Almost a hundred years ago, physicists theorized out what free fall should do to a quantum wave. If the solution they came up with is wrong, quantum mechanics and Einstein's theory of gravity flatly contradict each other. But testing it has been impossible because nobody has managed to build an interferometer that could perform the necessary measurement.
Now, a team led by Ron Folman, a physicist at Ben-Gurion University of the Negev, with collaborators in Germany, the UK, and the US, including Nobel laureate Roger Penrose, has done it. They built a new interferometer that gives a single atom two possible paths at once: one that involves a free fall, and another where it is held perfectly still. Both paths end at the same place at the same moment, allowing the team to measure what the fall does to a wave-like property of the atom.
Ever since Galileo, physicists have known how to describe a falling object—where it is, how fast it goes, or how quickly it accelerates. Quantum mechanics, though, insists that every object is also a wave. “Every particle, doesn't matter if it's a car or a spaceship or an atom, is a wave,” Folman says. “Everything that is a wave, like sea waves or sound waves, goes up and down. And if you're up or down, this is measured by something called a phase. A phase just tells you if you are at the top of the wave or at the bottom.”
© ALIOUI Mohammed Elamine
It turns out Jean-Luc Picard was an even better starship helmsman than the writers knew. A physicist has gone through the details of a warp-speed trick from the first season of Star Trek: The Next Generation and found a subtlety the show missed. But instead of a plot hole, the detail he found actually makes the maneuver more impressive… as well as a great opportunity to teach about a lesser-known feature of the theory of relativity.
Níckolas de Aguiar Alves, a physicist at the Federal University of ABC in Brazil, first watched Next Generation as a master’s student. When he got to the episode "The Battle" in the show’s first season, the plot reminded him of his relativity coursework.
In "The Battle," a Ferengi leader reminds Picard of a battle he fought years ago as captain of a ship called the Stargazer. Under fire from a mysterious attacker, Picard’s ship’s shields were down. He had to get closer without taking a hit, so he made a gamble. Picard ordered the Stargazer to charge the enemy ship at warp speed (meaning faster than light), then stop abruptly and fire. By going faster than light, Picard anticipated that the other ship would see two images of the Stargazer: where it reached warp speed and where it stopped. If they fired on the wrong image, they would miss the Stargazer, and Picard could win the battle.
© Paramount
It turns out Jean-Luc Picard was an even better starship helmsman than the writers knew. A physicist has gone through the details of a warp-speed trick from the first season of Star Trek: The Next Generation and found a subtlety the show missed. But instead of a plot hole, the detail he found actually makes the maneuver more impressive… as well as a great opportunity to teach about a lesser-known feature of the theory of relativity.
Níckolas de Aguiar Alves, a physicist at the Federal University of ABC in Brazil, first watched Next Generation as a master’s student. When he got to the episode "The Battle" in the show’s first season, the plot reminded him of his relativity coursework.
In "The Battle," a Ferengi leader reminds Picard of a battle he fought years ago as captain of a ship called the Stargazer. Under fire from a mysterious attacker, Picard’s ship’s shields were down. He had to get closer without taking a hit, so he made a gamble. Picard ordered the Stargazer to charge the enemy ship at warp speed (meaning faster than light), then stop abruptly and fire. By going faster than light, Picard anticipated that the other ship would see two images of the Stargazer: where it reached warp speed and where it stopped. If they fired on the wrong image, they would miss the Stargazer, and Picard could win the battle.
© Paramount
Scientists may have found a more realistic set of thermodynamic rules for black holes that never stop changing. Black holes are among the most extreme objects known in the universe. They compress enormous amounts of mass into remarkably small regions, creating gravitational fields so powerful that nothing, not even light, can escape once it crosses [...]Albert Einstein’s general theory of relativity predicts that a rotating mass like the Earth pulls the fabric of space and time around with it in a perpetual swirl. This phenomenon is known as frame dragging or the Lense-Thirring effect, after the two physicists who modeled it back in 1918. Frame dragging becomes more significant with larger masses and faster rotation, so we’ve mainly observed it around huge black holes.
