Back in 1971, the late physicist Stephen Hawking made an intriguing prediction: The total surface area of a black hole cannot decrease, only increase or remain stable. So if two black holes combine, the newly formed black hole will have a larger surface area. This became known as Hawking's area theorem. Analysis of the gravitational signal from a black hole merger detected in January provides the best observational evidence to date in support of Hawking's theorem, according to a new paper published in the journal Physical Review Letters.
The breakthrough just happens to coincide with the 10-year anniversary of the LIGO collaboration's Nobel Prize-winning first detection of a black hole merger. A second paper has been submitted (but not yet accepted), placing theoretical limits on a predicted third tone at a higher pitch that could be lurking in the event's gravitational wave signal.
Now known as LIGO/Virgo/KAGRA (LVK), the collaboration searches the Universe for gravitational waves produced by the mergers of black holes and neutron stars. LIGO detects gravitational waves via laser interferometry, using high-powered lasers to measure tiny changes in the distance between two objects positioned kilometers apart. LIGO has detectors in Hanford, Washington, and in Livingston, Louisiana. A third detector in Italy, Advanced Virgo, came online in 2016. In Japan, KAGRA is the first gravitational-wave detector in Asia and the first to be built underground. Construction began on LIGO-India in 2021, and physicists expect it will turn on sometime after 2025.
Each instrument is so sensitive that it also picks up small ambient vibrations, like a rumbling freight train or natural thermal vibrations in the detectors themselves. So the LIGO collaboration goes to great lengths to shield its instruments and minimize noise in its data. On September 14, 2015, at 5:51 am EST, both detectors picked up signals within milliseconds of each other for the very first time. The waveforms of those signals serve as an audio fingerprint—in this case, evidence for two black holes spiraling inward toward each other and merging in a massive collision event, sending powerful shock waves across spacetime. Picking up the signals was a stunning achievement, and nobody was surprised when the first direct observation of gravitational waves won the 2017 Nobel Prize in Physics.
Early detected mergers involved either two black holes or two neutron stars. In 2021, LIGO/Virgo/KAGRA confirmed the detection of two separate "mixed" mergers between black holes and neutron stars. Once the source was pinpointed, a network of telescopes around the globe was able to capture the accompanying “kilonova”—a massive burst of energy that behaves a bit like a high-powered strobe light, giving astronomers an unprecedented recording of a major celestial event that combined light and sound. It officially ushered in a new age of so-called multi-messenger astronomy (MMA).
A numerical relativity simulation of the recently observed GW250114 event, a binary black hole merger detected by LIGO on January 14, 2025.
The collaboration also detected asymmetrical mergers, where one black hole is much more massive than its partner, as well as discoveries that challenged the so-called "mass gap" between black holes and neutron stars. And this summer, the LIGO/Virgo/KAGRA collaboration detected the gravitational wave signal (dubbed GW231123) of the most massive merger between two black holes yet observed, resulting in a new black hole that is 225 times more massive than our Sun.
Looking for telltale overtones
LIGO is now nearly four times more sensitive than when it recorded that first Nobel-worthy black hole merger. And that sensitivity enabled the collaboration to record the sharpest gravitational wave signal thus far, dubbed GW250114. The event was remarkably similar to its 2015 "twin," involving two black holes of about 30 solar masses whose merger produced an equally "loud" signal and resulted in a new black hole of about 63 solar masses. But the difference in the two signals' fidelity enabled researchers to better isolate certain frequencies or tones in the "ringdown," using that information to calculate the new black hole's properties and compare it to theoretical predictions.
The breakthrough has been several years in the making. In 2019, we reported that physicists had "heard" the ring of an infant back hole for the first time by splicing the 2015 signal into the telltale "overtones" in the data. Not only were the overtones present, but the pattern of pitch and decay matched predictions for the black hole's mass and spin derived using the general theory of relativity. The result also supported the so-called "no hair" theorem for the classical description of black holes, which holds that all you need to describe black holes mathematically is their mass and their spin, plus their electric charge. It was the first experimental measurement that succeeded in directly testing the no-hair theorem.
But the final reverberations as the newly formed black hole settled into its new state, aka the ringdown, from that first event were significantly fainter, and scientists were unable to distinguish between the ringing from the initial collision and the ringdown. For GW250114, LIGO's improved sensitivity meant that scientists could measure the frequency and duration of the merged black hole's ringdown much more precisely. The resulting analysis bolsters the 2019 results confirming the "no hair" theorem.
