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BLACK HOLE FORMATION. “A more realistic situation for appearance of trapped surfaces is gravitational collapse. Here, the stress-energy tensor vanishes outside the boundary of the collapsing body (assumed spherical for simplicity).” https://lnkd.in/dusKMKM View in LinkedIn

SAND LINKS TO THE COSMOS. “Similarly, aspects of the CMB spectrum like non-Gaussianity may also show up as a feature of granular media observed experimentally. All-in-all, the assay portends an interesting future.” https://lnkd.in/dusKMKM View in LinkedIn

FRAME BY FRAME. “The spatial symmetries of granular interactions are manifest in every frame of the gravity analogue.” https://lnkd.in/dusKMKM View in LinkedIn

FEARLESS THINKING. “Perhaps one can also turn the analogy on its head, and use granular matter physics to explore phenomena that are yet unobserved in real cosmology. An example would be the existence of primordial gravitational waves which in the real universe are still shrouded in mystery.” https://lnkd.in/dusKMKM View in LinkedIn

THE BLACK HOLE. “The length scale rS characterizing this solution is called the Schwarzschild radius; r = rS is identified with the event horizon, and represents the boundary between events connected to asymptopia and those that are confined to the region r ≤ rS - the black hole region.” https://lnkd.in/dusKMKM View in LinkedIn

MAKING THE DATA FIT THE MODEL. “The analogue of Hubble friction in that case may help stabilize and stimulate growth of structures in the density profile. This is certainly a direction worthy of exploration.” https://lnkd.in/dusKMKM View in LinkedIn

IMAGINATIVE CONNECTION. “Isotropic jamming would correspond clearly to a situation with spherical symmetry. In this case, with Tμν = 0, the vacuum Einstein equation reduces to Rμν = 0 which admits the Schwarzschild solution.” https://lnkd.in/dusKMKM View in LinkedIn

FUDGE FACTOR. “If so, a partial remedy of this situation may emerge from introducing a cosmological constant into the analogy. An alternate mapping of the jamming state, especially shear jamming, may also emerge from considering expanding analogue spacetimes, rather than contracting ones as done here.” (Einstein’s “greatest mistake” was the cosmological constant). https://lnkd.in/dusKMKM View in LinkedIn

REPULSIVE FORCE. “Further, the attractive nature of gravity implies that a gravity analogue of granular matter may be deemed inadequate for describing microscopic granular repulsions.” https://lnkd.in/dusKMKM View in LinkedIn

THE ISSUE OF FRAGILITY. “The incipient, preliminary and necessarily incomplete general relativistic analogy presented here falls short of describing an important feature of granular matter, namely fragility.” https://lnkd.in/dusKMKM View in LinkedIn