Two spaces looking for a geometer
  In this talk I will introduces two spaces: the first space is the usual n-dimensional vector space with the unusual feature that n is non-integer, the second space is composed by the linear matrices acting on the previous space (physicists are particularly interested to study the limit n going to zero). These two spaces are not known to most of the mathematicians, but they are widely used by physicists. It is possible that, by extending the notion of space, they can become well defined mathematical objects. 
Giorgio Parisi