Category Archives: physics

Krauss and the greatest story ever told (so far)

We’re living in the best of times and the worst of times according to best-selling author and award-winning theoretical physicist Lawrence Krauss. The best is represented by the Large Hadron Collider (LHC), which has helped reveal the Higgs particle that ties together the standard model of physics. The worst is reflected by the president’s proposed federal budget that could derail physical science research. Krauss spoke about his latest book, The Greatest Story Ever Told—So Far: Why Are We Here? (Atria Books, 2017) last week at Town Hall Seattle. It was an informative and humor-filled lecture.

Lawrence Krauss

Author and physicist Lawrence Krauss spoke April 12, 2017 at Town Hall Seattle. Photo: Greg Scheiderer.

“This is really humanity at its greatest,” said Krauss of the discoveries at the LHC, which represent the work of thousands of scientists from all over the world. Krause’s talk was a walk through the history of discovery in physics, going all the way back to Plato and along the way bumping into Galileo, Newton, Faraday, Maxwell, Einstein, Fermi, Feynman, and more before arriving at quantum mechanics, the standard model, and the Higgs field.

“The real world is so different than the illusion that we see,” Krauss said. “The world of our experience is an illusion, and it’s an amazing story how we, over centuries, have been able to cut through that illusion to see reality underneath.”

We’ll leave the full tour of advances in physics to your reading of the book and, for this article, focus on Krauss’s take on the problems and challenges facing science today. He feels that much of the current mistrust of science stems from a common misconception that tomorrow’s science will make today’s obsolete, and that therefore scientific facts are little more than a subjective fad. Krauss said that is completely wrong.

Truth is eternal

“What is true today—and by true in science we mean what has satisfied the test of experiment today—will always be true,” he said. “Newton’s laws may have been supplanted at the extremes of scale by general relativity or quantum mechanics, but to describe baseballs or cannonballs or even rocket ships, they’re as true today as they were then, and whatever new physics we discover in quantum gravity or whatever, it’s not going to change. At the scale of humans, it’s got to revert to Newton’s laws. A million years from now, whatever we learn in science, if I let a ball go it’s going to fall as described by Newton’s laws.”

Krauss also let us in on what he jokingly referred to as a well-kept secret.

“Scientists are human,” he said. “That means they have prejudices and biases and pigheadedness, and that’s fine. What’s really neat is that science forces them in the right direction, kicking and screaming. The individual scientists are full of nonsense, but the scientific process protects us from that nonsense.”

Searching for a better toaster

Science is almost inextricably tied to technology, and Krauss frets that this causes people to wonder what new discoveries are “good for.”

“People don’t ask that for Mozart concertos or Picasso paintings or Shakespeare plays,” Krauss noted, “but it’s all the same thing. It’s what makes humanity worth living for. The fundamental importance of science, to me, is not the technology, but the fact that it forces us to confront reality and change our picture of our place in the cosmos. That’s what good literature, good music, good art do. That’s what the process of learning and growing as a society is all about.”

End of story?

The “So Far” in the title of the book is a reference to the notion that the story of discovery will continue to get more amazing if we keep asking questions. But Krauss is worried that we may not be able to do so. He noted that the president’s proposed federal budget would cut the Department of Energy—the primary funder of research in the physical sciences—by 20 percent, and eliminate funding for the National Endowment for the Arts, the National Endowment for the Humanities, the Corporation for Public Broadcasting, and the Institute of Museums and Libraries. That would save around $1.82 billion, while Krauss notes that the same budget would provide $2 billion to start building a wall between the United States and Mexico.

“To protect us against these unimaginable horrors, we’re willing to cut these things in our society that are so central,” Krauss observed. “We are in the process of getting rid of what is important for making the nation worth defending.”

“Art, literature, music and science are part of the greatest story ever told, and when we give that up in the name of defense, what are we really killing?” he asked.


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LIGO and the era of multimessenger astronomy

Multimessenger astronomy is a fairly new buzz word in the science. Dr. Joey Key, an assistant professor of physics at the University of Washington Bothell and a member of the LIGO Scientific Collaboration, talked about the concept at last month’s meeting of the Seattle Astronomical Society.

