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Relativity

All articles tagged with #relativity

Disco-ball satellite nails Einstein’s relativity test to 0.2%
science22 hours ago

Disco-ball satellite nails Einstein’s relativity test to 0.2%

A dense, thruster-free satellite named LARES-2, paired with the older LAGEOS, was laser-tracked from Earth to isolate the frame-dragging effect predicted by general relativity. By canceling Earth’s oblateness and tidal perturbations over a 1,050-day cycle, the team measured the Lense-Thirring precession to about 0.2% accuracy, confirming Einstein and narrowing alternatives like Chern-Simons theory, while also delivering a more precise Earth-tide benchmark.

via Ars Technica|
#frame-dragging#gravity#lares-2
Orbit Time: Astronauts Age Slightly Less Than Earthbound Counterparts
science2 days ago

Orbit Time: Astronauts Age Slightly Less Than Earthbound Counterparts

Astronauts in low-Earth orbit experience a tiny amount of time travel into the future due to special and general relativity: their clocks run slower because they move fast, while being higher up slightly speeds up time; the net effect is about 20–25 microseconds per day, amounting to a few milliseconds over six months and about nine milliseconds after a year; the phenomenon is real and measurable (as shown by Hafele–Keating experiments and GPS timing), but it is far too small to impact health—spaceflight’s health effects dominate.

via Space Daily|
#astronauts#clocks#relativity
Krikalev’s 0.02-Second Time Dilation: A Humble Relativity Lesson from Spaceflight
science17 days ago

Krikalev’s 0.02-Second Time Dilation: A Humble Relativity Lesson from Spaceflight

Sergei Krikalev’s combined 803 days in six ISS missions yield roughly 0.02 seconds of relativistic time dilation compared with Earth time, via the dominant special-relativity effect of orbital velocity (with a smaller counteracting general-relativity pull from gravity). The net result is a tiny aging difference, not true time travel, but it serves as a standard teaching example of how motion affects time. The figure remains a well-cited physics fact, though later cosmonauts have accumulated more time in space and each have their own, slightly larger cumulative dilations.

via Space Daily|
#international-space-station#lorentz-factor#relativity
The 1919 Eclipse That Made Einstein a Global Icon
science1 month ago

The 1919 Eclipse That Made Einstein a Global Icon

In 1919, two British expeditions—led by Dyson and including Arthur Eddington—photographed a total solar eclipse from Príncipe and Sobral to test whether the Sun’s gravity bends starlight as predicted by general relativity. The data, though limited and debated, supported Einstein and propelled him to global fame; later, more precise measurements confirmed the effect with greater accuracy.

via Space Daily|
#astronomy#einstein#expeditions
Relativity at GPS scale: why satellites are clocked slow on the ground
science1 month ago

Relativity at GPS scale: why satellites are clocked slow on the ground

GPS satellites carry atomic clocks that are deliberately set to run slow on the ground so that relativistic effects in orbit bring them to the correct rate; special relativity would slow moving clocks by about 7 microseconds per day, while general relativity would speed them up by about 45 microseconds per day, for a net gain of roughly 38 microseconds per day that would cause ~10 km of positional error daily if uncorrected. The main correction is a ground-based frequency offset (about 10.22999999543 MHz instead of 10.23 MHz) so the clock is right in orbit, with smaller orbital variations corrected by the receiver.

via Space Daily|
#atomic-clocks#gps#navigation
Five-Millisecond Time Gap: Relativity in Real Life on the ISS
space1 month ago

Five-Millisecond Time Gap: Relativity in Real Life on the ISS

The ISS travels at about 17,500 mph, causing time to pass slightly slower up there; after 340 days in orbit, Scott Kelly was about 5 milliseconds younger than his Earthbound twin Mark. The effect is real and purely relativistic, with gravity counteracting some aging, but the velocity effect dominates on the station. NASA studied the twin pair to track biological changes—telomeres lengthened, some gene expression stayed altered months after return, and various physiological shifts occurred—illustrating how long-duration spaceflight acts as a tiny, measurable form of time travel for humans.

