Take a mixture of a viscous liquid – like clay mud – and squeeze it between two glass plates and you’ll create a mostly-round layer of liquid. As you pry the two glass plates apart, air will push its way into that layer, forcing through the mud in a dendritic pattern. This is called the Saffman-Taylor instability or viscous fingering. It occurs because the interface between the air and mud is unstable. (Image and video credit: amàco et al.)
my type of meme
Night sky
Lieksa, Finland
October 2018
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“The measurements of the enormous pressure inside the proton, as well as the distribution of that pressure, show us what’s responsible for preventing the collapse of neutron stars. It’s the internal pressure inside each proton and neutron, arising from the strong force, that holds up neutron stars when white dwarfs have long given out. Determining exactly where that mass threshold is just got a great boost. Rather than solely relying on astrophysical observations, the experimental side of nuclear physics may provide the guidepost we need to theoretically understand where the limits of neutron stars actually lie.”
If you take a large, massive collection of matter and compress it down into a small space, it’s going to attempt to form a black hole. The only thing that can stop it is some sort of internal pressure that pushes back. For stars, that’s thermal, radiation pressure. For white dwarfs, that’s the quantum degeneracy pressure from the electrons. And for neutron stars, there’s quantum degeneracy pressure between the neutrons (or quarks) themselves. Only, if that last case were the only factor at play, neutron stars wouldn’t be able to get more massive than white dwarfs, and there’s strong evidence that they can reach almost twice the Chandrasekhar mass limit of 1.4 solar masses. Instead, there must be a big contribution from the internal pressure each the individual nucleon to resist collapse.
For the first time, we’ve measured that pressure distribution inside the proton, paving the way to understanding why massive neutron stars don’t all form black holes.
Enceladus and Saturn
Image credit: Gordan Ugarkovic
Hubble’s Jupiter and the Shrinking Great Red Spot
Image Credit: NASA, ESA, Hubble, OPAL Program, STScI; Processing: Karol Masztalerz
Andromeda’s actual size if it was brighter
via reddit
Liquid oxygen is magnetic
Liquid oxygen sticks between the poles of a strong magnet until it boils away into its gas state. This is because it has unpaired electrons, which make each oxygen molecule a tiny magnet with a dipole. Normally, when oxygen is in a flask or in the air, these microscopic magnets point in all directions, cancelling out and meaning that there’s no net magnetic field. When it pours over the permanent magnet, the magnetic molecules all slightly align, creating an induced magnetic field, which reacts with the permanent magnet, making the oxygen stick to the poles. This is called paramagnetism. Click here to watch the video.