Cosmologist concludes spring ‘Physicists’ series

Sonoma State University concluded its final lecture of this semester’s series, What Physicists Do, on Nov. 18 with Deborah Bard. She is a cosmologist from Stanford Linear Accelerator Center (SLAC) and Kavli Institute for Particle Astrophysics and Cosmology (KIPAC).

She originally studied to become a particle physicist, but was instead drawn to cosmology later in life. The interesting thing is that particle physics is the study of the properties, relationships and interactions of subatomic particles.

This is basically very small, precise things, whereas cosmology is the much more broad study of the universe such as its past and future fate.

“As a cosmologist we worry about what the universe is made of, what we think its made of and what tools we use to find out,” said Bard.

In a room packed with about 140 students and community members, Bard stood in front of a screen with the words, “The Dark Universe Through Einstein’s Lens” projected behind her.

She began her speech with a story of a hypothetical question her elementary teacher once posed to her while she was 11 years old asking,  “What would it be like if light could bend around corners?” 

Bard explained how this idea fascinated her and how her mind went bananas thinking of the amazing possibilities that would come from this idea.

As she grew older, she learned that this idea of light bending around corners is not only a fun thought experiment, but also a very real event that was originally posed by Albert Einstein a hundred years ago.

While Einstein was conducting studies, which eventually turned into his theory of general relativity, he posed an idea in which light is affected by gravity: meaning a star far off from Earth would appear in a different position than it truly is because of the light being bent around large objects, like the sun or other planets and galaxies.

In 1919, this theory was confirmed with a study of a solar eclipse and the stars appearance during that eclipse. To put it in easier terms for the audience to understand, she explained the idea of having a large metal sheet. If one were to put a heavy object on the sheet it would bend slightly.

The same idea is true with light; this bending of light is called “gravitational lensing.” In simple terms, using gravitational lensing Bard can use this as a “tool” to help better understand what is in the universe. 

On a pie graph that presented what the universe is made up of, it showed 22 percent dark matter, 74 percent dark energy and only four percent atoms. Bard’s current job is to learn more about and better study what dark energy is and how it works using the help of gravitational lensing.

Bard closed her speech with her new project that should be in construction starting next year known as the Large Synoptic Survey Telescope (LSST), which will be built on a mountain in Chili, and will be the largest digital camera ever built to date.

Due to its large aperture, this telescope will be able to take quicker photos: every 15 seconds, compared to the  average every 30 minutes, allowing the entire southern hemisphere to be completely pictured every three days.

From the great amount of pictures the LSST will take, Bard and her colleagues will be able to study long-term changes, even in the slightest bit of galaxies, their gases and dark energy.  Over the next 10 years Bard, with the help of the LSST, will be able to exponentially grow our currently minimal knowledge of dark energy.

The What Physicists Do lecture series will resume in January 2014, and will have an all new set of speakers. To find a list of both past and present speakers, visit the webpage at phys-astro.sonoma.edu.