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IN COSMOLOGY, it is often lamented that theorists get all the glory while the hard-working experimentalists get the shaft. Ann Finkbeiner is out to right this wrong in A Grand and Bold Thing, an inside look at the Sloan Digital Sky Survey (SDSS), which has created the most comprehensive 3D map of the universe ever made.

Finkbeiner鈥檚 story centres on Jim Gunn, the Princeton University astronomer who was awarded the US National Medal of Science in 2008. In the late 1980s, when Gunn began thinking about creating a massive digital survey of the sky, only around 10,000 galaxies had been catalogued. Fast-forward more than a decade, and the SDSS has mapped more than 230 million celestial objects, including more than 930,000 galaxies.

In this thoroughly researched book, Finkbeiner spends chapter after chapter detailing efforts by Gunn and others to get the project up and running. Such behind-the-scenes accounts of big scientific endeavours are rare 鈥� perhaps with good reason. The in-depth story of astronomers struggling to align the interests of their universities and navigating endless red tape while searching for funding simply isn鈥檛 very interesting.

The story picks up when Finkbeiner discusses how the SDSS has changed the way astronomy is done. She notes that 鈥淪loanies鈥� were among the first 鈥渁strocoders鈥� 鈥� astronomers who write software to gather and analyse their data. According to Gunn, she writes, 鈥渟ooner or later, the community will realise that its lone-astronomer days are over, that the subject has become too vast and complicated to be done by anything except large groups whose science can be realised only through code鈥�.

To my mind, though, the book is missing the most interesting story of all 鈥� the debate over the meaning of Sloan鈥檚 results. She notes that astronomers were surprised that Sloan didn鈥檛 turn up anything inconsistent with cosmology鈥檚 standard model, but there鈥檚 more to the story than that. The most intriguing debate over the SDSS is whether it shows a smooth, homogeneous universe, as the standard model predicts, or a hierarchical, fractal one, with ever-bigger structures as you look to ever larger scales.

The standard model predicts that the distribution of matter in the universe should smooth out at scales over 200 million light years, but some interpretations of the SDSS say it shows a fractal distribution that doesn鈥檛 smooth out even at more than 300 million light years, if at all. The question of whether the distribution of galaxies is fractal remains open. I wish Finkbeiner had skipped the committee meetings and funding proposals and got straight to the good stuff.