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News Science

Solving the Great Shower Curtain Mystery 244

Posted by michael from the too-much-free-time dept.
parvati writes: "The New York Times is reporting that a UMass professor, Dr. David Schmidt, used computer modeling to figure out why shower curtains suck inward during showers. He designed an image of his mother-in-law's shower, filled it with 50,000 3D velocity/pressure sensors, and turned on the virtual water. 1.5 trillion calculations later, he found that drag on the falling water drops creates a mini-hurricance, producing a low-pressure 'eye' that attracts the shower curtain."
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Solving the Great Shower Curtain Mystery More

Solving the Great Shower Curtain Mystery

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  • Re:Moral of the story (Score:1)

    by Anonymous Coward
    Better yet, and perhaps cheaper, would be for the Hampton Inn to equip all the bathrooms with high quality vacuum pumps, and curtain position sensors.

    By continuously monitoring the position of the shower curtain, they could detect the inward bowing of the curtain and then compensate by evacuating an appropriate amount of air from the bathroom.

    This would keep things cheap for customer by allowing them to keep their current curtains.

  • Re:Bernouli's (sp) Theory (Score:1)

    by Anonymous Coward
    Once again, common sense proves wrong, but the person with the 'common sense' refuses to even try to understand why.

    And what's the deal with calling yourself Dirac?
    You know that the quantum unit of work (i.e the smallest amount of work it's possible to do without doing nothing) is the Dirac? It's defined as the amount of useful research Dirac published per year.

  • Re:Great! (Score:1)

    by Anonymous Coward
    I think there is a flaw here. It is one thing to model shower droplet flow down through six feet of air inside a shower stall, but what about the inclusion of the human? This changes the physics. Assume a five and a half foot human blocking most of the water flow, so that there is about six inches of unimpeded flow, then the water hits the body, and pours off. I don't see where the vortex can be, now that I am standing in the shower, occupying space, deflecting any regular flow, and still observing the billowing. Any ideas? Did our researcher miss something vital?

  • Re:My own data (Score:4)

    by Anonymous Coward on Sunday July 15, 2001 @08:08PM (#83443)
    You must be an american. Here's why:
    • You assume that throwing things away is a good thing to do if you are too lazy to put any effort into fixing it.
    • You use the $ sign.


    Really, I don't mean to flame, but just because something is old, dirty, used, etc. dosen't mean that it is not worth putting a little elbow grease into. The environment is turning into shit. It may be nice and shiny where you are, but there are places (like where that shower curtian would go) that absolutely suck. It all has to go somewhere.

    I'm not saying keep everything! Of course, there are practicality reasons -- it may not be practical to clean the curtain if the chemicals to do so cost more than replacing it, or will potentially cause more environmental damage than just tossing the curtian.

    Then there is the lack of education. You may not know how to clean the shower curtian. I can't tell you how many times I have found electronics (tv's, computers, a few SGI's from LockheedMartin, you know the standard faire...) that were in some simple state of disrepair. I changed the plug and coord on a 32" tele that I found by my dumpster in the alley; otherwise it was in supreme condition. It works excelent! I assume they left it there because they either didn't have the time to fix it, or they didn't know how. This was an $800 dollar tv in it's day. Unless someone is so rich to spend an hour (as if) trying to fix it, it just seems unlikely.

    $800/hour! It makes me realize that fix-it guys can make it good if they market right.

    That said, I am an american. But as a whole, I really hate america for their lazy-throw_away-buy_a_new_one-McCulture attitude, and unthoughtfulness. They then go and prosecute anyone who does not agree with their opinion. I may be misjudging you, but as a whole, america agrees with a hearty "Smack my fro!"

    /me huffs and puffs on the witch-burning stake of prosecution.
  • Ha! A Hampton Inn I stay at semi freqently near Chicago is exactly the first thing that came to mind when I read this article!
  • Why would you clean something that can be replaced for $1.99?

    Your bathroom only costs $1.99 to replace?

  • You may be interested in this [monmouth.com] site.
  • Bernoulli principle - decreased pressure exerted by air in motion - the same physics that allows airplanes to fly and causes two sheets of paper to stick together when you blow between them (try it!).

    Or, more to the point, try blowing into an open plastic bag. The sides will still tend to come together.

    --

  • Well, when you do that, the floor is soaking wet. Kinda a pain if you want to use the toilet up to a day after you shower - floor stays wet!

    I guess I'm odd - at age 17 I never had an urge to just trash something. Though there have been times lately (many moons later) where I have really felt like walking around with a 30 pound sledge!

  • Moral of the story (Score:5)

    by Sabalon ( 1684 ) on Sunday July 15, 2001 @04:16PM (#83449)
    Plain and simple - Hampton Inn, who has the thinnest curtains I've ever seen, that suck inwards at the utterance of the words "I'm going to take a shower", needs to install some magnets on the bottom, or just spend an extra dollar per room for a real curtain.

