We prove explicit bilipschitz bounds on the change in metric between the thick part of a cusped
hyperbolic
–manifold
and
the thick part of any of its long Dehn fillings. Given a bilipschitz constant
and a thickness
constant
,
we quantify how long a Dehn filling suffices to guarantee a
–bilipschitz
map on
–thick
parts. A similar theorem without quantitative control was previously proved by
Brock and Bromberg, applying Hodgson and Kerckhoff’s theory of cone
deformations. We achieve quantitative control by bounding the analytic
quantities that control the infinitesimal change in metric during the cone
deformation.
Our quantitative results have two immediate applications. First, we relate the Margulis
number of
to the
Margulis numbers of its Dehn fillings. In particular, we give a lower bound on the systole of any
closed
–manifold
whose Margulis
number is less than
.
Combined with Shalen’s upper bound on the volume of such a
manifold, this gives a procedure to compute the finite list of
–manifolds whose Margulis
numbers are below
.
Our second application is to the cosmetic surgery conjecture. Given the systole of a one-cusped
hyperbolic manifold
,
we produce an explicit upper bound on the length of a slope involved in a cosmetic surgery on
. This reduces the cosmetic
surgery conjecture on
to an explicit finite search.