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Sand dunes can communicate, or at least give their neighbor a shove – CNN

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The scientists made the discovery after putting two identical piles of sand in a special, 6.5 feet (2 meters) across rotating tank that generated enough water flow to move the particles.
Sand dunes are known to move around, or migrate, in rivers, oceans and deserts and smaller dunes generally move faster than larger ones, Karol Bacik, a PhD candidate in Cambridge’s Department of Applied Mathematics and Theoretical Physics told CNN. He’s the first author on the paper that has been reported in the journal Physical Review Letters.
Bacik said he thought the two piles would move at the same speed since they were the same height and volume.
But that’s not what happened.
“There were all the reasons to suspect that they will move at the same rate, but it turns out that they move at different rates,” Bacik said. “They would move away from each other, as though they didn’t like each other.”
The dunes kept moving away from each other until they were at the opposite ends of the round tank.
Sand dunes tend to occur in vast dune fields or corridors, so understanding how they interact will help scientists understand the long term evolution of landscapes, Bacik said.
He said this phenomenon has been seen in satellite images of deserts, but scientists didn’t know what caused the dunes to repel each other.
They found that when the flow of water hits the first dune it generates turbulent swirls and curls that are similar to the wake of a boat. That turbulence pushes against the second dune as it flows downstream.
“So the upstream dune is actually generating a wake that speeds up the downstream dune to give it an extra kick,” said senior research fellow Nathalie Vriend with the BP Institute for Multiphase Flow, who led the research.
The size of the wake varies, depending on the size of the dune, Vriend said. They’re currently looking at how two different sized dunes behave in the test.
It takes about an hour to run the experiments in the lab, which Vriend says lets them make observations that would take decades in nature.
“We uncovered some beautiful physics that was previously unknown on Dune interactions,” Vriend said. “It’s sometimes a little bit strange to think that these inanimate objects, which aren’t humans, transmit information back and forth, which I find fascinating.”

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The U.S. Resets Its Sights on the Moon, Kicking Off the Next Space Race – Stratfor Worldview

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NASA’s Artemis I Moon rocket sits on the launch pad at the Kennedy Space Center in Cape Canaveral, Florida, on June 15, 2022.

(EVA MARIE UZCATEGUI/AFP via Getty Images)

Through NASA’s long-awaited Artemis program, the United States is seeking to secure its lead in the new space race, as a combination of technological advancements and the potential for lucrative natural resources on the moon and other planetary bodies draw more countries to venture beyond Earth’s atmosphere — with the United States’ top geopolitical rivals, China and Russia, being chief among them. After many delays, the first major mission launch under NASA’s Artemis lunar exploration program has been scheduled for Aug. 29, with Sept. 2 and Sept. 5 as the backup launch windows. The unmanned Artemis I mission will test the performance of the U.S. agency’s new Space Launch System (SLS) and Orion spacecraft in the hopes of certifying their use for future crewed missions.

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NASA’s moon rocket heads back to the launchpad – Kathimerini English Edition

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NASA’s big moon rocket is rolling out to the launchpad for the third time – and it actually is slated to launch to the moon.

For once, NASA is ahead of schedule.

For the past month and a half, the Space Launch System rocket, which is the most powerful since the Saturn V that took astronauts to the moon in the 1960s and 1970s, has been parked in a building at the Kennedy Space Center in Florida. There, technicians have been getting the rocket ready for its maiden flight, which could occur in two weeks.

The rollout from the building to the launchpad had been scheduled for Thursday, but NASA announced Monday that the move had been moved up to Tuesday evening. This all leads to the launch of NASA’s Artemis I mission, an uncrewed test of the giant rocket and the Orion spacecraft where astronauts will one day sit.

What happens during the rollout, and can I watch it?

It is about 4.2 miles from NASA’s huge Vehicle Assembly Building to the launchpad, which is known as Launch Complex 39B. NASA first used the pad during the Apollo program in the 1960s. The rocket and launch tower will sit on a gigantic vehicle that NASA calls a crawler-transporter. It is the same vehicle that carried the Saturn V for the moon landings, but it has been renovated and upgraded.

The crawler, indeed, crawls. Bigger in area than a baseball infield and able to carry up to 18 million pounds, it will move at a speed up to 1 mph over a gravel path to the launch site. The trip will take about 10 hours.

NASA started broadcasting the rollout at 3 p.m. Eastern time Tuesday on one of its YouTube channels when the doors of the Vehicle Assembly Building opened. The crawler and the rocket could actually start moving around 9 p.m.

What happens next?

Technicians will be making final preparations, including hooking up power and propellant lines to the rocket and the launch tower. Although the rollout is sooner, the target time for the Artemis I launch has not changed: Monday, Aug. 29 at 8:33 a.m. Eastern time.

What are the Space Launch System and Orion, and why are they important?

The Space Launch System and Orion are two of the core components of NASA’s plans to return astronauts to the surface of the moon in the coming years. Getting there requires a rocket powerful enough to push a large spacecraft out of low-Earth orbit to the moon, some 240,000 miles away. Orion is a capsule designed to carry astronauts on space voyages lasting up to a few weeks.