    Better yet, the plexiglass doors...that'd be one shower to make them bow in!
  • Why drivers lisense photos always turn out bad

    Because state DMV's never cared to properly adjust the contrast on their printing equipment.

    Polaroid makes ID making systems which correct themselves for those kinda factors automagically...they seem to create ok pictures (see this [counterfeitlibrary.com], in particular check out CO, DC and WV.)

    Consider moving to NJ or VT--they still issue non-photo licenses.
  • Easy ... just create a similar hurricane effect on the other side of your shower curtain to balance things out. I mean, if you don't mind flooding your house, of course.

    --

  • I can finally get to sleep tonight.

    Wait. Does the refrigerator light stay on after I shut the door? Oh man, I hope somebody submits a link answering that question next.

  • You make a very valid point. One thing that has always burned me up, from my 1-12 grade years was when some mindless mundane would ask "Is this going to be on the test?" and if the answer was no they'd veg out and not learn what was to come.

    Humorous anecdote: I had a similar situation in my 2nd year calculus course at the University of Wisconsin - Madison. It was a lecture about 5 hours prior to an exam and a student asked if a certain type of problem would be on the exam. The professor said no, but it was still important to know, and spent 10 minutes explaining how to do that type of problem. The student replied "thanks, but I just wanted to know if it was on the exam or not." This pissed the professor off so much that he altered the test to include that type of problem.

  • That link of yours doesn't refute Bernoulli's law, in fact it states that Bernoulli's law is sound and well proven. The page refutes the basic explanation of Bernoulli's law that is commonly taught to people.

    While certain military and stunt aircraft can fly upside down, they are probably neither as stable nor as effecient. They rely as much on powerful engines as they do on lift from the wings.

    Chris Cothrun
    Curator of Chaos

  • Instead of expanding outward against the curtain it would probably be the path of lesser resistance for the heated air to expand upwards (heat rises), leaving an area of decreased air pressure behind the curtain, but that's just off the top of my head, I don't have a supercomputer handy (or a sliver of a clue how to use it to explore that theory if I did have one).
  • I don't remember the conclusion, but there was an article in the Amateur scientist about this.
  • You can make a brick fly with the right angle of attack and enough thrust...
  • he is an educated math/science guy. What would make you figure he had any idea about how to present material in a way that would be appealing to the rest of us ;-)

  • Re:Registration-free link (Score:5)

    by FFFish ( 7567 ) on Sunday July 15, 2001 @04:38PM (#83461) Homepage
    Slashdot should just get its own "partners" link already. Why the hell do we need to go through this dumb-ass two-step system where the main article posts some NYTimes registration-required link and someone else ferrets out a no-reg-required link?

    Cut to the chase already, Slashdot. Beg, borrow or buy a damned registered partner account with the NYTimes and be done with it!


    --

  • World's biggest shower stall (Score:3)

    by XNormal ( 8617 ) on Monday July 16, 2001 @12:48AM (#83464) Homepage
    It seems that somebody is already planning to do that. [tufts.edu]

    -

  • This is getting waaaay off topic...

    There's no 'reverse lift' when you're flying upside down.

    A plane's wing is optimized to provide lift and reduce drag when it's right-side up. Just because wings are optimized, it doesn't mean that other things won't work.

    You can, for example, make a regular plane with flat boards as wings. You have to tilt them up at a high angle of attack, which greatly increases drag. With sufficient power, you'll get off the ground.

    When flying inverted, it's the same sort of thing. You have to increase the angle of attack (as you mention) and you'll get lift, even if you're using the wing "wrong". Takes more power, causes more drag, but it will work.

  • Well.... In my case, my drivers liscence photos are tipiclly the best photos of me

  • Yes, guilty as charged. I'm just saying. When you say, "News for Nerds", I certainly can't argue. But how this constitutes "Stuff that matters.", I certainly can't imagine. Nevertheless...

    I'm pretty sure that the comma in there implies boolean OR. "News for nerds" is true, thus the whole statement is true. ;) I've got glass-like doors on my shower, so this doesn't really "matter" to me either...

  • If you figure that thing out about sounding really bad when electronically replicated, but just kinda dorky in person, lemme know. I've got the same deal. I think it's something got do with the lower tones in my voice not getting grabbed by recorders, or the midtones being artificially enhanced...

  • Re:Could prove useful (Score:4)

    by cloudmaster ( 10662 ) on Sunday July 15, 2001 @05:03PM (#83471) Homepage Journal
    Holy crap! A waterfall down the center of the building would be really cool, since it'd have to be exposed to work... I'll have to work that into future houseplans. :)
  • Now I admit, I have no idea how knowing that a shower creates a small huricane will become personally useful to me. But that does not mean that some aspect of this will not become useful in the future.
    Well maybe someone can use his simulation to design a shower which does not have this problem. True there is the simple solution of a heavy shower curtain but some people are cheap. If the actual shower can be designed so that the sucking never happens and the solution is cheap it will eventually become the standard for new showers. Thus the problem will eventually go away -- even when a cheap light weight curtain is used.
  • Because if you get one for $10, then it might be heavy enough that it won't fly up at you.
    --
  • Funny, I was just wondering why shower curtains got sucked inwards. I always assumed it was due to a Bernoulli-type of effect, where air flowing across the curtain would create lower air pressure than on the other side. Of course I didn't read the article, so maybe that is part of it.

