Category Archives: physics

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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The history of the universe in ten minutes

As communicators of science our job is often to take huge amounts of complicated information and condense it into something understandable. Scientist, composer, and author Glenna Burmer recently took on a monumental task: explain the 13.8 billion year history of the universe in a ten-minute movie.

Glenna Burmer

Glenna Burmer talked during a presentation at the Museum of Flight about her process for creating her movie “The Big Bang.” Photo: Greg Scheiderer.

“There are some challenges being an amateur filmmaker and trying to condense this much information into a movie,” Burmer understated. She did it, though, and you will be able to see her work as part of the Origins: Life and the Universe multimedia concert that will be held Nov. 7 at Benaroya Hall. Burmer is one of eight composers whose work will be featured at the event. She and UW professor Matt McQuinn spoke at the Museum of Flight last Saturday to explain the Big Bang and preview Burmer’s film.

Burmer is a scientist; a molecular pathologist and expert in immunohistochemistry.

“As a passion, I have always loved astronomy,” she said in explaining her involvement in the project. Though a scientist, Burmer comes from a family of artists and musicians.

“Consequently, I’ve always wanted to try to synthesize science, art, and music, and this concert gives me the first-time opportunity to really do that,” she explained.

Among the challenges in doing a film about the Big Bang is that there’s no existing footage of the event, so creating visuals relied in part on particle animation technology. Burmer admits to being thrown off a bit by tensor calculus, membrane theory, and string theory, but she got enough understanding to help animators create a sequence demonstrating a Big Bang based on ekpyrotic theory. The animation shows two 3-D universes.

“They approach each other, they leak gravity, and they bud off our universe,” Burmer explained.

McQuinn

UW astronomy professor Matt McQuinn explained the evidence for the Big Bang during a talk Oct. 17 at the Museum of Flight. Photo: Greg Scheiderer.

Her film also uses pieces of many of the computer simulations McQuinn, a theoretical astrophysicist and cosmologist, used in explaining the Big Bang. He started out with an account of the discovery of the cosmic microwave background, the signature of the Big Bang. Our coverage of a recent Seattle lecture by Jim Peebles tells this tale as well.

McQuinn noted that the best evidence for a hot Big Bang is that there is way more helium in the universe than could have been created by fusion in stars. The explanation is that, soon after the Big Bang, hydrogen fused much more easily in the hot, dense new universe. Astronomers have built models based on the measurements of the radiation in the cosmic microwave background and how much helium such conditions would produce.

“The predictions from the hot Big Bang model just fall perfectly on the measurements,” of what is actually out there, McQuinn said. “This, coupled with the fact that we have seen the cosmic microwave background, makes it almost indisputable that there was a hot Big Bang. No respected scientist questions this picture any more.”

McQuinn explained that galaxies eventually formed because of fluctuations in the density of mass and energy. An as-yet undetected particle called the inflaton may be the cause.

originsposter“This particle seeded these density fluctuations,” McQuinn said. “The predictions of this model are in striking agreement with what we see, so people think that this is the answer for the source of energy fluctuation.”

“From studying the cosmic microwave background radiation, we’ve come to these profound conclusions,” McQuinn concluded. “We’re able to explain the universe down to planetary scales.”

The “Origins” concert is part of the celebration of the 50th anniversary of the Department of Astronomy at the UW. The concert will feature the work of eight composers and accompanying celestial photography. It is a benefit for the scholarship program at the University of Washington Astrobiology Program in the Department of Astronomy. Tickets are $32, $22 for students, and are available online or by calling the Benaroya Hall ticket office at 206-215-4747.

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Jim Peebles and the cosmic microwave background

Jim Peebles is a giant of science. He was studying physical cosmology long before it was considered a serious, quantitative branch of physics, and has done much to establish its respectability. Peebles also has contributed a great deal to the thinking about dark matter and dark energy.

Jim Peebles

Legendary physical cosmologist Jim Peebles makes a point during a lecture at the University of Washington May 19, 2015. Photo: Greg Scheiderer.

