Space and astronomy news
For nearly three decades now, it’s been clear that the expansion of the Universe is speeding up. Some unknown quantity, dramatically dubbed ‘dark energy’, is pushing the Universe apart. But the rate at which the Universe’s expansion is increasing – called the Hubble Constant – hasn’t yet been nailed down to a single number.
Not for lack of trying.
Continue reading “Red Giants Offer a New Way to Measure Distance in the Universe”
Over a century ago, astronomers Edwin Hubble and Georges Lemaitre independently discovered that the Universe was expanding. Since then, scientists have attempted to measure the rate of expansion (known as the Hubble-Lemaitre Constant) to determine the origin, age, and ultimate fate of the Universe. This has proved very daunting, as ground-based telescopes yielded huge uncertainties, leading to age estimates of anywhere between 10 and 20 billion years! This disparity between these measurements, produced by different techniques, gave rise to what is known as the Hubble Tension.
It was hoped that the aptly named Hubble Space Telescope (launched in 1990) would resolve this tension by providing the deepest views of the Universe to date. After 34 years of continuous service, Hubble has managed to shrink the level of uncertainty but not eliminate it. This led some in the scientific community to suggest (as an Occam’s Razor solution) that Hubble‘s measurements were incorrect. But according to the latest data from the James Webb Space Telescope (JWST), Hubble’s successor, it appears that the venerable space telescope’s measurements were right all along.
Continue reading “Webb Continues to Confirm That Universe is Behaving Strangely”
Nature, in its infinite inventiveness, provides natural astronomical lenses that allow us to see objects beyond the normal reach of our telescopes. They’re called gravitational lenses, and a few years ago, the Hubble Space Telescope took advantage of one of them to spot a supernova explosion in a distant galaxy.
Now, the JWST has taken advantage of the same lens and found another supernova in the same galaxy.
Continue reading “Webb Sees a Supernova Go Off in a Gravitationally Lensed Galaxy – for the Second Time”
In the 1920s, Edwin Hubble and Georges Lemaitre made a startling discovery that forever changed our perception of the Universe. Upon observing galaxies beyond the Milky Way and measuring their spectra, they determined that the Universe was expanding. By the 1990s, with the help of the Hubble Space Telescope, scientists took the deepest images of the Universe to date and made another startling discovery: the rate of expansion is speeding up! This parameter, denoted by Lambda, is integral to the accepted model of cosmology, known as the Lambda Cold Dark Matter (LCDM) model.
Since then, attempts to measure distances have produced a discrepancy known as the “Hubble Tension.” While it was hoped that the James Webb Space Telescope (JWST) would resolve this “crisis in cosmology,” its observations have only deepened the mystery. This has led to several proposed resolutions, including the idea that there was an “Early Dark Energy” shortly after the Big Bang. In a recent paper, an international team of astrophysicists proposed a new solution based on an alternate theory of gravity that states that our galaxy is in the center of an “under-density.”
Continue reading “If Our Part of the Universe is Less Dense, Would That Explain the Hubble Tension?”
According to some in the astrophysical community, there has been something of a “Crisis in Cosmology” in recent years. Though astronomers are all aware that the Universe is in a state of expansion, there has been some inconsistency when measuring the rate of it (aka. the Hubble Constant). This issue arises from the Cosmic Distance Ladder, where astronomers use different methods to measure relative distances over longer scales. This includes making local distance estimates using parallax measurements, nearby variable stars, and supernovae (“standard candles”).
They also conduct redshift measurements of the Cosmic Microwave Background (CMB), the relic radiation left over from the Big Bang, to determine cosmological distances. The discrepancy between these two methods is known as the “Hubble Tension,” and astronomers are eager to resolve it. In a recent study, an international team of astrophysicists from the Niels Bohr Institute suggested a novel method for measuring cosmic expansion. They argue that by observing colliding neutron stars (kilonovae), astronomers can relieve the tension and obtain consistent measurements of the Hubble Constant.
Continue reading “Colliding Neutron Stars Could Help Measure the Expansion of the Universe”
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.
Continue reading “Astronomers Have a New Way to Measure the Expansion of the Universe”
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”
In 2011, the Nobel Prize in physics was awarded to Perlmutter, Schmidt, and Reiss for their discovery that the universe is not just expanding, it is accelerating. The work supported the idea of a universe filled with dark energy and dark matter, and it was based on observations of distant supernovae. Particularly, Type Ia supernovae, which have consistent light curves we can use as standard candles to measure cosmic distances. Now a new study of more than 1,500 supernovae confirms dark energy and dark matter, but also raises questions about our cosmological models.
Continue reading “Astronomers Chart the Influence of Dark Matter and Dark Energy on the Universe by Measuring Over 1,500 Supernovae”
The Hubble space telescope has provided some of the most spectacular astronomical pictures ever taken. Some of them have even been used to confirm the value of another Hubble – the constant that determines the speed of expansion of the Universe. Now, in what Nobel laureate Adam Reiss calls Hubble’s “magnum opus,” scientists have released a series of spectacular spiral galaxies that have helped pinpoint that expansion constant – and it’s not what they expected.
Continue reading “Supernovae Were Discovered in all These Galaxies”