Tag Archives: Priyamvada Natarajan

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.


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.

You can purchase Mapping the Heavens by clicking the book cover or title link above. Buying through Seattle Astronomy helps defray our costs of creating and serving these articles. Thank you!


NEOWISE, Viking, and more on the calendar this week

The Seattle Astronomy calendar is packed with interesting events this week, with something going on just about every evening. Seattle gets two talks about NEOWISE, the Mars program premieres on the National Geographic Channel, and there are several other lectures of note.


NEOWISEWill an asteroid or comet one day smack into Earth again? One of the sets of eyeballs looking for Near Earth Objects (NEOs) is the Wide-field Infrared Survey Explorer (WISE). Joe Masiero, a JPL scientist with NEOWISE, will give two talks about the project this week in Seattle. He’ll speak at the monthly meeting of the Seattle Astronomical Society at 7:30 p.m. Wednesday, November 16 in the Physics/Astronomy Auditorium on the University of Washington campus. Masiero will return to the same room at 4 p.m. Thursday, November 17 for a presentation at the weekly UW astronomy colloquium. He will give an overview of the NEOWISE mission, and present some results from the latest dataset release.

Mapping the heavens

The cosmos, once viewed as stagnant, even ordinary, is now understood to be a fathomless universe, expanding at an accelerating pace, propelled by dark energy, and structured by dark matter. Theoretical astrophysicist Priyamvada Natarajan, author of Mapping the Heavens: The Radical Scientific Ideas That Reveal the Cosmos (Yale University Press, 2016), will give a talk about these ideas at 7:30 p.m. Monday, November 14 at Town Hall Seattle. Natarajan will explain the science behind some of the most puzzling cosmological topics of our time and discuss why there is so much disagreement within the science community about astronomical discoveries.

Tickets are $5 and are available online.

Preserving Viking

VMMEPPThe final of three Science Pub events about the Viking missions will be held at 6 p.m. Monday, November 14 at the Old World Deli in Corvallis, Oregon. Rachel Tillman, Founder and Executive Director of The Viking Mars Missions Education & Preservation Project, and others involved in the missions, will talk about Viking and its influence on technology and culture. The Science Pub is a program of the Oregon Museum of Science and Industry. It’s free!

If you are not able to attend this event and missed the previous ones in Portland and Eugene, fear not; Seattle Astronomy is working on a feature article about The Viking Mars Missions Education & Preservation Project. Stay tuned!

Eugene Astro

The Eugene Astronomical Society will hold its monthly meeting at 7 p.m. Thursday, November 17 at the Science Factory planetarium. The club’s mirror-grinding group will give a presentation about how reflecting telescopes’ primary mirrors are made, complete with demonstrations of the grinding process.

Cosmos on Tap

Astronomy on Tap Seattle, November 2016This month’s Astronomy on Tap Seattle event will be held at 7 p.m. Wednesday, November 16 at Peddler Brewing Company in Ballard. They’ll view episode five of the original Carl Sagan Cosmos series, complete with Cosmos bingo, trivia contests, prizes, and beer. Astronomers will discuss what’s changed, and what science has held up, since the series first aired.

Astronomy on Tap Seattle is organized by graduate students in astronomy at the University of Washington.

A home in the stars

Want to live on Mars? Maybe a bad idea. Planetary scientist Amanda Hendrix and science writer Charles Wohlforth have looked into space colonization, and suggest that Saturn’s moon Titan might be a better place. The authors of Beyond Earth: Our Path to a New Home in the Planets (Pantheon, 2016) will discuss their findings at 7:30 p.m. Friday, November 18 at Town Hall Seattle. Why Titan? It has a nitrogen atmosphere, a weather cycle, and an inexhaustible supply of cheap energy. Get the full story from Hendrix and Wohlforth; grab the book in advance.

Tickets are $5 and are available online.


MARS showOK, some may want to give Mars a shot! The television mini-series Mars premieres at 9 p.m. Monday, November 14 on the National Geographic Channel (although an online stream of the opening episode has been available online for several weeks now.) Part feature film, part documentary, the series takes a look at what a Mars mission might look like in 2033, and talks with today’s experts about the development of technology and capabilities that could make such a mission a reality. Ron Howard is an executive producer of the series, which has been directed by Everardo Gout.