Measuring how much the Earth twists spacetime as it rotates has been much more challenging because our pale blue dot of a planet is millions of times lighter than a typical black hole and rotates rather slowly.
But now, a team of astronomers led by Ignazio Ciufolini, a physicist at the Wuhan Institute of Physics and Mathematics in China, reports the most accurate measurement of the terrestrial Lense-Thirring effect to date. Their work brings our uncertainty down from a few percentage points to just 0.2 percent. And they did it with a satellite that looks like a cross between a golf ball and a disco globe.
© NASA
Relativity Space plans to launch a Mars orbiter in 2028 as part of a new initiative to privately develop planetary missions.
The post Relativity Space to privately develop Mars orbiter mission appeared first on SpaceNews.
Neutron stars are composed of some of the most extreme material in the universe, and their internal properties are challenging to determine. Recently, researchers investigated an unusual spectral feature that may help to probe the interiors of neutron stars.
This composite X-ray and optical image shows the supernova remnant 1E 0102.2-7219. The blue source at the center of the bright red ring inside the remnant is a neutron star that was created in the supernova explosion. [X-ray (NASA/CXC/ESO/F.Vogt et al); Optical (ESO/VLT/MUSE & NASA/STScI)]
By observing neutron stars, astronomers attempt to pin down their equation of state, or the relationship between their interior density and pressure. In a recent research article led by Rosario Iaria (University of Palermo) described a promising way to probe the interior of a neutron star.
This method relies on measurements of a spectral line that originates near the neutron star’s surface and is gravitationally redshifted as it escapes from the intense gravitational pull of the star. The gravitational redshift provides a direct measurement of the compactness of the neutron star, or the ratio of its radius to its mass. Despite the promise of this method, definitive identification of gravitationally redshifted absorption lines has been challenging.
Iaria’s team identified potential evidence of this phenomenon in Neutron star Interior Composition Explorer (NICER) observations of 4U 1820-30, a close binary system containing a neutron star that is accreting matter from a white dwarf companion. (4U 1820-30 is famous for having one of the most rapidly rotating neutron stars known, with a blistering rate of 716 rotations per second.)
Observations of 4U 1820-30 from the Monitor of All-Sky X-ray Image (MAXI) showing the sudden increase in counts during the superburst, which was followed by two observing epochs by NICER, marked with red and blue vertical lines. Click to enlarge. [Iaria et al. 2026]
The team proposed that the rare superburst paved the way for the gravitationally redshifted absorption line to appear. During the superburst, a powerful radiation-driven wind swept away most or all of the neutron star’s corona, a diffuse cloud of plasma floating above and below the accretion disk. After the superburst ended and the wind subsided, but before the obscuring corona reformed, the tell-tale absorption line was visible for a short time.
By interpreting the 3.8 keV absorption feature as a gravitationally redshifted spectral line arising near the neutron star’s surface, Iaria and collaborators measured a redshift of 1 + z ≅ 1.72. This corresponds to a compactness of 4.46 kilometers per solar mass, which translates to a radius of 6.4 km for a typical mass of 1.4 solar masses or a mass of 2.2 solar masses for a typical radius of 10 km.
The interpretation of the 3.8 keV absorption line as a gravitationally redshifted iron line is still tentative. Further measurements with NICER, or with future facilities like the Advanced Telescope for High-ENergy Astrophysics (Athena) X-ray observatory (planned launch in 2037) or the enhanced X-ray Timing and Polarimetry (eXTP) mission (planned launch in 2030), may help to advance the study of neutron star interiors using this technique.
“A Mysterious Feature in the NICER Spectrum of 4U 1820-30: A Gravitationally Redshifted Absorption Line?” R. Iaria et al 2026 ApJ 998 58. doi:10.3847/1538-4357/ae2758
The post A Mysterious Spectral Feature Could Help Crack the Case of Neutron Star Structure appeared first on AAS Nova.
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