Cosmology Archives

July 1, 2023July 1, 2023 by Matt Williams

Dark Matter Might Interact in a Totally Unexpected Way With the Universe

Image from Dark Universe, showing the distribution of dark matter in the universe. Credit: AMNH

According to Sir Isaac Newton’s theory of Universal Gravitation, gravity is an action at a distance, where one object feels the influence of another regardless of distance. This became a central feature of Classical Newtonian Physics that remained the accepted canon for over two hundred years. By the 20th century, Einstein began reconceptualizing gravity with his theory of General Relativity, where gravity alters the curvature of local spacetime. From this, we get the principle of locality, which states that an object is directly influenced by its surroundings, and distant objects cannot communicate instantaneously.

However, the birth of quantum mechanics has caused yet another conceptualization, as physicists discovered that non-local phenomena not only exist but are fundamental to reality as we know it. This includes quantum entanglement, where the properties of one particle can be transferred to another instantaneously and regardless of distance. In a new study by the International School for Advanced Studies (SISSA) in Trieste, Italy, a team of researchers suggests that Dark Matter might interact with gravity in a non-local way.

June 28, 2023June 28, 2023 by Matt Williams

Two New Space Telescopes Will Bring Dark Energy Into Focus

High-resolution illustration of the Euclid and Roman spacecraft against a starry background. Credits: NASA’s Goddard Space Flight Center, ESA/ATG medialab

Since the 1990s, thanks to observations by the venerable Hubble Space Telescope (HST), astronomers have contemplated the mystery of cosmic expansion. While scientists have known about this since the late-1920s and early-30s, images acquired by Hubble‘s Ultra Deep Fields campaign revealed that the expansion has been accelerating for the past six billion years! This led scientists to reconsider Einstein’s theory that there is an unknown force in the Universe that “holds back gravity,” which he named the Cosmological Constant. To astronomers and cosmologists today, this force is known as “Dark Energy.”

However, not everyone is sold on the idea of Dark Energy, and some believe that cosmic expansion could mean there is a flaw in our understanding of gravity. In the near future, scientists will benefit from next-generation space telescopes to provide fresh insight into this mysterious force. These include the ESA’s Euclid mission, scheduled for launch this July, and NASA’s Nancy Grace Roman Space Telescope (RST), the direct successor to Hubble that will launch in May 2027. Once operational, these space telescopes will investigate these competing theories to see which holds up.

June 10, 2023June 14, 2023 by Paul M. Sutter

Why Didn’t the Big Bang Collapse in a Giant Black Hole?

This is an artist’s impression of a black hole drifting through our Milky Way galaxy. The black hole is the crushed remnant of a massive star that exploded as a supernova. The surviving core is several times the mass of our Sun. The black hole traps light because of its intense gravitational field. The black hole distorts the space around it, which warps images of background stars lined up almost directly behind it. This gravitational "lensing" effect offers the only telltale evidence for the existence of lone black holes wandering our galaxy, of which there may be a population of 100 million. The Hubble Space Telescope goes hunting for these black holes by looking for distortion in starlight as the black holes drift in front of background stars. Credit: ESA

Despite the enormous densities, the early universe didn’t collapse into a black hole because, simply put, there was nothing to collapse into.

June 9, 2023June 12, 2023 by Brian Koberlein

Has JWST Finally Found the First Stars in the Universe?

Artist's view of several Population III stars. Credit: NASA/WMAP Science Team

In astronomy, elements other than hydrogen and helium are called metals. While that might make your high-school chemistry teacher cringe, it makes sense for astronomers. The two lightest elements were the first to appear in the universe. They are the atomic remnants of the big bang and make up more than 99% of atoms in the universe. All the other elements, from carbon to iron to gold, were created through astrophysical processes. Things like nuclear fusion in stellar cores, supernova explosions, and collisions of white dwarfs and neutron stars.

June 5, 2023June 5, 2023 by Andy Tomaswick

It Might Take Space Telescopes to Finally Resolve the Crisis in Cosmology

Gravitational wave (GW) observatories have been a great addition to cosmologists’ arsenal in the lack decade. With their first effective detection at the Laser Interferometric Gravitational Observatory completed in 2015, they opened up a whole new world of data collection for scientists. However, so far, they haven’t solved one of the fundamental problems at the heart of their discipline – the “Hubble tension.” Now a new paper discusses the possibility of utilizing a network of new, space-based gravitational wave observatories to get closer than ever to the real value of one of the most important numbers in the Universe.

