Author: Subir Sarkar, Emeritus Professor, Department of Physics, University of Oxford According to our best understanding, the universe is expanding – and is doing so at an accelerating rate. This is believed to be caused by something called the “cosmological constant”, which was first proposed by Albert Einstein in his theory of general relativity. In […]
The mystery of dark matter remains one of the most profound puzzles in modern astrophysics. We know it outweighs ordinary matter by a factor of five, yet it neither shines nor absorbs light. Its presence is betrayed only by the pull of gravity, shaping galaxies and bending light from more distant objects. For decades, scientists […]
wavelike All the matter that has ever been detected accounts for a mere 4.9% of the Universe. Most of the cosmos is the dark universe: a mix of dark matter (26.8%) and dark energy (68.3%), both of which have so far proved impenetrable puzzles. The existence of dark matter has been inferred from the motion […]
Astrophysicists from Yale University have recently claimed the discovery of a galaxy lacking dark matter . But, to fully understand (and assess) the excitement produced by this paper, let’s review a couple of things regarding dark matter and galaxies. In the current lambda-Cold Dark Matter (ΛCDM) paradigm, the most accepted “theory to model the Universe […]
One of the most striking discoveries made by the James Webb Space Telescope, together with earlier observations from the Hubble Space Telescope, is that many galaxies in the young universe look very different from those we see around us today. Instead of graceful spiral disks or rounded ellipses, a large fraction of galaxies observed when […]
In the vast expanse of the universe, galaxies are not isolated islands but are interconnected through a vast network known as the “cosmic web.” This intricate structure, composed of dark matter and gas, forms the backbone of the cosmos, guiding the formation and evolution of galaxies. Recent advancements have allowed astronomers to capture a high-definition […]
Imagine a Universe that started with a huge explosion setting the beginning of space and time to the point that such concepts have no meaning until then. Imagine a Universe that, after an inflationary phase (extremely fast expansion), kept expanding and forming stars and galaxies distributed in a sponge-like structure dominated by walls and filaments […]
When astronomers in the eighteenth century first turned powerful telescopes toward the Milky Way, they noticed something puzzling: tight, spherical swarms of stars scattered across the sky. Now we know that each contains hundreds of thousands of suns packed into a region just a few dozen light-years across. These objects, known today as globular clusters […]
The evolution of the cosmic star formation rate density paints a dynamic picture of galaxy evolution, with rapid stellar build-up at redshifts above 2, followed by a stark drop in SFRs of galaxies towards the present day. The origins of this down-turn are likely due to a mixture of feedback processes, broadly categorized as caused […]
spallation Progress in particle physics has traditionally been achieved by a symbiosis of experiments at the energy and intensity frontiers and model-building. This has led to the current situation of the Standard Model (SM) representing our best knowledge of particle physics, but which leaves a number of open questions to be resolved. These include the […]