Audio comparison of the 2015 and 2025 gravitational wave signals. Credit: LIGO/Virgo/KAGRA
With the latest event, physicists obtained an "exquisitely detailed view of the signal both before and after the black hole merger," said co-author Maximiliano Isi of Columbia University, who led a 2021 study using the same method on the 2015 data to observationally confirm Hawking's area theorem. As with the no-hair theorem, the clearer signal from GW250114 further bolsters that earlier result. The GW250114 data revealed that the two initial black holes had a total surface area of about 240,000 square kilometers, about the size of the United Kingdom. After the merger, the new black hole was about 400,000 square kilometers, about the size of Sweden.
“Even though it's a very simple statement—'areas can only increase'—it has immense implications," said Isi. Notably, Hawking and Jacob Bekenstein later showed that a black hole's area is proportional to its entropy, which also must increase per the second law of thermodynamics. This is a key element in ongoing attempts to develop a quantum theory of gravity. "It’s really profound that the size of a black hole’s event horizon behaves like entropy," said Isi. "It means that some aspects of black holes can be used to mathematically probe the true nature of space and time.”
Caltech physicist Kip Thorne, a longtime friend of Hawking, recalled that when LIGO detected its first gravitational wave signature, Hawking called and asked him if the collaboration would be able to test his theorem. Hawking died in 2018. "If [he] were alive, he would have reveled in seeing the area of the merged black holes increase," said Thorne.
Welcome to Edition 8.10 of the Rocket Report! Dear readers, if everything goes according to plan, four astronauts are less than six months away from traveling around the far side of the Moon and breaking free of low-Earth orbit for the first time in more than 53 years. Yes, there are good reasons to question NASA's long-term plans for the Artemis lunar program—the woeful cost of the Space Launch System rocket, the complexity of new commercial landers, and a bleak budget outlook. But many of us who were born after the Apollo Moon landings have been waiting for this moment our whole lives. It is almost upon us.
As always, we welcome reader submissions. If you don't want to miss an issue, please subscribe using the box below (the form will not appear on AMP-enabled versions of the site). Each report will include information on small-, medium-, and heavy-lift rockets, as well as a quick look ahead at the next three launches on the calendar.
North Korea fires solid rocket motor. North Korea said Tuesday it had conducted the final ground test of a solid-fuel rocket engine for a long-range ballistic missile in its latest advancement toward having an arsenal that could viably threaten the continental United States, the Associated Press reports. The test Monday observed by leader Kim Jong Un was the ninth of the solid rocket motor built with carbon fiber and capable of producing 1,971 kilonewtons (443,000 pounds) of thrust, more powerful than past models, according to the North’s official Korean Central News Agency.
Mobility and flexibility ... Solid-fueled intercontinental ballistic missiles, or ICBMs, have advantages over liquid-fueled missiles, which have historically comprised the bulk of North Korea's inventory. Solid rocket motors can be stored for longer periods of time and are easier to conceal, transport, and launch on demand. The new solid rocket motor will be used on a missile called the Hwasong-20, according to North Korean state media. The AP reports some analysts say North Korea may conduct another ICBM test around the end of the year, showcasing its military strength ahead of a major ruling party congress expected in early 2026.
Astrobotic eyes Andøya. US-based lunar logistics company Astrobotic and Norwegian spaceport operator Andøya Space have signed a term sheet outlining the framework for a Launch Site Agreement, European Spaceflight reports. The agreement, once finalized, will facilitate flights of Astrobotic's Xodiac lander testbed from the Andøya Space facilities. The Xodiac vertical takeoff, vertical landing rocket was initially developed by Masten Space Systems to simulate landing on the Moon and Mars. When Masten filed for bankruptcy in 2022, Astrobotic acquired its intellectual property and assets, including the Xodiac vehicle.
Across the pond ... So far, the small Xodiac rocket has flown on low-altitude atmospheric hops from Mojave, California, reaching altitudes of up to 500 meters, or 1,640 feet. The agreement between Astrobotic and Andøya paves the way for "several" Xodiac flight campaigns from Andøya Space facilities on the Norwegian coast. "Xodiac's presence at Andøya represents a meaningful step toward delivering reliable, rapid, and cost-effective testing and demonstration capabilities to the European space market," said Astrobotic CEO John Thornton.