Joey Key

Dr. Joey Key of the UW Bothell gave a talk about LIGO and the era of multimessenger astronomy at the Dec. 21 meeting of the Seattle Astronomical Society. Key made the same presentation to the Everett Astronomical Society Jan. 7. Photo: Greg Scheiderer.

As you probably know LIGO—the Laser Interferometer Gravitational-wave Observatory—made the first detection of gravitational waves, as predicted by Einstein’s theory of general relativity, back in December 2015 and announced the findings last February. So now what?

“The next big goal for LIGO is to have a gravitational wave detection where we also get an electromagnetic signal from the same source,” Key explained. She noted that various wavelengths of light, from gamma ray to radio, require different types of tools to detect and reveal different things about objects observed. Key said gravitational-wave astronomers refer to such science as “electromagnetic astronomy.” The big hope, then, is to learn even more if there can be an electromagnetic observation as well as a gravitational wave observation of the same event.

“That’s what we would call a multimessgenger source,” Key said.

A difficult search

Einstein never thought gravitational waves could be detected because he figured they would be too small. It took a century of technological advances to prove him right—again. Finding a multimessenger source may be an even more elusive needle in the cosmic haystack.

Key explained that, right now, it’s hard for LIGO to detect with precision from whence a source signal originates. When they detect a source they send an alert to about 60 electromagnetic astronomy partners and give them a general direction in which to look. In addition to the challenge of pinpointing the source, they also don’t really know what to look for. Key said their models aren’t very good, not yet anyway. Light from a source may have already passed, but there could be x-rays, gamma rays, afterglow, or shock waves under certain conditions.

Fortunately, LIGO is getting better. The addition of more Earth-based observatories will help better locate sources and discover collisions of neutron stars or stellar-mass black holes. Project LISA, scheduled to launch in 2029, will look for supermassive black hole collisions and “extreme mass ratio in-spirals” which occur when a little star or black hole falls into a big black hole. Pulsar timing arrays could detect when supermassive black holes collide in galaxy mergers. There’s even study of the cosmic microwave background to try to detect gravitational waves from early universe.

“Just like electromagnetic astronomy, different sources are detected by these different kinds of experiments,” Key said. “We need all these different kinds of gravitational-wave experiments to be able to study the gravitational-wave sky.”

The LIGO Scientific Collaboration includes more than a thousand scientists from 15 countries and 90 institutions. Four of the institutions are in Washington: The University of Washington, UW Bothell, Whitman College, and Bellevue College.

Unknown discoveries ahead

Key said it is an interesting time to be involved in the field as LIGO is just into its second observing run.

“We’re really going to be able to map out and explore the population of black holes in our universe,” Key said.

“We don’t know what we’ll discover, and that is always the story of a new astronomy,” she added. ”We do not know very much about black holes in general, and so this is a new way to study the universe and study what is out there. It will be very exciting!”

LIGO could discover new kinds of sources like cosmic strings, study supernovae, and maybe even lead to the detection of dark matter and dark energy.

“We are lucky we live in the era of gravitational-wave astronomy, and we hope soon that it will be the era of multimessenger astronomy,” Key concluded.

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Mapping the heavens with Priya Natarajan

Priyamvada Natarajan, a theoretical astrophysicist at Yale University, is excited to be working in physics and astronomy at a time she and others call the “golden age of cosmology.”

“The maturity of our theoretical understanding, the sophistication of our instruments and tools that allow us to get the data—spacecraft, detectors—and the advanced computing are all aligned at the moment,” Natarajan said this week during a talk at Town Hall Seattle.

Natarajan

Theoretical astrophysicist Priyamvada Natarajan spoke Nov. 14, 2016 at Town Hall Seattle.

Natarajan has done a lot of work on mapping dark matter and dark energy, on gravitational lensing, and on figuring out how supermassive black holes are formed. It’s the latter that has her excited for the launch of the James Webb Space Telescope. She’s been a leader in pushing the idea that supermassive black holes could be formed by the direct collapse of matter. The physics pencils out, and Webb will peer back and possibly find the most distant, and therefore the first, black holes, and perhaps validate her ideas.

“The fact that you can come up with an idea as a scientist, for me, that’s the privilege,” she said.

