Mapping Galactic Foam

Smithsonian astronomer Margaret Geller plotted the bubble structure of the universe. Now she’s working to find out how it got that way

"One of the great challenges of modern cosmology is to discover what the geometry of the universe really is."

Margaret Geller may be speaking to Harvard students in the popular astronomy course she's taught there for the past 15 years. But nothing could be closer to her true quest of understanding the geometry of the universe over time.

In 1986 Geller and her colleagues at the Harvard-Smithsonian Center for Astrophysics created a map of galaxies in the nearby universe. The map showed what few then believed possible: on the largest scale, the universe has a distinct structure, with "walls" of galaxies surrounding areas with very few galaxies. It has become known as the stickman map because some of the galaxies in it form what looks like a stickman.

Geller likens the universe's 3-D pattern to bubbles or foam and believes she has a clear picture of the structure of the current universe. Geller's latest foray into mapping galaxies, however, will look deep into space at a seven-billion-year-old universe. She hopes that charting that territory and comparing it with what the universe looks like now will show how objects in space form and evolve.

To better see and study this distant region, Geller will be using the Multiple Mirror Telescope (MMT) on Arizona's Mount Hopkins. New machines developed for this telescope ensure that measuring the distance of far-off galaxies will be faster than ever.

"There's something really beautiful about science," says Geller of her life's work, "that human beings can ask these questions and can answer them. You can make models of nature and understand how it works."