inscrutable interiors — Probing the mysteries of neutron stars with a surprising earthly analog Ultracold gases in the lab could help scientists better understand the universe.
Katie McCormick – Jul 9, 2023 11:34 am UTC Enlarge / Spectral analysis indicates that silica is present in this supernova remnant, Cassiopeia A.NASA/JPL-Caltech/ O. Krause (Steward Observatory) reader comments 28 with
Ever since neutron stars were discovered, researchers have been using their unusual properties to probe our universe. The superdense remnants of stellar explosions, neutron stars pack a mass greater than the Suns into a ball about as wide as San Francisco. A single cup of this star matter would weigh about as much as Mount Everest.
These odd celestial bodies could alert us to distant disturbances in the fabric of spacetime, teach us about the formation of elements, and unlock the secrets of how gravity and particle physics work in some of the most extreme conditions in the universe.
Theyre at the center of a lot of open questions in astronomy and astrophysics, says astrophysicist Vanessa Graber of the Institute of Space Sciences in Barcelona.
But to accurately interpret some of the neutron stars signals, researchers must first understand what goes on inside them. They have their hunches, but experimenting directly on a neutron star is out of the question. So scientists need another way to test their theories. The behavior of matter in such a superdense object is so complicated that even computer simulations arent up to the task. But researchers think they may have found a solution: an earthly analog.
Though young neutron stars can have temperatures in the millions of degrees in their interior, by one important energetic measure neutrons are considered cold. Physicists think that is a characteristic they can exploit to study the inner workings of neutron stars. Instead of looking to the sky, researchers are peering into clouds of ultracold atoms created in laboratories here on Earth. And that might help them finally answer some longstanding questions about these enigmatic objects. Advertisement Space oddities
The existence of neutron stars was first proposed in 1934, two years after the discovery of the neutron itself, when astronomers Walter Baade and Fritz Zwicky wondered if a celestial body made entirely of neutrons might remain after a supernova explosion. Though they didnt get all the details right, their general idea is now widely accepted.
Stars power themselves by fusing the nuclei of lighter atoms into those of heavier atoms. But when stars run out of those lighter atoms, nuclear fusion stops and there is no longer an outward pressure to fight against the inward force of gravity. The core collapses and the stars outer layer races inward. When this layer hits the dense core, it bounces off and explodes outward, producing a supernova. The dense core that remains afterward is a neutron star. Enlarge / The remains of a supernova witnessed in the year 1054, the Crab Nebula contains a rapidly spinning neutron star known as a pulsar.CREDIT: NASA: X-RAY: CHANDRA (CXC), OPTICAL: HUBBLE (STSCI), INFRARED: SPITZER (JPL-CALTECH)
It wasnt until the 1960s that Zwicky and Baades hypothetical neutron stars were finally detected. Radio astronomer Jocelyn Bell Burnell noticed a strange, regularly pulsed radio wave signal from space while working as a graduate student at the University of Cambridge. She was detecting something that had never been seen before: a special kind of neutron star called a pulsar, which flashes beams of radiation at regular intervals as it spins, like a lighthouse. (Her adviser, along with the director of the observatorybut not Bell Burnelllater received the Nobel Prize for the discovery.)
Since then, thousands of neutron stars have been detected. As some of the densest, highest-pressure objects in the universe, neutron stars might help us learn about what happens to matter at extremely high densities. Understanding their structure and the behavior of the neutron matter composing them is of paramount importance to physicists. Advertisement
Scientists already know that the neutrons, protons, and other subatomic particles that compose a neutron star arrange themselves differently depending on where in the star they are. In certain sections, they pack rigidly like water molecules in a block of ice. In others, they flow and swirl like a frictionless fluid. But exactly where the transition happens and how the different phases of matter behave, physicists arent sure.
A superdense star born of a nuclear fireball seems, on its face, to have very little in common with a dilute cloud of ultracold particles. But they can share at least one useful characteristic: They are both below a threshold known as the Fermi temperature that depends onand is calculated based onthe matter each system is made of. A system that is well above this temperature will largely behave according to the laws of classical physics; if it is well below, its behavior will be ruled by quantum mechanics. Certain ultracold gases and neutron star material can both be well below their Fermi temperatures and consequently can act in similar ways, says Christopher Pethick, a theoretical physicist at the Niels Bohr Institute in Copenhagen and coauthor of an early overview of neutron stars in the 1975 Annual Review of Nuclear Science.
