Have you ever wondered why the bubbles on top of your pint tend to “stick” to the side of the glass? The answer has been found by my colleague at OCCAM (Dominic Vella): it’s because of the “Cheerios effect”.
The reason for this is that most liquids love to stick to glass (i.e. they like to wet glass). This results in the formation of a concave meniscus – as shown in the figure to the right. Since bubbles float, they tend to rise to the top of the meniscus, i.e. to the side of the glass. Dr Vella has analysed this problem and concluded that it is the reason why Cheerios floating on milk tend to stick together. He wrote a clear and entertaining paper on the topic: enjoy the reading!