  We present an explicit reconstruction of the interior of an AdS$_2$ black
hole in Jackiw-Teitelboim gravity, that is entirely formulated in the dual SYK
model and makes no direct reference to the gravitational bulk. We do this by
introducing a probe "observer" in the right wormhole exterior and using the
prescription of [arXiv:2009.04476] to transport SYK operators along the probe's
infalling worldline and into the black hole interior, using an appropriate SYK
modular Hamiltonian. Our SYK computation recovers the precise proper time at
which signals sent from the left boundary are registered by our observer's
apparatus inside the wormhole. The success of the computation relies on the
universal properties of SYK and we outline a promising avenue for extending it
to higher dimensions and applying it to the computation of scattering
amplitudes behind the horizon.