    A mini-hurricane.. so does this mean that given an arbitrarily large shower and curtain, you could control the weather? My plan to take over the world is coming together at last..

    --

  • From your link: "A flaw in this explanation is that there is no known physical principle to explain how the starting vortex can cause wing circulation"... what, with the exception of conservation of angular momentum, for example? Exactly the same physical effect that is responsible for the opposite-identical vortices that come from the tips of the wings (because angular momentum is conserved in three dimensions).

    Sorry guys, it's to do with rotation over the wing sections. How do we think a spinning cricket/golf ball generates lift? The 'blowing air downwards' theory is all well and good, but in practice the air gets blown downwards as a by-product of what's really going on.

    If you're really up for it, "Aero-Hydrodynamics of sailing" by C.A.Marchaj is the book to get.

    Dave
  • Bernoulli's Principle isn't usually derived directly from Newton's laws. It's usually expressed as a conservation of mass/conservation of energy equation. Your expression is not totally dissimilar to the one we use in my aero classes.

    As far as planes flying upside-down, the angle of attack is critical in determining the magnitude and direction of the lift vector. That's why you raise the nose of an airplane to make it go up...increasing the angle of attack moves the stagnation point of the free stream down on the airfoil, increasing the distance the air must travel over the top of the air foil.

    Curvature is not necessary to generate lift. Flat plates (like your hand out the car window, or the balsa wood wing on your dime-store glider) generate lift due only to their angle of attack.
  • It's all about the angle of attack, baby! : )

    A symmetrical airfoil with zero angle of attack produces no lift. Think about the rudder on an airplane or a ship. However, when the AOA changes, the airfoil is no longer symmetrical with respect to the airflow.

  • My own data (Score:5)

    by spineboy ( 22918 ) on Sunday July 15, 2001 @03:57PM (#83484) Journal
    My own research suggests that the likelyhood of the shower curtain being attracted to your skin is directly proportional to the amout of scum on it.

  • Idiot (Score:2)

    by delmoi ( 26744 )
    It says right there in the artical that he ran the simulation with software he helped develop on his home computer.
  • Bologna. I dunno about your part of the world, but where I live, the water comes out of the tap at a nice warm 50 degrees Fahrenheit, or some 20 degrees F. below nominal room temperature.
  • I would sooner believe that it is thermal...

    to see for yourself, take a hot shower with
    both sides of the curtain sealed to the wall
    with water in a cool room. for obvious
    reasons this works better in winter...

    now watch how the curtain sucks inward.

    then separate the curtain from both walls--
    12 inches on the side farther from the shower
    head and 6 inches on the side closer.

    it no longer sucks in because the convection
    currents have more area in that plane through
    which to travel.

    just my two cents...

  • Re:Million dollar funding superchallenge! (Score:3)

    by tono ( 38883 ) on Sunday July 15, 2001 @04:36PM (#83497) Homepage
    question 1. there's a lip on it that the last drop can't crest, hence, still in the can

    question 2. you're ugly

    question 3. you're a dork

    see, I answered your questions and I don't even know you. Good luck finding anyone willing to shell out grant money for those.

  • This sort of "silly" research has produced unexpected benefits before. I can envisage some form of high-rise, for example, that has a waterfall down the central shaft to provide temperature and humidity regulation, as well as providing the air movements to refresh the building.

    Okay, so it sounds silly. But who's to say that something profound won't come of this! I say more power to people doing esoteric research.

  • Those who appealed to the chimney effect - hot air rising within the shower causes cool air to come in from below. This hypothesis can be readily defeated by taking a cold shower and observing that the curtain billows nonetheless.
    I've always found this particular refutation rather unconvincing. You'd be surprised how warm the water in a so-called "cold" shower is. Remember that your body heat is normally ~100F -- I'd be willing to bet that most cold showers don't go south of 90F. Which means that unless the "cold shower" experiment is performed on a very warm day, it's quite likely the water temp is still over the ambient air temp.

    --
  • The water coming out of my bathroom sink is 76F and that was just the stuff that's been sitting in the pipes all day (as opposed to the stuff that's been buried underground all day). Ambient apartment temp is about 83F.
  • ...than using computer modeling to figure out why shower curtains suck inward, it is surely the idea of potentially hundreds of /. denizens offering their various opinions (and arguing!) about anything pertaining to this matter in this forum.

    Yes, guilty as charged. I'm just saying. When you say, "News for Nerds", I certainly can't argue. But how this constitutes "Stuff that matters.", I certainly can't imagine. Nevertheless...