Peebles, the Albert Einstein Professor of Science emeritus at Princeton University, gave a lecture titled “Fifty Years of the Cosmic Microwave Background” recently at the University of Washington.

“The last 50 years have seen a truly transformative advance in our understanding of the world around us,” Peebles noted in opening the talk. He explained that the idea of the Big Bang had been bouncing around for a while, and in the early 1960s folks were setting out to prove it as fact. Peebles was a research associate with Bob Dickie at Princeton, and the two of them advanced the idea of the cosmic microwave background. Along with research associates Peter Roll and Dave Wilkinson, they built a microwave radiometer to detect the signature of a hot Big Bang.

Little did they know that the evidence had already been spotted and measured.

Several years earlier, Bell Telephone Laboratories in New Jersey had done an experiment in communication using microwave radiation.

“This was an important forerunner to the sight of our students wandering around campus staring at their cell phones,” Peebles quipped. The experiment also found a lot of background radiation despite the best engineering efforts to eliminate it. By 1963 Bob Wilson and Arno Penzias at Bell wanted to use the technology to do radio astronomy, but they needed to solve the problem of the system noise.

“The Bell people had this constant irritation,” Peebles said. “They were getting more radiation than they expected from their communications experiments.”

It must be the CMB

Peebles had already been doing lectures about the possibility of the cosmic microwave background. By 1964 the Bell folks and the Princeton people got together. Peebles and Dickie figured that the system noise plaguing Wilson and Penzias was actually the cosmic microwave background.

“We had the possibility of a great discovery,” Peebles recalled. “We already knew right away that this was something new. That was exciting because you have a new phenomenon, something new to measure, and something new to make theories about.”

Measuring to prove it

The measurement piece took a quarter century, and was accomplished with spectacular precision by two experiments just months apart in 1990: NASA’s Cosmic Background Explorer (COBE) satellite, headed by John Mather of the Goddard Space Flight Center and George Smoot of Berkeley, and a rocket-borne experiment launched by Herb Gush of the University of British Columbia, along with Mark Halpern and Ed Wishnow. Both projects, in development for about 15 years, made measurements that meshed perfectly with the theoretical predictions for the cosmic microwave background.

COBE all-sky map

COBE all-sky map. Image: NASA.

“It’s a glorious piece of evidence, I would say an iconic piece, that shows tangibly that the universe had to have evolved from a different state, because this is a thermal spectrum,” Peebles marveled. “Our universe as it is now is transparent for this radiation. There is no way it could force the radiation to relax to this thermal equilibrium. The universe had to have evolved from a state in which it was dense and hot enough to have relaxed to equilibrium and then expanded away from it.”

Interestingly, this is a tale of “missed it by that much” when it comes to Nobel Prizes. Dickie, Peebles, and the Princeton team were well on their way to making the measurement when they learned that Wilson and Penzias had already stumbled across it. The latter two won the Nobel in 1978 for their work. Mather and Smoot won the Nobel in 2006 for their COBE measurements, but Gush may have beaten them to it had it not been for equipment troubles that delayed the launch of his experiment.

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Bennett talk Wednesday at SAS: general relativity made easy

Dr. Jeffrey Bennett says you don’t have to have the brain of an Einstein to understand general relativity.

“If you want to deal with all the mathematics of it then it is pretty complex,” Bennett says, “but if you want to just understand it on a conceptual level, it’s not that difficult to get a general grasp of it.”

Bennett, the author of of What Is Relativity?: An Intuitive Introduction to Einstein’s Ideas, and Why They Matter (Columbia University Press, 2014), will talk about the book, and relativity, at next week’s meeting of the Seattle Astronomical Society. The meeting, which is free and open to the public, begins at 7:30 p.m. Wednesday, April 15, in room A102 of the Physics/Astronomy Building on the campus of the University of Washington in Seattle. There’s still time to pick up the book, by clicking the link above or the cover to the left, before the talk.

