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THE NUMBER LINKAGE. “It is clear that if the shear, twist and Ricci tensor vanish, the geodesic congruence is convergent, i.e., θ(τ) < 0 at every τ for θ(0) < 0. This is the case of spontaneous jamming, and is independent of any assumed symmetries of spacetime, spherical or otherwise.” https://lnkd.in/dusKMKM View in LinkedIn

METALLICITIES. “Important to all of these investigations is the realization that massive black hole formation is suppressed in stellar populations with higher metallicites.” https://lnkd.in/d8Jh7TB View in LinkedIn

FROM SAND TO GEODESICS. “An additional justification of this analogy of jammed states with trapped surfaces may be posited on the basis of the Raychaudhuri equation, for timelike geodesic congruence in the case of granular matter.” https://lnkd.in/dusKMKM View in LinkedIn

NOMENCLATURE. “In astronomy, metallicity is the abundance of elements present in an object that are heavier than hydrogen and helium. Most of the normal physical matter in the Universe is either hydrogen or helium, and astronomers use the word "metals" as a convenient short term for "all elements except hydrogen and helium". (ie: a measure of nucleosynthesis in stars). https://lnkd.in/d8DupZu View in LinkedIn

METHOD. “Using these ingredients, together with the current generation of stellar evolution codes, we can provide a grounded estimate of the global distribution of black holes as a function of black hole mass and galaxy stellar mass. With this as a starting point, we are able to quantify the astrophysical parameters needed to produce the observed BBH merger signals observed.” (BBH = binary black hole). https://lnkd.in/d8Jh7TB View in LinkedIn

GEOMETRY IN NATURE. “But the formative faculty of the earth does not take to her heart only one shape; she knows and is practiced in the whole of geometry. I have seen… a panel inlaid with silver ore; from it, a dodecahedron, like a small hazelnut in size, projected to half its depth, as if in flower.” (Johannes Kepler, 1610, The Six-Cornered Snowflake) https://lnkd.in/duxTaRF View in LinkedIn

THE START. “The key idea is that we have a good empirical understanding of the overall galaxy number density, stellar ages and metallicities as a function of galaxy mass, and estimates of the initial mass function of stars that formed in these galaxies.” https://lnkd.in/d8Jh7TB View in LinkedIn

STRATEGY. “In this work, we outline a simple way to compute the BBH merger rate for stellar remnant black holes that allows one to assess the uncertainties in the various required ingredients in a transparent manner.” (BBH = binary black hole). https://lnkd.in/d8Jh7TB View in LinkedIn

ORIGINS. “As the field now pivots from gravitational wave discovery to gravitational wave astronomy, there are a number of questions we hope to explore in more detail. One basic question is the origin of these massive black holes. Heavy (≳30  M⊙) black holes are expected to exist as the result of stellar evolution, and have been predicted to dominate the LIGO signal.” (M⊙ = solar mass ~equivalent to mass of the sun; LIGO = The Laser Interferometer Gravitational-Wave Observatory). https://lnkd.in/d8Jh7TB View in LinkedIn