A supermassive black hole lies at the heart of every galaxy, including the Milky Way. When a black hole is active, it pulls material in as a whirlpool of high-temperature gas and dust. As this cosmic material piles up and falls onto a black hole, it lights up its vicinity, radiating a huge amount of energy. The most energetic supermassive black holes are known as quasars, and they are some of the most active and luminous objects in the universe. These voracious systems take in so much material that the energy they emit can outshine all the light in the surrounding galaxy. The pattern of light from a quasar can give scientists clues to how active supermassive black holes shape the galaxies around them. Now astronomers at MIT and elsewhere have detected a quasar flickering from the very early universe. The scientists traced the light from the quasar back to the 'cosmic dawn,' just 850 million years after the Big Bang. The discovery represents the earliest flickering quasar detected to date....

Dark matter is thought to make up most of the matter in the universe, but the only way it interacts with its surroundings is through gravity. If two colliding black holes spiral through a dense region of dark matter and merge, gravitational waves rippling across space and time could carry an imprint of that dark matter. Researchers at MIT and in Europe have developed a method that makes predictions for what a gravitational wave should look like if it were produced by black holes that moved through dark matter, rather than empty space. They applied the technique to publicly available gravitational-wave data previously recorded by LIGO-Virgo-KAGRA (LVK), the global network of observatories that detect gravitational waves from black hole mergers and other far-off astrophysical sources. The researchers looked through the gravitational-wave signals recorded over the LVK's first three observing runs. From 28 of the clearest signals, the team found that 27 originated from black holes that merged in a vacuum, as physicists expected. But the pattern of one signal, GW190728, showed possible signs of a dark matter imprint....

On October 8, 2024, the field of physics was plunged into controversy. That day, the Nobel Prize in Physics was awarded for discoveries not involving black holes, cosmology, or strange new subatomic particles, but about AI. How could the discipline's highest award go to research about machines designed to mimic human brains' Where was the physics in that' For most of the 20th century, physicists largely ignored living systems. They understood living things as machines, albeit ones made of gooey parts. A subfield called biophysics uncovered specific physical mechanisms behind those molecular machines. Organisms as a whole, however, were not a major concern. But today, many of my colleagues in physics no longer agree with such dismissals. Instead, we have come to believe that a mystery is unfolding in every microbe, animal, and human'one that challenges basic assumptions physicists have held for centuries, and could answer essential questions about AI. It may even help redefine the field for the next generation....

If you look across space with a telescope, you'll see countless galaxies, most of which host large central black holes, billions of stars and their attendant planets. The universe teems with huge, spectacular objects, and it might seem like these massive objects should hold most of the universe's matter. But the Big Bang theory predicts that about 5% of the universe's contents should be atoms made of protons, neutrons and electrons. Most of those atoms cannot be found in stars and galaxies ' a discrepancy that has puzzled astronomers. If not in visible stars and galaxies, the most likely hiding place for the matter is in the dark space between galaxies. While space is often referred to as a vacuum, it isn't completely empty. Individual particles and atoms are dispersed throughout the space between stars and galaxies, forming a dark, filamentary network called the 'cosmic web.' The census comes to several hundred billion galaxies, each made of several hundred billion stars. The numbers are uncertain because many stars lurk outside of galaxies. That's an estimated 1023 stars in the universe, or hundreds of times more than the number of sand grains on all of Earth's beaches. There are an estimated 1082 atoms in the universe....