This week we had another lecture in the area of the physics of the vacuum (see Whoops! A Universe). It was the 11th Dennis Sciama Memorial Lecture, given by Professor Philip Candelas of the Mathematical Institute, University of Oxford. Here are the title and abstract:

 Simple Calabi-Yau Manifolds and the Landscape of String Vacua

 Abstract: It is widely known that there are a great many vacua of string theory. A small subset of these lead to four-dimensional worlds that are somewhat like the world that we observe. The great majority lead to worlds very different from our own. A vacuum is determined by a Calabi-Yau manifold together with certain extra structure. I will discuss the landscape of Calabi-Yau manifolds and a programme to find realistic string vacua based on simple cases.

You don’t need to understand the technical terms in order to follow the point I wish to make. All I want to emphasize here is that this lecture illustrates very well how completely wrong it is to describe the state of the universe in the absence of matter as somehow simple and not in need of explanation. Some of the best mathematical brains on the planet are puzzling over the nature of vacuum, and it is far from obvious or easy. And yet we continue to see utterly misleading headlines like the following (selected randomly from the web):

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