    "LET'S GET READY TO RUMMMMMMMMMMMMBLE!"
  • Those who appealed to the Bernoulli principle - decreased pressure exerted by air in motion - the same physics that allows airplanes to fly and causes two sheets of paper to stick together when you blow between them (try it!). This hypothesis also seemed a bit shaky since (a) the air in a shower never seems to move that fast...

    Since a shower curtain is considerably lighter than an airplane, I don't see why the water would need to move that fast in order to bring the shower curtain in. I still think the Bernoulli principle could be sufficient to explain the shower curtain problem.
  • It may be nice and shiny where you are, but there are places (like where that shower curtian would go) that absolutely suck.

    Wasn't the whole point of this article that it already sucks where shower curtains are?
  • I wasn't disputing Bernoulli's principle, I was disputing its utility in explaining why aircraft fly.

  • Re:Finally! A believable answer (Score:3)

    by nihilogos ( 87025 ) on Sunday July 15, 2001 @05:09PM (#83519)
    Bernoulli principle - decreased pressure exerted by air in motion - the same physics that allows airplanes to fly

    I've never found this believable, and thought a recent scientific american article addressed the problem well. As I understand it the traditional explanation goes like 'the top of the wind has more curvature and so the air has to travel further when the flow isn't turbulent so it has to be moving faster and so by Bernoulli's principle implies that the pressure above the wing is lower than the pressure below the wing so there is a net force upwards'.

    Where are Newton's laws of motion in this picture? And how does it explain airplanes successfully flying upside down? A more plausible answer(to me anyway) involves the angle of attack the wing makes. Air is forced downwards and by conservation of momentum something must be forced upwards - the plane. The curvature of the wing is necessary to maintain non-turbulent flow without which there wouldn't be a regular stream of air flowing downwards. Increasing the angle of attack too much causes this to break down.

    I find this explanation intuitive and more in accord with the rest of my knowledge of physics, but I'd love to hear objections ...
  • Wasn't the phrase "a solution looking for an application" most famously applied to the laser? You are now most probably reading this article on an OS installed off CD-Rom.

    Phillip.

  • What are we going to do tonight, Brain? (Score:5)

    by Greyfox ( 87712 ) on Sunday July 15, 2001 @04:46PM (#83521) Homepage Journal
    Tonight, my dear Pinky, we shall create a superweapon that creates hurricanes! First, we shall need to build the WORLD'S BIGGEST SHOWER STALL! ...
  • Actually the previous poster had a more plausible explanation. I suggest you try to find that recent scientific american and read the article. I have it somewhere so maybe I'll post a more detailed comment tomorrow(too late now).

    Basically it refutes the way bernoulli's principle is taught(according to my recollection) by simply stating that there is no scientific reason why the air travelling on top would have to arrive at the end of the wing at the same time as air on bottom.

    As a matter of fact they don't arrive simultanously although top still travels faster. The real reason planes stay up is due to the tendency of fluids(air counts) to stick to surfaces. Basically air travelling on top of the wing sticks to the wing and, as it is curved, is directed downwards. According to newtons laws this force has to be countered, and it is, by what we experience as lift. So as long as airflow around the wing has a downward component there is lift.

    Bernoulli's law, however, does work good enough that it can be used as an approximation..

  • Finally! A believable answer (Score:5)

    by renard ( 94190 ) on Sunday July 15, 2001 @04:18PM (#83524)
    Cecil Adams addressed this question many years ago in an unforgettable column [straightdope.com] of The Straight Dope [straightdope.com]. But this latest approach is even better.

    First a quick summary (apologies to those who read the article). Historically the billowing shower-curtain theorists have been divided into two camps:

    1. Those who appealed to the chimney effect - hot air rising within the shower causes cool air to come in from below. This hypothesis can be readily defeated by taking a cold shower and observing that the curtain billows nonetheless.
    2. Those who appealed to the Bernoulli principle - decreased pressure exerted by air in motion - the same physics that allows airplanes to fly and causes two sheets of paper to stick together when you blow between them (try it!). This hypothesis also seemed a bit shaky since (a) the air in a shower never seems to move that fast; and (b) there's a potential confusion of cause and effect going on here (for the shower curtain to billow, clearly something must be happening with the air pressure...).
    Now comes David Schmidt to demonstrate that both of these camps are wrong (in this he and Cecil agree). His theory instead focuses on the deceleration of the water droplets by the air producing a cyclone effect within the shower. This theory is similar to, but distinct from, the ``entrainment'' theory that Cecil put forward so many years ago. And to me, significantly more believable.

    The same dynamics that causes hurricanes, right there in our very bathrooms! Score one for Schmidt and his finite element approach to a classic problem.

    -Renard

  • Probably because a partners link is technically bypassing their "security measures." Slashdot legally considers its comments to be outside its control and owned by their creators, shielding them from harm. On the other hand, news stories are directly controlled (and reviewed by) editors, so /. can't use this defense. So, really, they can't post a partners link.

  • Re:Bernouli's (sp) Theory (Score:3)

    by Tiroth ( 95112 ) on Sunday July 15, 2001 @05:13PM (#83530) Homepage
    Maybe you should read the article before posting things like this. Of course, you got modded up, so the same should probably go for the moderators.

