What do you get if you take a bubble, turn it inside out and stick it under water?
And they’re not as difficult to make as you might think. I stumbled upon antibubbles while doing research for my book when I found this awesome video by Physics Girl (who I adore!).
A bubble is a drop of air surrounded by a shell of soapy water floating in
An antibubble is a drop of water surrounded by a shell of air floating in soapy water.
Aren’t they beautiful and bright? The air shell of the bubble reflects light especially well.
Make your own antibubbles! Here is what you will need:
- Tall clear jar (I used a nice straight sided vase I found at the Dollar Tree)
- Dish soap
- Pipette or small syringe (I used a syringe from the pharmacy for giving liquid medicine to infants)
- Small bowl
Fill the jar over about ¾ full of water. Add two squirts of dish soap and gently mix the soap in with a spoon being careful not to make bubbles.
Water is particularly sticky and makes a skin on the top surface. The soap lowers this surface tension of the water so that the antibubble can break through into the water.
Pour a tablespoon or more of sugar into the jar. The amount depends on the size of your jar but you want a small layer of sugar on the bottom. The sugar will cause a density gradient – which basically means the water will be denser at the bottom of the jar than at the top. It also provides a soft cushion for the antibubbles so they don’t pop when they land on the bottom of the jar.
Fill the small bowl with water. Gently mix in one squirt of dish soap and a teaspoon of sugar. The sugar will make your antibubbles denser than the water at the top of the jar so they sink and don’t immediately float up and pop.
Fill the pipette or syringe with the mixture in the bowl. Hold the tip of the syringe very close but just above the top surface of the water in the jar. Carefully release one drop at a time. Some of the water drops will briefly sit on the surface of the water before popping.
With a little practice you will be able to get drops that go under the surface of the water and slowly sink down to hover in the middle of the jar or rest on the sugar at the bottom. These are antibubbles!
If you are unable to get the drops to go down into the water, add a little more dish soap and gently stir it in without disturbing the sugar at the bottom.
You can also add food coloring to the water in the bowl to better see the antibubble and what happens to bubble when it pops.
Can you make antibubbles in other liquids? Try vegetable oil, rubbing alchohol and lemon-lime soda. Apparently you can also make antibubbles in beer!