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THE HOPE. “As more mergers are detected, the prospect of identifying the host galaxy population, either directly through the detection of electromagnetic counterparts of binary neutron star mergers or indirectly through the anisotropy of the events, will become a realistic possibility.” https://lnkd.in/d8Jh7TB View in LinkedIn

IMMINENT MERGER RATE. “If roughly 1 per cent of black holes are involved in a binary black hole merger, then the reported merger rate densities from advanced Laser Interferometer Gravitational-Wave Observatory can be accommodated for a range of merger time-scales, and the detection of mergers with >50 M⊙ black holes should be expected within the next decade.” (M⊙ = solar mass ~equivalent to mass of the sun). https://lnkd.in/d8Jh7TB View in LinkedIn

DISTRIBUTION. “Most low-mass black holes (∼10 M⊙) typically reside within massive galaxies (M⋆ ≃ 10(11)  M⊙) while massive black holes (∼50 M⊙) typically reside within dwarf galaxies (M⋆ ≃ 10(9)  M⊙) today.” (M⊙ = solar mass ~equivalent to mass of the sun). https://lnkd.in/d8Jh7TB View in LinkedIn

This image includes the most distant galaxies and protogalaxies we ever have seen. The largest galaxies in the image are as close as 6 billion light years, while the smallest dots are protogalaxies as far away as 30 billion light years. This image thus spans the edge of our affectable universe, with most of the places it shows being forever beyond our reach. https://lnkd.in/dHhggEG View in LinkedIn

REDUCTIONISM HAS FAILED. “Zen is holism, carried to its logical extreme. If holism claims that things can only be understood as wholes, not as sums of their parts, Zen goes one further, in maintaining that the world cannot be broken into parts at all. To divide the world into parts is to be deluded, and to miss enlightenment.” https://lnkd.in/dmfn9qW View in LinkedIn

SO ENDS this first of two weekends focused on a fearlessly imaginative essay linking William Blake’s grain of sand not just to the world, but to black holes, relativity and the very fabric of the universe, spacetime. It should be an Exemplar for students in the tradition of Darwin’s excavating earthworms, photonic crystals in beetle wings, and peacock feather Iridescence. Looking is not enough, but observing keenly with a primed mind is how science is built. https://lnkd.in/dusKMKM View in LinkedIn

THE ANALOGY. “On the other hand, for initially unjammed states with θ(0) = 0, but with non-vanishing shear, while the rotation still vanishes, there is still convergence θ(τ ) < 0, corresponding to shear jamming in granular matter, provided, we use the Einstein equation " "Rμν = (8πG/c4)(Tμν−(1/2)gμνT) (where T ≡ gμνTμν) with non-negative energy density Tμνnμnν ≥ 0. The presence of an external stress-energy tensor exacerbates jamming, if the analogy holds.” https://lnkd.in/dusKMKM View in LinkedIn

BLACK HOLE MASS. “For example, according to the calculations of Spera et al, a star of mass ≃90M⊙ will be required to produce a remnant of mass mbh = 30 M⊙ if its metallicity is Z/Z⊙ = −0.5. A more metal poor star (−1.5) will need to be only ≃33M⊙ to produce a 30 M⊙ BBH remnant.” (BBH = binary black hole; M⊙ = unit of stellar mass in suns). https://lnkd.in/d8Jh7TB View in LinkedIn

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