Natarajan is the author of Mapping the Heavens: The Radical Scientific Ideas That Reveal the Cosmos (Yale University Press, 2016). She said she wrote the book not only to help us understand new discoveries about black holes and dark matter, but also to demystify the process of science.

“I believe very strongly that the current rampant disbelief in science stems from the contingent nature, the provisionality of science.” Natarajan said. “It’s something that’s very hard for the public at large to understand.”

The plus side is that cosmology and astronomy have the potential to win converts.

“Unlike many other fields in science, the night sky belongs to all of us,” she said. “We have to just look up and it’s there; the glory and the awe of the night sky.”

We know a lot

Natarajan finds it interesting that we know so much about the universe, with pretty solid evidence for much of what has happened since the tiniest fraction of a second after the Big Bang.

“It still stuns me that with a cantaloupe-sized gelatinous thing in our skull we’ve been able to figure all of this out,” she laughed. Yet despite all we do know, she said there is still a lot of mystery about our peculiar universe.

“We happen to live in one in which the total energy content of the universe is dominated by two components that we don’t know what they are,” she said.

Matter graph

Chart: NASA

What we call them are dark matter, which makes up 24 percent of the universe, and dark energy, which makes up 71 percent. We and all the stuff we see are less than five percent. Though we don’t know what dark matter is, Natarajan said there is solid evidence that it is indeed out there.

“The idea came out of an empirical need to explain an observation,” she said. Oddly enough, one of her other research interests, black holes, were conceived in exactly the opposite fashion.

“Black holes were actually proposed as a mathematical entity,” she noted. “They were a mathematical solution to Einstein’s equations, and they eventually became real.”

A little history

Dark matter was first suggested by Fritz Zwicky in 1933. Vera Rubin and others looking at galaxies in the 1970s proposed it as the reason rapidly spinning galaxies don’t fly apart. Natarajan said more than 80 years of research has left little doubt.

“We have incontrovertible evidence from many independent lines of investigation for the existence of dark matter because of the effects it produces, although it has not been directly detected yet,” she said. “We don’t know the particle.”

There are two lines of evidence, according to Natarajan, that make dark matter far more than just an inference.

“We can exquisitely map it at the moment, even though we can’t see it, because of the gravitational influence that it exerts,” she said. “The other way in which we can detect dark matter is the impact that matter has on the propagation of light in our universe.”

This is where her work on gravitational lensing fits in. Large galaxy clusters, with as many as a thousand galaxies, can act as a sort of gravitational lens on steroids. Such clusters would be held together by enormous amounts of dark matter. The relativity “pothole” created by the cluster could be strong enough to split a beam of light.

“You end up seeing multiple images of an object where in reality there is only one object,” Natarajan said, noting that this has been observed many times now. Interestingly, she points out that the physics of both Newton and of Einstein would predict the effect.

“You can apply both of these arguments to clusters and you infer the same amount of dark matter,” she said. “In my opinion that is really, really strong evidence, compelling evidence, because they’re completely different world views and they still converge. There’s no escaping the concept of dark matter.”

Search for the holy grail

Natarajan said this sort of research may help us get to the holy grail of physics: a quantum theory of gravity.

“The motivation is to look for gaps, look for disagreements, and look for anomalies where an observation is actually inconsistent with our theoretical expectation,” she said.

A couple of great examples of this came out of the 1800s. The orbit of Uranus didn’t agree with Newton’s Laws, so they did the math and figured another planet could cause the observed discrepancies. That led to the discovery of Neptune. At the same time, there were anomalies in Mercury’s orbit, which led to the proposal that another planet, called Vulcan, was the cause. Vulcan was never found, but years later general relativity explained the precession of Mercury’s orbit perfectly.

“In one case the theory remained intact and an anomaly refined our understanding,” Natarajan said. “In the other case it pointed the way to the existence of a more fundamental covering theory that was yet to come.”

We can’t wait for the next breakthroughs in this golden age of cosmology.