The Tacoma Astronomical Society plans one of its free public nights for 7:30 p.m. Saturday, November 19 at the Fort Steilacoom campus of Pierce College. The all-weather presentation will be about the New Horizons mission to Pluto and beyond. If the skies are clear club astronomers will break out the telescopes for some observing.

Up in the sky

There’s a “supermoon” on Monday and the Leonid meteor shower peaks this week. This Week’s Sky at a Glance from Sky & Telescope magazine and The Sky This Week from Astronomy offer more observing highlights for the week.


Get the scoop on SpaceShipOne

A lesson on how to make a spaceship and several astronomy club events highlight the local calendar for the coming week.

Road to SpaceShipOne

Meet the principals in XPRIZE-winning SpaceShipOne project at 5:30 p.m. Monday, October 17 at the Museum of Flight. Author Julian Guthrie will discuss her book about the XPRIZE competition, How to Make a Spaceship: A Band of Renegades, an Epic Race, and the Birth of Private Spaceflight (Penguin Press, 2016). Three of the renegades will join her as Geekwire science correspondent Alan Boyle moderates a panel discussion including XPRIZE founder Peter Diamandis, co-founder Erik Lindbergh, and Dave Moore, project manager for Paul Allen on the XPRIZE-winning SpaceShipOne.

The evening will include a meet-and-greet reception from 5:30 until 6:30, Guthrie’s presentation at 6:30, the panel discussion at 6:45, and a question-and-answer session and book signing from 7:30 until 8:30. Cost is $10 and tickets are available online.

You can pick up a copy of the book at the link above or by clicking the image of the book cover.

Astro club events

Michael BarrattThe Rose City Astronomers will hold their monthly meeting at 7:30 p.m. Monday, October 17 at the Oregon Museum of Science and Industry in Portland. The guest speaker will be astronaut Michael Barratt, who spent 199 days in space as flight engineer for International Space Station expeditions 19 and 20 in 2009 and also flew on STS-133, the final flight of the shuttle Discovery, in 2011. Barratt is a native of the Portland area.

The Eastside Astronomical Society will hold its monthly meeting at 7 p.m. Tuesday, October 18 in the Willard Geer Planetarium at Bellevue College. Patti Terhune-Inverso, an astronomy instructor at the college and a member of Eastside Astronomical Society, will present the introduction to the constellations that she uses for her classes at the beginning of each quarter.

The Seattle Astronomical Society will hold its monthly meeting at 7:30 p.m. Wednesday, October 19 in room A102 of the Physics/Astronomy building on the University of Washington campus in Seattle. The program had not been published as of this writing.

Astronomy in Pierce County Saturday

Pierce College will host a couple of events at its Fort Steilacoom campus on Saturday, October 22.

haunted-night-skySpook-tober continues at the Pierce College Science Dome, which will be presenting a kids’ show called “Haunted Night Sky” on Saturdays through Halloween. Participants will be able to find creatures in the night sky, build a Frankenstein satellite, and take a tour of the Sea of Serpents on the Moon, the Witch’s Head Nebula, and other spooky places in the universe. Best for kids ages 3-12. Shows are scheduled for 12:30 p.m. and 2 p.m. each Saturday. Cost is $3.

The Tacoma Astronomical Society plans one of its public nights for Saturday evening at 7:30. The indoor program will be a Halloween special. They’ll break out the telescopes for observing if the weather cooperates.

Futures file

You can scout out future astronomy events on our calendar. New additions to the calendar this week include a talk by astrophysicist Priyamvada Natarajan at Town Hall Seattle November 14. Natarajan will talk about her new book, Mapping the Heavens: The Radical Scientific Ideas That Reveal the Cosmos (Yale University Press, 2016). Tickets are $5 and are available online.

Up in the sky

The Orionid meteor shower peaks this Friday and Saturday. Learn about the showers and other observing highlights for the week by visiting This Week’s Sky at a Glance by Sky & Telescope magazine and The Sky This Week by Astronomy.