via Space Daily|
#international-space-station#relativity#scott-kelly
Relativity in Real Life: The ISS Clocks Tick Slower, Astronauts Age Slightly
science1 month ago

Relativity in Real Life: The ISS Clocks Tick Slower, Astronauts Age Slightly

The ISS travels about 7.8 km/s, causing time dilation: its clocks run slightly slower than Earth clocks due to special relativity, while being higher in gravity would speed them up per general relativity. The net effect is a fraction-of-a-second aging difference for astronauts over six months, a result confirmed by atomic clocks and essential for GPS accuracy. The article also contrasts the relativistic effect with microgravity’s physiological impacts on astronauts, emphasizing that time is a local quantity tied to reference frames.

via Space Daily|
#astronauts#gps#relativity
Quantum Clocks Probe If Time Itself Can Be in Superposition
science2 months ago

Quantum Clocks Probe If Time Itself Can Be in Superposition

Physicists propose using ultra-precise atomic clocks and trapped ions to test whether time can behave as a quantum object, potentially existing in multiple states at once. By cooling ions, controlling quantum states, and exploring squeezed vacuum states, the work aims to reveal quantum signatures of time and explore how relativity and quantum mechanics describe the flow of time.

via SciTechDaily|
#atomic-clocks#quantum#relativity
Lab Triggers False Vacuum Analogy with Ring of Rydberg Atoms
science2 months ago

Lab Triggers False Vacuum Analogy with Ring of Rydberg Atoms

Physicists at Tsinghua University used a ring of highly excited Rydberg atoms to simulate false vacuum decay, engineering two competing vacuum states that act like false and true vacua. By breaking symmetry with lasers, the ring transitions toward the true vacuum, producing a quantum bubble that mirrors how a lower-energy state could nucleate and, in theory, sweep across the cosmos. The experiment provides a controllable platform to study the quantum–relativistic crossover and test predictions about how such a transition might unfold in principle, without posing any danger to reality.

via ScienceAlert|
#false-vacuum-decay#quantum-field-theory#quantum-simulation
Q-Desic: A Quantum Twist on Spacetime Opens Doors to Quantum Gravity Tests
science4 months ago

Q-Desic: A Quantum Twist on Spacetime Opens Doors to Quantum Gravity Tests

Vienna University of Technology researchers derive a q-desic equation by quantizing the spacetime metric in a simple gravitational field, predicting that quantum spacetime can subtly alter particle trajectories. The deviations are minuscule on small scales, but when the cosmological constant is included they become significant at cosmological distances, potentially offering an observable to test and distinguish quantum gravity theories using astronomical data.

via SciTechDaily|
#cosmology#geodesics#quantum-gravity
Scientists Photograph Light in Motion, Revealing Terrell Rotation at Near-Light Speeds
science4 months ago

Scientists Photograph Light in Motion, Revealing Terrell Rotation at Near-Light Speeds

Researchers from the University of Vienna used pulsed lasers and ultrafast cameras to photograph light moving at near-light speeds, recreating the Terrell–Penrose rotation and showing how objects would appear rotated rather than squashed; by capturing slices of light and stitching them, they slowed light to about 2 m/s to visualize the motion, with implications for relativity studies, particle physics, and astrophysics.

via The Daily Galaxy|
#high-speed-imaging#light-speed-photography#physics
LTE440: China's lunar clock aims to sync Moon time with relativity
space5 months ago

LTE440: China's lunar clock aims to sync Moon time with relativity

Chinese researchers unveiled LTE440, a lunar time ephemeris that uses Lunar Coordinate Time and relativistic corrections to convert Earth time to Moon time with long-term accuracy (about 1,000 years). Built on Kopeikin’s TCL framework, it aims to coordinate lunar time for navigation and communication during future Moon missions and could become an international benchmark alongside NASA and ESA efforts to standardize lunar clocks, helping prevent time-zone chaos in space.

via Live Science|
#lte440#lunar-clock#lunar-time