Ursa Major breaks ground in Colorado. Ursa Major on Wednesday said it has broken ground on a new 400-acre site where it will test and qualify large-scale solid rocket motors for current and future missiles, including the Navy’s Standard Missile fleet, Defense Daily reports. The new site in Weld County, Colorado, north of Denver, will be ready for testing to begin in the fourth quarter of 2025. Ursa Major will be able to conduct full-scale static firings, and drop and temperature storage testing for current and future missile systems.
Seeking SRM options ... Ursa Major said the new facility will support national and missile defense programs. The company's portfolio includes solid rocket motors (SRMs) ranging from 2 inches to 22 inches in diameter for missiles like the Stinger, Javelin, and air-defense interceptors. Ursa Major aims to join industry incumbents Northrop Grumman, L3Harris, and newcomer Anduril as a major supplier of SRMs to the government. "This facility represents a major step forward in our ability to deliver qualified SRMs that are scalable, flexible, and ready to meet the evolving threat environment," said Dan Jablonsky, CEO of Ursa Major, in a statement. "It’s a clear demonstration of our commitment and ability to rapidly advance and expand the American-made solid rocket motor industrial base that the country needs, ensuring warfighters will have the quality and quantity of SRMs needed to meet mission demands."
Falcon 9 launches first satellites in a military megaconstellation. The first 21 satellites in a constellation that could become a cornerstone for the Pentagon's Golden Dome missile-defense shield were successfully launched from California on Wednesday aboard a SpaceX Falcon 9 rocket, Ars reports. The Falcon 9 took off from Vandenberg Space Force Base, California, and headed south over the Pacific Ocean, reaching an orbit over the poles before releasing the 21 military-owned satellites to begin several weeks of activations and checkouts.
First of many ... These 21 satellites will boost themselves to a final orbit at an altitude of roughly 600 miles (1,000 kilometers). The Pentagon plans to launch 133 more satellites over the next nine months to complete the build-out of the Space Development Agency's first-generation, or Tranche 1, constellation of missile-tracking and data-relay satellites. Military officials have worked for six years to reach this moment. The Space Development Agency (SDA) was established during the first Trump administration, which made plans for an initial set of demonstration satellites that launched a couple of years ago. In 2022, the Pentagon awarded contracts for the first 154 operational spacecraft, including the ones launched Wednesday. "Back in 2019, when the SDA was stood up, it was to do two things. One was to make sure that we can do beyond line of sight targeting, and the other was to pace the threat, the emerging threat, in the missile-warning and missile-tracking domain. That's what the focus has been," said Gurpartap "GP" Sandhoo, the SDA's acting director.
Another Falcon 9 was delayed three times. SpaceX scrubbed launching a communications satellite from an Indonesian company for a third consecutive day on Wednesday, Spaceflight Now reports. Possible technical issues got in the way of a launch attempt after back-to-back days of weather delays at Cape Canaveral Space Force Station, Florida. The Falcon 9 finally launched Thursday evening with the Boeing-built Nusantara Lima communications satellite, targeting a geosynchronous transfer orbit. It’s the latest satellite from the Indonesian company Pasifik Satelit Nusantara.
A declining market ... This was just the fifth geosynchronous communications satellite to launch on a commercial rocket this year, all by SpaceX. There were 21 such satellites that launched on commercial vehicles in 2015, including SpaceX's Falcon 9, Europe's Ariane 5, Russia's Proton, ULA's Atlas V, and Japan's H-IIA. Much of the world's launch capacity today is used to deploy smaller communications satellites into low-Earth orbit, primarily for broadband connectivity rather than for the video broadcast market once dominated by higher-altitude geosynchronous satellites.
Putin urges Russia to build more rocket engines. Russian President Vladimir Putin urged aerospace industry leaders on September 5 to press on with efforts to develop booster rocket engines for space launch vehicles and build on Russia's longstanding reputation as a leader in space technology, Reuters reports. Putin, who spent the preceding days in China and the Russian far eastern port of Vladivostok, flew to the southern Russian city of Samara, where he met industry specialists and toured the Kuznetsov design bureau engine manufacturing plant.