Seattle Astronomy spoke earlier this week with Bennett, an adjunct research associate with the Center for Astrophysics and Space Astronomy at the University of Colorado. He says his Relativity Tour is a bit of an accident of timing. He’d been thinking about writing a book about relativity for several years. When the book came out last year it was just in time for the centennial of Einstein’s breakthrough, and Bennett decided to do his part for the International Year of Light and help the general public understand general relativity and how it makes so many everyday things possible.

Einstein was right

While Einstein proposed general relativity one hundred years ago, Bennett notes that many people still think of it as new physics, and others still strive to prove Einstein was wrong, but Bennett says that’s not going to happen.

“You can’t do that because it has checked out so much; you can’t make the evidence where it does check out go away,” Bennett explains. “In the same way, Einstein didn’t show Newton to be wrong. What you’re really looking for is to see if we can find a place where Einstein’s theory is not yet complete, and we need something else to take us to that next level.”

A good example of such a place is trying to find agreement between general relativity and quantum physics.

“That’s the known hole in our current understanding,” Bennett says. “Even though both work extremely well in the regimes in which they’ve been tested, they don’t quite meet up, and therefore there must be something else that we have not yet figured out that brings them together.”

Relativity for all audiences

Dr. Jeffrey Bennett

Dr. Jeffrey Bennett

Bennett, a recipient of the American Institute of Physics Science Communication Award in 2013, speaks to a wide variety of audiences, from adults down to elementary school kids, and has written children’s books as well as college texts.

“The commonality across all of the work that I do is that it’s all aimed at people who are not really very familiar with science and math, and in some cases, with the older audiences, maybe thinking they’re sort of afraid of these topics,” he says. “I’m always dealing on that introductory level—what science is and why you should care about it. When you’re dealing with it at that level, it’s not really that different to deal with children or with grownups, because either way you’re dealing with the same lack of knowledge and lack of understanding.”

Bennett recommends the talk he will do Wednesday for people from middle school on up, though he says younger kids often understand it as well.

“Come with an open mind,” he urges. “Even if you think this is something that you can’t understand, I think you’ll find you actually can, so I hope people will come in that spirit.”

More reading

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Inflation: A cold little swoosh

Max Tegmark says that when he was applying for graduate school in physics, you’d best not mention the idea of parallel universes if you wanted to be accepted. A quarter century later Tegmark, an MIT physicist, stood before the 225th meeting of the American Astronomical Society making a plenary address titled “Inflation and Parallel Universes: Science or Fiction?” that made the concepts seem downright plausible.

Tegmark’s 2014 book, Our Mathematical Universe: My Quest for the Ultimate Nature of Reality, has sparked a lot of conversation inside and outside the scientific community. AAS Vice President Jack Burns of the University of Colorado says that made Tegmark a great pick for a talk at the biannual confab of astronomers.

Tegmark

MIT physicist Max Tegmark speaks at the American Astronomical Society meeting Jan. 7 in Seattle.

“Max’s approach to cosmology and big-picture questions have really been largely non-traditional, and I find that exciting,” Burns said in introducing Tegmark at the Jan. 7 meeting in Seattle. “Max is a rebel within a highly orthodox infrastructure that we all have to work in.”

Tegmark said that we as a species have a history of thinking too small.

“If we ask what we humans have figured out so far during the 13.8 billion years of our cosmic evolution, I think it’s one long story of underestimation,” Tegmark said. “We’ve again and again and again underestimated the size of our cosmos, realizing that everything that we thought existed was just a small part of something much grander: a planet, a solar system, a galaxy, clusters of galaxies, our observable universe, and maybe, as we’ll explore in this talk, a hierarchy of parallel universes.”

Tegmark said he wasn’t there to prove that inflation or parallel universes exist, but to correct some misconceptions. Most particularly, he poked at the notion that the existence of parallel universes cannot be tested scientifically. He contends that inflation predicts many phenomena that can be observed and measured. We wouldn’t throw out general relativity just because we have yet to observe a black hole directly. Likewise he said we shouldn’t dismiss parallel universes because we have yet to visit one.

