. After thinking and discussing it with some non-technical people, though, I realize it's not a contradiction unless you also assume some physics knowledge. I (and probably you) have so deeply digested the fact that a pen and a heavy boot fall at the same rate that it seems like a logical failure to not incorporate it into a conclusion. It's quite possible that a person's understanding is simply inconsistent (at the frontiers of anyone's knowledge i think inconsistency is quite common; "learning" is largely a process of finding more data and working through implications to resolve them), but it not a foregone conclusion based on these answers. This is the main challenge in teaching people any technical subject - discovering the basic knowledge you have assimilated so deeply that you can't even imagine that others don't share it.
ckarmann 13y ago
The thing is, you can go on in life without understanding barely anything. That's one of the wonder of the modern life. You just need to be able to do enough arithmetics to buy stuff at the grocery and pays your bills and taxes. For your uncle and friend, understanding something doesn't mean you feel it's going to apply to you. Road accident are not only a matter of physics but also a matter of statistics and risk calculation. Some people are reckless because they can't compute the probability of accident and often underestimate it, feeling that since they think they are good drivers it won't happen to them. Humans in general are bad at assessing risk, it's a very difficult matter.

jeena 13y ago

Fascinating, I was so confused at first because I first misunderstood the fact who was right and who was wrong in this philosophy class. I will ask this question on parties, this will be funny :D

mnw21cam 13y ago

A long while back, I read a scifi book (really a kids scifi book) about a kid that finds a red pebble which cancels gravity for anything it's in contact with (except kids, obviously), causing those objects to be pulled strongly up into the sky. Why? Because they were attracted by the moon's gravity. They even got it to spin round and suggested using that for free energy. Can't for the life of me remember the title or author, but I remember it really grated against my sensibilities, and I never read anything by the same author again.

cynicalkane 13y ago
If you had a way to cancel gravity, you could use that to get free energy because the no-curl condition for energy conserving fields would no longer hold. You could create a closed path in space where gravity is always pulling you along the path.
dTal 13y ago
I couldn't resist crunching the numbers: the acceleration due to the moon's gravity as felt from the Earth is roughly 3.319×10^-5 m/s². By contrast, the centripetal acceleration due to Earth's rotation is 0.0337 m/s², several orders of magnitude larger (and just about perceptible as a gentle tendency to float up). (A similar example to your red pebble would be "Cavorite" from the H. G. Wells story "The first men in the moon", which also negated gravity causing objects to shoot violently upwards. The explanation given however was buoyancy, which makes more sense I suppose.)
teahat 13y ago
Pretty sure it was Antigrav by Nicholas Fisk. It was a cool story - if you were a kid. I never did find any red pebbles though.
- mnw21cam 13y ago
  That sounds about right.

rz2k 13y ago

I think a lot of people who are skeptical of this story just don't realize that they appended to be surrounded by people who have developed unusually accurate physical models. I recommend browsing Amazon reviews of (non heat pump) electric heaters for statements about which ones are more efficient. (The less efficient one produce more waste heat?) Because there are few consumer products that exercise people's understanding of gravity, basic thermodynamics might be a good proxy. However the real point of the article isn't all the misconceptions that must be "plucked out" one by one, but the struggle of trying to figure out how to encourage students to form more comprehensive models. I'd also add that an important goal in teaching is students' facility in applying principles, and confidence to question intuition and consensus.

jhonkola 13y ago
Well, in case of electric heaters used to heat a home the efficiency should really be measured in terms of "how much electricity is consumed if the heated room is kept at constant 20C measured at e.g. center of room". This is somewhat dependent on the quality of the thermostat controlling the heater. Then, I think that there are some real differences found in the efficiency of the heaters.
- alanctgardner2 13y ago
  I don't think energy efficiency is really so critical as the control system: how much steady-state error is there, and how quickly can it initially heat the room? Overheating the room is obviously a bit of a waste of power, but it's also uncomfortable.
- quasse 13y ago
  If you're still talking about electrical heaters here, there's literally no where for the energy used to go other than into heat for the room. If you have two 1000w heaters, one made from a potato and ten clothes hangers and the other made from the highest quality materials known to man, they will still both heat a room the same amount. Granted, one might have a better fan or more airflow and might therefore provide a more even heat distribution in the room, but they will both be providing the same amount of heat to the interior of the room. That's just how energy balances work. If 1000w is flowing from the plug into the heater and it's not being stored anywhere in the heater itself there's nowhere for it to go but into heat for the room.

