# Is a bubble a liquid?

**URL:** <https://boards.straightdope.com/t/is-a-bubble-a-liquid/273782>\
**Category:** Factual Questions\
**Created:** [November 9, 2004, 3:35am UTC](https://boards.straightdope.com/t/is-a-bubble-a-liquid/273782 "2004-11-09T03:35:30Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Princhester](https://avatars.discourse-cdn.com/v4/letter/p/3e96dc/32.png) [@Princhester](https://boards.straightdope.com/u/Princhester)\
**Post date:** [November 9, 2004, 3:35am UTC](https://boards.straightdope.com/t/is-a-bubble-a-liquid/273782/1 "2004-11-09T03:35:30Z")

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My 2 1/2 year old asked me what a bubble was made out of. He has a habit of asking hard questions.

Obviously it’s a gas in the middle, but what state of matter is the “shell”? Not a gas, not obviously a solid, although it holds its shape like one, but doesn’t flow like a liquid.

I’m thinking it’s a very thin layer of liquid, with surface tension holding it together on both sides, supported in a bubble shape by the gas inside.

What say you?

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**Author:** ![GorillaMan](https://avatars.discourse-cdn.com/v4/letter/g/50afbb/32.png) [@GorillaMan](https://boards.straightdope.com/u/GorillaMan)\
**Post date:** [November 9, 2004, 3:42am UTC](https://boards.straightdope.com/t/is-a-bubble-a-liquid/273782/2 "2004-11-09T03:42:30Z")

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Yep, surface tension is the key. With a bubble blown from a bubble-blower (which I guess is what initiated it) you have a slightly-higher pressure on the inside, counteracted by the surface tension. (The surface tension on the outside also pulls inwards.) Hence the balance needed to make a bubble.  
(Actually, this is a vague stab at the physics of it, so maybe sombody will prove me wrong…)

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**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\
**Post date:** [November 9, 2004, 3:56am UTC](https://boards.straightdope.com/t/is-a-bubble-a-liquid/273782/3 "2004-11-09T03:56:34Z")

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> [@Princhester](#):
>
> I’m thinking it’s a very thin layer of liquid, with surface tension holding it together on both sides, supported in a bubble shape by the gas inside.

That’s exactly right. In fact, if you look at the surface of a soap bubble carefully, you can sometimes see the liquid that composes it "flow’’ within the layer.

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**Author:** ![AussieSilverback](https://avatars.discourse-cdn.com/v4/letter/a/5daacb/32.png) [@AussieSilverback](https://boards.straightdope.com/u/AussieSilverback)\
**Post date:** [November 9, 2004, 4:03am UTC](https://boards.straightdope.com/t/is-a-bubble-a-liquid/273782/4 "2004-11-09T04:03:54Z")

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Is the bubble the ‘shell’ of liquid, or is it the gas inside? What of bubbles rising in a bottle of, say, soda water? In that case there is no ‘shell’ to bubble is only the gas.

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**Author:** ![GorillaMan](https://avatars.discourse-cdn.com/v4/letter/g/50afbb/32.png) [@GorillaMan](https://boards.straightdope.com/u/GorillaMan)\
**Post date:** [November 9, 2004, 4:08am UTC](https://boards.straightdope.com/t/is-a-bubble-a-liquid/273782/5 "2004-11-09T04:08:43Z")

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> [@AussieSilverback](#):
>
> Is the bubble the ‘shell’ of liquid, or is it the gas inside? What of bubbles rising in a bottle of, say, soda water? In that case there is no ‘shell’ to bubble is only the gas.

That’s different - it’s a bubble within a liquid, rather than one on the surface. One in the liquid can reach the surface and burst, or it can reach the surface and become a bubble as has been described already.