Neutrally buoyant balloon

Martin sez, "During a recent stay at our cottage in norther Wisconsin, I awoke to find this balloon hovering above a futon in the corner of the room. It was eerie. I didn't know what was going on for a second or two. There was no air movement, even though all the windows to the cottage were open. Perfect neutral buoyancy!"

The video is awesomely David Lynchian -- something about the cottage decor.

Hovering Balloon (Thanks, Martin!)


  1. Tie a helium balloon to the floor of a van and step on the gas. Which way will the balloon swing?

  2. Im not completely sure whats so special about this video, im sure we’ve all had balloons just sitting around till they got there. But it is nice to note, because you can never really beat that childish infatuation with big red balloons. Now i want one too. =/

  3. WOW i think – obviously it had helium but it must have been at a precise level to make it just sit their. Perfect bouancy alright. Ease up DUNGE you can’t honestly think that it isn’t just a little bizarre.

    Ben from the increase vertical hub.

  4. Could be the balloon heated up in the sun after which the room teperature dropped due to air gushing through the windows after which the balloon started floating because the warmer air inside the balloon was enough to provide lift.

    That or they were smoking pot…

  5. Yep, it’s just a phase of life every helium filled balloon goes through. But this video is good though. Nice composition.

    What’s with the guy with a balloon in his van? Helium isn’t some wondergas inverting all natural laws, so why would this possibly be interesting


  6. I’m calling fake. The knot of the balloon should be at the bottom as it should be the slightly heaviest part.

  7. There is nothing unexplainable to it but it is quite exceptional. When something very rare happens our attention gets focused automatically, to the point of fascination; moreover, we all want to believe.

    @ JFrancis: the balloon will move toward wherever the air pressure is lower, if no greater opposite force exist. Front in your example, up for an helium balloon, downwind since it gets sucked by the aerodynamic effect…

    There are loads of scientists and engineers reading here you know…

  8. @#2 it’ll swing backwards of course!
    By of course, I mean I have to pull out of my driveway in reverse.

  9. @IAmInnocent: I believe JFrancis was referring to this. Where the balloon is inside the vehicle, with closed windows – not the same air pressure differences as being tied to the back as per your assumption.

  10. Neutral boyancy is one thing, but I smell a rat here… When was the last time you saw a balloon floating on its side?

    I reckon that it’s not quite such a natural occurrence, rather that the careful application of small bits of sticky tape might have something to do with it.

  11. jfrancis @2: Depends on your frame of reference. To a person outside of the van, it ‘swings’ in the same direction as the van is going. But to the Youtuber inside van, it’ll swing towards the rear.

    Yes, the air is moving too, but the balloon has to catch up.

    stinkyweezleteet @ 8: The sideways balloon: the knot at the ‘bottom’ and the extra/thick/deflated layer at the ‘top’ are roughly equi-weighted. Unusual, but I wouldn’t say rare.

  12. I have noticed a different type of “morning after the party” weirdness about balloons.

    A helium filled balloon is floating up against the ceiling, trailing a streamer. I give the streamer a gentle tug and the balloon falls slowly until the streamer touches the floor, reducing the total weight of the system. Often I can push the balloon back to the ceiling and it will stay there but fall to the floor if I tug it again.

    So why does this happen? Does static electricity attach the balloon to the ceiling? Any suggestions?

  13. I am calling shenanigans!

    Neutral buoyancy is not difficult to explain or achieve, but what is is that the heaviest part, THE KNOT is on the side… should be pointed down. Me suspects ball bearings inside the balloon.

    Therefore, nobody awoke to this phenomenon… they created it.

  14. One way to achieve this is to half-fill the balloon with helium, then blow it up by mouth the rest of the way, until it feels juuuuust buoyant.

    I’ve done this for parties and it only takes an hour or two for the helium to leak out of the balloons and them to start drifting like this one.
    They deflate at different rates, too, so you get a succession of balloons gently detaching themselves from the ceiling and coming down to mingle with the guests!

    Magical moment: sitting quietly, winding down after a party, and noticing one of the neutral buoyancy balloons rising above me in the minuscule updraught from my body heat, then drifting away and down before getting pulled into the updraught again and rising.

  15. This video needs a threatening pulsing soundtrack.

    Sinister goings on in Wisconsi…

  16. When I was a kid, we used to attach groups of Legos to the strings of new balloons until we had weighted them down to the point of neutral buoyancy, so they would float in the middle of the room, at least for a while. Getting it just right was not very easy. sometimes you had to add some paperclips to the string. I wish I had thought to use this as a science fair project, weighing the Legos and extra ballast to see how much lift balloons of different sizes had.

  17. #16, wil9000:

    When I was a kid, we used to attach groups of Legos to the strings of new balloons until we had weighted them down to the point of neutral buoyancy

    If you can attach ice to the string (those toroidal ice ‘cubes’ work well), the balloon will accelerate upwards as the ice melts and drips off.