A shell of its former self ... "It is important to consistently renew production capacity in terms of engines for booster rockets," Russian news agencies quoted Putin as saying during the visit. "And in doing so, we must not only meet our own current and future needs but also move actively on world markets and be successful competitors." The Kuznetsov plant in Samara builds medium-class RD-107 and RD-108 engines for Russia's Soyuz-2 rockets, which launch Russian military satellites and crew and cargo to the International Space Station. Their designs can be traced to the dawn of the Space Age nearly 70 years ago. Meanwhile, the outlook for heavier-duty Russian rocket engines is murky, at best. Russia's most-flown large rocket engine in the post-Cold War era, the RD-180, produced by a company called Energomash, is out of production after the end of sales to the United States.
India nabs a noteworthy launch contract. Astroscale, a satellite servicing and space debris mitigation company based in Japan, has selected India's Polar Satellite Launch Vehicle (PSLV) to deliver a small satellite named ISSA-J1 to orbit in 2027. This is an interesting mission. The ISSA-J1 spacecraft will fly up to two large pieces of satellite debris in orbit to image and inspect them. ISSA-J1, developed in partnership with the Japanese government, is one in a series of Astroscale missions testing different ways of approaching, monitoring, capturing, and refueling other objects in space. The launch agreement was signed between Astroscale and NewSpace India Limited, the commercial arm of India's space agency.
Rideshare not an option ... "We selected NSIL after thorough evaluations of more than 10 launch service providers over the past year, considering technical capabilities, track record, cost, and other elements," said Eddie Kato, president and managing director of Astroscale Japan. India's PSLV is right-sized for a mission like this. ISSA-J1 is a rarity in that it must launch on a dedicated rocket because it has to reach a specific orbit to line up with the pieces of space debris it will approach and inspect. Rideshare launches, such as those that routinely fly on SpaceX's Falcon 9 rocket, are cheaper but go to standard orbits popular for many different types of satellite missions. A dedicated launch on a Falcon 9 would presumably have been more expensive than a flight on India's smaller PSLV. Rocket Lab's Electron, another rocket popular for dedicated launches of small satellites, lacks the performance required for Astroscale's mission.
Russian cargo en route to ISS. Another cargo ship is flying to humanity's orbital outpost with the successful launch of Russia's Progress MS-32 supply freighter on Thursday from the Baikonur Cosmodrome in Kazakhstan, NASASpaceflight.com reports. The supply ship launched aboard a Soyuz-2.1a rocket and arrived in orbit about nine minutes later, kicking off a two-day pursuit of the International Space Station. This was the 300th launch of an assembly, crew, or cargo mission to the ISS since 1998, including a handful of missions that didn't reach the complex due to rocket or spacecraft failures.
Important stuff ... The Progress MS-32 cargo craft will dock with the aft port of the space station's Russian Zvezda service module on Saturday. The payloads flying on the Progress mission include food, experiments, clothing, water, air, and propellant to be pumped into the space station's onboard tanks. The spacecraft will also reboost the lab's orbit.
Metallic tiles? Not so great. It has been two weeks since SpaceX's last Starship test flight, and engineers have diagnosed issues with its heat shield, identified improvements, and developed a preliminary plan for the next time the ship heads into space, Ars reports. Bill Gerstenmaier, a SpaceX executive in charge of build and flight reliability, presented the findings Monday at the American Astronautical Society's Glenn Space Technology Symposium in Cleveland. The test flight went "extremely well," Gerstenmaier said, but he noted some important lessons learned with the ship's heat shield.
Crunch wrap reigns supreme ... "We were essentially doing a test to see if we could get by with non-ceramic tiles, so we put three metal tiles on the side of the ship to see if they would provide adequate heat control, because they would be simpler to manufacture and more durable than the ceramic tiles. It turns out they're not," Gerstenmaier said. "The metal tiles... didn't work so well." One bright spot with the heat shield was the performance of a new experimental material around and under the tiles. "We call it crunch wrap," Gerstenmaier said. "It's like a wrapping paper that goes around each tile." On the next Starship flight, SpaceX will likely cover more parts of the heat shield with this crunch wrap material. Gerstenmaier said the inaugural flight of Starship Version 3, with upgraded engines and more fuel, is now set to occur next year.
An SLS compromise might be afoot in DC. The Trump administration is seeking to cancel NASA's Space Launch System rocket after two more flights, but key lawmakers in Congress, including Republican Sen. Ted Cruz of Texas, aren't ready to go along. So is this an impasse? Possibly not, as sources say the White House and Congress may not be all that far apart on how to handle this. The solution involves canceling part of the SLS rocket now, but not all of it, Ars reports.
