Curated by RSF Research Staff
Hydrodynamic Simulations of Rotating Black Holes
Hydrodynamic analog systems are capable of simulating the conditions of ultra-small scale phenomena—like particle-wave behaviors—and cosmological scale phenomena, like gravitational interactions and the conditions around the event horizon of a black hole. As such, it is becoming increasingly evident how fluid dynamics plays a central role in the path towards unification of the two predominant domains of physics’ field theories—quantum mechanics and general relativity—and how hydrodynamic analog systems are becoming increasingly powerful laboratory tools for studying phenomena that are inherently challenging to test directly:
QG-Lab Outreach: Quantum Gravity Laboratory
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The science of modeling and describing the behavior of fluids, referred to as fluid dynamics, is surprisingly pivotal to understanding some of the most elementary constituents and processes underlying physical phenomena. Fluid dynamics can tell you everything from how a plane or bird flies through the air to how quantum vortexes form in superconductors, Bose-Einstein condensates and superfluids.
Helicity is a measure of cork-screw-like motion described by the amount of twisting, writhing, and linking in a fluid. Total helicity is conserved for ideal fluids, but how helicity changes in real fluids with even tiny amounts of viscosity has been an open question. Scheeler et al. provide a complete measurement of total helicity in a real fluid by using a set of hydrofoils to track linking, twisting, and writhing (see the Perspective by Moffatt). They show that twisting dissipates total helicity, whereas writhing and linking conserve it. This provides a fundamental insight into tornadogenesis, atmospheric flows, and the formation of turbulence.
New simulations of the dynamics of black holes have shed light on an intriguing possibility. If there exists in nature a bosonic particle with an exceptionally small mass, then a black hole may spontaneously grow “long hair,” in the form of highly amplified excitations of the field that are trapped in the vicinity of the black hole — leading to exponential growth, instability, collapse, and a bosenova explosion.
recent unified approach proposes MOND phenomenon from dark matter superfluidity — postulating that our galaxy is spinning in a superfluid medium.
Scientists have combined light with electrons to make a room-temperature superfluid. A superfluid is a kind of fifth-state of matter — a macroscopic quantum state in which the coupling of matter is so strong it no longer consists of separate individual quanta but instead merges into a single indivisible waveform.
Physicists have modeled superfluid helium with computer simulations and found that it’s entropic properties are the same as those of black holes. Entropy is a measure of the information of a system. Black holes are maximum entropy objects. Somewhat enigmatically, thermodynamic investigations of black holes demonstrated that their entropy grows in proportion to the surface area of the event horizon, not the internal volume.