adplus-dvertising
Connect with us

Science

James Bardeen, an expert in solving Einstein's equations, has died at the age of 83 – electriccitymagazine.ca

Published

 on


James Bardeen, who helped elucidate the properties and behavior of black holes, paving the way for what has been called the golden age of black hole astrophysics, died on June 20 in Seattle. He was 83 years old.

His son William said the cause was cancer. Dr. Bardeen, professor emeritus of physics at the University of Washington, was living in a nursing home in Seattle.

Dr. Bardeen was a descendant of a famous family of physicists. His father is John Twice won the Nobel Prize in Physics, for the invention of the transistor and the theory of superconductivity; his brother, Williaman expert in quantum theory at the Fermi National Accelerator Laboratory in Illinois.

300x250x1

Dr. Bardeen was an expert in solving equations of Einstein’s general theory of relativity. This theory attributes what we call gravity to the curvature of spacetime with matter and energy. Its most mysterious and disturbing consequence has been the possibility of black holes, places so dense that they become endless one-way exit ramps from the universe, swallowing even light and time.

Dr. Bardeen will find the work of his life investigating those mysteries, as well as related mysteries about the evolution of the universe.

said Michael Turner, a cosmologist and professor emeritus at the University of Chicago, who described Dr. Bardeen as a “gentle giant.”

James Maxwell Bardeen was born in Minneapolis on May 9, 1939. His mother, Jane Maxwell Bardeen, was a zoologist and high school teacher. After his father’s business, the family moved to Washington, D.C.; To the Summit, NJ; Then to Champaign-Urbana, Illinois, where you graduate from University of Illinois High School Laboratory.

He attended Harvard University and graduated with a degree in physics in 1960, despite his father’s advice that biology was the wave of the future. “Everyone knows who my father is,” he said in an oral history interview recorded by the Federal University of Paraguay in 2020, adding that he did not feel the need to compete with him. “It was impossible anyway,” he said.

Work under the supervision of a physicist Richard Feynman And an astrophysicist William Fowler (who would both become Nobel Prize laureates), Dr. Bardeen received his Ph.D. He received his Ph.D. from the California Institute of Technology in 1965. His thesis was on the structure of supermassive stars millions of times the mass of the Sun. Astronomers are beginning to suspect that they are the source of the massive energies of quasars detected in the cores of distant galaxies.

After holding postdoctoral positions at the California Institute of Technology and the University of California, Berkeley, he joined the Department of Astronomy at the University of Washington in 1967. An enthusiastic hiker and mountaineer, he was drawn to the school by its easy access to the outdoors.

By then, what a Nobel Prize winner Cape Thorne, a professor at the California Institute of Technology, points out that the golden age of black hole research was in full swing, and Dr. Bardeen was swept up in international meetings. At one, in Paris in 1967, he met Nancy Thomas, a Connecticut high school teacher who was trying to improve her French. They married in 1968.

In addition to his son William, a senior vice president and chief strategy officer of The New York Times Company, and his brother William, Dr. Bardeen’s wife survives him, along with another son, David, and two grandchildren. Sister Elizabeth Gretke passed away in 2000.

attributed to him…Eduardo Braniff

Dr. Bardeen was a member of the National Academy of Sciences as well as his brother and father.

Although he was fast at math, Dr. Bardeen didn’t write faster than he spoke. William Price, a former student of Dr. Thorne now at the University of Texas, remembers being sent to Seattle to finish a paper Dr. Bardeen was supposed to write. Nothing is written. Dr. Bardeen’s wife then ordered the two to sit at opposite ends of the sofa with a sheet. Dr. Bardeen would write a sentence and pass the paper on to Dr. Press, who would either reject it or approve it and then put the pillow back. Dr. Bryce said that each sentence took a few minutes. It took them three days, but the paper was written.

One of the historical moments in those years was the month-long “Summer School” in Les Hoechs, France, in 1972 that included all the eminent black hole scientists. Dr. Bardeen was one of six invited speakers. It was during that meeting, Stephen Hawking from the University of Cambridge and Brandon Carternow from the Paris Observatory, wrote a landmark paper called “The Four Laws of Black Hole Mechanics,” which became a springboard for future work, including Dr. Hawking’s surprising calculation that black holes can leak and eventually explode.

In another famous account that same year, Dr. Bardeen deduced the shape and size of a black hole’s “shadow” as seen against a field of distant stars – a circle of light surrounding dark space.

Dr. Thorne said the shape was made famous by the Event Horizon Telescope observations of black holes in the galaxy M87 and at the center of the Milky Way, and by visualizations in the movie “Interstellar.”