steveridout 13y ago

I think the people who answered wrongly aren't thinking in a first principles, physics-based mindset, but just instead just recalling previous memories and reasoning in an intuitive, fuzzy kind of pattern-matching. We've all seen images of pens floating weightless in space on films and TV, and we probably haven't ever seen pens falling on the moon. But the moon is in space right? so... yeah, why not, it floats. And for the guys on the moon, well I haven't got any memories of astronauts without boots on, and those boots sure look big and heavy, they're special gravity boots, I'm sure I heard that on TV once, yeah, that's probably it. The first principles approach of applying the concept of universal gravitational attraction probably isn't even entering their heads, even if they've been taught it. This used to get on my nerves, how can people be so stupid? Why won't they just think for a moment!? But recently I've been focussing some effort on learning a language (Spanish) and realise that in that this case the first-principles style of learning that works so well for physics and maths is largely useless, and it's better to turn off the analytical side of your brain and not think too much, just keep exposing yourself, trying to communicate, and let your subconscious do it's stupid fuzzy pattern-matching, and it does a remarkably good job!

judk 13y ago
Check put the PhD thesis and TED talk of the guy running veritasium. It is all about sciencrofic misconceptions and education. Veritasium is an extension of that work.
- jlees 13y ago
  TED talk link: https://www.youtube.com/watch?v=RQaW2bFieo8 https://www.youtube.com/watch?v=RQaW2bFieo8
ghayes 13y ago
It would have been really interesting to ask people to draw a free-body diagram listing out each of force acting on the rock, prior to asking the question of what would happen when dropped. It would be hard to make up a force besides lunar gravity and any Physics 101 student should now answer correctly by analytic reasoning.

b3tta 13y ago

And that's my basic problem with talking with other people: It's hard for me to understand how one can not know or comprehend what I know and classify as "basic knowledge"... Of course I understand that and can for instance explain it to them, but it often still remains surprising for me.

deleted 13y ago

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DateK 13y ago

One explanation for the wrong answers is how people use the phrase 'pen floats', and how people are imprecise about using words. The gravitational constant is 1/6 of the Earth's. This means that I can jump on the Moon 6 times higher than here and the pen will tale 6 times longer to fall down. It will take 6 times longer for gravity to 'kick-in' and cause the perceivable movement, as we got used to here on Earth - where on Earth the pen moved already 6 cm on the Moon the movement is still 1 cm. It looks as if the things are moving slower. I can catch a falling egg before it reaches the ground, my reactions are like of a fly on Earth. So I can say that the things are floating on Moon, because they are not accelerating and falling fast enough, in common terms. In interstellar space the pen will fall onto the neighbor galaxy, but will do this so slow, that I will perceive as if it is floating. If the pen will move alongside with an object much smaller than the Moon (a rock), the pen will fall onto the rock with much slower acceleration. For time perception of humans it will float in space. Another explanation for wrong answers is that if you feed people with stupid questions, you will get stupid answers. Have you asked me to answer these questions I will surely answer wrongly 'pen floats' and 'heavy boots' on purpose only to prove the point. These answers seem to be serious enough to mislead you.

informatimago 13y ago
The gravitational constant is constant DUH! It's worth the same 6.67384 × 10-11 m3 kg-1 s-2 on the Moon than on Earth than in the other corner of the Universe! (AFAWCK for the other corner of the Universe, from the kind of stellar light we get from there).
- DateK 13y ago
  Thanks, you caught me in my incompetency. The standard gravity on Moon it supposed to be.
kens 13y ago
No, it does not take the pen 6 times longer to fall down on the Moon compared to Earth. Not even close. That's not how acceleration works. [I can give the equation, but I think it's more instructive if people think about it themselves :-) ] Also, actually try dropping a pen, like right now. Gravity "kicks in" immediately - there's no perceptible delay. (Unless your perception is way different from mine.)

