This one came up at Tall Blokes talk shop – see https://tallbloke.wordpress.com/2021/06/22/giant-arc-stretching-3-3-bill… … a giant arc of galaxies stretching 3.3 billion light years across the universe, should not exist, we are told. It seems it does. It is also rotating – see https://phys.org/news/2021-06-largest-universe-light-shifted-rotation.html … and www.livescience.com/giant-arc-in-space.html … a newly discovered crescent of galaxies in one of the largest structures in the universe, as seen as yet. It challenges mainstream thinking. Rather, assumptions. One of them is the 'cosmological principle' – at the largest scales matter is more or less evenly distributed through space. Uniformitarian space, one might say. It seems that over the years a number of other large structures have been observed out there in the universe. It strongly suggests material is not distributed evenly. For the cosmological principle see https://en.wikipedia.org/wiki/Cosmological_principle …
Over at https://phys.org/news/2021-06-dark-real-misunderstood-gravity.html … is dark matter real – or have we misunderstood gravity? Good question to pose for astronomers, physicists, cosmologists etc. In 2016 Dutch physicist Erik Verlinde proposed the theory of emergent gravity. It didn't go very far, as far as the public conception is concerned. However, new research published this week pushes the limits of dark matter observations to the unknown outer regions of galaxies, and in doing so, re-evaluates some of the dark matter models and alternative theories on gravity. It appears to support Verlinde we are told – and his idea of Modified Newtonian Dynamics. The findings also seem to agree with computer simulation of the universe that suggests dark matter is real. So, impasse – or what? Bigger and more expensive telescopes perhaps. Key in Euclid – the new kid on the block.