Even as the “supernova of a generation” came into view in backyards across the northern hemisphere last August, physicists and astronomers who had caught its earliest moments were developing a surprising and much clearer picture of what happens during a titanic Type Ia explosion. Now they have announced the closest, most detailed look ever at one of the universe’s brightest “standard candles,” the celestial mileposts that led to the discovery of dark energy.

Saul Perlmutter of Lawrence Berkeley National Laboratory’s Physics Division and the University of California at Berkeley has won the 2011 Nobel Prize in Physics for the discovery of the accelerating expansion of the universe through observations of distant supernovae. Perlmutter, a founder of the Supernova Cosmology Project at Berkeley Lab, shares the prize with Brian Schmidt and Adam Riess, members of the High-z Supernova Search Team who made the same discovery.

The Supernova Cosmology Project’s Union2 compilation and reanalysis of decades of the world’s best supernova surveys, with the addition of six high-redshift supernovae, puts new bounds on possible values for the nature of dark energy. Einstein’s cosmological constant comfortably fits the data, but there’s still plenty of room at the top for dynamical theories.

Members of the Nearby Supernova Factory based at Berkeley Lab discovered and analyzed a rare Type Ia supernova whose progenitor star had a mass some two and a half times that of our sun – much more mass than a Type Ia progenitor should be able to accumulate before it explodes. The data they gathered is the most complete ever for such an unusual beast; only one model really fits, the merger of two white dwarf stars.

A superbright supernova found in a dwarf galaxy by the Nearby Supernova Factory based at Berkeley Lab is the first confirmed example of a pair-instability supernova, the result of the partial core collapse and thermonuclear detonation of an enormously massive star, like the earliest stars in the Universe.

Three-quarters of the Universe is dark energy, but nobody knows what it is. Is it an unknown form of energy that fills space, or an illusion caused by extra dimensions of space? Or is it just a flaw in Einstein’s theory of gravity? Proven techniques for investigating these questions are being refined, while new techniques are beginning to be applied to one of the most pressing problems in 21st-century physics. Part 1 discusses supernovae as standard candles.

Finding rare and fleeting cosmic events not only requires the right kind of telescope and camera, it depends on high-performance computing that can pinpoint objects of interest among thousands of sky images while there’s still time for follow-up observations. Caltech and DOE’s NERSC join forces in just such a search, the Palomar Transient Factory.

Generations of Berkeley Lab nuclear scientists have contributed to FRIB, the Facility for Rare Isotope Beams, a $550 million heavy-ion accelerator to study rare nuclear processes that will be built at Michigan State University. Crucial components of FRIB are its ion source, based on the 88-Inch Cyclotron’s record-breaking VENUS, and GRETA, the gamma-ray detector designed and now under construction here. Nuclear Science Division Director James Symons participates in the launch of the new accelerator.

The Nearby Supernova Factory has discovered an efficient method for standardizing the intrinsic brightness and thus the distance to the cosmic milestones known as Type Ia supernovae. The discovery underlines the crucial importance of spectroscopy in the quest to understand dark energy.