    What you describe is NOT the cause of the movement, as determined by Dr. Schmidt. He clearly states that the motion results from the water droplets giving up energy to the air as drag occurs. Effectively even the cold water is heating the air due not to temperature but because of its slowing velocity. (lots of drops=lots of surface area to volume=lots of drag)

    The article justs states that (something magic happens, and then) you have a miniature hurricane. Probably this is due to temperature differentials in the system, in the same way that weather is created in the "real world."

    It really isn't overkill. It's a much more subtle problem than your comment indicates.
  • ...it would have stopped me from creating another bogus account on the NYTimes website. My gosh, thanks to the wonderful news reported on /., I've made up about 20 or so bogus accounts now for NYT. bogusid, bogusaccount, fakeid (3-5, 7...fakeid, fakeid1, fakeid2, and fakeid6 were already taken), idforsale, blowmandown Course, it has kept the NYT system busy sending all that SPAM to all those fake email addresses... just keeping the sysadmins from taking too much time reading the paper and not doing what they should! Course, my humble apologies to fake@id.com if you actually have this email address.

  • Why would he want to do that? (Score:5)

    by 11thangel ( 103409 ) on Sunday July 15, 2001 @04:06PM (#83536) Homepage
    Since I'm not married, I'm not certain, but would many of the readers here want even a mental image of their mother-in-law's shower, much less a super accurate computer picture?
  • Now I admit, I have no idea how knowing that a shower creates a small huricane will become personally useful to me. But that does not mean that some aspect of this will not become useful in the future.

    Well, To address the poster to whom you were replying to:

    Fuel economy - the efficiency of the combustion process (in an internal combustion engine) is directly proportional to the level of homogeneity [m-w.com] of the gas/air charge in the cylinders at the time of combustion (gas isn't actually fuel until you mix it homogenously with air).

    Atomization of the gasoline is very important but simply atomizing it isn't good enough in many cases. New research has led to "direct injection" which places the fuel injector in the combustion chamber like a spark plug instead of on the other side of the intake valves. I believe Seat [seat.co.uk] (an Audi/VW subsidiary) has introduced one of the worlds first direct injection engines which uses gasoline injection at a pressure of 1450psi (normal cars use under 50psi)! At these pressures, things like mini hurricanes become very important to understanding exactly what is going on in the combustion chamber.

    Thinkaboutit
  • Well, now I know that it does not help to balance temeratures on both sides of curtain, but I should really just turn the shower to the wall when the water is not comming down at me. I personally am really thankful to prof. Schmodt for the answer :)

  • I agree that seems like overkill... One's physical common sense easily answer's this problem, to a first approximation of course. Think of the stream of water pushing the surrounding air downwards. This creates a region of lower pressure compared to the air outside of the shower curtain. Alas, the curtain would move towards the area of lower pressure.

    Of course, this just explains the large, global effect. More interesting (and complicated) stuff occurs, such as these vortices the author describes, but the overall effect is pretty simple to undertsand.

    Paul

  • Re:That's cool! (Score:3)

    by jbarnett ( 127033 ) on Sunday July 15, 2001 @04:42PM (#83551) Homepage

    The pursuit of knowledge.

    There is yet 3 stages of science.

    Observation.
    Discovery.
    Technology.

    Ask any geek, the more "sexy" stage of science is the last one, the stage where that we can lay our hands on it and turn into something usefully and productive. Yet the first 2 stages of science are seen as a "waste of time" or sometimes even "worthless". Hardly NOT so! You can have this sexy technology without the other two!

    The guy in the above article did both 1 and 2 for us, it is our turn to make 3 happen. What could we use this for? Oh I don't know, say find a way to better predict when a hurricane is coming? Now that would be "sexy" technology that you would see on the 6:00 news.

    That is not his job, he did 1 and 2 and did it very well if I might add, very detailed and very though.

    The next guy that says "this guy has way to much time on his hand" really needs to think about it and really ask himself if he is in it for the "geek" or the "glory"

    If the "glory" is what you are into that is fine, but please do give up respect to the guy in the above article that did all the "geek" for you.


  • The Rincon Center in San Francisco has a large waterfall/shower thingy in the middle of it's indoor courtyard. In addition to being attractive and providing a soothing background noise, it is also said to lower the temperatur in the immediate area by 3-4 degrees (if memory serves). This isn't due to any 'hurricane' effect though, it's simple evaporative cooling (a'la swamp coolers, or those cooling 'water bongs' that overclockers use to replace radiators).

  • Re:Finally! A believable answer (Score:3)

    by djrogers ( 153854 ) on Sunday July 15, 2001 @08:54PM (#83563)

    And how does it explain airplanes successfully flying upside down? A more plausible answer(to me anyway) involves the angle of attack the wing makes. Air is forced downwards and by conservation of momentum something must be forced upwards - the plane

    You're trying too hard here, why can't you both be right? Planes that fly upside down do not do so indefinately, and require a greater amount of thrust and angle of attack to overcome gravity and 'reverse lift' than an aircraft in normal flight. They also are incapable of maintaining a constant altitude during inverted flight, with few exceptions (trust me, I used to fly stunt planes, it's not as simple as it appears).

