Galaxy clusters—the big cities of the universe—are home to many giant elliptical galaxies that have completed their growth and are not forming stars. However, it is still unclear what has shut down star formation. In a new study, researchers utilized the James Webb Space Telescope to observe an ancestor of galaxy clusters, revealing the role of supermassive black holes in slowing star formation and allowing them to evolve into giant elliptical galaxies.

Water oxidation offers a promising path to achieve sustainable energy by efficiently generating oxygen. This study investigates how optimizing Ru(II) photosensitizers, metal oxide catalysts, and pH conditions can enhance water splitting efficiency. By introducing a simplified method to estimate catalyst performance, researchers make it easier to design more effective systems. These findings provide crucial insights for advancing clean energy solutions and accelerating the transition to renewable energy.

Isolated atoms in free space radiate energy at their own individual pace. However, atoms in an optical cavity interact with the photons bouncing back and forth from the cavity mirrors, and by doing so, they coordinate their photon emission and radiate collectively, all in sync. This enhanced light emission before all the atoms reach the ground state is known as superradiance. Interestingly, if an external laser is used to excite the atoms inside the cavity moderately, the absorption of light by the atoms and the collective emission can balance each other, letting the atoms relax to a steady state with finite excitations.

However, above a certain laser energy level, the nature of the steady state drastically changes since atoms inside the cavity cannot collectively emit light fast enough to balance the incoming light. As a result, the atoms keep emitting and absorbing photons without reaching a stable, steady state. While this change in steady-state behaviors was theoretically predicted decades ago, it hasn’t yet been observed experimentally.  

Recent research at the Laboratoire Charles Fabry and the Institut d’Optique in Paris studied a collection of atoms in free space forming an elongated, pencil-shaped cloud and reported the potential observation of this desired phase transition. Yet, the results of this study puzzled other experimentalists since atoms in free space don’t easily synchronize. 

To better understand these findings, JILA and NIST Fellow Ana Maria Rey and her theory team collaborated with an international team of experimentalists. The theorists found that atoms in free space can only partially synchronize their emission, suggesting that the free-space experiment did not observe the superradiant phase transition. These results are published in PRX Quantum. 

Microgravity is known to alter the muscles, bones, the immune system and cogni­tion, but little is known about its specific impact on the brain. To discover how brain cells respond to microgravity, Scripps Research scientists, in collaboration with the New York Stem Cell Foundation, sent tiny clumps of stem-cell derived brain cells called “organoids” to the International Space Station.