The 31st Annual SLAC Summer Institute (SSI) will take on the very big (the universe) and the very small (sub-atomic particles) from July 28 to August 8.

SSI’s theme, Cosmic Connections, reflects the growing links between cosmology, astrophysics and particle physics—exemplified by the new Kavli Institute for Particle Astrophysics and Cosmology being built here at the Lab.

"I think it’s a spectacular opportunity for SLAC people. A lot of big names and talented people are coming here," said SSI Program Director John Jaros (EA). The other program directors are Charles Prescott (EA), JoAnne Hewett (Theory) and Tune Kamae (GLAST).

Everyone from advanced graduate students to Nobel laureates are welcome to participate in SSI, which aims to bring people up to speed on the basics as well as the latest experimental results, and to strengthen ties between the various physics fields being discussed. Afternoons are reserved for discussions and socializing to get participants actively involved.

"This program is an excellent doorway for people who would like to go into this new emerging area," said Kamae. "There will be time to get to know the important people and learn what training you need to go through."

Amazing discoveries in the last decade point to a universe far different than previously imagined or depicted in textbooks. "It’s a radical change of view. It’s getting even more Copernican – we keep getting smaller and less significant," Jaros said.

Particle physics appears close to discovering answers to some of the biggest questions in cosmology. Big machines meant to create and detect tiny particles will shine a light upon the entire universe.

One pressing question is: What makes up the universe? The building blocks of matter—sub-atomic particles discovered at SLAC and elsewhere—only account for some three to four percent of the entire universe’s mass-energy. Nearly 25 percent is attributed to dark matter—all the matter we can’t see or detect—and the rest is mysterious ‘dark energy.’

Particle physics supplies a leading candidate for dark matter, Supersymmetry, which might be found at the Large Hadron Collider—a collider under construction at CERN—or at the Next Linear Collider, currently under design by physicists worldwide. For every known particle, there is a supersymmetric cousin, similar to the way each matter particle is related to an antimatter particle. Supersymmetric particles feel the same forces as their counterparts, but their spins differ by one-half unit, and their masses are much greater.

Particle physicists "could create what the rest of the universe is made of for the first time on earth and know it and measure it," said Jaros.

SLAC is also searching in space for dark matter and dark energy. SLAC heads an international collaboration of particle physicists and astrophysicists designing GLAST, a gamma-ray telescope that will be launched into space in 2006.

Using detector technology similar to SLAC’s, GLAST will measure the extremely energetic gamma rays generated by massive black holes, supernovae and colliding galaxies which cannot themselves be directly measured. Scientists believe these extreme astronomical objects are some of the major players that determined the evolution of the universe from a homogeneous soup of matter (like chicken broth) to stars and galaxies (more like a chunky stew), according to Kamae.

There are other intriguing connections between particle physics and cosmology. The BABAR detector is looking for clues about why the universe ended up being virtually all matter and no antimatter. Recent data from supernovae show evidence for a ‘dark energy’ that pushes out everything in the universe faster than gravity pulls it together. The nature of dark energy is completely unknown, and therefore attracting a lot of experimental and theoretical attention. "This dark energy could point towards exciting discoveries in quantum gravity," said Hewett.

SSI attendance "appears to be greater than in recent years because there is a broad interest in the topic," said organizer Eileen Brennan.

Everyone at SLAC is welcome to come to the reception on Monday, July 28 at 6 p.m. outside the Research Office Building, and to the dinners on July 29, August 4 and August 7 outside the Auditorium. "Great food and entertainment will be provided, so bring the whole family," Brennan said. Dinner tickets are $7 or $4 for students and children, and will be sold in the Auditorium Breezeway.

To register for the SLAC Summer Institute, see: http://www-conf.slac.stanford.edu/ssi/2003.