    Basically, when inverted, the angle of attack is changed such that the 'reverse lift' (downward force generated by pressure differential) is minimized as much as possible, at the same time allowing some thrust to be converted to lift (by pointing the prop/jet output slightly down). This is basically the the 'kite' type of flight that you refer to.


    Now, about those exceptions - aircraft capable of producing enough thrust to overcome gravity without the help of lift are often known as rockets, or in some cases military aircraft. Take a Mig27, with ~40,000lbs of thrust and wighing only ~30,000lbs, the wings are almost superflous, however they still remain, primarily as control surfaces, and efficiency aids (fuel goes fast when producing enough thrust to throw a 20 ton mass directly skyward).


    I know it seems a tad illogical at first, but get a good hands-on book on flying, and try some of the experiments, you'll be amazed at what is proveable....

  • Sounds like something to help you avoid that whole Psycho [imdb.com] shower scene...
  • Judging from the large number of posts here from people who didn't bother to read the article, one can draw one of several conclusions: (a) Many Slashdot readers think they know everything already, (b) Many Slashdot readers do not take showers, or (c) Many Slashdot readers are secretly employed by physics textbook manufacturers.

    -Elentar

  • That's more or less what I've always thought. I guess now it's more like Bernouli's Principle on crack.

  • You, my friend, need to take a cold shower.

    No, really. As the article says, the curtain still sucks inwards during cold showers.

  • This is just in time, since I'm currently staying with my mother-in-law while my house is being remodeled, and she has a particularly irritating shower curtain!

    Hey, I've been critical of Slashdot's editorial policies in the past, but here is NEWS I CAN USE!!!


    --

  • A waterfall down the center of the building would be really cool

    Perhaps it could be used as a giant air conditioning unit. Of course, it'd probably draw a lot more power than a straight A/C box...

  • Re:Million dollar funding superchallenge! (Score:3)

    by IdahoEv ( 195056 ) on Sunday July 15, 2001 @10:50PM (#83584) Homepage
    You hear your voice directly from inside your head as the sound reaches your ears via the eustachian tubes that go

    What if this isn't true? I always assumed the shower curtain thing was heat conduction, and I was wrong.

    Try this:
    <ALTERNATE HYPOTHESIS>
    The answering machine voice dorkification effect is caused by a neural association/feedback change. When you speak, your brain is not only hearing the sounds you make, but is also sending commands to your vocal apparatus instructing it to make those sounds. The correlation between hearing and speech center activity results in a difference in perception from just hearing alone.
    </ALTERNATE HYPOTHESIS>

    Weird you say? There's even a precedent for my idea. When you move your eyes, images sweep across them at hundreds of degrees per second - but the world doesn't look like it's moving to you. But if you look at a screen, hold your eyes still, and sweep images at those rates everything looks like it's moving. Why? Because when you move your eye, your brain takes a copy of the eye-motion commands and subtracts that motion from what the eye really sees, resulting in a perception that the world didn't move.

    I admit, it's pretty far-fetched and I'm still inclined to believe the eustachian tube hypothesis, but the truth is we don't know unless someone's actually done the science to tell.

    Research like this is great because it replaces supposition with real knowledge. Three cheers to this shower dude.

  • A unified theory of physics.

  • Re:That's cool! (Score:3)

    by milo_Gwalthny ( 203233 ) on Monday July 16, 2001 @05:47AM (#83588)
    The three stages of a new idea*:
    1) Everyone ignores it
    2) Everyone attacks it
    3) Everyone claims it is obvious

    * Blatantly plagiarized from some quantum physicist whose name I can't recall, probably Wheeler.

  • Been getting my news lately from this site, who listed the shower curtain story [ananova.com] on July tenth.

    -Mynn the Museless

  • Or (d) Many slashdot readers are trying to get their two cents in before they get buried way down at comment #932 or something.

    Such is the path to karma whoring.... Even Taco suggests posting early to increase karma.

    Perhaps there should be some kind of time delay between introducing the article and allowing comments?

  • Re:My own data (Score:3)

    by RhetoricalQuestion ( 213393 ) on Sunday July 15, 2001 @04:56PM (#83595) Homepage

    My own research suggests that the likelyhood of the shower curtain being attracted to your skin is directly proportional to the amout of scum on it.

    Here's a neat trick: try CLEANING your shower curtain.

    After that, try the same cleaning trick on the rest of your bathroom.

  • Re:Great! (Score:5)

    by RhetoricalQuestion ( 213393 ) on Sunday July 15, 2001 @04:14PM (#83596) Homepage

    Now I can die happy knowing that shower curtains get sucked inward due to a small hurricane. I love science! We could be spending research time finding a way to get 500 miles to a gallon instead of worrying about showers.