Cosmology was among Dr. Bardeen’s other interests. In a 1982 paper, he, Dr. Turner and Paul Steinhardt of Princeton described how submicroscopic fluctuations in matter and energy density in the early universe would grow and give rise to the pattern of galaxies we see in the sky today.

Dr. Turner said, “Jim was glad we used his formalities, and he was sure we got it right.”

Dr. Bardeen transferred to Yale University in 1972. After four years, dissatisfied with the academic bureaucracy in the East and anxious abroad again, he returned to the University of Washington. Retired in 2006.

But it did not stop working. Dr. Thorne recounted a recent telephone conversation in which they recalled the hiking and camping trips they used to take with their families. In the same conversation, Dr. Bardeen described the last thoughts he had about what happens when a black hole evaporates, noting that it might turn into a white hole,

“This was one aspect of Jim in a nutshell, thinking deeply about physics in new creative ways until the end of his life,” Dr. Thorne wrote in an email.

“Reader. Infuriatingly humble coffee enthusiast. Future teen idol. Tv nerd. Explorer. Organizer. Twitter aficionado. Evil music fanatic.”

Adblock test (Why?)

728x90x4

Source link

Continue Reading

Science

Marine plankton could act as alert in mass extinction event: UVic researcher – Langley Advance Times

Published

 on


A University of Victoria micropaleontologist found that marine plankton may act as an early alert system before a mass extinction occurs.

With help from collaborators at the University of Bristol and Harvard, Andy Fraass’ newest paper in the Nature journal shows that after an analysis of fossil records showed that plankton community structures change before a mass extinction event.

“One of the major findings of the paper was how communities respond to climate events in the past depends on the previous climate,” Fraass said in a news release. “That means that we need to spend a lot more effort understanding recent communities, prior to industrialization. We need to work out what community structure looked like before human-caused climate change, and what has happened since, to do a better job at predicting what will happen in the future.”

300x250x1

According to the release, the fossil record is the most complete and extensive archive of biological changes available to science and by applying advanced computational analyses to the archive, researchers were able to detail the global community structure of the oceans dating back millions of years.

A key finding of the study was that during the “early eocene climatic optimum,” a geological era with sustained high global temperatures equivalent to today’s worst case global warming scenarios, marine plankton communities moved to higher latitudes and only the most specialized plankton remained near the equator, suggesting that the tropical temperatures prevented higher amounts of biodiversity.

“Considering that three billion people live in the tropics, the lack of biodiversity at higher temperatures is not great news,” paper co-leader Adam Woodhouse said in the release.

Next, the team plans to apply similar research methods to other marine plankton groups.

Read More: Global study, UVic researcher analyze how mammals responded during pandemic

Adblock test (Why?)

728x90x4

Source link

Continue Reading

Science

Scientists Say They Have Found New Evidence Of An Unknown Planet… – 2oceansvibe News

Published

 on


In the new work, scientists looked at a set of trans-Neptunian objects, or TNOs, which is the technical term for those objects that sit out at the edge of the solar system, beyond Neptune

The new work looked at those objects that have their movement made unstable because they interact with the orbit of Neptune. That instability meant they were harder to understand, so typically astronomers looking at a possible Planet Nine have avoided using them in their analysis.

Researchers instead looked towards those objects and tried to understand their movements. And, Dr Bogytin claimed, the best explanation is that they result from another, undiscovered planet.

300x250x1

The team carried out a host of simulations to understand how those objects’ orbits were affected by a variety of things, including the giant planets around them such as Neptune, the “Galactic tide” that comes from the Milky Way, and passing stars.

The best explanation was from the model that included Planet 9, however, Dr Bogytin said. They noted that there were other explanations for the behaviour of those objects – including the suggestion that other planets once influenced their orbit, but have since been removed – but claim that the theory of Planet 9 remains the best explanation.

A better understanding of the existence or not of Planet 9 will come when the Vera C Rubin Observatory is turned on, the authors note. The observatory is currently being built in Chile, and when it is turned on it will be able to scan the sky to understand the behaviour of those distant objects.

Planet Nine is theorised to have a mass about 10 times that of Earth and orbit about 20 times farther from the Sun on average than Neptune. It may take between 10,000 and 20,000 Earth years to make one full orbit around the Sun.

You may be tempted to ask how an entire planet could ‘hide’ in our solar system when we have zooming capabilities such as the new iPhone 15 has, but consider this: If Earth was the size of a marble, the edge of our solar system would be 11 kilometres away. That’s a lot of space to hide a planet.

[source:independent]

Adblock test (Why?)

728x90x4

Source link

Continue Reading

Science

Dragonfly: NASA Just Confirmed The Most Exciting Space Mission Of Your Lifetime – Forbes

Published

 on


NASA has confirmed that its exciting Dragonfly mission, which will fly a drone-like craft around Saturn’s largest moon, Titan, will cost $3.35 billion and launch in July 2028.