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The end of the beginning of the universe

Miguel Morales has been spending a lot of time pondering what he calls “the end of the beginning of the universe”—the cosmic microwave background. Morales, professor of physics at the University of Washington, heads up the university’s Dark Universe Science Center, a group working to figure out gravity, dark matter, dark energy, galaxy formation and evolution, and other cosmological mysteries. Morales gave a talk earlier this month titled “The End of the Beginning.” It was the second of a four-part lecture series, The Big Bang and Beyond, sponsored by the UW alumni association in celebration of the 50th anniversary of the Department of Astronomy.

CMB

The now-famous rendering of the cosmic microwave background “looks like Pollock. It’s kind of a mess!” jokes Prof. Miguel Morales. Yet it may hold clues to how the universe formed and how we all got here. Image: ESA and the Planck Collaboration.

Morales gave a “Cliff’s Notes” history of the formation of the universe, noting that the end of the beginning came about 380,000 years after the Big Bang, when the hydrogen and helium plasma formed by that event cooled sufficiently to change phase and release light.

“It froze from an opaque helium hydrogen plasma to a clear, neutral gas,” Morales explained.

The “glowing wall of gas” left behind is the cosmic microwave background. Recent measurements have confirmed temperature fluctuations in the CMB.

“These are real, hot and cold spots that we see on the sky,” Morales said. “This is the writing of creation on the wall.”

Ghostly evidence

Morales noted that this writing is extremely faint. He pointed out that the differences between the red an blue sections of the now-famous Planck map of the cosmic microwave background are just one part in 100,000.

Miguel Morales explains how oscillations in plasma created sound waves that can be spotted within the cosmic microwave background. Photo: Greg Scheiderer.

Miguel Morales explains how oscillations in plasma created sound waves that can be spotted within the cosmic microwave background. Photo: Greg Scheiderer.

“This is really a testament to precision measurement,” he said. He noted that, given this level of accuracy, we can learn a lot about what was going on in the early universe from the evidence left behind.

For example, scientists have teased out sound waves from the cosmic microwave background. The waves were created when the plasma oscillated in what was essentially a tug-o-war between gravity trying to collapse the mass and photons resisting that force. How those sound waves propagate could hold clues to what was going on in the early universe.

Changing tactics

The early observations measured temperature, but Morales said the state of the art is to look at the polarization of the light, which could lead to a needle in the cosmic haystack.

“You might be able to see, in the polarization, the ghost of gravity waves from inflation,” he said. They actually thought they had something in observations from the BICEP2 telescope at the South Pole, but what they saw actually turned out to be spinning dust.

“The polarization that BICEP saw is contaminated by the galaxy,” Morales said. “We’re seeing stuff on the windshield here; it’s not all primordial.”

One of the greatest challenges in making these observations is fine-tuning the instruments to ignore the noise and not be faked out by the data.

“BICEP is a technical tour de force, the measurement is awesome. It’s just a little contaminated, and, to be honest, Planck is not sensitive enough to say how bad the contamination is,” Morales explained.

That, he said, is science.

“We’ll keep looking, scratching our heads, building yet more sensitive instruments as we learn to read the words about the universe written faintly on the sky.”

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Spooky action explained

Some eighty years ago Albert Einstein derided the notion of quantum entanglement as “spooky action at a distance.” Today, according to author and journalist George Musser, “We’re starting to see the hazy outlines of an answer,” to questions about the how particles in different locations appear to act on each other. He is quick to add that there are still scientists who don’t really believe that non-locality is a real thing.

Musser

Author George Musser explains separate particles magically acting on each other during his talk Nov. 3 at Town Hall Seattle. Photo: Greg Scheiderer.

Musser is the author of Spooky Action at a Distance: The Phenomenon That Reimagines Space and Time—and What It Means for Black Holes, the Big Bang, and Theories of Everything (Scientific American / Farrar, Straus and Giroux, 2015). He spoke about the book and the science earlier this month at Town Hall Seattle.

Musser noted that Einstein was clearly bothered by some aspects of quantum mechanics, particularly the notion that randomness governs the universe. This led to his famous observation that God does not place dice.

“It was arguably Einstein’s number one concern,” Musser noted. “His deeper worry, actually the worry that led him to the worry about randomness, was the worry about non-locality. What is non-locality? How can this magic sorcery kind of thing be happening in the real world?”

That’s the quality that got Musser interested in writing about the subject.

