Gravitational waves from neutron-star mergers are expected to provide stringent constraints on the structure of neutron stars. At the same time, recent advances in nuclear theory have enabled reliable calculations of the low density equation of state using effective field theory based Hamiltonians and advanced techniques to solve the quantum many-body problem. In this paper, we address how the first observation of gravitational waves from GW170817 can be combined with modern calculations of the equation of state to extract useful insights about the equation of state of matter encountered inside neutron stars. We analyze the impact of various uncertainties and we show that the tidal deformability extracted from GW170817 is compatible, while less constraining, than modern nuclear physics knowledge. GW170817: the first observation of gravitational waves from binary neutron star merger We are living an exciting time for the understanding of dense matter properties in compact stars. Both gravitational wave detectors and accurate X-ray observations are expected to bring decisive constrains that will hopefully help to answering many of the present questions, such as the equation of state (EoS) of dense matter, the onset of phase transitions, and the composition of matter at very high density. Neutron-star merger events, for instance, simultaneously emit gravitational waves (GWs) and electromagnetic (EM) signals, from gamma-rays, X-rays, optical, infrared, to radio waves, and neutrinos. The first observation of a NS merger by the LIGO and Virgo (LV) interferometers, GW170817 in the GW spectrum, GRB 170817A in the gamma-ray spectrum, and AT 2017gfo in the electromagnetic (EM) spectrum, was made on August 17, 2017, and in the weeks thereafter [1, 2, 3, 4]. Triggered by the Fermi and Integral telescopes [3, 5], this observation provided detailed spectral and temporal features both in GWs and EM radiation. Theoretical efforts to interpret this data has provided insights into the production of heavy r-process elements in NS mergers [6], and constraints on the EOS of dense matter [7, 8, 9, 10, 11]. NS mergers have the potential to provide detailed information on the properties of the merging compact stars, such as their masses and radii [12], as well as on the properties of the densest baryonic matter to be observed in the universe. Since the O3 run of the Advanced LV interferometers have started on April 1st 2019, for a full year, a large number of new detections of NS mergers will provide even stronger constraints on the EoS of strongly-interacting matter and the r-process. The LV collaboration observed the GW signal of GW170817 for about 100s (several 1000 revolutions, starting from 25 Hz) and performed detailed analyses of the wave front [4]. Because the chirp mass M chirp , defined as M chirp = (m 1 m 2) 3/5 (m 1 + m 2) 1/5 , (1)