Titan is the only other world in the solar system other than Earth that has weather and liquid on the surface. It has an atmosphere, rain, lakes, oceans, shorelines, valleys, mountain ridges, mesas and dunes—and possibly the building blocks of life itself. It’s been described as both a utopia and as deranged because of its weird chemistry.

Set to reach Titan in 2034, the Dragonfly mission will last for two years once its lander arrives on the surface. During the mission, a rotorcraft will fly to a new location every Titan day (16 Earth days) to take samples of the giant moon’s prebiotic chemistry. Here’s what else it will do:

300x250x1
  • Search for chemical biosignatures, past or present, from water-based life to that which might use liquid hydrocarbons.
  • Investigate the moon’s active methane cycle.
  • Explore the prebiotic chemistry in the atmosphere and on the surface.

Spectacular Mission

“Dragonfly is a spectacular science mission with broad community interest, and we are excited to take the next steps on this mission,” said Nicky Fox, associate administrator of the Science Mission Directorate at NASA Headquarters in Washington. “Exploring Titan will push the boundaries of what we can do with rotorcraft outside of Earth.”

It comes in the wake of the Mars Helicopter, nicknamed Ingenuity, which flew 72 times between April 2021 and its final flight in January 2023 despite only being expected to make up to five experimental test flights over 30 days. It just made its final downlink of data this week.

Dense Atmosphere

However, Titan is a completely different environment to Mars. Titan has a dense atmosphere on Titan, which will make buoyancy simple. Gravity on Titan is just 14% of the Earth’s. It sees just 1% of the sunlight received by Earth.

function loadConnatixScript(document)
if (!window.cnxel)
window.cnxel = ;
window.cnxel.cmd = [];
var iframe = document.createElement(‘iframe’);
iframe.style.display = ‘none’;
iframe.onload = function()
var iframeDoc = iframe.contentWindow.document;
var script = iframeDoc.createElement(‘script’);
script.src = ‘//cd.elements.video/player.js’ + ‘?cid=’ + ’62cec241-7d09-4462-afc2-f72f8d8ef40a’;
script.setAttribute(‘defer’, ‘1’);
script.setAttribute(‘type’, ‘text/javascript’);
iframeDoc.body.appendChild(script);
;
document.head.appendChild(iframe);

loadConnatixScript(document);

(function()
function createUniqueId()
return ‘xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx’.replace(/[xy]/g, function(c) 0x8);
return v.toString(16);
);

const randId = createUniqueId();
document.getElementsByClassName(‘fbs-cnx’)[0].setAttribute(‘id’, randId);
document.getElementById(randId).removeAttribute(‘class’);
(new Image()).src = ‘https://capi.elements.video/tr/si?token=’ + ’44f947fb-a5ce-41f1-a4fc-78dcf31c262a’ + ‘&cid=’ + ’62cec241-7d09-4462-afc2-f72f8d8ef40a’;
cnxel.cmd.push(function ()
cnxel(
playerId: ’44f947fb-a5ce-41f1-a4fc-78dcf31c262a’,
playlistId: ‘aff7f449-8e5d-4c43-8dca-16dfb7dc05b9’,
).render(randId);
);
)();

The atmosphere is 98% nitrogen and 2% methane. Its seas and lakes are not water but liquid ethane and methane. The latter is gas in Titan’s atmosphere, but on its surface, it exists as a liquid in rain, snow, lakes, and ice on its surface.

COVID-Affected

Dragonfly was a victim of the pandemic. Slated to cost $1 billion when it was selected in 2019, it was meant to launch in 2026 and arrive in 2034 after an eight-year cruise phase. However, after delays due to COVID, NASA decided to compensate for the inevitable delayed launch by funding a heavy-lift launch vehicle to massively shorten the mission’s cruise phase.

The end result is that Dragonfly will take off two years later but arrive on schedule.

Previous Visit

Dragonfly won’t be the first time a robotic probe has visited Titan. As part of NASA’s landmark Cassini mission to Saturn between 2004 and 2017, a small probe called Huygens was despatched into Titan’s clouds on January 14, 2005. The resulting timelapse movie of its 2.5 hours descent—which heralded humanity’s first-ever (and only) views of Titan’s surface—is a must-see for space fans. It landed in an area of rounded blocks of ice, but on the way down, it saw ancient dry shorelines reminiscent of Earth as well as rivers of methane.

The announcement by NASA makes July 2028 a month worth circling for space fans, with a long-duration total solar eclipse set for July 22, 2028, in Australia and New Zealand.

Wishing you clear skies and wide eyes.

Adblock test (Why?)

728x90x4

Source link

Continue Reading

Trending