    Think of it as an indirect approach. For example, I was reading somewhere (cannot recall the source, but it was some magazine) about a scientist who decided to figure out why it was that coffee spills always dried with a dark ring around the outside. A whole lot of research later, science now knows a lot more about how molecules interact in fluids, which has led to practical applications such as (among many others that I cannot remember) fast-drying paint.

    Many people make the same argument you're making about fields like pure mathematics -- the research doesn't always have any immediate practical value. But the knowledge often makes itself valuable in everyday life in unanticipated ways. How do you really know if a particular scientific "discovery" is useful unless you know what that discovery is in advance?

    It's a disturbing trend nowadays that believes research time should only be spent on immediately practical applications. The pursuit of pure knowledge, or even simple curiousity, is increasingly pushed to the side. Yes, research is time-consuming and often expensive, but to solely measure the value of attaining knowledge based on its immediately foreseeable applications is (IMO) somewhat short-sighted.

    Now I admit, I have no idea how knowing that a shower creates a small huricane will become personally useful to me. But that does not mean that some aspect of this will not become useful in the future.

  • Isn't this just a very advanced way of saying "Pressure in a moving stream is lower than that around it"?
    -Hyperbolix
  • Someone has WAY to much time on his hands. On the other hand, so do I, considering that I am bothering to post a comment on that article.

  • Registration-free link (Score:4)

    by drift factor ( 220568 ) on Sunday July 15, 2001 @03:57PM (#83600)
    Here [nytimes.com].
  • "Why would you clean something that can be replaced for $1.99?"

    Hell, why would you spend $1.99 on a shower curtain when you can eat for two weeks on that?

    IBM had PL/1, with syntax worse than JOSS,
  • It might be because it's illegal to collect info on users under 13. And to login you need to give personal info.

    Trolls throughout history:

  • Anybody else notice this? (Score:3)

    by kgutwin ( 243912 ) <kgutwin@yahoo.com> on Sunday July 15, 2001 @05:32PM (#83615) Homepage
    In the end, Dr. Schmidt's home computer crunched numbers for the better part of two weeks...
    First of all, for all you detractors, he probably wasn't exactly wasting a whole lot of resources - the article even states that he developed the $20,000 piece of software.

    Second, I think it's pretty obvious - this guy is definitely geek material. I mean, come on - crunching a 1.5 trillion calculation program over the span of two weeks on your free time? How many of us would love to have an excuse to do something like that?

    Honestly, I wouldn't be surprised if he reads Slashdot :)

    -Karl
    -------------
    [root@kgutwin /dos]# file msdos.sys

  • I'd love to know where the money for studies like this come from :)
  • hmm. One bogus account seemed to do the trick for me just fine. Do you get some sort of enriched content on the site if you have multiple bogus accounts?

    ___
  • voice recorders always sound different than your voice (to yourself). The bad news is what you hear on the recorder is a hell of a lot closer to how you actually sound to other people than what you hear yourself.
  • Even though you proved my point with this sentence: "it may not be practical to clean the curtain if the chemicals to do so cost more than replacing it, or will potentially cause more environmental damage than just tossing the curtian", my comment was meant to be funny, and was moderated as such. You've got to learn to chill a bit dude.

    BTW, I'm not American, I'm Canadian. So there ;-)

  • Re:My own data (Score:4)

    by agallagh42 ( 301559 ) on Sunday July 15, 2001 @05:27PM (#83626) Homepage
    Why would you clean something that can be replaced for $1.99?

  • Frank Lloyd Wright beat you to it (Score:3)

    by drew_kime ( 303965 ) on Monday July 16, 2001 @06:14AM (#83627) Journal

    Fallingwater [wpconline.org]

    Built in the '50s. Widely regarded as one of the most reconized private homes in America. (Now a museum, of course, but originally a residence.)

  • Butterfly Effect (Score:3)

    by mctanis ( 319096 ) on Sunday July 15, 2001 @05:27PM (#83635)
    So if a butterfly flaps it's wings and causes a tornado [caltech.edu] on the other side of the planet -- what do millions of little huricanes in our showers every day do?
  • Same, I wonder if he made the calculation using a 3d human model actually USING the shower?
  • Do we know everything we need to know about hurricane behavior as it is? If not, could this discovery be used to model hurricanes on a small scale, saving the need to fly a damn plane through one?
  • I dunno, the knowledge of your own imminent demise doesn't seem particularly powerful.

    If you gain advanced knowledge of someone coming to get you, you can prepare for their arrival.

    Though it may not change the outcome, you can take some of them with you. That IS power.

  • Your point suggests that the testing and grading system is defective because it encourages bad habits that can last into adulthood.

    My intent was to point to a flawed attitude that some people have towards education. You are in that classroom to learn, for the sake of learning.

  • Re:Great! (Score:3)

    by No Tears In The End ( 452319 ) on Sunday July 15, 2001 @08:20PM (#83655)
    But the knowledge often makes itself valuable in everyday life in unanticipated ways. How do you really know if a particular scientific "discovery" is useful unless you know what that discovery is in advance?