  18. Pop culture references, in case anyone’s puzzled:
    #1 – Stephen King’s “It”
    #6 – TV series “The Prisoner.” (Love how you got your comment into exactly the right spot on the thread, #6!)

    @#9 – #13 probably explained why it’s on its side. It may have a mix of helium & CO2. The CO2 will contain moisture from the lungs. When the balloon initially hit the ceiling it rolled onto its side for the same reason any ovoid or elliptical shape will when laid down (Weebles being the exception). The moisture pooled in the part of the balloon facing the floor. As the helium leaked out and the balloon descended, the moisture acted as ballast. (Also, you may have noticed a sort of “araeola” at the end of a balloon opposite the mouth; that’s where the membrane is slightly thicker. This acts as a counterbalance to the mouth-end during this stage of the balloon’s “life.”

  19. @ #2 “jfrancis” asks: “Tie a helium balloon to the floor of a van and step on the gas. Which way will the balloon swing?”

    Well, I’ve seen something very similar to this: A helium balloon floating at the roof of a normal car. As the car accelerates, the balloon bobs forwards. Yes, forwards. This is not a theoretical prediction, it’s what was observed to happen.

    It’s counter-intuitive until you realise that what’s happening is that the air around the balloon (which is heavier than the balloon) is flowing backwards in the car with more force than the balloon, pushing the balloon forwards.

  20. @ PaulR:

    jfrancis @2: Depends on your frame of reference. To a person outside of the van, it ‘swings’ in the same direction as the van is going. But to the Youtuber inside van, it’ll swing towards the rear.

    That’s the common assumption, but is actually wrong. Take a helium balloon in a car with you some day!

    The air, being heaver, is actually pushed to the back of the van more than the balloon is when you accelerate. Therefore the denser air pushes the balloon forward (from everyone’s frame of reference).

    Another way to think about it: gravity and acceleration are absolutely indistinguishable. If you are in a car with no windows, you cannot by any test determine whether you are accelerating forward or tipping backwards with the front wheels in the air. Well, if you were tipping backwards with the front wheels in the air, which way would you expect the helium balloon to go? Towards the front wheels.

  21. having seen and played with lots of balloons…

    yes, they will do this quite often actually. given a large number of balloons, as each loses helium, they will all be neutrally buoyant at one point or another.

    also, for fun: rub a balloon on your head and toss it at the ceiling or wall. this usually works best when its cold and/or dry.

  22. Balloons bring either the best or worst in us.


  23. Have none of you actually kept a helium balloon? The helium molecules are too small to stay in the balloon forever– over days, they will leak out and the balloon will become less and less light. For every balloon, there will be a point between light enough to float away and heavy enough to sink where it will be neutrally buoyant.

    To reproduce this:

    1.) get balloon
    2.) wait
    3.) look at balloon– is it neutrally buoyant? If so, then end. Else, goto step 2.

  24. We had a balloon lose helium and start following people around the house (which I presume just has to do with air currents when you move), but it was made immeasurably more creepy by the fact that the balloon was one of those foil ones with a tiki mask on it and so would scowl menacingly as it followed you or hung in a corner facing you.

  25. Mylar balloons last longer. Whenever I have one nearby, I hang things from the ribbon until it’s free to wander around the room following the air currents.

  26. Mark@~26: Michael Bay would have this balloon destroy one of our beloved cities / national monuments in a huge fireball.

    Just when you thought we were safe from (fill in the blank) Michael Bay brings you…


    *sounds of screaming people running away in horror*

    (Aspiring film makers pay attention, and send me a royalty check when this parody makes it onto teh Youtubes, if it lands you a contact. You’ve been wondering what to do with that old trainset anyway, right?) ;D

  27. @3 …because you can never really beat that childish infatuation with big red balloons. Now i want one too.

    I dunno… My memories of balloons look a bit more like this. :/

    And I can’t find where the post says that the balloon was actually filled with helium. Could a regular air balloon float like this under some rare circumstances?

  28. LUKE: Look at him. He’s headed for that small balloon.

    HAN: I think I can get him before he gets there… he’s almost in range.

    OBI-WAN: That’s no balloon! It’s a space station.

    HAN: The knot is on the side, it can’t be a space station.

    LUKE: I have a very bad feeling about this.

    HAN: Yeah, I think your right. Full reverse! Chewie, lock in the auxiliary power.

  29. I think the knot would be at the bottom if the balloon was perfectly spherical, but it isn’t.

  30. On second thought, scratch that. It’s probably just air currents holding it temporarily in that position.

    Ok. My work is done here. ;)

  31. Reminds my artist Will Rogan. He specializes in these kinda bizarre occurrences of everyday objects. In one video a paper airplane flies across the room and gets its nose wedged in a keyhole. Crazy!

  32. I’m no physicist, but why does everyone think the knot end should point down?

    It’s at the narrow end, and I would expect there to be more non-helium air in the fatter end, hence balancing out the knot end.

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