Naked Science Forum

General Science => General Science => Topic started by: Tomassci on 01/06/2018 09:54:13

Title: How big can a bubble get?
Post by: Tomassci on 01/06/2018 09:54:13
Theoretically, what is the limit for size of soap bubble?
Title: Re: How big can a bubble get?
Post by: Colin2B on 01/06/2018 10:32:55
I believe the world record for a free floating bubble is about 96m3
Title: Re: How big can a bubble get?
Post by: chiralSPO on 01/06/2018 12:42:50
Interesting question.

As far as the actual soap is concerned, there is no upper limit to the size of a soap bubble--one can easily observe the formation of a planar section of soap film when a supporting structure is provided (like a loop of string with which we blow bubbles). That the planar configuration is stable indicates that a bubble with infinite radius would be stable if it could be formed.

So there is no intrinsic upper limit to the size of a bubble (there are some limitations to how small a bubble can be, but I won't go in to those because that's not the question asked). But once we consider extrinsic factors, a number of limitations present themselves:

• Our atmosphere is only so large, and varies in temperature and pressure--this is not ideal for stable bubbles. This can be avoided theoretically, but only by performing the experiment not on Earth.
• The gravitational field of the Earth presents an asymmetric environment for the bubble to exist in, and the larger the bubble is, the stronger the effects of this asymmetry. Essentially, the mass of the top half of the bubble will increase with the square of the radius, and the amount of bubble holding it up (circumference) increases linearly with the radius. Eventually the bubble will be too heavy to maintain its spherical shape, and if that distortion increases beyond a limit, the bubble will collapse.
• etc.
Title: Re: How big can a bubble get?
Post by: Colin2B on 01/06/2018 16:24:14
There are some practical issues. Water evaporates from the soap bubble and this usually causes them to fail, so commercial bubble mixtures often include additives  eg glycerin to slow the evaporation.
Also as the bubble gets bigger the liquid thins out to the point where it cant exert enough surface tension to resist the internal pressure. The typical bubble wand can only hold a limited amount of liquid limiting the bubble size, so I assume the record breaking bubble makers must have a mechanism for continually feeding liquid onto the bubble surface as it inflates.
Title: Re: How big can a bubble get?
Post by: chris on 01/06/2018 18:00:42
Quote from: Colin2B on 01/06/2018 10:32:55
I believe the world record for a free floating bubble is about 96m3


And what shape was it?
Title: Re: How big can a bubble get?
Post by: Colin2B on 01/06/2018 18:22:47
I don’t know, unlikely to be spherical, which is probably why they quote size in m3.
I wonder if they measure the amount of air going in?
Title: Re: How big can a bubble get?
Post by: evan_au on 01/06/2018 23:44:44
I have seen some very large sausage-shaped bubbles, formed by waving a loop through the air to extend a flat sheet of soap solution. But they didn't last very long (probably evaporation, like Colin says).
Title: Re: How big can a bubble get?
Post by: Colin2B on 03/06/2018 06:09:39
Quote from: chris on 01/06/2018 18:00:42
And what shape was it?
If you look at the pics (at bottom) of this world record holder you can see the shape @evan_au mentions http://www.partybubbles4you.com/
Title: Re: How big can a bubble get?
Post by: rami999 on 13/08/2018 19:08:29
less than 100m2
Title: Re: How big can a bubble get?
Post by: Colin2B on 14/08/2018 09:10:14
Quote from: rami999 on 13/08/2018 19:08:29
less than 100m2
Do you have any evidence for that.
Do you mean a surface area of 100m2.