“It’s the closest thing that we have in contemporary science to real, honest-to-god, Harry Potter magic,” he said. He noted that it turns up in many different sciences, and isn’t just a “freak show” over in quantum mechanics.

Space is constructed

Muster detailed the experimental evidence that has established that entanglement is a real phenomenon. String theory, loop quantum gravity, and other attempts to explain what’s happening have, at their cores, a similar idea, according to Musser. That idea is that space isn’t just empty and out there; it’s made of something.

“Anyone working on quantum gravity thinks that at some level space is constructed,” Musser explained. “That gives you the opening to deal with non-locality. No longer is that an insoluble puzzle that has been hanging in the air since Einstein’s days.”

Muster suggested thinking about water to illustrate the idea. A single molecule of H2O does not have the properties of water. It’s only when you get a whole bunch of that molecules together that water can flow or have surface tension.

“Likewise, if space consists of atoms, each individual atom is not spacial. Each individual atom lacks the properties we associate with spacial things,” Musser said. “Those spacial properties are derived collectively from the interactions among atoms.”

Given that idea, it’s possible that space can also change its state, just like water can boil and evaporate or freeze, and perhaps that’s part of what is driving our perception of different locations and entanglement.

“It seems that these things are in a predetermined location, but maybe that quality of being in a predetermined location is actively being generated all the time, below our level of consciousness, below the level even of our theories,” Musser said. “There’s some deeper machinery in the natural world.”

It’s a complicated concept to work into a 500-word blog post or a 45-minute lecture. You can listen to an audio recording of Musser’s talk on the Town Hall Seattle website. He is an engaging speaker, and Spooky Action at a Distance promises to be a good read.

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Dark matter may have killed the dinosaurs

Harvard particle physicist and author Lisa Randall has a new hypothesis about what killed the dinosaurs, and it’s a surprisingly simple one. The possible culprit: dark matter.

Lisa Randall

Physicist Lisa Randall spoke at Town Hall Seattle about her hypothesis that dark matter may have triggered the events that killed the dinosaurs. Photo: Greg Scheiderer.

Randall visited Town Hall Seattle last week to talk about her ideas, explained in her new book Dark Matter and the Dinosaurs: The Astounding Interconnectedness of the Universe (Ecco, 2015).

Randall noted that ordinary matter forms into disks like our galaxy and solar system because it interacts with light, radiates photons, cools, and collapses. Dark matter, on the other hand, doesn’t interact with light and so stays diffuse. It is believed that the Milky Way Galaxy sits inside an essentially spherical halo of dark matter.

Here’s where Randall throws in a what-if. The model for dark matter presumes it consists of only one type of particle. But that’s not necessarily so.

“Maybe there’s a new type of dark matter in addition to the dark matter that people talk about,” Randall said.

“Suppose you had dark matter which could radiate,” she speculated. “Maybe dark matter interacts with its own light, which I’m going to call dark light.”

If that’s the case, this particle also could form structure, Randall said.

“Most of the dark matter is going to stay intact in a spherical halo, but this small fraction, maybe five percent of dark matter that interacts with dark light, can also collapse into a disk,” she said. This thin disk of dark matter would be embedded in the plane of the galaxy.

Here’s how that could have been the death blow for the dinosaurs, and a big chunk of the rest of the life on Earth, about 66 million years ago. Randall noted that, as our solar system rotates around the galaxy, it doesn’t follow a simple, flat course.

“As it goes around it actually bobs up and down through the plane of the Milky Way,” every 30 million years or so, she said.

“When it goes through that mid-plane, if there is a dark-matter disk there will be an enhanced gravitational force,” Randall explained. “So our hypothesis is that every time it goes through the mid-plane it can trigger comets getting dislodged from the Oort Cloud, and one of those could have been the comet that actually did in the dinosaurs.”

Randall stresses that this is all highly speculative, but she’s looking for evidence in her current research. She’s hoping to get data to further test the notion from the Gaia satellite, which will make precise measurements of the motions of about one billion stars. That will help us get a better handle on dark matter and where it is.

In the meantime Randall marvels at the interconnectedness of the universe. Galaxies could not have formed without dark matter, yet it may also have set into motion events that wiped out much of the life on our planet, also paving the way for large mammals, like us, to flourish.

