The vacuum is not always so empty. “When we talk about a vacuum in cosmology, we do not mean completely devoid of energy,” explains David Wands, Professor at the Institute of Cosmology & Gravitation at the University of Portsmouth. “A vacuum is rather a state in which a field sits at a minimum of its energy. The true vacuum is the lowest possible minimum, but there can also be local minima, which we call false vacua.” We can picture this as a landscape made up of valleys of different depths: the true vacuum is the deepest one, while the others are false vacua. Something sitting in one of these depressions can remain “trapped” there even if, somewhere else, a lower-energy state exists. This is exactly what can happen to quantum fields, fundamental physical objects that permeate the Universe. A classical field is something that has a value at every position in space, like a magnetic field, whose strength changes from point to point. Quantum fields behave in a similar way, and their excitations appear as particles. In a new study published in JCAP, Robson Christie, Jaewoo Joo, Greg Kaplanek, Vincent Vennin and David Wands used a simplified model to investigate what determines which vacuum a field may end up in within an expanding Universe.

Researchers tested a "sunflower" antenna layout on AAVS3, a full-scale prototype station built for the SKA-Low radio telescope. Computer simulations predicted the layout would lose sensitivity directly overhead at around 125 MHz. Real sky observations confirmed this loss and traced the problem to the layout's repeating geometry. As a result, the Observatory decided not to adopt the design for the telescope's final configuration and selected a modified layout instead.

A team of scientists from Arizona State University (ASU) and Raman Research Institute (RRI) has discovered observational evidence of how supermassive black holes lying at the very centers of galaxies impact the entire galaxy within and beyond its visible boundary, and dictate their ultimate fate.

Contrary to conventional wisdom holding that early galaxies were composed of mostly hydrogen and helium, new observations suggest that galaxies were seeding the cosmos with heavy elements just 500 million years after the Big Bang.