  We introduce a lattice model of glass transition in polymer globules. This
model exhibits a novel scenario of ergodicity breaking in which the disjoint
regions of phase space do not arise uniformly, but as small chambers whose
number increases exponentially with polymer density. Chamber sizes obey power
law distribution, making phase space similar to a fractal foam. This clearly
demonstrates the importance of the phase space geometry and topology in
describing any glass-forming system, such as semicompact polymers during
protein folding.