Goodbye EUS? ... The compromise might be to cancel a large new upper stage for the SLS rocket called the Exploration Upper Stage. This would save NASA billions of dollars, and the agency could instead procure commercial upper stages, such as those built by United Launch Alliance or Blue Origin, to fly on SLS rockets after NASA's Artemis III mission. It would also eliminate the need for NASA to finish building an expensive new launch tower at Kennedy Space Center, Florida. The upper stage flying on the first three SLS missions is no longer in production. Sources indicated to Ars that Blue Origin has already begun work on a modified version of its New Glenn upper stage that could fit within the shroud of the SLS rocket.
Next three launches
Sept. 13: Soyuz-2.1b | Glonass-K1 No. 18L | Plesetsk Cosmodrome, Russia | 02:30 UTC
Sept. 13: Falcon 9 | Starlink 17-10 | Vandenberg Space Force Base, California | 15:41 UTC
Sept. 14: Falcon 9 | Cygnus NG-23 | Cape Canaveral Space Force Station, Florida | 22:11 UTC
In the last two years, Jerry Seinfeld has broken from his typically apolitical public persona to become a vocal supporter of Israel in the wake of the October 7 terrorist attacks. Appearing at Duke University on Tuesday to introduce Omer Shem Tov, a former Israeli hostage who was abducted by Hamas, Seinfeld made further anti-Palestine remarks. “‘Free Palestine’ is, to me, just—you’re free to say you don’t like Jews. Just say you don’t like Jews,” the comedian said, per the university’s student newspaper The Chronicle.
“By saying ‘free Palestine’, you’re not admitting what you really think,” he continued. “So it’s actually—compared to the Ku Klux Klan, I’m actually thinking the Klan is actually a little better here because they can come right out and say, ‘We don’t like Blacks, we don’t like Jews.’ Okay that’s honest.”
Comparing all utterances of “free Palestine” (often, if not most frequently, stated in non-violent, anti-genocidal protest) to one of the United States’ most notorious hate groups is of course extreme. Even taken as a comparison on rhetoric alone, “Free Palestine” and the pro-Palestine movement as a whole are not inherently antisemitic, as many around the world have argued, including prominent anti-Zionist Jewish figures. Unfortunately, Seinfeld has made his disinterest in such nuances clear. “I don’t care about Palestine,” he said plainly after being ambushed by an activist earlier this year.
Seinfeld had previously told GQ his decision to travel to Israel after October 7 stemmed from simply being Jewish, and growing up keenly aware of antisemitism. “Every Jewish person I know was surprised by how hostile the reaction was,” he said. However, he claimed, “I don’t preach about it. I have my personal feelings about it that I discuss privately. It’s not part of what I can do comedically, but my feelings are very strong.” While it may not be part of his comedic act, the remarks made at Duke lean as close to preaching as he’s yet come.
In a statement given to The Chronicle, a spokesperson for Duke said, “Tuesday’s talk was a Chabad at Duke student-led event that invited Omer Shem Tov to share the story of his spiritual journey during 505 days in captivity. Jerry Seinfeld introduced the speaker and requested his appearance not be announced beforehand, given Omer Shem Tov’s experiences were the focus of the event. Duke does not preview the remarks of speakers who are invited to campus, and the invitation of speakers to campus does not imply any endorsement of their remarks.”
In this issue of our environmental newsletter, we look at the more affordable EV models available in Canada — and why there are fewer here compared to other countries; see how plug-in solar panels for balconies work; and find out how beavers can fight wildfires.
"If we allowed the Chinese vehicles into the Canadian marketplace, that would sort of be the end of our automotive industry as we transition to EVs, because the Chinese are about 15 to 20 years ahead of us." And we get to enjoy things that are 15-20 years behind.
Federal Trade Commission Chair Andrew Ferguson has called his agency's rule banning noncompetes unconstitutional. Still, he says protecting workers against noncompetes remains a priority.
> Ryan LLC argued that the noncompete ban would inflict irreparable harm by enabling its employees to leave for the competition, potentially taking with them valuable skills and information gained on the job
lol like the skills and knlowedge they gained at their _previous_ job they brought to you, dipshit? It’s called growth.
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