All articles tagged with #gravity
A NASA-led study refines measurements of Earth's center of mass, finding its annual wobble is about half of previous estimates—only a few millimeters—driven by seasonal transfers of water, ice, and air, using LAGEOS lasers and GRACE-FO data to improve reference systems for GPS and navigation.
After a decade of blind testing and meticulous analysis, NIST researchers reported G = 6.67387 × 10^-11 m^3 kg^-1 s^-2, about 0.0235% lower than the 2007 BIPM result, a small but persistent discrepancy that leaves big G less precisely known than other fundamental constants; the experiment used a torsion balance with copper and sapphire masses, included air-pressure corrections, and the blinding correction was recovered from a sealed envelope.
New measurements show Deimos’s tiny gravity makes a circular orbit just above its surface about 14.2 km/h, while about 20.1 km/h would let you escape local gravity—speeds comparable to elite racewalking and a modest sprint. The result highlights how movement on this small, irregular moon blends running, hopping, and orbital dynamics, with three-body effects, surface gravity variations, and a tiny Hill sphere limiting practical options. Real missions would require navigation margins, anchors, tethers, or small propulsion, not a simple two-body burn, and direction and terrain matter due to Deimos’s rotation and irregular shape.
Two identical GRACE-FO satellites fly about 220 km apart and use a laser-ranging interferometer to detect tiny changes in their distance as they pass over Earth's mass distribution. Those micro-variations are converted into monthly gravity maps; after subtracting solid-ground signals, the residuals reveal changes in large-scale water stores—ice loss, groundwater, and soil moisture—allowing scientists to weigh continental water over time.
ETH Zurich and the Paul Scherrer Institute have produced a narrow, cold-like muonium beam inside superfluid helium, enabling a future atom-interferometry experiment to test how gravity acts on a second-generation particle. While the gravity of muonium has not yet been measured, the method could reach about 1% precision after roughly 100 days of measurements, extending tests of Einstein’s weak equivalence principle to new frontiers beyond ordinary matter.
A team led by Ron Folman built the Quantum Galileo Interferometer (QGI) to place a single atom in a superposition of two trajectories—one undergoing free fall and the other held stationary—and then recombine them to measure gravity’s effect on a quantum wave. The observed phase aligns with the equivalence principle within about 2.5%, demonstrating gravity can act on a quantum system in superposition and outlining future tests with heavier objects (like nanodiamonds) to probe whether gravity is truly quantum or induces wavefunction collapse.
Researchers analyzing collapse models (Diósi–Penrose and Continuous Spontaneous Localization) find that if such models reflect reality, time itself would have a tiny intrinsic uncertainty, implying a fundamental limit on clock precision far beyond current detection; the effect doesn’t affect everyday timekeeping but could provide a testbed for connecting quantum mechanics and gravity and guiding future experiments in quantum gravity.
Sandra Bullock opens up about the “really dark time” surrounding her 2010 split from Jesse James, explaining in an Interview magazine chat with Jennifer Aniston how grieving her marriage while filming Gravity gave her a sense of meaning. She described feeling isolated in a “locked box” with nine hours of thinking and juggling paparazzi interest as she raised her newborn son Louis, stressing the need for privacy and trustworthy people around her. Bullock later moved on with Bryan Randall, who died in 2023 after a private ALS battle. She also touched on fears about empty-nesting and keeping her family close amid public scrutiny.
An international team used the Quantum Galileo Interferometer to split ultracold rubidium atoms, letting one part fall while the other stayed stationary, then recombined them to detect a minute gravity-induced quantum phase. The measured phase agrees with Einstein's equivalence principle extended to quantum objects, providing a direct laboratory link between gravity and quantum mechanics—without claiming a full quantum theory of gravity—and pointing toward future tests with heavier objects.
Physicists used a Bose-Einstein condensate of about 20,000 rubidium atoms in a two-path atom interferometer to measure a gravity‑induced quantum phase. The observed phase grows with the cube of the fall time, matching theoretical predictions and showing Einstein’s equivalence principle holds at quantum scales. The experiment, dubbed the quantum Galileo interferometer, ran 633 cycles across several hours, supporting compatibility between quantum mechanics and general relativity while outlining future tests with rotating frames and heavier objects to probe gravity’s effect on quantum superpositions.
Astronomers using GRAVITY+ have identified S301, a faint star on an 8.7-year orbit around the Milky Way’s central black hole Sagittarius A*, passing within about 136–142 Schwarzschild radii at roughly 25,000 km/s (≈8% of light). The current data cannot yet measure the black hole’s spin, and the orbit has two mirror solutions due to the lack of radial velocity. Forecasts show that with improved astrometry and spectroscopy—potentially by 2035–2036 under optimistic conditions—a spin constraint could be detected with high significance, though a robust result will require more data and second post-Newtonian modelling.
New gravity data analyzed with tidal tomography from three NASA Mars missions (MGS, Mars Odyssey, MRO) show the southern hemisphere’s mantle is 200–400 C warmer than the north, possibly partly molten. This non-symmetric interior helps explain Mars’s pronounced north–south dichotomy and has implications for its volcanic and magnetic history, hydrology, and crustal evolution. The finding, published in Nature, points to future missions probing the planet’s interior.
A gravity-based study using archival data from Mars Global Surveyor, Mars Odyssey, and Mars Reconnaissance Orbiter with a tidal tomography method shows the southern mantle is 200–400°C warmer than the north, implying a hotter, potentially partially molten interior that helps explain Mars’ hemispheric surface dichotomy and seismic/magnetic clues. The exact cause—ancient giant impact vs crustal thickness differences—remains uncertain, and future gravity data could test the 3D interior model.
John Mayer paid tribute to Dolly Parton by performing a tender cover of I Will Always Love You during his SiriusXM concert at the Stephen Talkhouse in the Hamptons, opening the intro to Gravity; the two-hour set drew heavily from Continuum and Sob Rock and featured a encore of Tom Petty’s Free Fallin’, with the show slated to air on Life With John Mayer.
Researchers from the University of Waterloo and University of British Columbia propose a minimal modification to gravity—a 'cosmic glitch'—where gravity is about 1% weaker on cosmological scales (billions of light-years) than predicted by general relativity, captured by the parameter Ωg. Analyses of Planck 2018 data yield Ωg ≈ -0.0087 ± 0.0046 and a Hubble constant near 68.6 km/s/Mpc; in some data combinations this can lessen the Hubble tension, but the improvement isn't universal across all datasets. The model preserves GR on smaller scales and could be tested by future CMB and large-scale structure surveys (DESI, Euclid). If confirmed, it would hint at physics beyond general relativity at cosmic distances.