    You make a very valid point. One thing that has always burned me up, from my 1-12 grade years was when some mindless mundane would ask "Is this going to be on the test?" and if the answer was no they'd veg out and not learn what was to come.

    For example, in and of itself it does no good for the ordinary person wo understand additive/subtractive properties of color when it comes to light/pigments however if you do know a little about them, it can help you to adjust the tint on your TV or adjust the color balance on your computer.

    Trying to figure out which genetic traits were dominant/recessive in pea plants may have seemed like wasted research at the time, however that research was the foundation for later research that may (and probably will) lead to cures for diseases ranging from down's syndrom to cancer.

    To quote the game company Midway, "There is no knowledge that is not power".

  • While a scummy shower curtain has no more attraction to your skin than a clean curtain, the stickiness of the scum will increase both the length of and disgustingness of contact between skin and curtain.
  • I think the guy probably did this study on his own time, with equipment that had already been purchased for other work. It didn't cost a dime to do this.
  • Hey, every little bit helps, right?
  • It's b.

  • Answers: (Score:4)

    by ColGraff ( 454761 ) <maron1 AT mindspring DOT com> on Monday July 16, 2001 @08:36AM (#83662) Homepage Journal
    The last dribbles of softdrink never come out of the can because of a couple factors. One, the surface tension of the droplets tends to make it "stick" to the can surface. Two, the inside of the top of the can is not perfectly smooth, and the opening in the can is relatively small. As a result, it's easy for a drop to get "stuck" in a nook or cranny on the can.

    Driver's liscence photos always turn out bat because the DMV cares not a whit about how you look, so they don't bother with the higher-end cameras or even decent lighting that professional photographers use. Also, the photo is generally taken shortly after the driving exam, which tends to stress a person, effecting their appearence. Finally, few people bother to wear a nice shirt or whatever to make themselves look nicer in the photo.

    People generally sound like dorks on answering machines because the sound quality on playback is usually poor, and strips most enotional nuances from speech. Thus, the recording sounds flat and "dorky". In addition, people are generally not used to giving monologues. When I talk, someone next to me usually gives a response, even if it's just "Shut up, Ethan". It's disconcerting to be prepared to speak with a person, and suddenly have to give all the information you intended to provide without any of the feedback you would have in a normal conversation. If you're calling to discuss, say, dinner plans, the other person you're calling can't ask for any clarifications (where are we eating? Which road should I take? Is it a formal dinner?) You need to provide all that information at once, and the added strain and performance anxiety leads to the normal verbal respones to stress. These include stammering, "null data" sounds such as "uh", "um", and mumbling. All of these sound "dorky". Of course, one could simply say "I'll call back later," but circumstances may not permit that, or you may simply feel pressured to provide the data to the machine then and there.

    Of course, it is entirely possible that the reason you in particular sound dorky on answering machines, Nathdot, is that you are in fact a dork. I have not data to support that conclusion one way or the other, but it must be considered. After all, the simplest explanation is usually the correct one, as Occam's Razor asserts.

    As for your plans to model and study these questions on supercomputers, well, more power to you! One problem, however: since you are studying absolutes (soda dribbles NEVER come out, liscense photos ALWAYS look bad, and you ALWAYS sound like a dork...on answering machines), how will you model each and every existing soda can, DMV camera, and answering machine? It's not enough even to model the different makes of these items, as each can, camera, or answering machine is at least slightly different from every other one, due to quirks in the manufacturing process. Even if you found a factor in one soda can using your supercomputer that contributed to "stuck soda", how would you prove all other soda cans have the same problem?

  • Now I can die happy knowing that shower curtains get sucked inward due to a small hurricane. I love science! We could be spending research time finding a way to get 500 miles to a gallon instead of worrying about showers.
    ---
  • Huh, now I know why. I'll probably get flamed for this, but I think the time spent on this research is well worth it. Think about how many people go to showers everyday (except for a few) and few actually realize what's going on with the shower curtain. Another question answered!

  • Re:Great! (Score:3)

    by UberOogie ( 464002 ) on Sunday July 15, 2001 @04:32PM (#83674)
    Frankly, this is the kind of--albeit somewhat silly--science that gets the public interested in science. This is physics in everyday life in ways nearly everyone can relate to.

    Yeah, in a perfect world of one-to-one dollar translation, there might be "better" things to spend it on, but, eh, it was cool, and he did it.

    Good for him.

  • Million dollar funding superchallenge! (Score:5)

    by Nathdot ( 465087 ) on Sunday July 15, 2001 @04:16PM (#83675)
    Some of my own proposed projects:

    * Why the last dribbles of softdrink never make it out of the can
    * Why drivers lisense photos always turn out bad
    * Why I always sound like a dork on answering machines

    I plan to model each one of these confounding human mysteries on a supercomputer using not 1, not 2, but 3 trillion!!! calculations...

    Now!... Gimme that sweet sweet grant money!

    :)

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