All articles tagged with #gravity
Scientists modeling Earth’s interior propose a long-lived, hot, low-density mantle upwelling originating beneath Africa drifts east beneath the Indian Ocean, reducing local mass and producing the observed geoid low. The idea, supported by 100-million-year simulations and the Indian plate’s motion, explains why satellite data show a persistent dip in the sea surface, though the interpretation is still debated.
An Iranian physicist proposes the Great Pyramid of Giza served as a gravitational transmitter and interstellar beacon to communicate Earth's position to extraterrestrials; he cites its coordinates and alignments as encoded data, but the idea is speculative, not peer-reviewed, and physicists say there was no ancient technology to broadcast such signals.
Using the kinematic Sunyaev-Zeldovich effect on about 686,000 galaxies in clusters 5–7 billion light-years away, researchers measured cluster speeds and found gravity weakens with distance consistent with Newtonian/Einsteinian gravity, strengthening the case for dark matter as the source of anomalous gravitational effects, though many questions remain. The study was published in Physical Review Letters.
After a decade-long effort at the National Institute of Standards and Technology to measure Newton’s gravitational constant Big G, Schlamminger and colleagues report a value of 6.67387e-11 m^3 kg^-1 s^-2 that is about 0.0235% lower than the replicated result and inconsistent with the CODATA standard, highlighting the long-standing scatter in Big G measurements. The team blind-tested the experiment to avoid bias and published their findings in Metrologia, underscoring that precision metrology often raises questions and may point to small systematic biases rather than new physics.
Physicists show that spontaneous quantum-collapse models, possibly tied to gravity, would make time itself intrinsically uncertain, setting a fundamental limit on clock precision. The predicted effect is far too small to affect current technology, but it offers a testable path toward unifying quantum mechanics with gravity.
Researchers exposed fruit flies to 4–13G hypergravity in a centrifuge. Initial hyperactivity at moderate Gs gave way to reduced activity at higher Gs, but both groups eventually returned to normal behavior, and a multi‑generational test showed some populations thriving for 10 generations, suggesting gravity directly shapes energy use and movement and highlighting the resilience of biological systems with implications for future space exploration.
The 1,100-foot asteroid Apophis will pass about 20,000 miles above Earth on April 13, 2029—closer than many satellites and described as a very rare encounter—offering scientists a unique chance to study its internal structure and how Earth's gravity will alter its orbit and rotation, with NASA confirming there is no danger to Earth.
A NASA-led study suggests a faint fifth fundamental force could exist but is hidden locally by environmental screening (e.g., chameleon or Vainshtein effects), becoming potentially influential on cosmic scales; detecting it would require next-generation missions and data from Euclid and DESI to probe tiny deviations from general relativity beyond solar-system tests.
Australian physicist Enbang Li has built a compact, three‑foot device that uses gravity to bend light via spiraled fiber-optic coils, detecting tiny picosecond time delays to sense gravitational changes. The approach could enable high‑precision gravity sensing for mapping underground features, monitoring magma, and improving sensing on moving platforms like planes and submarines. While still in early lab stages, the work suggests photons can interact with Earth’s gravitational field in new ways and may prompt fresh thinking about light’s behavior, with findings published in Scientific Reports.
Using data from the Atacama Cosmology Telescope and the kinematic Sunyaev–Zeldovich effect, researchers tracked hundreds of thousands of galaxy clusters across hundreds of millions of light-years and found gravity obeys the inverse-square law on cosmological scales, aligning with Newtonian and Einsteinian gravity, reinforcing dark matter as the source of extra gravitational effects and challenging alternative gravity theories like MOND.
A NASA physicist argues that a proposed fifth force—potentially screened in dense environments—could explain cosmic acceleration while staying hidden in the Solar System; current observations align with general relativity locally, so any breakthrough would require a dedicated, falsifiable mission built on precise predictions and guided by cosmological survey data to bridge local gravity tests with the large-scale universe.
A University of Wollongong physicist has built a compact fiber-optic laser system that leverages gravity’s bending of light to enable a mobile, high-precision sensing device. The ~1-meter instrument uses two long coils to compare tiny picosecond delays between light beams, a method dubbed gravity mapping that could support aerial underground surveys, submarine navigation, and geological monitoring. Described as an early proof-of-concept, the tech shows promise but researchers caution more work is needed to understand fluctuations and how gravity might influence light beyond Einstein’s postulate of a constant light speed.
A team studying quantum-collapse models (Diósi–Penrose and Continuous Spontaneous Localization) linked to gravity finds that time itself may have a minute intrinsic uncertainty, implying a fundamental limit on how precisely time can be measured. The effect is unimaginably small and would not affect current timekeeping, but it suggests deep connections between quantum mechanics and gravity and offers a way to experimentally distinguish collapse models from standard quantum theory.
A study of 11 astronauts (2 women, 9 men) over at least five months on the ISS found that the brain retains a gravity imprint that shapes how they grip and move objects in microgravity; on Earth, they tend to grip more firmly than needed and mispredict object mass, but movements quickly re-adapt after return. The research, published in The Journal of Neuroscience, highlights gradual neural reprogramming as the brain recalibrates to Earth's gravity, with some astronauts noting objects feel heavier even after re-entry.
A decade-long effort by NIST to measure the universal gravitational constant G, using a torsion-balance setup and multiple test masses, produced a value of 6.67387×10^-11 m^3/(kg·s^2) that is 0.0235% lower than the BIPM's result, sustaining a small but persistent discrepancy among precision measurements. An unusual blinding step— a colleague secretly altered some data to hide the true result until the envelope reveal—meant Schlamminger only learned the outcome at the end. Although the difference is too small to affect everyday life, it keeps G as an open question and underscores the need for further, careful measurements.