Richard Massey Demystifying Dark Matter.

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Richard Massey makes the invisible visible. His job: mapping the presence of so-called "dark matter" in the universe. "Everything that science has studied so far is ordinary material—it's the periodic table and the standard model of particle physics," says Massey, an astronomer at the Royal Observatory Edinburgh, in Scotland. "But that's just this tiny tip of the iceberg. There's five times as much dark matter, about which we know basically nothing."

Follow the Bending Light

Massey uses a technique called "gravitational lensing" to find dark matter. He analyzes pictures of the cosmos taken by the Hubble Space Telescope, which he describes as a simple digital camera with a big, zoom lens. Dark matter does not emit, reflect or absorb light, so we can’t see it directly, but it exerts a gravitational effect on things we can see. For instance, distant galaxies appear bigger and brighter than they are because dark matter, which resides along the billions of light years between them and us, bends the light they emit.

In gravitational lensing, the shapes of distant galaxies are distorted both by dark matter and the optics of Hubble's camera, but Massey and his colleagues can correct for the latter because they know the satellite inside and out. "We are using these galaxies as backlights for dark matter," Massey explains. "Even though the dark matter doesn't absorb the light, it subtly affects the light rays in a way that we can use to reconstruct its location."

Mac Decodes Hubble's Images

The high-resolution images from Hubble are several terabytes in size and contain upwards of two million galaxies. Massey uses a Mac Pro—which he bought for hardcore image analysis: finding all the galaxies in a given survey, measuring their shapes with extreme accuracy and removing any effects due to Hubble's optics.

The Mac simply snapped onto Caltech's massive Linux center, allowing Massey to use existing software libraries developed over more than a decade. Most of the programs for processing the Hubble images are written in Java and C shell scripts, whereas the visualization algorithms use IDL to analyze the shapes of galaxies and map out the dark matter. The Terminal application in Mac OS X let Massey take advantage of the command line input environment, a scientific standard. "The Mac just worked, and we were able to build on a repository of techniques and algorithms that had already been developed," he says. "It's a standing on the shoulder of giants kind of thing."

From Data to Dark Matter

Arguably the greatest success in Massey's still-young career came in early 2007. An effort he led to map out dark matter in a patch of space about the size of eight or nine full moons landed on the cover of the prestigious journal Nature. For publication, Massey collaborated with colleagues at the European Space Agency—using QuickTime Pro, along with Adobe products Photoshop and Illustrator—to create videos and graphics to portray the scaffolding that dark matter creates in the universe.

Once again, Mac's versatility rose to the occasion, and Apple LED Cinema Displays offered unparalleled views for their presentations. "There's no point in doing the hardcore analysis unless you can visualize and interpret the results, and there's no point in visualizing the results unless you can present them to the world," he says. "To be able to do all this on one machine was a fabulous surprise."

More Dark Matter Data for Mac

In fact, after being won over by Mac, Massey championed the platform at the more traditional Royal Observatory Edinburgh. "I bought a Mac Pro to go with my existing setup across the Atlantic, and more and more people are now buying Macs," he says, noting that he takes advantage of Apple iChat's screen sharing function to access his California-based Mac remotely. "Even places reticent to switch from UNIX, which has been the traditional way of doing things, are gradually converting."

Massey and his colleagues have aspirations to map dark matter throughout the whole universe. That means more terabyte, or rather, petabyte-sized images to analyze. Because of its all-in-one abilities to shepherd information from raw data to rich graphics, Mac will certainly play a crucial role in determining how our universe came to be and what its ingredients are.