informatimago 13y ago

I think the key is this sentence: "Many students thought the pen would float away. One year, she asked them instead about a crescent wrench instead of the “apocryphal pen.” They all answered that question correctly!" People just DO NOT think. Everybody has SEEN (on TV, where they spend more time in front of, than in school or reading books) astronauts in orbit demonstrate they're weighless, by showing a pen float in front of them. So space = floating pens, in their visual memory. Moon is in space, therefore pens float. What about a wrench? Oops, no visual memory to answer, bummer, they'll have to think! And of course, some of the little teaching they had pegged, and they can answer correctly. That's all. People DO NO think. Why do you think, IBM had to put up "THINK!" panels in its offices?

DanBC 13y ago
That's one possible reason. The other might be "pen == light, wrench == heavy".
dennisgorelik 13y ago
> People just DO NOT think. People think. They just generally do not think about Physics.
- Double_Cast 13y ago
  I think he's referring to cached thoughts. Thinking critically takes more effort than retrieving cached thoughts. So why think critically in lieu of a ready made meme?
mml 13y ago
I've found that the main problem is that people do think. About things that they've seen on tv, or read, that are just plain fictional. Humans have a huge advantage in being able to communicate knowledge across generations, and a huge disadvantage in being able to communicate bullshit across generations.

DanBC 13y ago

See also this website. They ask the question to students, and we know the courses the students are taking. http://www.falstad.com/gravity.html http://www.falstad.com/gravity.html > Physics 324 - Modern Physics for Engineers > "A body is at rest tends to stay at rest, plus there's no gravity" > "The gravity of the moon can be said to be negligible, and also the moon's a vacuum, there is no external force on the pen. Therefore it will float where it is." > "The pen will float away because the gravitational pull of the moon, being approximately 1/6 that of the earth, will not be enough to cause the pen to fall nor remain stationary where it is. The gravatational pull of other objects would influence the pen" It's a bit scary seeing what the answers are. I guess we need to remember just how long ago it was that anyone was on the moon, or any distance into space. An ASCII diagram. e g m earth geosynchronous moon Since 1980 we've sent people maybe a pixel from e.

christianmann 13y ago
>> "The gravity of the moon can be said to be negligible, and also the moon's a vacuum, there is no external force on the pen. Therefore it will float where it is." That one's almost correct; it's just an issue of scale; they don't realize how big/heavy the moon actually is.
- Crito 13y ago
  The issue is that they presumably understand that the moons gravity isn't negligible, since damn near everybody on earth has seen the Apollo 11 moon landing videos. They are not merely missing information needed to answer the question and making the wrong assumption. They have all of the necessary information, but get it wrong anyway because for whatever reason, they aren't using all of the information they have.
  - DanBC 13y ago
    > since damn near everybody on earth has seen the Apollo 11 moon landing videos. Is that true? I suspect it's true for people over 30 or who have special interest in STEM, but not so true for anyone else.

josephlord 13y ago

From the comments: > I answered gravity on a physics test in high school for the question “What force works at a distance” and got it wrong because the professor wanted electromagnetism. When I took the paper up to him to contest it, he told me that gravity doesn’t count because it only exists between planets. I got the physics book and ..." I was sure at that point he was going to say "dropped it on the floor" but no such luck. > "...read to him out of it but he cut me off and claimed that what I had read proved his point."

leoc 13y ago

The heavy-boots answer seems pretty justifiable in the case where you have a correct intuition about how gravity itself works but simply underestimate how strong the Moon's gravity happens to be. Set the parameters just-so and there would be a threshold effect, as on an asteroid massive enough to walk on but not-massive enough to jump off.

