Tag Archives: Jim Peebles

Our favorite Seattle astronomy events from 2015

Happy New Year from Seattle Astronomy! Yesterday we ran down our top five news stories of the past year. Today, let’s take a look back at our top talks and events from 2015.

Comet Hunter

Scheiderer and MachholzRenowned comet hunter Don Machholz was the keynote speaker last year at the annual banquet of the Seattle Astronomical Society. Machholz has discovered eleven comets visually, without the aid of CCD cameras and other modern aids, and that’s the record. He does it the old-fashioned way, sitting at the eyepiece for hours at a time and sweeping the sky for something that wasn’t there before.

Machholz told a wonderful tale about his techniques of comet hunting and about the intensely personal reasons that drove him to the quest. It was an informative, touching, and often hilarious presentation filled with images and music.

It’s all relative

Jeffrey Bennett at the UW's physics/astronomy auditorium. Photo: Greg Scheiderer.

Last year was the international year of light and marked the 100th anniversary of the publication of Einstein’s theory of relativity. Jeffrey Bennett toured the country to help us better understand relativity, and stopped in at the April meeting of the Seattle Astronomical Society to give a well-received talk about the concepts of relativity. Bennett is an engaging lecturer and his book, What Is Relativity?: An Intuitive Introduction to Einstein’s Ideas, and Why They Matter, (Columbia University Press, 2014) is a big help, too, that makes a topic that is so mind-bending and daunting to so many truly accessible to a broader audience.

We did a preview interview with Bennett as well.

Physics pioneer

Jim Peebles

Science is mostly about brainpower and creativity, and testing, but there’s some luck involved, too. Case in point: back in 1965 Jim Peebles and colleagues at Princeton were on the hunt for what we now know as the cosmic microwave background, the lasting signature of the Big Bang. Up the road at Bell Telephone Labs, Bob Wilson and Arno Penzias had found the CMB, but didn’t realize what they had! To the latter went the Nobel Prize, but Peebles has been in the forefront of research on the CMB for the past 50 years. We now know a lot about the history of our universe, except for the first fleeting moments that remain a mystery. Peebles talked about that history at a UW lecture in May.

Space tourist

SimonyiCharles Simonyi shelled out a lot of cash to fly to the International Space Station in a Soyuz capsule with the Russians—speculation is that his tab for two trips, in 2007 and 2009, came to about $60 million. Simonyi gave a talk at the University of Washington in September about the practicalities of space travel, and when it might be possible for those of us with somewhat lesser means.

The answer, sadly, is not that soon, but Simonyi envisions a day when the cost of launching a kilogram of mass into space might be driven down to $100, and that might make the cost of space travel something that more people could consider.

Simonyi’s story was an entertaining one that was as much about the training for his two trips to space as it was about the technical aspects of getting there.

Dark matter and the dinosaurs

Lisa RandallHarvard particle physicist and author Lisa Randall has a new hypothesis about what may have killed the dinosaurs on Earth. It’s a surprisingly simple notion, at least once you get past the fact that it depends on a new sort of particle that we haven’t yet detected.

Randall spoke at Town Hall Seattle in November about her ideas and her new book, Dark Matter and the Dinosaurs: The Astounding Interconnectedness of the Universe (Ecco, 2015). The theory in a nutshell: suppose that there’s a type of dark matter that interacts with light. Such dark matter could collapse into a disk, just like our galaxy. As our solar system orbits the galaxy, we periodically go up and down through the galactic plane. Passing through the plane would also move us through this disk of dark matter, which could gravitationally dislodge comets from the Oort Cloud and send them hurtling our way.

It is an interesting idea that Randall says she’ll devote much time to testing in the coming years.

Honorable mention on our list: the lecturers of the Big Bang and Beyond series at the UW, including Andy Connolly, Miguel Morales, Julianne Dalcanton, and Adam Frank; George Musser, who spoke about his 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 (Scientific American / Farrar, Straus and Giroux, 2015); and Curiosity rover chief engineer Rob Manning, who gave a talk based on his tome Mars Rover Curiosity: An Inside Account from Curiosity’s Chief Engineer (Smithsonian Books, 2014).


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.