Tag archives for physics

  1. Guinness bubbles problem – solved!

    By Leonid Mamchenkov

    If you are a beer fan, you’ve probably heard about the famous Guinness bubbles problem.  While bubbles in most other beers rise up, in Guinness they go down.  A lot of people were puzzled by that fact, and now, it seems, the puzzle is solved.

    According to the article in Technology Reviews, Irish mathematicians came up with an answer:

    Today, a dedicated team of Irish mathematicians reveal the answer. Eugene Benilov, Cathal Cummins and William Lee at the University of Limerick say the final piece in this puzzle is the shape of the glass, which has a crucial influence over the circulatory patterns in the liquid.

    To understand how, first remember that the motion of every bubble exerts a drag on the liquid around it. Now imagine what would happen if there were a region of liquid containing fewer bubbles near the wall of a pint glass and consequently a region of higher bubble density near the middle of the glass.

    Benilov and co say that the drag will be higher in the region where the bubble density is higher, in other words near the centre of the glass. This creates an imbalance that sets up a circulation pattern in which the liquid flows upwards in the centre of the glass and downwards near the walls.

    That’s exactly as observed in a pint of Guinness.

    There are more details and image of an anti-pint in the article.  Read it.

    Also, while reading up on the subject, I’ve learned something else about Guinness – the widget.

  2. Atomic physics resources

    By Leonid Mamchenkov

    Doing my duty in promotion of knowledge and science, I bring you this collection of resources on atomic physics.  With the way the world goes, who knows when you’d need a quick reference to some research.  And, in case you are a bit rusty on what atomic physics is, here is a quick quote for you from the Wikipedia.

    Atomic physics (or atom physics) is the field of physics that studies atoms as an isolated system of electrons and an atomic nucleus. It is primarily concerned with the arrangement of electrons around the nucleus and the processes by which these arrangements change. This includes ions as well as neutral atoms

    [...]

    The term atomic physics is often associated with nuclear power and nuclear bombs, due to the synonymous use of atomic and nuclear in standard English. However, physicists distinguish between atomic physics — which deals with the atom as a system consisting of a nucleus and electrons — and nuclear physics, which considers atomic nuclei alone.

    As with many scientific fields, strict delineation can be highly contrived and atomic physics is often considered in the wider context of atomic, molecular, and optical physics. Physics research groups are usually so classified.