jere 13y ago
Exactly! This reminded me of the Little Planet what if http://what-if.xkcd.com/68/ http://what-if.xkcd.com/68/ Munroe claims on a small, super massive planet, you could overcome escape velocity with a sprint. It doesn't work the same on the moon obviously, but only because the moon has significant gravity. >Which, pointed out a discussant, suggests that students are using buoyancy as an analogy — if you’re heavy enough you sink, if you’re light enough you float. Why is this such a stupid assumption? That's how it works on Earth. I don't believe that these kids are failing to think; they're using reasonable analogies, but lacking specific knowledge about the environment on the moon. >"All science is either physics or stamp collecting." - Ernest Rutherford Basically the authors are complaining that the students haven't collected a specific stamp.
- leoc 13y ago
  Well, the lack of an atmosphere on the Moon should rule out buoyancy. Myself I don't doubt that many of the wrong answers really were the result of faulty intuitions or dodgy reasoning.
  - jere 13y ago
    Of course, but that's another environmental variable.
- informatimago 13y ago
  No, on the contrary! It's a packers vs. mappers question. The packers collect stamps, and when asked whether the pen falls on the Moon, get out the stamp that says that pens don't fall in space. The mappers will apply the physics model, the formula, and come out with the right answer (or approximation) corresponding to the right situation. That's a big problem with packers: you teach them stuff, but they retain only half of it, forgetting the applicability conditions. "Nothing can go faster than light!" Only material stuff, and only in the vacuum. But there are mediums where light will go slower than a walking human. "There's no perpetual motion machine!" Right, only when you consider a CLOSED system. There's no physical entity smaller than the Universe that's a closed system. Even black holes have inputs AND outputs! And so on.

fosap 13y ago

I call it bullshit. I just asked that question to a seminar of paedagogic students, without a single person with physics background. 2 Choose answer the first answer, 3 the sencond one, the other 20 choose the correct answer. I expect much better results for students with physics background. /edit, well bullshit is a bit strong, but replication failed

mml 13y ago
Only counts if you forbade them to communicate with each-other.

dennisgorelik 13y ago

If 47% of students fail that "pen on the Moon" question -- that means that about half of professionals are clueless about physics. On the other hand, most professionals are quite functional in their role (if it wasn't the case, why would employers pay them?). These two observations mean that understanding of physics is not mandatory for being functional professional.

informatimago 13y ago
No, it means they're not functional, and that employers pay them to heat their chairs. Why else would employers insist on having people come to the office, instead of working at home, as we almost all could, in this day and age? Further: http://www.technologyreview.com/view/519241/report-suggests-nearly-half-of-us-jobs-are-vulnerable-to-computerization/ http://www.technologyreview.com/view/519241/report-suggests-...

robmcm 13y ago

This is why Super Mario Galaxy is a great educational tool!

downer95 13y ago

That entire article made me angry like when I hear about creationism and evolution being taught as equal theoretical concepts.

mml 13y ago

My wife posited that perhaps their gravity suits kept them on the ground (which i found charming, at least she was thinking of gravity, and/or science fiction). My 8 year old daughter thought for a second and said the rock would fall, then on her way out of the room said it would float (no doubt taking some time to catalogue everything she's ever seen or read about space). I'm fairly sure if the question were posed as multiple choice, they both would have answered correctly. No indictment of either (or anyone else who would answer incorrectly). After all, not many people think of physics very often on a day to day basis, particularly physics of extraterrestrial bodies.

njharman 13y ago

I'm more stunned by this than when people go around and ask college students who the VP is or where is France. Those are facts and you either studied and memorized them or not. That many people suck at "reasoning" about problems boggles my mind. Most these students knew the facts of Newtonian mechanics but could not apply them (in my opinion) to a very simple problem. Not bragging. I must be good enough at reasoning that I am cognitively unable to comprehend that other people have trouble with it. Everyone knows how to breath or think about future. I assumed everyone can take things they know, combine/apply them to new situations. What I would call reason about things. Maybe they can. And the results are an artifact of college environment (study/memorize/pass test vs actually learn/challenge/grow). See, I so can't comprehend it that I'm trying to come up with rationalizations.

