New findings back Einstein

Einstein's theory of relativity first introduced the idea of cosmic magnification — which pertains to the study of light — and how it is distorted on its way to Earth from distant quasars. A century later, scientists have confirmed Einstein's idea of cosmic magnification using data from the Sloan Digital Sky Survey.

By studying 200,000 quasars, the researchers were able to detect for the first time cosmic magnification on large scales.

"The theory of relativity is just a generic statement that space and time aren't separate things," said Gordon Richards '94, a University research scientist. "Mass tells space-time how to bend and the curvature of space-time tells objects how they'd move in space-time. Einstein was saying that the universe wasn't as simple as it looks."

The Sky Survey, one of the largest projects in modern astronomy, aims to digitally map a quarter of the sky. Confirming cosmic magnification was one of the side-projects of some who are working with the Survey.

"If you have a set of objects, like quasars, which are farther away than another set of objects, like nearby galaxies, then light coming towards us by the quasars can get distorted by the effect of gravity between us and the quasar," Richards said. "So what happens is that this gravitational bending of the light makes the background quasars look brighter than they would look if the galaxies weren't there."

This finding — to be published in the next issue of The Astrophysical Journal — verifies what scientists hypothesized to be true about the structure of the universe.

"What's interesting about cosmic magnification is that the answer we get matches really well with our current understanding of cosmology, so it's another way of confirming that we know more about the structure of the universe today than we knew a few years ago," Richards said.

He began working with the Sky Survey after graduating from the University in 1994. Richards was responsible for finding the quasars to study in the cosmic magnification project. It took a year to compile a sample of quasars.

Richards became interested in studying cosmic magnification because "it's one of those things where you read the literature and you realize that we have this data set that can do this better."

This project is just one of many accomplished with data taken from the Sloan Digital Sky Survey. The purpose of the project is to chart the history of the universe since the Big Bang.

"There is so much data that you can spend your whole life looking at it," Richards said.