Category: Uncategorized

ETERNAL FUTURE. “According to classical general relativity the volume of space behind the horizon of a black hole grows linearly (with time), into the eternal future.” (Time present and time past/Are both perhaps present in time future,/And time future contained in time past./If all time is eternally present/All time is unredeemable.” TSE Four Quartets). https://lnkd.in/dByfCJV View in LinkedIn

PUSHING THE ANALOGY. “Thus, θ(τ) < 0 for every τ may be proposed as the signal of jamming in this analogue gravity formulation of granular matter.” https://lnkd.in/dusKMKM View in LinkedIn

FRAGMENT FROM NATURE continues and concludes this weekend on the wonderful article that leaps from jammed sand to black holes. It is rare to find such bold leaps and interesting connection of the dots. It is this spirit of raw enquiry which stimulates debate, opens vistas, and regardless of the eventual truth, contribute to the dialogue. Truth is slippery and gets overprinted with new data, but the process of enquiry is the Shackleton drive that opens new territory. View in LinkedIn

FLUIDS VS SOLIDS. “Analogue gravity in barotropic, in viscid fluids with acoustic perturbations is now well-understood both theoretically and observationally. In that case, the knowledge of the basic fluid mechanics equations (Euler-Navier-Stokes) for centuries provides a relative advantage over the case of granular matter where fundamental theoretical understanding is still being sought.” https://lnkd.in/dusKMKM View in LinkedIn

VECTOR SUM. “The interplay between gravity (which is inherently attractive) and background space- time sets up the analogue contact forces, purely repulsive or attractive, frictional or frictionless. In our analogy it is not necessary to add any tensorial polarization field due to bound vector charges as in the VCT.” https://lnkd.in/dusKMKM View in LinkedIn

COSMIC LENSING. “A further interesting aspect of this correspondence is the analogue lensing in a photo-elastic material. The physical measurable quantities in this scenario are the correlators of refractive index which depend on the central difference rather than an absolute measure.” https://lnkd.in/dusKMKM View in LinkedIn

A wild garlic blossom, pure and relatively unscented. View in LinkedIn

EXTRAORDINARY LEADERSHIP. “New Zealand aims to create smoke-free generation. Proposals include making sale of cigarettes to anyone born after 2004 illegal. The plan will begin the final demise of tobacco products in this country.” I usually do not comment on politics, but this is different. https://lnkd.in/dNJBbAP View in LinkedIn

COSMOLOGY. “In the physical universe, the vector mode dies out fast due to the expanding spacetime. In the analogue gravity/cosmology situation addressed here, even though we are dealing with a contracting spacetime, we are at liberty to ignore the vector mode in the first place without altering the curl-free and non zero trace condition of χij.” https://lnkd.in/dusKMKM View in LinkedIn