May 19, 2023May 13, 2023 by Paul M. Sutter

A Brief History of the Discovery of Cosmic Voids

An artist's impression of the cosmic web, the filamentary structure that fills the entire Universe. Credit: M. Weiss/CfA

At first the sum total of large, orderly structure in the Universe appeared to arrive in two categories. There were the clusters of galaxies – an unoriginal but descriptive name – each a dense ball with anywhere from a few dozen to a few hundred galaxies, all bound together by their mutual gravitational embrace. And then there were the field galaxies, lonely wanderers set apart and adrift from the clusters, not bound to anyone but themselves. That was it: the clusters of galaxies, the field galaxies, and the megaparsecs of emptiness that enveloped them all.

May 17, 2023May 17, 2023 by Brian Koberlein

Astronomers Have a New Way to Measure the Expansion of the Universe

Multiple observations of the Refsdal supernova. Credit: Kelly,et al

The cosmos is expanding at an ever-increasing rate. This cosmic acceleration is caused by dark energy, and it is a central aspect of the evolution of our universe. The rate of cosmic expansion can be expressed by a cosmological constant, commonly known as the Hubble constant, or Hubble parameter. But while astronomers generally agree this Hubble parameter exists, there is some disagreement as to its value.

May 8, 2023May 8, 2023 by Brian Koberlein

JWST Fails to Disprove the Big Bang

A portion of the Renaissance Simulation centered on a cluster of young galaxies. Credit: Advanced Visualization Lab, National Center for Supercomputing Applications

The James Webb Space Telescope (JWST) is revolutionizing our understanding of the early universe. With a mirror larger than Hubble and the ability to observe deep into the infrared, JWST is giving us a detailed view of that period of the universe when galaxies were just starting to form. The results have been surprising, leading some to argue that they disprove the big bang. But the big bang is still intact, as a recent study shows.

April 19, 2023April 19, 2023 by Matt Williams

The First Light in the Universe Helps Build a Dark Matter Map

A view of Stephan’s Quintet, a visual grouping of five galaxies from the James Webb Telescope. Credit: NASA/ESA/CSA/STScI

In the 1960s, astronomers began noticing a pervasive microwave background visible in all directions. Thereafter known as the Cosmic Microwave Background (CMB), the existence of this relic radiation confirmed the Big Bang theory, which posits that all matter was condensed onto a single point of infinite density and extreme heat that began expanding ca. 13.8 years ago. By measuring the CMB for redshift and comparing these to local distance measurements (using variable stars and supernovae), astronomers have sought to measure the rate at which the Universe is expanding.

Around the same time, scientists observed that the rotational curves of galaxies were much higher than their visible mass suggested. This meant that either Einstein’s Theory of General Relativity was wrong or the Universe was filled with a mysterious, invisible mass. In a new series of papers, members of the Atacama Cosmology Telescope (ACT) collaboration have used background light from the CMB to create a new map of Dark Matter distribution that covers a quarter of the sky and extends deep into the cosmos. This map confirms General Relativity and its predictions for how mass alters the curvature of spacetime.

March 15, 2023March 15, 2023 by Evan Gough

Prelude to a Supernova: The James Webb Captures a Rare Wolf-Rayet Star

The luminous, hot star Wolf-Rayet 124 (WR 124) is prominent at the centre of the NASA/ESA/CSA James Webb Space Telescope’s composite image combining near-infrared and mid-infrared wavelengths of light. Image Credit: NASA, ESA, CSA, STScI, Webb ERO Production Team

Massive stars are sprinters. It might seem counterintuitive that stars 100 or 200 times more massive than our Sun could only survive for as few as 10 million years. Especially since smaller stars like our Sun can last 10 billion years. Massive stars have huge reservoirs of hydrogen to burn through, but their massive size means fusion eats through their hydrogen much more quickly.

These massive stars are destined to reach the finish line quickly and explode as supernovae. There’s no other conclusion for them. But before they explode, some of them become Wolf-Rayet stars. That stage doesn’t last long, and the James Webb Space Telescope caught one in the act.