Matter that is below its Fermi temperature can obey remarkably universal laws. This universality means that, while we dont have easy access to several-million-degree neutron star matter, we could learn about some of its behavior by experimenting with ultracold gases that can be created and manipulated in laboratory vacuum chambers on Earth, says theoretical astrophysicist James Lattimer of Stony Brook University in New York, author of a summary of the science of nuclear matter in the 2012 Annual Review of Nuclear and Particle Science.
Of particular interest to Lattimer is a theoretical state called a unitary gas. A gas is unitary when each of its particles sphere of influence becomes infinite, meaning that they would influence each other no matter how far apart they are. This is impossible to have in reality, but ultracold atom clouds can get closeand so can the matter inside of neutron stars. Its similar to a unitary gas, Lattimer says, but its not a perfect unitary gas. Page: 1 2 Next → reader comments 28 with Advertisement Channel Ars Technica ← Previous story Next story → Related Stories Today on Ars
The agreement has sparked celebrations in Pakistan, with people in many cities, including Lahore, taking to the streets. Chants of “Pakistan Zindabad” – “Long Live Pakistan” in English – are ringing out.
But the deal doesn’t undo the events of the past two weeks, which will continue to weigh heavily on the minds of many here.
The military action has been the most significant between the countries in decades and dozens have died on both sides.
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Pakistan fires missiles at India
Just this morning, Pakistan inflicted some serious damage to India’s military sites and New Delhi did not waste time responding with further strikes.
It was a reminder, for many, of the uncertainty of the situation between India and Pakistan.
Image: A house damaged in Indian shelling, in Shah Kot, in Neelum Vallery. Pic: AP/M.D. Mughal
Representatives from each country will speak again on Monday and even with the strikes halted, for now, the next 48 hours will be a very testing moment.
Both sides have often shown striking strategic restraint. And in the past fortnight, neither has launched a full-scale attack.
But their enmity has been enduring, and even with the agreement in place, it feels a bit complacent to assume India and Pakistan will just walk back from the brink.
What will the series tally be in Caps-Canes when it heads back to D.C. — and will the Knights win at least one in Alberta so they even see a Game 5 back in Las Vegas?
Read on for game previews with statistical insights from ESPN Research, a recap of what went down in Friday’s games and the three stars of Friday from Arda Öcal.
With the Canes and Capitals tied up 1-1 heading to Raleigh for Games 3 and 4, ESPN BET has Carolina as the -215 series favorite. Washington is +180 to win the series.
Capitals defenseman John Carlson scored a power-play goal in Game 2, his 13th career playoff power-play goal, which breaks a tie with Brian Leetch for third for such goals by an American-born defenseman. He still trails Chris Chelios (14) and Brian Rafalski (17).
For the first time in his postseason career, Tom Wilson reached all of these thresholds: 2 points, 3 shots on goal, 2 hits and 2 blocked shots. His seven points this season is the most he has had in a playoff run since the Cup-winning year of 2018 (15).
The Hurricanes have not held an in-game lead since Game 4 of the first round against the Devils. They won the series in Game 5 in a double-overtime game, then won Game 1 of this series 2-1 in OT after trailing 1-0. Since that lead in Game 4 of the first round, they have trailed for 89:28 and been tied for 117:55.
Among qualified goaltenders this postseason, Frederik Andersen leads by a wide margin in goals-against average (1.55), and is second in save percentage, at .930. The netminder ahead of him in SV%? Washington’s Logan Thompson.
Following two wins by the Oilers in Vegas, ESPN BET now lists Edmonton as the -550 favorites to win this series, with the Golden Knights at +380. Edmonton is also the current favorite to win the Cup, at +300, narrowly ahead of the Stars, at +325. Vegas is now +1800, the longest odds of any team remaining in the playoffs.
Leon Draisaitl and Connor McDavid combined to score the game-winning OT goal in Game 2. It was the second OT goal this postseason for Draisaitl, and he is now tied for the most such goals in a single postseason in Oilers history with Esa Tikkanen in 1991.
McDavid is second among playoff scorers with 14 points through eight games, trailing only Mikko Rantanen‘s 15. McDavid’s 1.75 points per game this postseason is ahead of his rate in playoff seasons past (1.58) and well ahead of his rate during last year’s run to the Stanley Cup Final (1.36).
