All articles tagged with #dark energy
NASA's Nancy Grace Roman Space Telescope, named for the agency's early astronomy leadership, is nearly ready for launch from Kennedy Space Center and will orbit about a million miles from Earth on a wide-field survey to search for exoplanets, exploding stars, and dark-energy clues, with a five-year primary mission and potential to operate for at least a decade.
NASA’s Nancy Grace Roman Space Telescope is on track for an Aug. 30 liftoff from Kennedy Space Center aboard SpaceX’s Falcon Heavy. The observatory will spend about 30 days en route to the sun–Earth L2 point (roughly 1.5 million km from Earth), followed by a multi‑month checkout before it begins surveys for exoplanets and dark energy and investigates distant stars.
NASA's Nancy Grace Roman Space Telescope, launching from Kennedy Space Center, will map hundreds of millions of stars and galaxies with a wide infrared view, search for up to 200,000 exoplanets via transits and microlensing, and probe dark matter and dark energy through weak gravitational lensing—potentially addressing key cosmological tensions and expanding our understanding of the universe.
Physicist Savvas Koushiappas suggests the Universe’s accelerating expansion could arise from a quantum modification to cosmic geometry at the cosmological horizon, meaning dark energy might be replaced by a macroscopic imprint of quantum gravity. By tying the uncertainty in simultaneously knowing the Universe’s size and expansion rate to altered expansion equations, the model could explain acceleration and even allow a bouncing origin instead of a Big Bang, though it leaves several questions unresolved. Future data from DESI, Euclid, and the Vera Rubin Observatory could test these ideas and refine our understanding of cosmic expansion.
A new Physical Review D paper by Savvas Koushiappas suggests the Universe’s accelerating expansion may arise from a macroscopic quantum uncertainty in simultaneously knowing the Universe’s size and expansion rate, effectively tying cosmic acceleration to quantum gravity at the cosmological horizon rather than to dark energy. The model can modify the expansion history and even allow a Big Bang replacement by a bounce in some configurations. Observations from DESI, Euclid, and the Vera C. Rubin Observatory could test these ideas, but the proposal remains speculative with open questions about consistency and interpretation.
The article explains that the Big Bang was not a violent explosion but the starting expansion of the universe, which has been growing for about 13.8 billion years. Evidence from galaxies moving apart and the Cosmic Microwave Background supports this view. Importantly, there was no space or time before the Big Bang, so asking what happened “before” is tricky. The universe’s expansion continues today and is accelerating, a behavior tied to dark energy though its nature remains not well understood.
Southampton researchers re-analyze a 2025 Yonsei claim that the universe’s expansion isn’t accelerating and find the result was a false alarm. After correcting for galaxy-mass calibration and local stellar ages in Type Ia supernovae, the data remain consistent with an accelerating universe and dark energy remains needed. The Yonsei team still argues age effects matter in some analyses, but the broader cosmology community will gain more decisive data from upcoming surveys like the Vera Rubin Observatory to settle the issue.
Astronomers using the DESI Legacy Imaging Surveys have released the largest 2D map of the universe to date — a 5.6‑trillion‑pixel panorama spanning roughly three‑quarters of the sky and detailing nearly four billion celestial objects. Built from more than 263,000 telescope exposures over a decade and covering visible to near‑infrared wavelengths, the map provides the 2D foundation for DESI’s much larger 3D cosmic map and will aid dark‑energy studies, galaxy evolution research, and training AI systems for future observatories.
Over 13 years, 263,407 images from NSF NOIRLab’s Mayall and Blanco telescopes using the 570‑megapixel Dark Energy Camera yielded the DESI Legacy Imaging Surveys, the largest 2D map of the universe, covering about 75% of the sky and containing nearly four billion objects. The 5.6‑trillion‑pixel map will underpin the DESI project’s upcoming 3D cosmic mapping and dark energy studies, and is already referenced in more than 1,800 scientific papers with data publicly accessible via the Legacy Imaging Viewer.
New analysis of Type Ia supernovae data, with progenitor-age corrections from the Pantheon+ catalog, suggests the universe’s expansion may be mildly anisotropic and not accelerating uniformly in all directions. If younger supernova progenitors are fainter after standardization, distant observations could mimic acceleration, meaning the apparent cosmic acceleration could be a local, directional effect tied to our motion through the cosmos. This challenges the isotropy assumed in ΛCDM and raises doubts about dark energy's role, while also intersecting with the ongoing Hubble tension between local and early-universe expansion rates.
Astronomers have re-evaluated the Boötes Void, a vast region once hailed as the largest hole in the universe. Earlier redshift surveys suggested it should contain about 2,000 galaxies, but later measurements found far fewer galaxies (around 60) and a smaller radius, showing the void is large but not anomalously so. Modern studies view Boötes as a fairly ordinary, oversized void likely formed by the merging of smaller voids, a common feature in the cosmic web. Nevertheless, such voids remain valuable for testing cosmology, dark energy, and gravity at the largest scales.
NASA’s Nancy Grace Roman Space Telescope will launch on Aug 30, 2026 aboard a SpaceX Falcon Heavy to the Sun–Earth L2 point, using a 2.4-meter mirror with a sky-wide field of view about 100 times larger than Hubble’s to map dark energy across a billion galaxies and hunt for exoplanets via microlensing, with a coronagraph tech demonstrator to pave the way for direct imaging of distant worlds.
A sweeping, decade-spanning tour of 20 landmark cosmic discoveries—from early parallax and Neptune’s discovery to the emergence of dark energy and gravitational-wave astronomy—showing how each breakthrough reshaped our understanding of the universe and spurred new questions.
Quanta Magazine’s The Joy of Why interview with Adam Riess traces how Type Ia supernovae revealed the universe’s accelerating expansion, explains the local vs. early-universe measurements of the Hubble constant, and frames the current Hubble tension that challenges the Lambda-CDM model. Riess discusses how standard candles and redshift work together to map expansion, the role of dark energy (potentially a cosmological constant), and how upcoming observatories like the Nancy Grace Roman Space Telescope, Rubin Observatory, Euclid, and JWST aim to resolve whether the tension signals new physics or hidden systematics.
A study by Subir Sarkar and collaborators argues the universe may be anisotropic (showing a cosmic dipole) and that directional biases in Type Ia supernova measurements could mimic cosmic acceleration, undermining the FLRW framework and dark energy in the ΛCDM model. If confirmed, this could trigger a paradigm shift to a data-driven cosmology, though many cosmologists remain cautious and independent validation is needed.