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Astro happenings every night this week

There’s plenty to do in Seattle this week for those interested in astronomy, as there is at least one event every evening through Saturday.

Physics week at Town Hall

Town Hall Seattle will welcome two authors to the city this week. Harvard particle physicist Lisa Randall will speak at 7:30 p.m. Monday, Nov. 2, about her new book, Dark Matter and the Dinosaurs: The Astounding Interconnectedness of the Universe (Ecco, 2015). Did dark matter kill the dinosaurs? Randall draws a connection between the Milky Way and the dislodged comet that smashed into Earth 66 million years ago. She’ll describe the ins and outs of this idea, explain what historical galactic events have to say about the present, and, perhaps most importantly, instill a greater appreciation for the interconnectedness of the universe we live in. Tickets, $5, here.

Town Hall will feature more physics on Tuesday, Nov. 3, as journalist George Musser of Scientific American talks about his new book, Spooky Action at a Distance: The Phenomenon That Reimagines Space and Time—and What It Means for Black Holes, the Big Bang, and Theories of Everything (Farrar, Straus and Giroux, 2015). The title is a nod to Einstein’s critique of quantum mechanics, and Musser will look at the universe, black holes, the Big Bang, wormholes, and other somewhat unknown areas of physics. In this month, which marks the centennial of the publication of Einstein’s theory of relativity, he will celebrate today’s best scientific thinking and help us understand it. Musser’s talk will begin at 7:30. Tickets are $5 here.

UW astro anniversary celebration continues

Morales

Morales

The University of Washington Alumni Association is helping to celebrate the 50th anniversary of the university’s Department of Astronomy with a series of four lectures titled The Big Bang and Beyond: Four Excursions to the Edges of Time and Space. The second in the series will be held Wednesday, Nov. 4 at 7:30 p.m. in room 120 of Kane Hall on the UW campus in Seattle. UW professor Miguel Morales will give a talk titled “The End of the Beginning,” focusing on how scientists read the subtle patterns in the cosmic microwave background to infer what happened in the first few moments of our universe’s history.

All of the free tickets for this lecture, and for the others in the Big Bang and Beyond series, have been claimed. It may be possible to gain admission on a waiting list should there be no-shows. Check our previous post for a rundown of other anniversary events.

Spacefest comes to Museum of Flight

spacefestlogoThe Museum of Flight will host a three-day Spacefest beginning Thursday, Nov. 5 and running through Saturday the seventh. Highlights of the event include astronaut John Herrington leading a glider-building session during the museum’s free-admission evening on Thursday, discussions Friday about the rigors of human spaceflight, and a look Saturday at the challenges of a trip to Mars.

Visit the museum website for a full schedule of the three-day festival.

Origins

originsposterThe centerpiece of the UW astronomy anniversary celebration is a multimedia concert, Origins: Life and the Universe, at 2 p.m. Saturday, Nov. 7 at Benaroya Hall in downtown Seattle. Eight Seattle composers have created original orchestral music that showcases the complexity and beauty of our universe. The symphonic concert will be accompanied by projected high-resolution movies created using some of the most spectacular imagery, videos and conceptual art from the Hubble Space Telescope and a variety of other sources. The live concert will feature Grammy-award winning conductor David Sabee and the renowned Northwest Sinfonia orchestra.

Check our previous previews of pieces of the concert, with composers Nan Avant and Glenna Burmer.

The concert is a benefit for scholarships in the UW Department of Astronomy and Astrobiology program. Tickets are $32, $22 for students, and are available through the Seattle Symphony website.

TAS and spectroscopy

The Tacoma Astronomical Society will hold one of its public nights beginning at 7:30 p.m. Saturday, Nov. 7 at the Fort Steilacoom campus of Pierce College. The night will feature a presentation about spectroscopy. In addition, club members will have telescopes on hand should weather conditions be favorable for observing the heavens.

Don’t forget to look up

Venus, Jupiter, Mars, and the Moon are holding a little dance during the mornings all week. Check them out high in the southeast before dawn. The Taurid meteor shower peaks on Nov. 5, but watch out for a few days before and after as well. EarthSky has a good article about watching the Taurids, and Astronomy magazine’s The Sky This Week has daily observing highlights.

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