What problems occurred during the dress rehearsal?

NASA first rolled the SLS rocket to the launchpad in mid-March. In early April, it attempted to conduct a “wet dress rehearsal” of countdown procedures, including the loading of more than 700,000 gallons of liquid hydrogen and liquid oxygen rocket propellants. However, technical glitches, including a hydrogen leak during three rehearsal tries, cut the countdowns short.

NASA then rolled the rocket back to the Vehicle Assembly Building to conduct repairs. In June, the rocket returned to the launchpad for another attempt at the wet dress rehearsal. That attempt, on June 20, encountered a different hydrogen leak, in a fuel line connector to the rocket’s booster stage. However, the propellant tanks were fully filled for the first time, and controllers were able to continue the rehearsal until the countdown terminated with 29 seconds left. Originally, the aim was to have the countdown stop with just under 10 seconds, when the engines would start for an actual launch.

Despite the leak, NASA officials decided that all of the critical systems had been sufficiently tested and declared the test a success. The rocket headed back for the Vehicle Assembly Building once again for final preparations, including the installation of the flight termination system, which would blow up the rocket in case something went wrong during launch and eliminate the possibility of crashing into a populated area.

The flight termination system’s batteries, installed Aug. 11, are normally only rated to last for 20 days, but the part of the United States Space Force that oversees launches from Florida, granted NASA a waiver that extends the period to 25 days. This allows the Aug. 29 launch date as well as backup opportunities on Sept. 2 and Sept. 5.

NASA hopes it fixed the hydrogen leak, but it will not know for sure until the Aug. 29 countdown, when the propellant line is cooled down to ultracold temperatures, something that cannot be tested in the Vehicle Assembly Building.


This article originally appeared in The New York Times.

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Physicists and business figures gather in Vancouver to crack theory of everything

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VANCOUVER — Some of the world’s brightest minds are gathering at a hotel conference centre in Vancouver this week to try to solve a question that has baffled physicists for decades.

The two pillars of modern physics — the theories of quantum mechanics and general relativity — have been used respectively to describe how matter behaves, as well as space, time and gravity.

The problem is that the theories don’t appear to be compatible, said Peter Galison, a professor in history of science and physics at Harvard University.

“These theories can’t just harmoniously live in splendid isolation, one from the other. We know our account of the world is inadequate until we figure out how to make them play nicely together,” he said in an interview after giving a talk on how black holes fit into the equation.

Galison is among several leading thinkers who arrived at the Quantum Gravity Conference for the launch a new global research collaborative known as the Quantum Gravity Institute in Vancouver.

While speakers at the conference are primarily scientists, including Nobel laureates Jim Peebles, Sir Roger Penrose and Kip Thorne, those behind the institute come from less likely fields.

The Quantum Gravity Society represents a group of business, technology and community leaders. Founding members include Frank Giustra of Fiore Group, Terry Hui of Concord Pacific, Paul Lee and Moe Kermani of Vanedge Capital and Markus Frind of Frind Estate Winery. They are joined by physicists Penrose, Abhay Ashtekar, Philip Stamp, Bill Unruh and Birgitta Whaley.

During a panel discussion, Lee said he’s been asked several times why Vancouver would host such an event or institute.

“Why Vancouver? Because we can,” Lee said.

Hui, who studied physics as part of his undergraduate degree, said organizing the conference and launching the institute felt like fulfilling a childhood dream.

“I left the field to pursue other things, you know,” he said in an interview.

“How do I put this?” he said, before likening it to being a guy who never made the high school hockey team getting to hang out in the Canucks’ locker room.

Hui said he wanted to help and saw his role as philanthropic, adding he believed it would benefit Vancouver economically.

As a non-local and the founder of the Black Hole Initiative at Harvard, Galison said he’s happy to see more interdisciplinary support for exploring some of the biggest questions in science.

He called the conference an interesting event for bringing together people in technology and venture capitalism with scientists from varied fields. The launch of the institute is also meaningful, he said.

“It’s also a kickoff event for something much bigger and longer-lasting.”

As for the central question of the conference, Galison said it’s an opportunity to explore where the theories overlap and where they don’t from different angles.

“One place they intersect is clearly at the beginning of the universe, early cosmology, because when energy is incredibly compressed, when you have enormous energy densities, you’re at the limit where the bending of space and time creates so much energy that quantum effects come into play,” he said.

The theory of quantum mechanics, introduced in the 1920s, entered a world already shaken by Albert Einstein’s theory of relativity, which inspired responses not just from scientists but from poets and philosophers, he said.

“That these things are not compatible is really unnerving,” Galison said.

Cracking the code for why isn’t something that will happen in a moment, a week or a year, he said.

“There’s a tremendous amount of work,” he said. “It’s more like building a cathedral than throwing up a bicycle shed.”

This report by The Canadian Press was first published Aug. 17, 2022.

 

Amy Smart, The Canadian Press

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