ivan_ah 13y ago

I think the false association in this context is the following: space --> weightlessness Thinking this makes people look for "alternate" explanations, like the weight of the boots, etc. People who have not been trained in physics often have a different "intuition" about the laws of physics. An interesting effort to qualify these "physics misconceptions" is the Force Concept Inventory (FCI) questionnaire[1], which which asks students to answer some basic qualitative problems from Newtonian mechanics. You should try it and see how you fare... Interestingly, researchers have found that even after taking a Newtonian mechanics class, many students still hold on to their misconceptions---their score on the FCI is only slightly improved... [1] http://prst-per.aps.org/multimedia/PRSTPER/v3/i1/e010102/e010102_app.pdf http://prst-per.aps.org/multimedia/PRSTPER/v3/i1/e010102/e01...

essayist 13y ago

I can't find the reference now, but in the 1980's, there was a study done on honors physics students -- undergraduates IIRC -- at Johns Hopkins. They were asked questions that they had the physics training to answer, but that were not problem set or exam questions. For instance: Coil a garden hose in a spiral, then force a ping pong ball out through the hose from the center to the periphery with a blast of air; how does it move once it leaves the hose: (a) continues in spiral (b) straight out - the tangent of the spiral where the hose ends (c) bending outward, away from the spiral. Some large percentage of the students got it wrong. Explanations: (i) students limited their "physics know-how" to the textbook context, and this was something different; (ii) textbook problem sets are, over time, edited to weed out confusing problems, even if they're valid. I've encountered something similar in teaching basic financial present value analysis to engineers - even the students who do well in the class go back to "folk" thinking when we discuss their mortgages and credit cards. To me, it says that the cue of the classroom, or the awareness that "this is part of Physics 101" is critical to getting some people to apply a particular frame, and without that cue, they go back to "common sense". That does explain what happened (in the blog post) in the Philosophy class, and in the phone poll, but not as well what happened when the blog author tested her physics students.

sb23 13y ago
Well shit, now I want to know the answer. It's "straight out" right?
- quasse 13y ago
  From a simple F=m*a standpoint maybe, but I'm thinking that the hose would probably put a spin on the ball so it would likely curve outwards? A ball with no spin on it would travel straight outwards because there would be no force acting on it to make it curve in any other direction. I think a ball with spin on it would curve outwards because the ball would rotate the air around itself, which would provide the force needed to accelerate it outwards.

gmoot 13y ago

Here is a related question that has bothered me for some time: in Jules Verne's "From the Earth to the Moon" (1865), he writes the travelers as only achieving weightlessness for a small moment, at just the point where the moon's gravity exactly cancels out the earths gravity. This makes an intuitive kind of sense: you would gradually lose weight as you get farther from earth, then after a moment of weightlessness gradually 'gain' weight as you approach the moon. Obviously this is wrong, but why?

matthewmacleod 13y ago
(I'm not a physicist, so take the following with a grain of salt!) It's not wrong, but it would never happen. Let's say we've built a moon elevator. Like a space elevator, but tethered to the moon. You travel from the earth; there is a brief period of acceleration, then you settle down to a steady speed for your journey. After you reach the steady state, you are going to experience normal Earth gravity. As you move further from the earth, however, you will experience less of it. As you approach the moon, its gravity will eventually be stronger - with this transition occurring at the Lagrange point L1 between the earth and the moon, where the gravitational pull from each is equal. In practice, until we build a moon elevator, this isn't going to happen. Instead, we have to throw you at the moon using a rocket. Most of the energy we use for this is actually spent making you go sideways, instead of directly up. It's kind of cool actually - if you are orbiting the earth in, say, the ISS, you are actually experiencing nearly the same gravitational pull as if you were on the surface. You are just moving so ridiculously quickly in a circle around the earth that the centripetal force cancels out gravity - like someone is swinging you around on an invisible rope. Since this is happening to both you and the spaceship you are in, there is no relative acceleration - so you appear to be weightless. If we fire some more rockets to accelerate you towards a lunar orbit, nothing else changes - you are still not accelerating relative to your spacecraft (assuming you are strapped in!) and so you continue to appear weightless. You transfer into orbit around the moon - and you are in the same situation you were in when orbiting earth. But if you drop a lunar lander, which slows itself down - it'll fall! Orbital mechanics and gravity can certainly be counterintuitive, but it's thoroughly fascinating.

