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 […]
For more than two decades, the standard picture of the Universe has rested on a surprisingly simple idea. Space is expanding, galaxies are moving farther apart, and a mysterious ingredient called dark energy is driving that expansion to accelerate. In the simplest model, dark energy is constant through time, an unchanging property of empty space […]
Dark matter is a mysterious, invisible substance that makes up about 27% of the Universe’s total energy content. We cannot see it directly, only infer its presence through the gravity it exerts. For decades, cosmologists have described dark matter haloes as the invisible scaffolding within which galaxies form and live. Every galaxy, including our own […]
When we look at the night sky, we see a scattered collection of stars and galaxies, but to an astrophysicist, these are merely the glowing foam on the crest of a much deeper, invisible ocean. The vast majority of the matter in our universe is dark matter, a substance that does not emit, absorb, or […]
Author: Enrique Gaztañaga, Professor at Institute of Cosmology and Gravitation (University of Portsmouth) Wormholes are often imagined as tunnels through space or time — shortcuts across the universe. But this image rests on a misunderstanding of work by physicists Albert Einstein and Nathan Rosen. In 1935, while studying the behaviour of particles in regions of […]
Scientists have created the highest resolution map of the dark matter that threads through the universe—showing its influence on the formation of stars, galaxies and planets. The findings, using new data from NASA’s James Webb Space Telescope (Webb) tells us more about how this invisible substance helped pull ordinary matter into galaxies like the Milky […]
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 […]
There’s always a touch of melancholy when a chapter that has absorbed years of work comes to an end. In the case of the Atacama Cosmology Telescope (ACT), those years amount to nearly 20—and now the telescope has completed its mission. Yet some endings are also important beginnings, opening new paths for the entire scientific […]
Author: Florian Neukart, Assistant professor of Physics, Leiden University For more than a century, physics has been built on two great theories. Einstein’s general relativity explains gravity as the bending of space and time. Quantum mechanics governs the world of particles and fields. Both work brilliantly in their own domains. But put them together and […]
We’re often told it is “unscientific” or “meaningless” to ask what happened before the Big Bang. But a new paper by cosmologist Eugene Lim, of King’s College London, UK, and astrophysicists Katy Clough, of Queen Mary University of London, UK, and Josu Aurrekoetxea, at Oxford University, UK, proposes a way forward: using complex computer simulations […]