Victor Olofsson had two goals and an assist in a losing effort in Game 2. Both goals were on the power play, and he joins Jack Eichel as the only players in Knights history with multiple power-play goals in a single playoff game.
Speaking of Eichel, he finished with three assists, joining Shea Theodore and William Karlsson as the only players in Knights history with two three-assist playoff games on their résumé.
Öcal’s three stars from Friday
After a rough first round against the Blues, Hellebuyck shut out the Stars in Game 2. He made 21 saves en route to the fourth clean sheet of his postseason career.
Ehlers had his second career multigoal game and added an assist in a big Game 2 effort that tied Winnipeg’s series with Dallas 1-1.
The former Bruin continues to haunt the Maple Leafs, this time with the overtime winner to get the Panthers on the series board at 2-1. It was his fourth career playoff OT goal, and he extended his own NHL record for most consecutive postseasons with a game-winning goal (nine).
Toronto entered with a 2-0 series lead and got out to a 2-0 start in the game as well, with goals from Matthew Knies and John Tavares, before Aleksander Barkov drew the Panthers back to within a goal with his third goal of the postseason. Tavares added a power-play tally at 2:52 of the second period on a slick deflection, before the Panthers ripped off two goals in quick succession to tie the score. The first was thanks to Sam Reinhart poking the puck in during a wild scramble in the Leafs’ crease, the second after a superb pass from Sam Bennett to Carter Verhaeghe. Jonah Gadjovich put the home squad up 4-3, but Morgan Rielly tied things up midway through the third. It took until the final five minutes of the first OT, but Brad Marchand came through with another game-winning goal. Full recap.
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Brad Marchand’s OT winner sparks pandemonium from Panthers crowd
Brad Marchand scores a massive overtime goal to deliver the Panthers a 5-4 win over the Maple Leafs.
If this is the kind of goaltending the Jets will now get from Connor Hellebuyck, the Stars (and the rest of the NHL) are in trouble. Hellebuyck stopped all 21 shots sent on the Jets’ goal en route to his fourth career postseason shutout. On the offensive side, Gabriel Vilardi and Nikolaj Ehlers got the party started in the first. Adam Lowry added his fourth goal of the postseason in the second, and that 3-0 lead stood until 16:20 of the third, when Ehlers capped off the festivities with an empty-net goal. Full recap.
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Nikolaj Ehlers rolls in an empty-net goal for Winnipeg
Nikolaj Ehlers scores his second goal of the game to pad the Jets’ lead late in the third period vs. the Stars.
Kristen Shilton is a national NHL reporter for ESPN.
FORT LAUDERDALE, Fla. — Maple Leafs goaltender Anthony Stolarz continues to work his way back but doesn’t appear close to a return in Toronto’s second-round Eastern Conference playoff series against the Florida Panthers.
“He’s progressing in the right direction,” Maple Leafs coach Craig Berube said Saturday. “But he has not skated yet [since getting hurt].”
Stolarz was injured during Game 1 on Monday. The goaltender took a puck off his mask and an elbow to the head from Panthers forward Sam Bennett in the second period, exiting shortly after the Bennett hit. Stolarz, who was ill on Toronto’s bench before he left the game, was later transported to a hospital for evaluation.
The veteran was able to rejoin his teammates Tuesday at their facility but did not travel with the Maple Leafs to Florida ahead of Friday’s Game 3.
Joseph Woll took over the starting duties from Stolarz and helped stake Toronto to a 2-0 lead in the best-of-seven series. But Woll struggled in Game 3, recording an .861 save percentage as the Panthers mounted two multigoal comebacks to down the Maple Leafs 5-4 in overtime.
Berube said after the loss that he “thought [Woll] was really good” but that he didn’t love when Panthers fourth-liner Jonah Gadjovich beat the goaltender cleanly from outside the right faceoff circle to give Florida its first lead of the game at 4-3.
Woll also has been adjusting to playing the puck amid Florida’s smothering forecheck.
“They rim a lot of pucks,” Woll said Friday. “I’m just trying to do my best to help us break out.”
Florida hasn’t made it easy on Toronto in that respect. Berube anticipates Woll can learn from Friday’s mistakes and improve, though.
“It’s difficult,” Berube said. “A lot of those rims are up; they’re not on the ice. And that’s designed. If they can get a good lick on it, they’re going to get it on the glass. It’s pretty tough for him to come out and play those. He did get to a lot of them. But they’re coming hard. He’s going to have to move it quick.”