Saul Perlmutter, Brian Schmidt and their respective teams received the Gruber Cosmology Prize last Friday at the University of Cambridge. Doubtless the awards will keep coming, for these are the researchers who discovered, more or less simultaneously, that the expansion of the universe was accelerating. That, in turn, gives us a look at the far future, suggesting that the universe will expand faster and faster forever.

It hasn’t even been a decade since the discovery was announced, but now we routinely discuss a dark energy force that seems to account for three-quarters of the density of our universe, a dazzling notion that recapitulates Einstein’s cosmological constant and humbles us with the thought that, between dark energy and dark matter, we see only four percent of what is actually out there. Needless to say, interstellar theorists note with interest the idea of an effect that seems to oppose gravity itself. If such things exist, will we one day make enough sense of them to learn how to engineer their effects?

Perlmutter (UC Berkeley) continues his work on dark energy with SNAP, the SuperNova/Acceleration Probe, designed to record the distance and redshift of some 2,000 Type Ia supernovae a year. The space-based observatory will carry a two-meter telescope by way of generating high resolution sky maps. Schmidt (Australian National University), meanwhile, works on a mapping project of his own. SkyMapper is a surveying telescope aimed at producing a digital map of the southern sky that will look at everything from nearby asteroids to distant galaxies.

Image: A cutaway illustration of SNAP showing some of the interior optics. Credit: Lawrence Berkeley National Laboratory

Interestingly, SNAP will function not only by studying supernovae but also by employing weak gravitational lensing. Here’s co-principal investigator Michael Levi (Lawrence Berkeley National Laboratory) on the matter:

“Weak gravitational lensing has been part of the SNAP concept since its beginning in 1999. SNAP will make a high-resolution map of the sky covering an area 2,000,000 times larger than the Hubble Deep Field. This map will be sensitive to the minute distortions of distant galaxy shapes when their light passes through uneven distributions of matter — a phenomenon called ‘weak lensing.’ Weak lensing promises a powerful way to measure the distribution of dark matter and to probe dark energy’s effect on the growth structure of the universe. The huge survey map will also provide astronomers with an unparalleled wealth of high-resolution images never before seen.”

SNAP is one of three competing proposals in the Joint Dark Energy Mission (JDEM) program — all are profiled on the JDEM site. With the recent news that the National Research Council has chosen JDEM as the first of NASA’s Beyond Einstein cosmology missions to be launched, NASA and the Department of Energy will have to choose between the rival projects. Beyond Einstein has a broad charter, but dark energy, as one of the outstanding problems in all of physics, has captured more and more interest from researchers worldwide. Clearly, the need to account for something this elemental, this ubiquitous, drives the sense of urgency.