Tegmark noted that inflation is more than just a mainstream idea now.

“It’s really, in my opinion, the most audacious idea we have, the most audacious extrapolation of physics so far,” he said. He noted that human growth interestingly parallels an inflationary early universe. Our number of cells double daily after conception, but the growth rates slows down soon after. The same happened with inflation. He points out that many people often think incorrectly that inflation followed the Big Bang.

“Inflation creates the Big Bang,” Tegmark said. “I think it’s more logical to say that before our Big Bang there was a cold little swoosh. That’s the early stages of inflation.”

“Inflation does this great party trick,” he added. “You can start with a tiny finite volume, less than a proton, and within there you can make an infinite volume inside the finite volume.”

Beings within a pocket may not be aware of what is going on outside.

“It’s pretty crazy, but that’s what you can do with general relativity,” Tegmark said. “Moreover, if there are many places where inflation doesn’t end, there’s nothing preventing you from having multiple, disconnected pockets like this.”

So how does Tegmark answer his own question? Are inflation and parallel universes science or fiction?

“Inflation has emerged as the most mainstream explanation for what happened early on,” he contended. “Whether it actually occurred and produced parallel universes is, of course, not yet settled. It remains controversial. But the key point that I want you to take away from this is that this controversy is clearly a scientific controversy, not a philosophical one, because the way it’s being settled is with data, not by people beating each other over the head with bottles in a bar.”

“2015 should bring much more clarity to what is going on,” Tegmark concluded. “Our universe is going to be an exciting place this year.”

The talk was engaging and the book should be a good read.

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Tessering around the universe with A Wrinkle in Time at OSF

It is a bonus when our interests in theater and astronomy intersect, and that is happening this season at the Oregon Shakespeare Festival in Ashland with its production of A Wrinkle in Time, based on the 1962 novel of the same title by Madeleine L’Engle. The OSF play is a world premiere adapted and directed by Tracy Young.

A_Wrinkle_in_Time

Alejandra Escalante as Meg Murry in the Oregon Shakespeare Festival production of A Wrinkle in Time.

In A Wrinkle in Time math whiz Meg Murry (Alejandra Escalante), her über-genius little brother Charles Wallace Murry (Sara Bruner), and pal Calvin O’Keefe (Joe Wegner) zip around the universe in search of missing papa Murry (Dan Donohue). They accomplish their travel by bending time and space in a tesseract, or “tessering,” as explained by the helpful science fair project by Science Girl (Jada Rae Perry).

Kids traversing the universe make for some imaginative and wonderfully silly stage effects and costumes, and we think especially of the multi-tentacled Aunt Beast (Daniel T. Parker), for whose costume a good half-dozen vacuum cleaners must have given their lives, or at least their hoses.

The performances are top-notch. We single out Escalante and Bruner especially, as well as Judith-Marie Bergan, who was much fun as Mrs. Whatsit, something of an intergalactic tour guide for the adventurers. Bergan, we think, can play anything, from the comic to the manic (as we note my Sweetie, the official scorer’s, recent review of last year’s production of The Tenth Muse.)

For all of its goofiness, the play takes on some serious themes about the mysteries of the universe, the nature of time and space, the dangers and advantages of technology, and of the strength and importance of family ties and love. The science isn’t so heavy that you need to be a cosmologist or physicist or a math geek like Meg to get it, though a bit of sci-fi familiarity with the concept is helpful.

According to the program notes the book took criticism from all sides when it came out, some charging it with being too religious and others saying it is too secular. That feels like it hit the right spot! The book also has some Cold War undertones about how things would look under a totalitarian society.

We’ve not read the book but plan to pick it up when we return home from Ashland. The play runs at the Angus Bowmer Theatre through November 1. It’s great fun; check it out!

***

This review is republished from the West Seattle Weisenheimer.

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