aaron695 13y ago

Myth: This story Truth: There are dumbasses in this world... those who believe this story, because it gives them a superiority over (mythical) others. Lol, those stupid uni students who don't even know there's gravity on the moon. Lucky I didn't get a degree and become dumber/Lucky my Uni was better. It's even a friend of a friend of a friend. Seriously, why is this on the front page?

moo 13y ago

I could have benefited from an unhurried, contemplative learning about science in elementary school. The primary concern approach with example and counter example even seems fun. The "heavy boots" problem of focusing on what is not the primary concern is a problem in understanding other issues like in politics. In politics though people have a self interested agenda and will warp reality to make it fit like having the earth the center of the galaxy. People should strive in political learning to use the first principle approach of the article, like eliminate oppression, and unbiasedly apply it universally.

novaleaf 13y ago

it blows my mind that half got the first question wrong... :(

stcredzero 13y ago

I wonder what the poll percentages would be like in other countries? I suspect that fewer people would be this ignorant in industrialized countries other than the US.

brownbat 13y ago

Towards the end, there are some guesses as to what theory of gravity the students hold, if it's a buoyancy analogy, or a threshold theory... A lot of people don't really subscribe to any coherent system of the world at all. When you press someone, it's not uncommon for them to just pile on another fact about the subject matter and reassert the claim. It's like brute force puzzle solving, kind of like I used to do in adventure games - you know the result you want, juggle all the stuff in your inventory or mind until it works. And for a lot of subjects, for a lot of education, that approach works really well. You're told three facts about some historical event. You're asked a question on a test about the event. List one of those facts to win. I'm guessing they jump to "boots" because the bootprint on the moon is a pretty widely seen and memorable image, and boots in our normal life are sometimes heavy. Heavy things make it harder to float, that's what heaviness sort of means. Having arrived at "floating's hard," they then call it a day without really understanding anything about how they got there. There's no underlying theory, they kick away the scaffolding as soon as they get to any answer. People don't have a list of facts in their heads that are constantly checked for mutual consistency, and people can stubbornly hang on to any premise they want. In other words, the students (+ phil TA) aren't just stupid on this point, they are so stupid, the physics teachers don't even understand how stupid they are.

foobarian 13y ago

When I read the title I thought this would be about space walks. Having heavy boots would help create a greater gravitational attraction to the space station, making it harder to float away. It's interesting to consider the forces involved. At 10m, with a 100kg astronaut and a 15 ton space station the gravitational force is about 1e-7 Newtons. At that acceleration, if the astronaut kicked off at the speed of 1cm/s--or 36 meters per hour--and assuming the force doesn't change, it would take about 24 days to get back.

7402 13y ago

Great video of Apollo 15 astronaut dropping feather and hammer on the moon: http://youtu.be/03SPBXALJZI http://youtu.be/03SPBXALJZI Too bad this isn't part of current events any more.

brownbat 13y ago

On a few sites, a commenter known as "Russ Brown" claims he posted the original on usenet, referring to a class he took in 1981. He claims that the quiz results were added to his version of events. http://www.openeducation.net/2009/05/07/how-were-apollo-astronauts-able-to-walk-on-the-moon-why-heavy-boots-of-course/ http://www.openeducation.net/2009/05/07/how-were-apollo-astr... http://worldofweirdthings.com/2009/04/27/a-gravity-fail-goes-viral-but-is-it-real/ http://worldofweirdthings.com/2009/04/27/a-gravity-fail-goes... I believe this is the original: https://groups.google.com/forum/#!search/"heavy$20boots"$20after$3A1988$2F01$2F01$20before$3A1990$2F12$2F31/sci.astro/nooS8qezfRE/80FcCjnIvDwJ https://groups.google.com/forum/#!search/"heavy$20boots"$20a...