The Universe is expanding, and it’s doing so at an ever-increasing pace. Whether due to a dark energy field throughout the cosmos or due to a fundamental of spacetime itself, the cosmos is stretching the space between distant galaxies. But nearby galaxies, those part of our local group, are moving closer together. And how they are falling toward each other could tell us about the nature of cosmic expansion.Continue reading “We Might Be Able to Measure Dark Energy Through the Milky Way's Collision With Andromeda”
Dark energy may evolve in time, and it may even connect through a new force of nature with dark matter. And a researcher believes that we may have already seen evidence for this.Continue reading “Dynamical Dark Energy Might Explain Strange 21-cm Signal”
On Saturday, July 1st (Canada Day!), the ESA’s Euclid space telescope lifted off from Cape Canaveral in Florida. This next-generation astrophysics mission will spend the next few weeks flying to the Earth-Sun L2 Lagrange Point, where it will spend the next six years observing one-third of the sky. During that time, Euclid will observe billions of galaxies to a distance of 10 billion light-years, leading to the most extensive 3D map of the Universe ever created. This map will help astronomers and cosmologists resolve the lingering mystery of Dark Matter and Dark Energy (DM & DE).Continue reading “ESA's Euclid Mission is Off to Explore the Dark Universe”
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.Continue reading “Two New Space Telescopes Will Bring Dark Energy Into Focus”
Large astronomical projects like the Dark Energy Survey and the James Webb Space Telescope provide innumerable benefits to society, like technological spin-offs, national prestige, and a way to satisfy our common human curiosity.Continue reading “The Hidden Benefits of Large Science Projects”
The Force is with us, according to cosmologists working to understand a mysterious “something” that’s making the universe expand. Its name? Dark energy. And, it turns out that it’s been present everywhere throughout cosmic history.Continue reading “Dark Energy Was Always Present, Everywhere and at Every Time”
What contains a petabyte of data on more than a billion galaxies in one of the most extensive sky maps? The answer: the ever-expanding Dark Energy Spectroscopic Instrument (DESI) Legacy Imaging Survey. The galaxies it charts are part of the largest two-dimensional map of the sky ever made. And, just recently, it grew even larger with the addition of new data from telescopes in the U.S. and Chile.Continue reading “A New Survey of the Sky Contains Over One Billion Galaxies”
By the 1920s, astronomers learned that the Universe was expanding as Einstein’s Theory of General Relativity predicted. This led to a debate among astrophysicists between those who believed the Universe began with a Big Bang and those who believed the Universe existed in a Steady State. By the 1960s, the first measurements of the Cosmic Microwave Background (CMB) indicated that the former was the most likely scenario. And by the 1990s, the Hubble Deep Fields provided the deepest images of the Universe ever taken, revealing galaxies as they appeared just a few hundred million years after the Big Bang.
Over time, these discoveries led to an astounding realization: the rate at which the Universe is expanding (aka. the Hubble Constant) has not been constant over time! This led to the theory of Dark Energy, an invisible force that counteracts gravity and causes this expansion to accelerate. In a series of papers, an international team of researchers led by the University of Hawaii reported that black holes in ancient and dormant galaxies were growing more than expected. This constitutes (they claim) the first evidence that black holes could be the source of Dark Energy.Continue reading “Are Black Holes the Source of Dark Energy?”
According to the most widely-accepted cosmological theories, the Universe began roughly 13.8 billion years ago in a massive explosion known as the Big Bang. Ever since then, the Universe has been in a constant state of expansion, what astrophysicists know as the Hubble Constant. For decades, astronomers have attempted to measure the rate of expansion, which has traditionally been done in two ways. One consists of measuring expansion locally using variable stars and supernovae, while the other involves cosmological models and redshift measurements of the Cosmic Microwave Background (CMB).
Unfortunately, these two methods have produced different values over the past decade, giving rise to what is known as the Hubble Tension. To resolve this discrepancy, astronomers believe that some additional force (like “Early Dark Energy“) may have been present during the early Universe that we haven’t accounted for yet. According to a team of particle physicists, the Hubble Tension could be resolved by a “New Early Dark Energy” (NEDE) in the early Universe. This energy, they argue, would have experienced a phase transition as the Universe began to expand, then disappeared.Continue reading “Could a Dark Energy Phase Change Relieve the Hubble Tension?”
In 1916, Einstein finished his Theory of General Relativity, which describes how gravitational forces alter the curvature of spacetime. Among other things, this theory predicted that the Universe is expanding, which was confirmed by the observations of Edwin Hubble in 1929. Since then, astronomers have looked farther into space (and hence, back in time) to measure how fast the Universe is expanding – aka. the Hubble Constant. These measurements have become increasingly accurate thanks to the discovery of the Cosmic Microwave Background (CMB) and observatories like the Hubble Space Telescope.
Astronomers have traditionally done this in two ways: directly measuring it locally (using variable stars and supernovae) and indirectly based on redshift measurements of the CMB and cosmological models. Unfortunately, these two methods have produced different values over the past decade. As a result, astronomers have been looking for a possible solution to this problem, known as the “Hubble Tension.” According to a new paper by a team of astrophysicists, the existence of “Early Dark Energy” may be the solution cosmologists have been looking for.Continue reading ““Early Dark Energy” Could Explain the Crisis in Cosmology”