Anthropic constraint on transient variations of fundamental constants
  The anthropic principle implies that life can emerge and be sustained only in
a narrow range of values of fundamental constants (FCs). We extend the
anthropic arguments to a regime of transient variations of FCs. Such regime is
characteristic of clumpy dark matter models where inside the clumps FCs can
reach values vastly different from their everyday values. We show that the
passage of such a macroscopic clump through Earth would make Earth
uninhabitable. The periodic table of elements is truncated and water fails to
serve as a universal solvent. Anthropic principle enables us to improve
existing astrophysical bounds on certain dark matter model couplings by five
orders of magnitude.
